ALBERT

Notes: Abstract. The soil sequestration components of recent estimates of the carbon mitigation potential of UK agricultural land were calculated on the basis of a percentage change to the soil carbon stock present in the soil. Recent data suggest that the carbon stock of soil in UK arable land has been overestimated, meaning that potential soil carbon sequestration rates were also overestimated. Here, we present a new estimate of the carbon stock in UK arable land, and present revised estimates for the carbon mitigation potential of UK agricultural land. The stock of soil organic carbon in UK arable land (0–30 cm) is estimated to be 562 Tg, about half of the previous estimate. Consequently, the soil carbon sequestration component of each mitigation option is reduced by about half of previously published values. Since above-ground carbon accumulation and fossil fuel carbon savings remain unchanged by these new soil carbon data, options with a significant non-soil carbon mitigation component are reduced by less than those resulting from soil carbon sequestration alone. The best single mitigation option (bioenergy crop production on surplus arable land) accounts for 3.5 Tg C yr−1, (2.2% of the UK's 1990 CO2-carbon emissions), whilst an optimal combined land-use mitigation option accounts for 6.1 Tg C yr−1 (3.9% of the UK's 1990 CO2-carbon emissions). These revised figures suggest that through manipulation of arable land, the UK could, at best, meet 49% of its contribution to the EU's overall Kyoto CO2-carbon emission reduction target (8% of 1990 emissions), and 31% of the greater target accepted by the UK (12.5%). Even these reduced estimates show a significant carbon mitigation potential for UK arable land.

Notes: Abstract. Nitrogen losses via nitrate leaching, ammonia volatilization and nitrous oxide emissions were measured from contrasting outdoor pig farming systems in a two year field study. Four 1-ha paddocks representing three outdoor pig management systems and an arable control were established on a sandy loam soil in Berkshire, UK. The pig management systems represented: (i) current commercial practice (CCP) - 25 dry sows ha−1 on arable stubble; (ii) ‘improved’ management practice (IMP) - 18 dry sows ha−1 on stubble undersown with grass, and (iii) ‘best’ management practice (BMP) 12 dry sows ha−1 on established grass. Nitrogen (N) inputs in the feed were measured and N offtakes in the pig meat estimated to calculate a nitrogen balance for each system. In the first winter, mean nitrate-N concentrations in drainage water from the CCP, IMP, BMP and arable paddocks were 28, 25, 8 and 10 mg NO3 l−1, respectively. On the BMP system, leaching losses were limited by the grass cover, but this was destroyed by the pigs before the start of the second drainage season. In the second winter, mean concentrations increased to 111, 106 and 105 mg NO3-N l−1 from the CCP, IMP and BMP systems, respectively, compared to only 32 mg NO3-N l−1 on the arable paddock. Ammonia (NH3) volatilization measurements indicated that losses from outdoor dry sows were in the region of 11 g NH3-N sow−1 day−1. Urine patches were identified as the major source of nitrous oxide (N2O) emissions, with N2O-N losses estimated at less than 1% of the total N excreted. The nitrogen balance calculations indicated that N inputs to all the outdoor pig systems greatly exceeded N offtakes plus N losses, with estimated N surpluses on the CCP, IMP and BMP systems after 2 years of stocking at 576, 398 and 264 kg N ha−1, respectively, compared with 27 kg N ha−1 on the arable control. These large N surpluses are likely to exacerbate nitrate leaching losses in following seasons and make a contribution to the N requirement of future crops.

Notes: Book reviewed in this articles: Cycles of Soils - Carbon, Nitrogen, Phosphorus, Sulfur, Micronutrients. By F.J. Stevenson & M.A. Cole.

Notes: Abstract. A large soil block was constructed to determine the importance of preferential flow routes compared with matric flow pathways at a pasture site in mid-Devon. The sandy loam soil was well structured and uniform. The soil block measured 5 m×3 m×1 m and was instrumented with an array of 54 tensiometers, TDR wave guides and suction samplers connected to an in situ chloride analysis system. Four steady state irrigation experiments were conducted with a range of rainfall intensities. During each experiment chloride and nitrate tracers were applied and the patterns of movement were observed. Although the application of tracer was uniform and the soil was relatively homogeneous, there was large variability across the block in terms of time taken to reach the peak concentration (TPC) and the peak concentration itself. About 44 samplers operated at the greatest intensities (10–2 mm h−1) and only 35 at the smallest (1 mm h−1). No relationship was found between TPC and depth. The fastest TPC and largest concentrations were associated with the greatest rainfall intensities. Relative importance of the individual water pathways was a function of soil heterogeneity: parts of the soil block were highly active with several pathways having short TPCs and conductivities in excess of 4 m day−1 whereas other areas had longer TPCs and conductivities of 1–2 m day−1. The pattern was also dynamic, with conductivities of the pathways changing through time, though most of the faster pathways maintained their greater conductivities for more than one year.

Notes: Abstract. There is a need to develop sustainable nitrogen (N) management systems that minimize environmental losses by maximizing the use efficiency of applied fertilizers, particularly with wide-row annual crops that are often poor at utilizing N. A key approach is to match nitrogen supply with crop demand using improved methods of fertilizer application and timing. One technique is to target liquid ‘starter’ fertilizers close to the seed, or around the roots of transplants, and to omit or reduce conventional broadcast applications. This paper examines the effects of starter fertilizer combined with various rates of seedbed and/or top-dressed N on the growth and yield of bulb onion (Allium cepa L.), crisp lettuce (Lactuca sativa L.), forage maize (Zea mays Bonaf.) and sugarbeet (Beta vulgaris L.). Starter fertilizer improved early growth and, in combination with reduced rates of supplementary N, gave yields comparable with higher rates of base N with each crop, except sugarbeet. The use of top-dressed N was as effective as base N in supplementing starter fertilizer and had the benefit that it allowed a top-dressing requirement to be estimated accurately using a simple nitrogen balance equation. These results, taken with earlier work, show that starter fertilizers offer clear opportunities for reducing N inputs, while maintaining yield and quality of these crops.

Notes: Abstract. This paper describes the results of laboratory-based research which investigated the losses of the herbicide, isoproturon, and a non-adsorbing solute, bromide, from topsoil aggregates under high (7 mm h−1 and low 2.7 mm h−1) intensity simulated rainfall. The structures of the micro- and macro-aggregates from a clay soil of the Denchworth Series (from Wytham, Oxfordshire, UK) were observed using a scanning electron microscope, and the slaking of the topsoil aggregates was also investigated in order to provide a context for interpreting the experimental results. The topsoil at Wytham was found to have a bimodal structure with small microaggregates of 0.71 to 1 mm diameter clustered together to form larger macroaggregates of up to several centimetres diameter. Selected aggregates were air dried and then repacked in Buchner funnels to several centimetres depth in order to remove variability in the experimental results due to the effects of surface microrelief. Under saturated surface conditions high intensity simulated rainfall was less efficient at removing both non-adsorbing and adsorbing solutes from the repacked topsoil aggregates than low intensity rainfall. The observed decrease in the concentration of isoproturon and bromide in the leachate with time could be explained by a transport non-equilibrium effect.

Notes: Abstract. There is increasing evidence that phosphorus has been accumulating in the surface horizons of agricultural soils to the extent that some soils represent a potential diffuse source of pollution to surface waters. The relationships between equilibrium phosphorus concentration at zero sorption (EPC 0) of soil and a number of soil physicochemical variables were investigated in the surface layers of arable and grassland agricultural soils sampled from the Thame catchment, England. Soil EPC0 could be predicted from an equation including soil test (Olsen) P, soil phosphate sorption index (PSI) and organic matter content (OM) (R2=0.88; P〈0.001) across a range of soil types and land use. The simple index Olsen P/PSI was found to be a good predictor of EPC0 (R2=0.77; P〈0.001) and readily desorbable (0.02 m KCl extractable) P (R2=0.73; P〈0.001) across a range of soil types under arable having soil organic matter contents of 〈10%.

Notes: Abstract. Emissions of N2O were measured from different agricultural systems in SE Scotland. N2O emissions increased temporarily after fertilization of arable crops, cultivation of bare soil, ploughing up of grassland and incorporation of arable and horticultural crop residues, but the effect was short-lived. Most of the emission occurred during the first two weeks, returning to ‘background’ levels after 30–40 days. The highest flux was from N-rich lettuce residues, 1100 g N2O-N ha−1 being emitted over the first 14 days after incorporation by rotary tillage. The magnitude and pattern of emissions was strongly influenced by rainfall, soil mineral N, cultivation technique and C∶N ratio of the residue. Comparatively large emissions were measured after incorporation of material with low C∶N ratios. Management practices are recommended that would increase N-use efficiency and reduce N2O emissions from agricultural soils.

Notes: Book reviewed in this articles: Nutrient Disequilibria in Agroecosystems Edited by E.M. Smaling, O. Oenema & L.A. Fresco

Notes: Abstract. The effects of pig slurry applications to a hydrologically isolated field treatment plant (at Solepur) were studied over a period of eight years. Thirty repeated doses, averaging 160 m3 ha−1 were applied from April to October of each year (1991–1995), to reach a total application of 4930 m3 ha−1. All slurry samples were analysed for their total solids (TS), macronutrient (C, N, P, K, Ca) and micronutrient (Cu, Zn) content. In total, 284 tonnes of total solids (57 t TS ha−1 yr−1), 115 tonnes of carbon (23 t C ha−1yr−1), 24.5 tonnes of nitrogen (4900 kg N ha−1 yr−1), 7964 kg of phosphorus (1593 kg P ha−1 yr−1), 16 518 kg of potassium (3304 kg K ha−1 yr−1), 183 kg copper (37 kg Cu ha−1 yr−1) and 266 kg zinc (53 kg Zn ha−1 yr−1) were applied to the soil. Thus, this site provides an opportunity to assess the balance and to examine the long-term behaviour of nutrients under conditions of intensive land application of pig slurries or similar effluents.The main nutrient fluxes through the soil-water system were determined for each element. Over 40% of the total carbon applied was retained by the soil. About 25% of the slurry nitrogen applied remained in the soil profile and 12.5% was leached through the drainage water as nitrate. Most of the slurry phosphorus applied was retained in the soil profile either as P-Dyer extractable (83%), or as total soil phosphorus (112%); 〈0.01% was found in the drainage water. Forty-three per cent of the potassium applied in the slurry was recovered from the soil profile and 15% was recovered in the drainage water. Most of the copper (62%) and zinc (74%) applied in the slurry remained in the soil as EDTA extractractable forms; very low percentages (0.05% and 0.6% respectively) were found in the drainage water.

Notes: Abstract. Volcanic ash soils are generally recognized as soils with excellent and stable physical properties. Here we characterized the porosity and water properties of volcanic ash Andosols and Nitisols from Guadeloupe in contrasting banana systems: (1) perennial crop without mechanization, (2) mechanized and regularly replanted crop. Desiccation from 1 kPa to 1550 kPa moisture tension leads to significant shrinkage in the Andosol, representing a 50% reduction of the void space. The clayey Nitisol exhibited limited shrinkage. Soil clods from the mechanized plots had a significantly smaller macroporosity than that from perennial plots. The soil hydraulic conductivity was also drastically reduced in the compacted layers of the mechanized plots. However, Nitisols appeared to be less affected than Andosols. Laboratory compression tests showed that both soils were susceptible to compaction at soil moisture close to field capacity. The shrinkage properties of the Andosol were due to microaggregation of non-crystalline components upon drying. The relative stability of the macroporosity in the Nitisol was probably related to the presence of stable microaggregates made of halloysite and iron oxide. Two major processes promote soil structure degradation in the Andosol under mechanized banana cropping, surface desiccation and soil compaction. They are both induced by repeated tillage after clearing.

Notes: Abstract. This paper describes a soil classification system developed for agronomists in Cambodia that has proved useful in improving soil fertility management. The classification system relies on soil characteristics that are easily identifiable in the field and have agronomic relevance. The system was used in the on-farm trial programme of the Cambodia-IRRI-Australia Project (CIAP) in 1996 and 1997 to determine whether it could adequately discriminate between soil types and improve fertility management.  Using diagnostic criteria that could be identified in the field, 11 soil groups were defined and subdivided into a further 20 phases. Soil groups were defined as units of morphologically similar soils, which occurred at the same position in the landscape. Classification of soil phases within a soil group was primarily based on soil properties that had significance for crop production, this included information gained from local experience and expertise. A modified version of the Fertility Capability Classification (Sanchez et al., 1982) was added as a third level to allow a more quantitative classification in cases where soil analytical data was available, and to facilitate the transfer of agronomically important soil information from outside Cambodia.  The soil groups adequately predicted differences in grain yields of rice grown on the different soils in on-farm trials and provided the basis for soil-specific management recommendations. Local agronomists have welcomed the system and have incorporated it into their research and extension operations.

Notes: Book reviewed in this articles: Impact of land-use change on nutrient loads fromdiffuse sources. Edited by Louise Heathwaite

Notes: Abstract. A novel agronomic system of soil classification for managing rice soils in Cambodia (CASC) was developed recently. It integrates local knowledge about the soil with its conceptual and taxonomic understanding by soil scientists. Using quantitative soil survey data we evaluated the agronomic efficacy of the classification system. Although the CASC is based on simple field criteria it explained 25 to 44% of the variation in soil prop-erties relevant for agronomic decision making. It failed, however, to differentiate soil types based on pH (6% of variances explained). Despite its simplicity it performed as well or better than the most widely used soil map in Cambodia (Crocker, 1962), and unlike this small-scale soil map it allows classification on a field-specific basis. The average values of soil properties were often significantly different between groups. Organic carbon, clay content and plant available magnesium and calcium contributed most to the discrimination of CASC soil groups. The predictive accuracy when allocating new samples on the basis of quantitative survey data to soil groups of the CASC was 50% to 100%, except for soil groups Kein Svay (0%) and Kampong Siem (20%). The CASC is valuable for managing Cambodian rice soils and may also be used for up-scaling and mapping of soil information.

Notes: Abstract. Broadcast granular fertilizers are inefficient at supplying nitrogen (N) to wide-spaced row crops. Substantial nitrate residues can remain in the soil post-harvest, even when recommended fertilizer practices are followed. This paper explores the benefits of an alternative strategy based on targeting small amounts of liquid nitrogen starter fertilizer close to the seed at drilling to increase N use efficiency and reduce potential pollution. Bulb onion (Allium cepa) and crisp lettuce (Lactuca sativa) were grown with various rates and combinations of ammonium phosphate (AP) and urea ammonium nitrate (UAN) as ‘starters’, in comparison with seedbed incorporated ammonium nitrate. AP consistently improved early growth and final yield of both crops compared to broadcast ammonium nitrate, but UAN showed no additional benefits. AP in combination with broadcast N, or injected UAN, generally increased N recovery, and produced yields of marketable quality produce matched only by much higher rates of broadcast N. A reduced N input system based on starter fertilizers is likely to be acceptable to the industry, but would rely on a method to predict how much N is required to supplement that provided by the starter.

Notes: Abstract. Daily measurements of precipitation and temperature at 82 locations in Denmark for periods of 10 to 43 years, were used for calculation of the impact energy and intensity of rain, climatic erosivity (hereafter called erosivity). The computed erosivity values were analysed for trends and variations in time and space. Analysis of 43 years of data from 6 locations showed a change in the annual distribution of intense (erosive) precipitation, with a tendency to bi-modality, increasing erosivity in September, and decreasing erosivity in August. Amounts of precipitation in autumn have generally increased, but the erosive power of rain has increased even more. The geographic location of high erosivity varied considerably from year to year. Using a simple crop model, the interaction between crop cover and erosivity was investigated. This suggested that changes in climate in combination with changes in cropping and management practice have increased risk of serious erosion over the period 1954 to 1996. We recommend that present and future cropping and management practices be evaluated for risk of adverse interaction with high erosivity events.

Notes: Abstract. Arable crops in the UK make a large contribution to nitrate leaching by virtue of the land area they cover (〉4.5 million ha). By contrast horticultural crops occupy only a small area (〈 0.2 million ha) but can leach very large amounts of nitrogen. The application of nitrogen fertilizer to arable and horticultural crops is very cost-effective, stimulating its use. MAFF's Nitrate Research Programme for arable and horticultural crops aims to reduce nitrate leaching and maintain productive farming through Best Management Practice. The Programme has led to the development and testing of methods to measure nitrate leaching, the identification of ‘leaky’ crops, soils and practices, and strategies to optimize the use of fertilizer nitrogen. Data have been used to construct and test models of nitrate leaching, which in turn have been used to evaluate the leakiness of potential rotations. Current best practice to minimize nitrate leaching requires measures to improve the efficiency of nitrogen use by crops, combined with measures to protect soil nitrogen from leaching during the late autumn to spring drainage period. This involves consideration of many factors: an appropriate crop variety must be chosen; a green cover must be maintained for as much of the year as is practicable; crops should be drilled early; fertilizer requirements should be calculated using a recommendation system and allowing for soil mineral nitrogen and any manures applied; fertilizers should be spread evenly with a properly calibrated spreader, perhaps using split applications; starter fertilizers and banding of fertilizers should be used where appropriate to reduce losses from vegetables; pest and disease infestation must be minimized; any irrigation must be applied carefully with scheduling. Research is now moving on to study whole farm systems and the interactions between losses of nitrogen and other pollutants to the environment with the aim of minimizing total environmental impact.

Notes: Abstract. A national agri-environmental database and nitrate modelling system has been developed to support the UK government's nitrate policy development. The framework, ‘MAGPIE’, consists of a database and models linked within a Geographical Information System and provides a user interface which allows detailed spatial and statistical investigation of the current state (data and model output) and the impact of changes in conditions or agricultural practice. Data on crops and livestock numbers taken from the annual agricultural census were modified in relation to land cover data derived from remote sensing, and other sources. These data and data on climate, soils and altitude were interpolated to a 1 km grid. The models of nitrate loss were adapted to work with this data set while retaining as far as possible the salient features of the more detailed models and data from which they were derived. The resulting Policy Decision Support System was found to give estimates of mean annual flow and nitrate load for agricultural catchments which matched measured data closely. The system has contributed to work on a number of policy issues both within the UK and in the UK's contribution to international policy development on pollution derived from agriculture.

Notes: Book reviewed in this articles: SOILpak for dryland farmers on the red soil of Central Western NSW 1999. Edited by A.N. Anderson, D.C. McKenzie & J.J. Friend.

Notes: Abstract. A methodology is presented that explores soil survey information at the national level (1:1 M), generating sustainability indicators for wheat cultivation in Uruguay. Potential yields were calculated for simplified crop production situations under several constraints, such as limitation of water availability calculated from soil physical properties and climatic conditions, and limitation of nutrient availability calculated from soil fertility and climatic conditions. Land quality sufficiency was examined by comparing these yields with the constraint-free yield conditioned only by solar radiation, temperature and the crop's photosynthetic properties. Crop growth was simulated only for areas suitable for the defined agricultural use. Model runs were repeated with inclusion of a topsoil loss scenario over 20 years as defined from an erosion risk analysis. Comparison between crop growth simulations for the two situations, gives an indication of the changes in land quality status, which supplies an indicator for agroecological sustainability.On the basis of crop growth simulation it is concluded that wheat production constraints in Uruguay appear to be mainly related to water availability limitations, while nutrient availability is near optimal for the suitable soils. The simulated loss of topsoil impacts most on soil physical properties, expressed in reduced water-limited yields. Soil fertility status, evaluated by change in nutrient-limited yields, was little affected by the scenario.

Notes: Book reviewed in this articles: The Carbon Cycle. Edited by T.M.L. Wigley & D.S. Schimel

Notes: Abstract. After six years of bush-fallow, residual effects on soil productivity of tillage practices prior to the fallow were investigated on an Alfisol in south western Nigeria. In 1996 fallow was followed by maize intercropped with cover crops of Pueraria phaseoloides, Mucuna pruriens or cowpea (Vigna unguiculata) and no intercrop. Parameters measured included soil properties, ground cover, crop growth and yield, rainfall erosivity, runoff and soil loss.In spite of six-years of bush-fallow and establishment of cover crops, soil erosion was significantly greater on plots that had been conventionally cultivated previously using disc ploughs, harrows and mechanical rotovators (1.78 t ha−1season−1) compared to previously no-till plots (1.34 t ha−1season−1). Crop growth and yields were least and soil loss greatest (2.83 t ha−1season−1) on the previous bare plot.Maize grain yield was highest using Pueraria phaseoloides as an intercrop (2.15 t ha−1) followed by a cowpea intercrop (1.92 t ha−1), maize without intercrop (1.87 t ha−1) and Mucuna pruriens intercrop (1.71 t ha−1). The maize grain yields reflected levels of competition from the cover crops. Cowpea–maize intercrop may be most suitable for farmers because maize yields were satisfactory and cowpea grain serves as additional subsistence. Cowpea yields were 390 kg ha−1. Soil erosion was also moderate using cowpea as an intercrop (1.71 t ha−1season−1). However, Pueraria phaseoloides gave the best erosion control with a soil loss of 1.34 t ha−1season−1.

Notes: Abstract. Composted domestic waste was applied either as a mulch or was incorporated into the topsoil. Mulching reduced the seasonal midday soil temperature ranges from between 14 °C and 27.5 °C to between 14 °C and 26 °C, averaging a 0.6 °C fall. However, at sub-optimal temperatures for maize production under the temperate conditions of South East England, the difference may be critical. Compost mulch also improved soil-water conservation in an average year, but not in a very dry year. Compost application increased soil-available N, but increased K uptake was considered to be more important for crop yield than either N additions or the effect on retained soil water. Overall, compost applied as a surface mulch, or incorporated into medium-textured soils in the south and east of England increased crop yield.

Notes: Abstract. A five year field experiment was conducted to assess the influence of crop rotation and field pea residue incorporation into the soil on maize yield. The data indicated a 30% increase in maize yield grown in rotation with field pea compared to when it was grown after wheat and a further increase of 35% when field pea residues were incorporated into the soil. The effect of field pea and residue incorporation was greater in the presence of fertilizer nitrogen indicating the enhanced capacity of the crop to utilize N from the residue. Legume residue management in sub-tropical regions of the world, having coarse textured soils low in organic matter, could help to increase the yield of cereals besides saving some of the expensive fertilizer input.

Notes: Abstract. Land requirements for Pinus halepensis Mill. growth were studied in thirty plots of a 40 year-old plantation in the semiarid Lower Ebro valley, northeast Spain, by comparing site index values to land characteristics. Site index at 40 years ranges from 4.1 m to 12.3 m. Moisture availability is the basic requirement for growth while nutrient availability has only a minor influence. Changes in moisture availability in the area are controlled by changes in soil rootable depth, with a minor effect of aspect. Soils developed on Tertiary gypsum rock are not suitable for afforestation with this species. Geomorphic and soil information may be combined, at various degrees of detail, to provide reliable estimates of Aleppo pine growth.

Notes: Book reviewed in this articles: Urban soils—Applications and Practices. By P. J. Craul

Notes: Book reviewed in this articles: Managing Soil Fertility for Intensive Vegetable Production Systems in Asia By Morris, R. A. (ed.).

Notes: Abstract. Diffuse soluble reactive P (SRP) & total P (TP) loads from over 50 major river catchments in Northern Ireland were predicted using an export coefficient modelling approach. Phosphorus export coefficients for each CORINE land cover class, derived from satellite imagery, allowed the prediction of P loads from a breakdown of the CORINE land cover classes by catchment using a GIS. This approach was validated using observed P loads calculated from flow and concentration data. Mean measured Olsen-P concentrations in the soil A-horizon were also determined on a catchment basis. Plots of P loads to the watercourse versus Olsen-P concentrations in the soil showed a breakpoint around 22 mg Olsen- P l−1 for both SRP & TP data. Below Olsen-P concentrations of 22 mg l−1, SRP & TP losses were essentially independent of Olsen-P at 0.28 and 0.63 kg P ha−1 yr−1, respectively. Above Olsen-P concentrations of 22 mg l−1, there was considerable spread in the P loss data. Nevertheless, significant upward trends in SRP and TP losses to watercourses were detected with increasing Olsen-P at a rate of approximately 0.5 and 1.0 kg P ha−1 yr−1, for SRP and TP respectively, for each 10 mg l−1 increase in Olsen-P.

Notes: Abstract. The paper highlights the advantages of modelling to simulate dynamic processes and to couple environmental data more closely with effects on crops. The CERES-Maize crop model and the DSSAT software package were selected for the work and the region of the Triângulo Mineiro in the state of Minas Gerais was selected as the study area. The results showed that there are differences in the potential production of the Latosols of the Triângulo Mineiro and this should be taken into account when extrapolating or transferring technology for other regions within the same cerrado ecosystem of central-west Brazil. It is essential to improve the number of points with weather data collection since, as demonstrated for Frutal, the climate of the Triângulo can determine differences in potential agricultural production as well as risk for production. The study showed that the use of crop models can improve land suitability evaluations, for land use planning, or establishing strategies for rural funding.

Notes: Abstract. The catchment simulated comprises 57 hectares of heavy clay soil managed as six arable fields. Mole and pipe drains carry surplus water into two ditches, one feeding into the other. Their combined flow was passed through a flume with an automatic water sampler, samples from which were analysed for nitrate. Measurements of nitrate concentration made during periods of water flow from 1990 to 1993 were simulated using a model comprising sub-models for leaching, mineralization, nitrogen uptake by crops and subsoil denitrification. The simulations were plotted against the measurements. For statistical evaluation, the correlation coefficient was used to assess the degree of association between the measurements and the simulations and the mean difference to assess the agreement. The correlation between the simulations and the measurements was significant in two of the three seasons, but the mean difference was significant in all three. However, taking all three seasons together gave a very highly significant correlation and a non-significant mean difference.

Notes: This study critically evaluates alternative estimates of China's GDP level and growth, as well a s its PPP GDP conversions, and, based on this evaluation, it draws important implications for the understanding of China's economic performance in both historical and international perspectives. It finds that although almost all empirical results have supported the downward-bias hypothesis for China's GDP level and the upward-bias hypothesis for China's GDP growth, they vary greatly, and that PPP estimates for China are also diversified. These estimates, if accepted, may substantially alter the existing views on the Chinese economy, particularly, its size, TFP level and catch-up performance. The discussion focuses on the theories, methodologies and data used in these studies, and particularly, the possible biases in their results thereby. It argues, however, that despite differences in estimates, they could still provide sensible boundaries for researchers to gauge the “real” values and hence assess China's “real” living standard and growth performance.

Notes: In a number of underdeveloped countries today, adequate statistics for estimating national output by traditional national accounting methods are unavailable or unreliable. However, many of these same countries do publish data on monetary variables at an early stage in their development. These data can now be used to estimate national income.In this study the money supply was defined to include all currency in circulation, private deposits subject to check at all banks and postal systems, all government deposits, and unused overdrafts less float. The national accounts data were taken from United Nations sources and data supplied by various foreign statistical offices. To make the accounts more comparable in terms of coverage and to limit reported income to the monetized sector of the economy, non-monetary imputations were deleted.The monetary and national accounts data were combined in a multiple, stepwise regression. National income was used as the dependent variable and money supply and other data were used as the independent variables. The final estimating equations explained about 96 per cent of the variation in income between countries. Other tests were conducted using the currency ratio, transactions velocity, population, and per capita consumption. However, these variables did not augment the explanatory power of the regression equations.When the equations were used to estimate national income for twenty-two under-developed countries, the derived estimates showed a high degree of concordance with reported income where it existed for comparative purposes. The results indicate that monetary data can be used to estimate national income for underdeveloped countries with a relatively high degree of accuracy, between countries, and from year to year within a country.

Notes: In The Present Paper The Author Reviews The Results Of An Investigation Aimed At Estimating The relative level of stocks in Hungary in terms of international comparisons. Though international comparison was limited by scarcity of data, it has still become evident that stocks as a whole, compared to production and sales, seem to be unnecessarily high. The investigation has been carried out in relation both to the level of stocks and their rate of increase.The global volume and building of stocks, however, did not give a satisfactory explanation, and the investigation had to be extended to the individual groups of stocks separately. In order to facilitate the comparison, stocks were classified into the following groups: agricultural stocks, goods in process, industrial finished goods and manufactures held by users, and retail stocks. The classification was based on the different function of the individual groups. This classification of stocks could be compared only with the data of the U.S A.The international comparison revealed that both the volume and the rate of increase of stocks in Hungary is unreasonably high. They are high even if we consider that the growth rate of the economy in Hungary was greater than in any of the countries examined.The author refers to the fact that the stock problem was one of the starting issues in the economic research process which led to the reform of the Hungarian economic management system introduced on 1st January 1968.

Notes: The national income and product account (United Nations concept) in current prices itemized by distributive shares and by type of expenditure is given for the period 1929–1937. The national income by industrial origin and the reproducible national wealth are computed for the year 1930. Differences between the U.N. and the material concept are explained by means of the 1939 data.The national product series in real terms are computed (a) by means of the price deflation of the types of expenditure, and (b) as the physical output of goods and services by industrial origin (since 1926). Major changes In distributive shares are explained with the help of Price-cost analysis.The national product in real terms attains the lowest point in 1935 and not in 1933, as the industrial production and foreign trade series indicate. The structure of gross national expenditure reveals the same pattern of shifts, as is well known from other industrially developed countries during the business cycle.The development of national product by industrial origin, however, reveals some conspicuous singularities. Especially the uninterrupted increase in trade services (in terms of both persons engaged and turnover in constant prices) is an anomaly in the period of 1929–1937.Further, the Increase of rent (due to the gradual abolition of rent control), contrasting with the general fall of prices, led to a major shift in the distribution of national income during the early thirties. The other remarkable change resulting mainly from the changing price structure was the decrease of the farmers' share in national income.The production, transportation and distribution series in real terms reveal some time-lags. These result partly from the shift from the foreign to the home market, partly from the compensatory effects of stock movements, and partly from the delayed adjustment of consumers to declining income.

Notes: This paper presents a new annual series for United Kingdom gross national product, at current and constant prices, calculated from the expenditure side. These results differ significantly from previous estimates in that they go back to the beginning of the railway age on an annual basis and also in that the constant price estimates involve a detailed deflation of the main components of expenditure on consumption and capital formation. The implications of the new results are summarised, with particular reference to rates of growth and relative price changes, and an appendix describes the sources of the estimates.

Notes: Study of relationships between outputs, inputs, prices, and final demands in the United States can be strengthened by: (1) eliminating disparities in official measures of output (mainly the Index of Industrial Production and Real Gross National Product), and (2) obtaining agreement on the conceptual framework for studying these relationships.Real Gross Product has provided a consistent framework for study of productivity and prices for the total economy and for broad industry groups, but has not easily permitted the analysis of commodity detail particularly for intermediate commodities. Industrial Production, on the other hand, has considerably extended the detailed analysis of commodity output but has not provided a basis for systematic analysis of productivity and prices within a consistent framework for the total economy.This paper illustrates the effect of some of the disparities between Industrial Production and Gross Product in manufacturing on the analysis of relations between prices and output and prices and productivity. This is done for the 1954–1958 period when benchmark data are available for both measures. Inconsistencies for a number of industries cause difficulties in analyzing the interplay of demand and cost influences on price changes; for example, industries which rise above average in output and below in price in one measure are not the same as those in similar price-quantity relationships in the other measure.The paper concludes by recommending improvements in data and concept in order to eliminate some of the disparities and to enable analysts to reap the benefits of both types of measures of real output.

Notes: Because of the recent public concern over the brain drain, this study attempts to measure the U.S. gain of highly skilled manpower. The paper discusses the serious short-comings of the data on gross immigration of scientists and engineers provided by the U.S. immigration authorities as a measure of true U.S. gains. In a case study of Swedish scientists and engineers it was found, for example, that whereas the U.S. data showed a gain of 106 Swedish scientists and engineers over a number of years, the net figure was only 26 after adjustment for remigration and the application of the proper OECD education criteria.The paper then reports the findings of a statistical study which uses the stock data on U.S. scientists in the National Register of Scientific and Technical Personnel to estimate the number of foreign born in this stock and analyse their characteristics with respect to age, educational attainment, and employment preferences.It was found that nearly 7 percent of all U.S. scientists are of foreign origin (foreign born and foreign secondary education), whereas 11.5 percent of all scientists with a Ph.D. are of foreign origin. The percentage among Ph.D. holders is highest in meteorology (22.3), followed by linguistics (18.7), physics (17.1) and statistics (14.6).The greatest percentage of scientists comes from Canada (10.4 per thousand), followed by Germany (8.3 per thousand) and the United Kingdom (6.7 per thousand). However, after adjustment of these data for the different sizes of the total foreign born population from each country in the U.S., it turns out that by this measure the greatest shares of scientists are supplied by the Japanese, followed by the Austrian-Swiss, Benelux and Canadians.The analysis of the age composition of all foreign born reveals that in the age groups that were 20–29, 45–54, and 65 and over in 1964 foreigners represent a smaller than average share, probably reflecting war casualties and education completed at a later age. Germans and Austrians are heavily concentrated in the group 55–64 years old in 1964, suggesting that a great share of scientists from these countries may have been victims of a brain push.

Notes: This review article initially summarizes some of the highlights of the volume Why Growth Rates Differ, including the use of income shares as weights for the various factor inputs and some of the major factual conclusions drawn from the inter-country comparisons. Some of the main factors in differences in income levels and differences in growth rates are then reviewed.In appraising the contribution of the volume, the monumental task is emphasized. This study illustrates the adaptability of the approach which Denison developed initially in The Sources of Economic Growth. The volume meets many of the questions and criticisms raised of his earlier study, and should encourage a shift of the discussion from methodology towards the substance of the empirical results.The volume introduces some shifts in emphasis on the importance of different factors in growth. The role of demand variations and the contribution of capital is considered, but the evidence in the volume gives less emphasis on the importance of these factors than earlier work by others in both the United States and Europe. The volume gives some emphasis to shifts out of agriculture and the self-employed in the high postwar growth in many individual European countries. It considers the effects of reductions in trade barriers, and follows the view of most economists in playing this down. Advances in knowledge are also considered.Those who are interested in questions of economic growth, past and future, and economic policy in this area will find much in this volume for study and reflection.

Notes: This study assesses the relationship of education and economic growth, economic development and economic progress in aggregate, in structural and in micro-economic terms on the basis of one hundred years of Canadian experience. Education is considered as a factor of input. The contribution made by knowledge resulting from additional education expands the capacity to produce, and increases the demand for goods and services and the desire for greater leisure. The dual function of education is stressed: the demand and supply effect. Education is examined both as a cause and a consequence of economic growth, economic development and economic progress, through its contribution to the quality of the labour force, earning capacity, both individual and national, productivity, the rate of economic growth and the character of economic development.The Canadian experience suggests that educational progress generally occurred in line with economic development during the first eight decades, with the real take-off in educational advancement only occurring in the last two decades, when the nation reached the stage of technological maturity and high mass-consumption. Among the reasons for the lower ratio of gross national product devoted to education in the first eight decades were the low priority attached to education, the emphasis on investment in physical capital because of its shorter pay-off period than investment in human capital, and the heavy reliance on a substantial flow of immigrants who had obtained their education and training abroad. A distinct change occurred, however, in the last two decades, partly as a result of new technological challenges and partly as the result of changes in private and public attitudes, as the recognition of the rewards of education in terms of individual advancement and social progress led to a greater willingness to devote an increasing proportion of the nation's resources to investment in human capital, long pay-off periods notwithstanding.

Notes: Human capital concepts and measures have been applied and misapplied to an increasing variety of economic problem areas, two of which are examined.One of these is measurement of human capital gains and losses through migration. First requirements here are specification of the gaining or losing entities and of the relevant welfare functions. Alternatives in these respects are outlined. It is then argued that an appropriately adapted Fisherian present-value assessment of human capital is normally the correct measure. Replacement costs are a legitimate substitute only for young migrants with little cumulated learning through experience and even then they have usually been fallaciously applied. Probability adjustments for migration and re-migration are required in both cost and present-value assessments of human capital effects of migration-relevant policy alternatives, but the nature of those adjustments differs with the measurement approach used.For longitudinal analysis of contributions of human capital to economic growth, all measures of human capital stocks are inappropriate. A first principle of such analysis is measurement of resource inputs as flows. A coordinate principle requires that disaggregation be carried as far as necessary to distinguish essentially homogeneous categories of labor inputs. Though a way of separating out the schooling versus on-the-job-experience components of human capital is illustrated, it requires some strong assumptions. Splitting men into abstracted human capital components is better avoided in growth analysis. Furthermore, categorization of labor-force sub-groups could equally well provide the basis for rate-of-return assessments of marginal changes in the pace of investments in humans. Such assessments would incorporate the main elements of capital theory except valuation of the capital asset itself.Ultimately, human resource measurements for use in major public policy decisions relating to either growth or migration (or both) must incorporate modifications or error components that allow for development phenomena that elude marginal assessments. Among developing countries especially, a consideration of educational diffusion processes and dynamic productivity scale effects, for example, could have critical measurement and policy implications.

Notes: This article discusses the revival of interest in research on cyclical behavior in the socialist countries, and the resulting shifting requirements placed upon the national income accounts. The first section discusses the economic experience and the institutional factors leading to this shift in emphasis. The second section deals with the use of national accounts in cyclical analysis, with particular reference to the Czechoslovak experience. The third section extends the discussion to the use of national accounts data for economic forecasting. The final section discusses the theory of economic fluctuations under socialism, and compares it with cyclical behavior in capitalist economies.

Notes: The system of social accounts described in this article is based on the following five principles:(1) Producers of goods and services are working organizations which represent groups of people or individuals organized for the purpose of earning a living by producing goods and services that satisfy individual or collective needs. Business, government, profit and nonprofit, corporate and unincorporated working organizations are treated in a uniform way.(2) Since the behaviors of the market and non-market sectors differ considerably, these two sectors are consistently separated throughout the accounting system.(3) There are four basic activities: (a) production, (b) consumption, (c) investment, and (d) income redistribution. These call for four separate accounts: (a) Working Organizations, (b) Households, (c) Community, including government and certain non-government institutions, and (d) Accumulation. The fifth account, Rest of the World, serves for balancing purposes.(4) The same classifications of transactions are used for activities and institutions, making possible complete matching of social product and financial flows accounts.(5) The system strives to achieve the maximum analytical flexibility. Some of its possibilities are visible from the classification of industries: A. Market (Material) Sector: 1. Agriculture, II. Forestry, III. Mining and Manufacturing, IV. Construction, V. Transportation, VI. Trade and Catering, VII. Handicrafts; B. Non-Market (Non-Material) Sector: VIII. Housing and Communal Economy, IX. Education, Culture, and Social Welfare, X. Public Services Social Organizations (Political, Religious, etc.), Finance and Insurance, Public Administration and Judiciary, National Defence. Sector A corresponds to the material definition of social product. Sectors A + B correspond to the SNA definition. Sectors A + B minus Industry × reflects the welfare definition. Further, Industries I-IV produce goods, V-VII market services, VIII and IX non-market services with welfare content, X intermediate nonmarket services, V-X all services.

Notes: The widespread use of common depth point techniques has emphasized the need for accurate static corrections. Manual interpretation methods can give excellent results, but a computer technique is desirable because of the great volumn of data recorded in common depth point shooting. The redundancy inherent in common depth point data may be used to compute a statistical estimate of the static corrections. The corrections are assumed to be time-invarient, surface-consistent, and independent of frequency. Surface consistency implies that all traces from a particular shot will receive the same shot static correction and all traces from a particular receiver position will receive the same receiver correction.Time shifts are computed for all input traces using crosscorrelation functions between common depth point traces. The time shift for each trace is composed of a shot static, a receiver static, residual normal moveout if present, and noise. Estimates of the shot and receiver static corrections are obtained by averaging different sets of the measured time shifts. Time shifts which are greatly in error are detected and removed from the computations.The method is useful for data which has a moderate to good signal to noise ratio. Residual normal moveout should be corrected before estimating the statics. The program estimates the statics for correctly stacking common depth point traces but it is not sensitive to constant or very slowly changing static errors.

Notes: It was found in Part I of this paper that approximating the sharp cut-off frequency characteristic best in a mean square sense by an impulse response of finite length M produced a characteristic whose slope on a linear frequency scale was proportional to the length of impulse response, but whose maximum overshoot of ±9% was independent of this length (Gibbs' phenomenon). Weighting functions, based on frequency tapering or arbitrarily chosen, were used in Part II to modify the truncated impulse response of the sharp cut-off frequency characteristic, and thereby obtain a trade-off between the value of maximum overshoot and the sharpness of the resulting characteristic. These weighting functions, known as apodising functions, were dependent on the time-bandwidth product Mξ, where 2ξ, corresponded to the tapering range of frequencies.Part III now deals with digital filters where the number 2N–1 of coefficients is directly related to the finite length M of the continuous impulse response. The values of the filter coefficients are taken from the continuous impulse response at the sampling instants, and the resulting characteristic is approximately the same as that derived in Part II for the continuous finite length impulse response. Corresponding to known types of frequency tapering, we now specify a filter characteristic which is undefined in the tapering range, and determine the filter coefficients according to a mean square criterion over the rest of the frequency spectrum. The resulting characteristic is dependent on the time bandwidth product Mξ= (N–1/2)ξ up to a maximum value of 2, beyond which undesirable effects occur. This optimum partially specified characteristic is an improvement on the previous digital filters in terms of the trade-off ratio for values of maximum overshoot less than 1%. Similar to the previous optimum characteristic is the optimum partially specified weighted digital filter, where greater “emphasis is placed on reducing the value of maximum overshoot than of maximum undershoot”. Such characteristics are capable of providing better trade-off ratios than the other filters for maximum overshoots greater than 1/2%. However these filters have critical maximum numbers 2.NC–1 of coefficients, beyond which the resulting characteristics have unsuitable shapes. This type of characteristic differs from the others in not being a biassed odd function about its cut-off frequency.

Notes: In Part I of this paper, we examined the properties of the best mean square approximation to the sharp cut-off frequency characteristic by an impulse response of finite length. It was found that the sharpness of cut-off for the resulting frequency characteristic depended on the length of the impulse response–but because of the discontinuous nature of the specified frequency characteristic, this best mean square approximation always had a maximum overshoot of ± 9%, independent of the length of the impulse response (Gibbs phenomenon).In Part II, we investigate ways of reducing this ± 9% overshoot at the expense of a reduced sharpness of cut-off. The discontinuous frequency characteristic is first approximated by a continuous characteristic with linear or cosine frequency tapering. The impulse response for such tapered characteristics consists of the impulse response of the discontinuous frequency characteristic weighted by a certain function corresponding to the type of tapering employed. The best mean square approximation to the tapered characteristic by an impulse response of finite length M will produce a frequency characteristic whose properties are now dependent on the time-band width product Mζ, where 2ζ is the tapering range.A trade-off exists between the maximum overshoot and the sharpness of cut-off for the resulting characteristic for both forms of frequency tapering. Instead of considering other forms of tapering in the frequency domain, we now investigate arbitrarily chosen weighting functions in the time domain to determine the minimum length of impulse response for a minimum value of maximum overshoot and a maximum value of sharpness of cut-off.Part III will discuss the digital realization of the above finite length impulse responses together with the optimum partially specified digital filter approximation to the desired frequency characteristic.

Notes: Book reviewed in this article:Le Filtrage en Sismique, Tome IJ. AUBOUIN “Geosynclines” (Developments in Geotectonics 1). Elsevier Publishing CompanyEarth and Planetary Science Letters Vol. 1. Nr. 2H. Ramberg Gravity, Deformation and the Earth's Crust Academic Press“Potassium Argon Dating” Compiled by O. A. Schaeffer and J. Zähringer

Notes: Deep seismic sounding was performed along two profiles which cross at the Dinarides area right angles. One of the profiles goes far into the Adriatic Sea.Besides considerations on the lithophysical conditions, characteristics of the registered waves are analysed. The amplitude curves and curves of amplitude ratios are shown. Special attention was paid to the frequency of the registered waves.In order to obtain a better knowledge of the registered wave pattern three-component recordings of waves were carried out. The analysis of the records obtained is given, with particular regard to the possibility of creating converted waves.The Earth's crust structure along the profiles II and III is given.

Notes: Nomograms for solving equations in multilayer and dipping layer cases are presented. The nomograms constructed are used to solve the following equations: I. Intercept-time formula. 2. Critical distance formula. 3. Critical angle formula. 4. Critical angle and dip angle formula. 5. Vertical depth formula.

Notes: When, in a two-layer earth, the substratum is insulating or infinitely conducting, the thickness of the top layer can be determined from surface potential measurements along a radius from a single point power electrode. The observed potential needs to be numerically integrated in a direction perpendicular to the said radius, and Figure 4 can then be used to find the thickness. A field example is included.

Notes: In order to increase the seismic efficiency of the Sparker-system developments were made in 1966/67. Results illustrating the main steps of this development are discussed. A new type of electrode called Transploder electrode was field-tested and proved to be promising.

Notes: The theory of electrical dipole soundings proved that this method can produce resistivity measurements, which are comparable with those obtained by electrical soundings of the Wenner or Schlumberger type. Their main advantage is the use of short cable lengths, which is important if the depth of penetration should be large.A considerable disadvantage of the dipole method is the great sensitivity to lateral discontinuities. Though these have an influence on the Schlumberger arrangement as well, they can disturb a dipole sounding to such an extent than an interpretation based on a horizontal layer case is no more possible.There are six different dipole arrays, which differ from each other with respect to the angle enclosed by the two dipole orientations-the current dipole AB and the measuring dipole MN. The theoretical comparison of the dipole arrays with the Schlumberger array concerning their sensitivity to lateral discontinuities is a useful basis for the choice of the most suitable configuration.Considering geological subsurface conditions the right choice of a dipole array can give an optimal result, i.e. a dipole sounding for which the sensitivity to lateral discontinuities is as small as possible under the given circumstances.

Notes: Deconvolution and deringing are well known subjects and it is not necessary to state again their objectives nor the basical methods used to reach them. Let us just remember that, generally, among many others, the two following assumptions are made for simplification purposes:〈list xml:id="l1" style="plain"〉—for deconvolution, it is assumed that the recorded seismic signal is constant, meaning that its shape is the same all along the time interval during which the trace is to be deconvolved;—for de-ringing, it is assumed that the ringing period is constant and that the intensity of the ringing phenomenon is independant of the time.With these two assumptions, a single constant operator can be applied for deconvolving, deringing or both. In most cases, the time variations of the signal or of the ringing are small enough and the error resulting of the application of a constant operator is acceptable. It results into a slight increase of the noise level or into a small residual ringing in the processed trace.When this noise or the residual ringing are too important, the assumption of a constant signal and ringing period must be rejected. This is the case that is examined here according to the following steps:〈list xml:id="l2" style="plain"〉—short definition of the problem;—fast evaluation of some possible solutions;—the selected solution: resulting approximations and how to obviate them, computing method and a remark about the operators;—theoretical example: the efficiency of the process used is evaluated on data in which the results aimed at are known; the influence of the selection of numerical values to be assigned to the parameters is examined;—real cases: comparison of results obtained with the Protee process and with more conventional processes assuming a time invariance or including a weighted composition of several conventional processes each with a different operator.

Notes: Sharp cut-off frequency filtering is carried out in the discrete time domain on digital computers. A convolution of the digital filter impulse response with the sampled input yields the output. For practical reasons, the length of the filter inpulse response, corresponding to the number of filter coefficients, is limited, and consequently the resulting frequency characteristic will no longer be identical to that originally specified. This is analogous to synthesising some specified frequency characteristic with a finite number of resistive, capacitative and inductive components.In Part I of this paper, we examine the effect of approximating the sharp cut-off frequency characteristic best in a mean square sense by an impulse response of finite length. The resulting frequency characteristic corresponds to the truncated impulse response of the specified frequency characteristic. It has a cut-off slope proportional to, and a mean square error inversely proportional to, the length of the impulse response, and is a biassed odd function about the cut-off frequency point. Because of the Gibbs phenomenon for discontinuous functions, the resulting frequency characteristic will always have a maximum overshoot with respect to the specified characteristic of ± 9%, regardless of the length of the corresponding impulse response. Equal length truncated impulse responses of specified filters with different cut-off frequencies yield frequency characteristics which are almost identical about their respective cut-off points. Now on a log frequency scale (as against a linear frequency scale implied previously) such characteristics may be made almost identical about the respective cut-off points by having the truncated impulse responses composed of an equal number of zero crossings. Results for the low-pass filter are applicable to the high-pass and band-pass characteristics.In the latter case, the mean square error is double that for a single slope characteristic (low-pass or high-pass) and the slopes at both edges of the passband are approximately equal in magnitude to the length of the impulse response (linear frequency scale).Part II of this paper is concerned with reducing the ± 9% overshoot that results from the discontinuous nature of the sharp cut-off frequency characteristic and which is not dependent on the length of the truncated impulse response. The reduction is achieved, at the expense of the steepness of cut-off for the resulting frequency characteristic, by the use of functions which weight the truncated impulse response of the specified frequency characteristic. These functions are called apodising functions. Among other variables, the length of the truncated weighted impulse response will determine the amount of maximum overshoot since the effective frequency characteristic being approximated is no longer a discontinuous function. The digital realization of the finite length impulse responses of Parts I and II is discussed in Part III, together with the optimum partially specified digital filter approximation to the desired frequency characteristic.

Notes: The purpose of this report is to show a method of determining the top of a refractor departing from the times and slopes of the direct and inverse dromocrones. The method does not need topographical correction and can be applied without knowledge of the distance between the geophone and the shot point.These results having been obtained, the commonly accepted point of view is upset: instead of looking for two points on the surface corresponding to one point of the refractor, we try to etablish, starting with only one point from the surface, the two corresponding points from the top of the refractor.This method can be applied to isolated points and does not demand interpretative hypotheses of any kind, excluding the velocity evaluation of the overburden and of the refractor.The necessary calculations can be easily executed by means of a digital computer to which the dromocrone times and the distances between the geophones must be given. These calculations can also be executed by a person having no knowledge of refraction seismology.This report also examines the validity of the approximations involved in the method proposed.

Notes: Determining the shape of a pulse generated by an explosion solely from the data provided by the recorded seismic trace is a difficult and even ambitious task.Knowledge of parameters such as length and number of “arches” of the pulse under study is, in fact, indispensable in solving this problem.These parameters cannot be found directly in the seismic trace, which nevertheless contains a great amount of information. Autocorrelation, with its mathematical and statistical properties, is an efficient way of making the best of this information.We compute all the autocorrelations of reflections having a given number of arches which fulfil certain conditions determined in advance. Then, after statistical testing of some parameters pertaining to the autocorrelations (abcissae of zeros, of extrema …), we select only those with a maximum likelihood. It is sufficient to consider only the reflections whose autocorrelations have been selected and to arrange them in groups according to their shape and arch number in order to obtain average pulses.In so doing several solutions are arrived at, but when considering a given number of traces, a single record for instance, it is possible by comparing these results with each other to considerably reduce their number.In the last part of the paper the nature of the impulse obtained with our method is examined in order to find out whether it is “minimum phase” for carrying out deconvolutions.

Notes: In recent years considerable work has been done to devise a satisfactory non-dynamite seismic system that would replace dynamite in offshore areas. Prior to the advent of digital recording and processing, the non-dynamite sources have generally not provided the depth of penetration or the resolution required for satisfactory seismic interpretation.More recent developments in non-dynamite offshore marine sources include adaptation of the Vibroseis from a land unit to a marine unit, and adaptation of the Dinoseis unit from a land to a marine unit. The SUE (Seismic Underwater Explorer) system is a thermodynamic non-dynamite source utilizing a mixture of propane and oxygen detonated in a special chamber approximately 15 feet below the water surface. This source gives penetration to more than 4 sec in areas typified by Gulf of Mexico type geology and shows deeper penetration than had previously been obtained by dynamite along the western United States in areas with 20 lb charge limitations. A pneumatic source, the airgun, has been in production use in the United States since June 1966. This non-dynamite source provides an intriguing amount of versatility and can be expanded to provide additional energy as necessary to obtain the penetration desired. Tests using systems comprised of from eight to twenty-three airguns show penetration in excess of 5 seconds in many areas. Power spectra comparisons both in amplitude and frequency content demonstrate that this is a controlled source generating a controlled seismic wavelet and a controlled frequency spectrum that can be tailored to fit requirements of particular areas. Sample sections obtained in the Gulf of Mexico and the Pacific Ocean offshore California show adequate penetration to 5.0 seconds reflection time.Quantitative measurements with the airguns demonstrate the effect of:〈list xml:id="l1" style="custom"〉1Variation of the number of guns in the system;2Shaping the frequency spectrum by using different sizes of airguns in the system;3Effects on signal-to-noise ratios as a result of stacking several small energy sources together;4Reproducibility of the initial pulse wavelet from shot to shot.The improvement in record quality as a result of advanced digital processing with non-dynamite sources is comparable to that obtained with dynamite sources. Non-dynamite sources make additional improvements possible where high source multiplicity is advantageous. Excellent dynamic correlations yield accurate velocity control as well as definitions of apparent velocities attributable to multiples and primary-to-multiple amplitude relationships.Non-dynamite sources are being used more and more extensively in offshore exploration. The advent of digital recording and processing provides a means for improving depth of penetration and resolution of many non-dynamite sources.

Notes: A number of experiments are reported in which comparisons were made, using calves, or ewes and lambs, between Tetila Tetrone and S22 or Danish Italian rye-grasses or between Reveille and S24 perennial ryegrasses.In general, the differences over the whole growing season were not large, but grazing experiments with calves during 1963-5 all showed that a substantial advantage in live-weight gain, can be obtained in the later part of the grazing season (July to September) by using T. Tetrone rather than S22 or Danish Italian ryegrasses.

Notes: By controlling the high populations of leatherjackets in two experimental leys it was shown that the loss of grass from this pest could be heavy. The most serious loss occurs in early summer. As soon as the larvae cease feeding in mid-June recovery begins and subsequent growth is satisfactory. Clover is damaged more heavily than grasses, but recovers completely by early autumn. The implications of these experiments are discussed.

Notes: Two experiments are described in which data were collected on yield, floral characteristics and winter greenness of a number of indigenous hill grass species. Differential cutting treatments, besides affecting total yield, affected yield and floral vigour in the subsequent year. Differences in sensitivity to cutting were present among the species. The date at which the grasses were last cut in autumn affected their winter greenness though responses differed among species. The significance of these results in relation to performance and management of hill pastures is discussed.

Notes: The growth curves of closed grassland swards obtained during the growing seasons of six successive years were compared with each other and with theoretical growth rates calculated by de Wit's method and based on the mean light energy input data for the same years. The form of the growth curve consisted of a period with a constant rate, lasting for 6–7 weeks in May-June, then rapidly shortening to 3 weeks in August-September, after which there was a rather abrupt change to zero values. A comparison with theoretical values showed that a period of constant growth rate was possible, because the promoting influence of increasing LAI counteracted the effect of increasing respiration. Before the longest day this period was lengthened by an increasing daylength; thereafter the reverse was found. There is no ready explanation for the sudden decline to zero values. This is thought to be associated with changes in the rate of photosynthesis.

Notes: In two experiments the growth of clover undersown to wheat was linearly related to the amount of light available. There were strong indications that clover growth and light within N.-S. rows were superior to those within E.-W. rows of wheat, and within N.-S. rows, those along the middle position were superior to others. The large difference between the growth of clover sown alone and with wheat indicated that beneath wheat the clover suffered from competition for other factors, probably soil moisture, which was even greater than that for light. Beneath wheat at the reduced level of growth there was a positive linear relationship between yield of clover and available light.

Notes: Two pot experiments were carried out in a semi-controlled environment to examine the response of individual plants to competitive stress in simple systems incorporating varying cutting frequencies and soil–nitrogen levels. A third experiment was set up outdoors to examine the effect of competition on individuals in an association, on the association as a whole, and to extend the controlled environment studies to a more complex model involving micro-plots. Phalaris coerulescens, although its seedlings possessed a high competitive ability, showed a dramatic decline in competitive ability in later stages of the association, this decline being associated with extensive floral development. In micro–plots the effect of competition was so severe as to prevent the expression of seasonal growth characteristics by P. coerulescens.Considerable inter-specific differences existed in the response to competition of leaf-area production per tiller during periods of regrowth.Whilst P. coerulescens remained highly productive and maintained a dense tiller population in monocultures, its tiller regeneration following flowering was severely suppressed in competition with vegetative plants of HI ryegrass or Festuca arundinacea.The number of heads produced per plant, head length and time of head emergence were all affected by competitive stress, the former response being a reflection of the relative competitive abilities at the time of floral initiation. The response of the latter two characters reflected the decline in competitive ability which occurred during later stages of the growth and development of P. coerulescens.

Notes: The use of lime and phosphates in reclaiming heather moorland was investigated in two experiments.Large initial dressings of hme resulted in a rapid rise in pH. An initial dressing of 9 tons CaCO3/ac resulted in a more rapid rise to pH 6 than did 6 tons/ac and the soil was maintained above pH 6 for a longer period. Three annual dressings of 3 tons/ac gave a slower rise in pH and a longer period above pH 6. Split treatments, half before and half after the first ploughing, gave no long–term advantage where a programme of pioneer cropping was being followed.Basic slag and North African phosphate were as effective as superphosphate for root crops at low pH values. Basic slag was as effective as superphosphate for grassland establishment and gave a greater rise in soil phosphate. North African phosphate was virtually worthless as a source of phosphate for establishing grasses and clovers, and gave a negligible rise in soil phosphate.Given adequate supphes of lime and phosphate, frequent small apphcations of N over the first 2 or 3 years are vital to the success of a reclamation programme under the conditions described.

Notes: There was a marked increase in basal cover of veld grasses after the first 2 to 3 years of cutting, and this effect continued over a period of 9 years. Short grasses, such as Cynodon dactylon and Heteropogon contortus, increased at the expense of tall tussock grasses, such as Hyparrhenia dissoluta.

Notes: Two experiments were established to compare the effect on the yield of continuously cut herbage of varying amounts of potassium fertilizer applied either in one large dose to the seedbed, or as 3 equal dressings applied to the seedbed and in the summer of the 2 following years. Responses in dry–matter yield were recorded up to the higher rates of potassium fertilizer applied. Establishment and yield in the first 12 months were improved by seedbed applications of up to 4 cwt/ac of muriate of potash (60% K2O). Although total yields over the whole period were similar, whether the potassium was applied to the seedbed only or in annual dressings, yields from “all–in–seedbed” dressings declined towards the end of the period. Soil analysis indicated that annual dressings left behind higher residues of K.

Notes: During the winter months of 1963 and 1964, mature non–pregnant Clun Forest ewes at pasture were equipped with pedometers to study the value of these instruments for measuring distances walked, and to investigate the importance of weather on the distances travelled. Approximately 80 periods were recorded, each of about 24 hours. The accuracy of the measurements was checked by using a rangemeter and it was found that the reliabihty of pedometer records must be assessed on the animal from which they are obtained. The individual characteristics of the pedometers and/or the sheep gave rise to inaccurate records from about 50% of the instruments studied.Multiple regression analysis of data for each of the three sheep which provided suitable records revealed that, in dry weather, the average distance walked per hour of recording period increased signiJBcantly with mean air temperature in one case and with hours of bright sunshine in another. Wind–speed effects were unimportant. The distance walked by all three sheep increased significantly with hours of daylight per recording period, and this was the only variable found to affect distance walked in wet weather. Differences between average distances walked per hour under dry–and wet–conditions were non–significant.It is concluded that for measuring the distances walked by sheep, the disadvantages of the pedometer outweigh its advantages.

Notes: Methods of testing grass varieties are discussed and the efifects of differences in management and of nitrogen fertilizer on quality are shown. In a grazing-management system with 9 cuts per season, cocksfoot was higher than perennial ryegrass in protein and fibre and lower in soluble-carbohydrate content and in vitro dry-matter digestibility throughout the season. All species showed the lowest value for digestibility in August.Curves for digestibility in primary growth were plotted for 4 varieties of ryegrass for leaf and stem fractions. The tetraploid variety Reveille was slightly more digestible than S24 in leaf and stem throughout the period, while at ear emergence S23 was lower in digestibility in both fractions than S24.There were significant differenees in composition and digestibility between experimental centres, but relative differences between varieties were consistent. The level of N fertilizer did not materially alter the comparison between varieties in quality data.

Notes: A series of experiments in eastern Scotland, carried out over a 7–year period, on the application of N fertilizers to Italian ryegrass for producing early spring grass, indicated that maximum yields are likely to be produced if the fertilizer is applied not later than the middle of March in most seasons. Only rarely did application in February result in a loss of N and in reduced herbage yields. Italian ryegrass appears to be able to make some growth at temperatures below 40†F.Increasing the rate of N application resulted in increased DM yield, the response averaging 9–4 lb DM per lb N. Herbage N concentration was increased by the additional N fertilizer. Nitro–chalk and ammonium sulphate were equally effective in producing early grass, irrespective of application date.

Notes: The treatments in this summer–grazing experiment were designed as a 2 × 3 factorial, there being two levels of nitrogenous fertilizer (nitro–chalk), supplying 0 and 336kg of N/ha per annum (NO and N3, respectively) and three stocking rates. The fertilizer was applied in 7 dressings at approximately three–weekly intervals. The animals used were Hereford x Friesian steers; these were slaughtered at the end of the grazing season. The stocking rates were calculated on the basis of expected herbage production. The experiment was laid out in 6 randomized blocks which were grazed in rotation. Two blocks were cut for conservation before grazing each year; up to the end of June only 4 blocks were used for grazing.There was little contamination of the swards with unsown species. With the NO swards the clover contents declined each year, but remained fairly high at over 20% in 1965. Clover contents also declined each year in the N3 swards and by 1965 were only 2 to 4%.The quantities of herbage cut for conservation were higher from the swards receiving N. The live–weight gains of the cattle (per head) were higher at the lower stocking rates, the effect of stocking rate being more noticeable in the July to Oct. period. Live–weight gains per ha increased at the higher stocking rates. In 1963 and 1965, as stocking rates increased carcass weights per animal decreased and carcass quality, as indicated by the commercial grades, was poorer. In 1964, a dry spell from July to Oct. necessitated the removal of cattle from the experiment and the effects of treatment on carcass weight and quality were not apparent.

Notes: Book reviewed in this article:BAKER, R. D., SPEDDING, A. W., KILKENNY, J. B. and TAYLER, J. C. An intensive system of beef production from grassland, using autumn-born calves from the dairy herd.M.A.F.F. At the farmer's service, 1967-8.M.A.F.F. Aspects of dairy economics, 1962-1965.DAVIES, WILLIAM. [The grasslands of Spain.]DIVISION OF PLANT INDUSTRY, CSIRO. Australian herbage plant register.

Notes: The use of MKS system units in preference to the cgs system facilitates accurate numerical calculation in magnetostatic problems in geophysics and the practice of stating the precise dimensions of every unit guards against confusion. Suggestions are made for the unique definition of quantities such as magnetic potential, etc. for which the undesirable circumstance of arbitrary alternatives still persists.

Notes: The Fourier transform formula for a two-dimensional fault truncating a horizontal bed at an arbitrary angle of inclination is derived. The amplitude spectrum of the Fourier transform is found to give information about the depth to the top of the upper part of the faulted bed and the inclination of the fault-plane. Under suitable conditions the thickness and the displacement of the bed involved can be obtained. With actual field data, these transforms can be obtained at discrete points by a Fourier analysis of the gravity anomaly. A field example from the Logan fault area near Montreal, Que., Canada, is given.

Notes: Die Interpretation magnetischer Anomalien durch Modellkörper geschieht bevorzugt nach der indirekten Methode (trial und error). Dieses von Hand aufwendige Verfahren läβt sich mit Hilfe der Ausgleichsrechnung nach der Methode der kleinsten Quadrate Rechenautomaten übertragen.Die allgemeinen Grundlagen des Verfahrens werden beschrieben. Wesentliche Voraus-setzungen sind:〈list xml:id="l1" style="custom"〉1)die Annahme bestimmter Körperformen2)das Vorhandensein von Näherungswerten der Unbekannten (Lage, Magnetisierung etc.)3)eine genügend groβe Anzahl von Meβwerten, um den Ausgleichsprozeβ durchführen zu können.Die Vorteile der Methode sind:〈list xml:id="l2" style="custom"〉1)weitgehende Automatisierung und schnelle Arbeitsweise bei Verwendung von Rechenautomaten2)Ermittlung der Fehler der UnbekanntenDie Methode wurde angewandt auf die Interpretation 2-dimensionaler ΔZ- und ΔT-Anomalien. Drei Körpertypen werden dem Rechenprogramm zugrunde gelegt, und zwar die unendliche und endliche diinne Platte und der Kreiszylinder. In die Maschine ein-gegeben werden nur die Meβwerte. Die Interpretation erfolgt im einzelnen in folgenden Schritten:〈list xml:id="l3" style="custom"〉1)Ermittlung von Näherungswerten2)Bestimmung der Körper bester Annäherung3)Iteration für den Körper bester Annäherung.Die Maschine gibt die Endwerte der Unbekannten (Lage, Einfallen, Magnetisierung etc.) mit Angabe der mittleren Fehler sowie die hierzu gehörigen Modellanomalien aus. Diese Endwerte werden einem Zeichenautomaten übergeben, der die gemessene Kurve, die theoretische Kurve und die gesuchten Modellkorper zeichnet.Interpretationsbeispiele werden vorgeführt.

Notes: In the first part, the author, recalling the principle of d/c current measurements, shows by means of some examples, different experimental results relative to the induced polarization phenomenon. He presents the case of the negative induced polarization which can be explained by geometric effects. He gives some examples of saturation curves and discusses the problem of the linearity of the I.P. phenomenon. Then he shows some aspects which demonstrate that I.P. decay curves do not always conform to the general law. He concludes by showing the influence of the current electrodes, the position of which, relative to the polarizable bodies, may alter the shape of the I.P. anomalies.In the second part, the author presents different case histories of I.P. mineral surveys where I.P. is compared to other geophysical methods and drilling results.

Notes: Magneto-telluric measurements were carried out at a group of eight sites, from Braunschweig to Lübeck, to determine the resistivity values associated with the North German conductivity anomaly. The data were analyzed for scalar and tensor apparent resistivities over the period range 5–2000 seconds. The results in general indicate very conductive (˜I Ω-m) sediments overlying a resistive basement which is strongly lineated.Interpreted basement depth (˜6 km) is compatible with published seismic refraction data. Principal conductivity axes in the basement appear to be directly related to trends of salt domes and major troughs. A major change in axis direction occurs near the center of the North German anomaly.

Notes: Leaves of different ages were removed 7 times between June and October. Each defoliation was timed to match the appearance of successive leaves on each tiller. The removal of leaves at progressively younger stages reduced total production above ground, but the most severe treatment, the removal of all expanded leaves repeatedly, still produced about 75% as much as the least severely defoliated sward. Clipping with shears 3 times reduced yield as much as removing all expanded leaves 7 times. A crop allowed to grow untouched apparently produced more than any defoliated treatment, but this may have been an artefact.The lower production following increasingly drastic defoliation was not associated with reduced concentrations of nitrogen or potassium in the foliage removed, or in the crop left behind. The total quantity of these elements recovered in the crop was greatest in those treatments where least dry matter was produced. Explanations for the results depend on the capacity of swards of predominantly young leaves to assimilate carbon more rapidly than those containing old and senescent tissue.

Notes: The effect of the physiological status of grazing ewes on diet selection was studied, using ewes with oesophageal fistulae. The diets of dry ewes grazing Phalaris annual grasses and subterranean clover pastures, over a range of availabilities, were compared with those of ewes in various stages of pregnancy and lactation. There were no significant differences at any stage of reproduction in the botanical composition of the diets. However, small differences in diet digestibility, soluble carbohydrate and nitrogen content were found during pregnancy and lactation. These occurred at all levels of availability of pasture. The differences did not appear to have nutritional significance in the particular pasture ecosystems studied because levels of N, soluble carbohydrates and digestibility of the diet were such that selection for survival was unlikely to be necessary.It is concluded that dry fistulated ewes can be used to obtain samples for assessing diet N and soluble carbohydrate contents for ewes in other physiological states. The use of in vitro digestibility tests of diets of dry ewes to assess diet digestibility for ewes in other physiological states may be subject to error.

Notes: The seed-producing capacity of two varieties of meadow fescue, S215 and S53, sown at three different spacings, was compared. One level of nitrogen was applied on three different dates in the spring. Tiller counts were made periodically during the growth of the crop. Fertile-tiller production was found to be related to vegetative growth.The varieties differed not only in yield, but also in growth dynamics. A larger percentage of overwintering shoots became fertile in the hay variety, than in the pasture variety.Drill spacings had significant effects on plant establishment and on vegetative-and fertile-tiller numbers. In both years N applied in March gave the highest production of fertile tillers. Date of N application did not produce marked trends in yield. The influence of spacing and date of N application on the number and density of spikelets indicated that the plant adjusted itself to environmental factors. Thus spikelet numbers were reduced in early heads with narrower drill spacing and with late applications of N. Head emergence was earlier in narrow drills, but time of N application in the spring did not produce significant differences in this respect.

Notes: A newly sown sward of Lolium rigidum was set-stocked from one week after emergence onwards at 7.4 sheep/ha.The proportion of dry matter removed from the sward by grazing each week fell from 20 to 1%/day over the first 7 weeks after emergence.Time-lapse stereo photography showed that in the immediate post-emergence period sheep tended to graze the elongating, or incremental, component of dry matter rather than the fully expanded butts of previously defoliated mature leaves.Frequency of defoliation decreased with time. 97% of plants were defoliated in the second week after emergence, but only 44% in the eighth week.

Notes: Nitrogen levels of 0,184 and 368 Ib (0,83.47 and 166.94 kg) were applied, as calcium ammonium nitrate, in six dressings throughout the grazing season to a perennial ryegrass/white clover sward. Herbage samples taken, periodically from each treatment and analysed nitrate for, indicated that the latter increased with increasing levels of applied nitrogen. Herbage nitrate levels were higher towards the end of the grazing season than at any other time. There was no consistent relationship between applied nitrogen and total plant nitrogen, although the latter tended to run parallel with applied nitrogen levels during the early part of the year.Sheep performance was significantly increased with the first increment of 184lb (83.47 kg) of nitrogen; a second increment of 1841b resulted in a further, but non-significant, increase. High-nitrate pastures did not significantly reduce liver vitamin A storage in sheep. It is suggested that approximately 350 Ib (158.79 kg) of nitrogen, applied uniformly throughout the grazing season, results in pasture nitrate levels which have no adverse affect on sheep performance.

Notes: Book reviewed in this article:BICKOFF, E. M. Oestrogenic constituents of forage plants.HUMPHREYS, L. R. Pasturas mejoradas para regiones tropicales y sub-tropicales. Un guia. [A guide to better pastures for the tropics and subtropics.]HAVARD-DUCLOS, B. Les plantes fourrageres tropicales. [Tropical forage plants.]INSTITUT F OR GRONLAND UND FELDFUTTERBAU DER KARL-MARX-UNIVERSITAT, LEIPZIG. [Fodder plant seed produetion. Papers and diseussion eontributions presented at the 4th Leipzig Grassland Symposium, 17-19 Mareh 1966.]

Notes: The effects of soil water conditions and soil temperatures on the growth of grass and clover roots and on the number of new adventitious roots were examined in the field and in glasshouse experiments.Although significantly more new roots were produced when swards were irrigated during extremely dry periods, the effect was small, In general, irrigation appeared to have little effect on the seasonal pattern of production of new roots from the base of the plant.High soil temperatures affected root growth. Branching of roots was increased by high temperatures, but the number of new roots formed at the base of the tillers was decreased, and the mean diameter of the roots was decreased. A multiple regression analysis of the number of new roots beneath a unit area of sward with soil-water conditions and soil temperatures at the time of sampling gave a significant inverse relationship with soil temperature. No relationship could be demonstrated

Notes: Previous work has shown that on deep peat the root systems of sown grasses are shallow. In order to study the effect of cultivation on root development, an experiment was laid down in an area of deep peat where sown grass swards were established on plots which had been subjected to different cultivation treatments. Root development is shown to be affected by depth of cultivation and this is discussed in relation to surface sowing of peatland areas.

Notes: In each of a series of sub-divided containers, two plants of cocksfoot (Dactylis glomerata) were planted in one of four arrangements to study the effects of: (a) no competition; (b) aerial competition, considered to be competition for light; (c) edaphic competition, considered to be competition for nitrogen; (d) full (aerial plus edaphic) competition, for light and N.The weight of seed produced per plant was reduced by aerial compeition, but not by edaphic competition, except where aerial competition also existed. With the exception of the seed, the weights of the components of the plants at harvest were reduced substantially by edaphic competition.The concentration of N in the various parts of the plant varied considerably, but only in the culms was it significantly affected by treatment so that the uptake of N was approximately proportional to the weight of the plant. Edaphic competiton gave most tillers per plant and full competition least. Aerial competition decreased the number of ears per plant.

Notes: A series of trials was carried out in which barn-dried hay and silage were fed to young fattening cattle with or without supplementary barley. Liveweight-gains on silage and barn-dried hay alone were too low to provide an adequate finish during winter feeding. Liveweight-gains on hay alone were always higher than those obtained on silage alone, the difference being more marked in lighter animals. There was a marked response to supplements of 3 and 4 lb (1.4 and 1.8 kg) of barley, the response being significantly greater in silage-fed cattle than in those fed on barn-dried hay. There was some evidence of growth compensation with the introduction of a barley supplement to cattle on silage diets, but there was no such response in those fed on hay. Compensatory growth was not accompanied by improved digestibility or N retention.

Notes: A study of birdsfoot trefoil (Lotus corniculatus L.) variety trial management was conducted with three variables, variety, stubble height and harvest date. The range in maturity for the three varieties used was 12-14 days. All plots were harvested thrice per season. The harvest dates for the two management regimes imposed differed by about two weeks for the first cut, by about one week for the second and were identical for the third cut. Stubble heights were two and six inches (5.08 and 15.24 cm).Late-cut material outyielded that cut early, but suffered more winter damage. Material cut at a stubble height of two inches (5.08 cm) outyielded that cut at six inches (15.24 cm), but it also suffered more winter-killing. The ranking of varieties varied with management.Alternative management schemes, designed to provide maximum yields and survival consistent with good-quality forage, are proposed and discussed.

Notes: Two experiments were set up in a semi-controlled glasshouse environment to determine the nature of the competitive stress, and the characters associated with competitive ability, during the seedling growth of some grass species. Over a period from sowing until the attainment of a relatively stable tiller population root competition was almost entirely responsible for the suppression of Festuca arundinacea in association with H1 ryegrass at two densities. In contrast, root and shoot competition were of equal importance in bringing about the suppression of Phalaris coerulescens in association with H1 ryegrass, an effect which only occurred at the high density.Differences in the patterns of root growth of the species and populations are discussed in relation to differences in their competitive abilities.It is suggested that the rate and extent of nodal root production are closely associated with seedling competitive ability.

Notes: A model of the electronic instrument described by Campbell et al. (3) was built at the Grassland Research Institute and was found to behave in a very similar way to their New Zealand model. A considerable amount of field work was undertaken with it in 1964 and this demonstrated that no general relationship of acceptable accuracy had yet been found; nor could it be sufficiently improved by the inclusion of the meteorological and botanical factors recorded. This forces one to a consideration of double-sampling techniques, which appear worth while; they will be discussed in Part 2 of this paper.