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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent and robotic systems 8 (1993), S. 267-284 
    ISSN: 1573-0409
    Keywords: Intelligent control ; simulation ; agriculture ; robotics ; melon harvesting ; intelligent systems ; planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An intelligent control system for an agricultural robot which performs in an uncertain and unstructured environment was modelled as distributed, autonomous computing modules that communicate through globally accessible blackboard structures. The control architecture was implemented for a robotic harvester of melons. A CAD workstation was used to plan, model, simulate and evaluate the robot and gripper motions using 3-D, real-time animation. The intelligent control structure was verified by simulating the dynamic data flow scenarios of melon harvesting. Control algorithms were evaluated on measured melon locations. Picking time was reduced by 49% by applying the traveling salesman algorithm to define the picking sequence. Picking speeds can be increased by a continuous mode of operation. However, this decreases harvest efficiency. Therefore, an algorithm was developed to attain 100% harvest efficiency by varying the vehicle's forward speed. By comparing different motion control algorithms through animated visual simulation, the best was selected and thereby the performance improved.
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  • 2
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    Natural hazards 6 (1992), S. 109-129 
    ISSN: 1573-0840
    Keywords: Drought ; agriculture ; hydrology ; monitoring ; research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The 1988 drought conditions, which prevailed over the southern portion of the Canadian prairie provinces, resulted in severe impacts on agriculture, water resources, forestry, and waterfowl production. In this paper, the climatological aspects of the drought are reviewed and the impacts of the drought are described. In addition, a number of the environmental factors that may have aggravated the drought's impacts are discussed. Processes contributing to the 1988 drought are considered in terms of their scales, relative importance and possible effects. It was evident from the information needs of government agencies and private businesses which had to cope with the effects of the 1988 drought, that studies are needed to effectively monitor drought and adjust to its impacts. In this paper, these needs are discussed; several specific hypotheses concerning drought-related processes are advanced and a framework for addressing the scientific aspects of droughts on the Canadian prairies is proposed. It is anticipated that many of these identified research needs and opportunities are applicable to other drought-prone areas of the world.
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  • 3
    ISSN: 1573-322X
    Keywords: climate change ; food ; agriculture ; ethics ; technologies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Burning fossil fuel in the North American continent contributes more to the CO2 global warming problem than in any other continent. The resulting climate changes are expected to alter food production. The overall changes in temperature, moisture, carbon dioxide, insect pests, plant pathogens, and weeds associated with global warming are projected to reduce food production in North America. However, in Africa, the projected slight rise in rainfall is encouraging, especially since Africa already suffers from severe shortages of rainfall. For all regions, a reduction in fossil fuel burning is vital. Adoption of sound ecological resource management, especially soil and water conservation and the prevention of deforestation, is important. Together, these steps will benefit agriculture, the environment, farmers, and society as a whole.
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  • 4
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    Journal of agricultural and environmental ethics 3 (1990), S. 5-20 
    ISSN: 1573-322X
    Keywords: agriculture ; waste ; environment ; economic ; social ; costs ; erosion ; pesticides ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Because the agriculture/food sectors appear to be driven by short-term economic and political forces, cheap energy, and agricultural-chemical technologies, waste and environmental/social problems in the agricultural/food sectors are estimated to cost the nation at least $150 billion per year. Most of the waste and environmental/social problems can be eliminated through better resource management policies and the adoption of sustainable agricultural practices.
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  • 5
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    Journal of agricultural and environmental ethics 7 (1994), S. 157-172 
    ISSN: 1573-322X
    Keywords: press ; agriculture ; ethics ; newspapers ; farm magazines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract All major journalism ethical codes explicitly state that journalists should protect editorial copy from undue influence by outside sources. However, much of the previous research on agricultural information has concentrated on what information various media communicate (gatekeeping studies) or communication's role in increasing innovation adoption (diffusion studies). Few studies have concentrated specifically on organizational and structural constraints that might adversely affect agricultural journalists' ethical standards; those that have, focus largely on farm magazines. A study of newspaper reporters who cover agricultural news found that the most pressing ethical concern is the effect of advertiser (agri-business) pressure on editorial copy, and that their concerns in general parallel those of farm magazine writers and editors. The majority reported being in situations in which they might be exposed to advertiser pressure, including pressures to change or withhold editorial copy. Large minorities suggested that advertising pressures affect the overall environment in which agricultural journalists work, and more than one in ten said they allow advertiser pressures to influence editorial decisions. The newspaper reporters who cover agricultural beats showed slightly more resistance to advertiser pressure than did farm magazine editors in a parallel study.
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  • 6
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    Journal of applied phycology 6 (1994), S. 301-308 
    ISSN: 1573-5176
    Keywords: eutrophication ; immobilization ; Selenastrum capricornutum ; running water ; agriculture ; microcosms ; biotesting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells of the green algaSelenastrum capricornutum were immobilized in alginate beads. The alga was able to grow inside these beads without being grazed by zooplankton. For P-limited immobilized cells, however, a lower µ m and initial slope of the Monod growth curve µ m /K s were found than for free cells. To study the feasibility of immobilized algae to estimate algal growth potentialin situ in aquatic ecosystems, a series of experiments were conducted in indoor model ecosystems (microcosms) and in a small stream. The use of immobilized algae allowed a continuous registration of algal growth potential integrated over periods with natural fluctuations in the environment. The method of encapsulation of the algae can, however, still be improved. The alginate matrix is exposed to marked degradation by microorganisms when incubated in polluted streams for a period longer than two weeks. The applicability of other types of matrices should be tested.
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  • 7
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    Water resources management 5 (1991), S. 121-147 
    ISSN: 1573-1650
    Keywords: Irrigation ; agriculture ; soil moisture ; salinity ; crop yield models ; mathematical modelling ; water use in agriculture ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract This paper is concerned with the simulation of the water allocation and salt movement in the root zone of a particular crop. A mathematical model of four ordinary differential equations is developed. The model performs water balance and salt balance in unsaturated and saturated regions of the root zone. It is a lumped input and lumped parameter conceptual model, which considers the average soil moisture and salt concentration in the root zone. The equations are solved numerically over the time period of the growing season. Precipitation and irrigation water are treated as inputs. The analyzed results indicate that, for the shallow water table case, the water table elevation has an important effect on the soil moisture depletion dynamics of the unsaturated zone. An appreciable amount of water from the saturated zone is transferred through capillary rise to the unsaturated zone particularly in the case of sandy loam soils. It was found that the water table elevation varies significantly during the growing season. The salt movement simulation indicates a salt concentration build up in the unsaturated zone during the growing season. Contours of equal crop yield reduction as a function of the unsaturated zone initial salt concentration and the irrigation water salt concentration are obtained. The model was tested with data from the Mashtul Pilot Area in Egypt and its performance was satisfactory.
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  • 8
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    Plant and soil 159 (1994), S. 27-35 
    ISSN: 1573-5036
    Keywords: agriculture ; arbuscular-mycorrhizas ; economic analysis ; management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The benefits of management of mycorrhizas in agricultural and horticultural croppiing systems remains problematic except where the indigenous fungal population is low. Most experiments have focused on the introduction of exotic fungal isolates. Promotion of plant growth by mycorrhizas can be enhanced by increasing the effectiveness of the indigenous fungi as well as by introducing more effective species. Lack of reliable methods for identification of fungal species colonizing roots is a major limitation to characterizing the change in mycorrhizal populations. Assessment of the role of mycorrhizas in commerical food production systems must include an economic analysis. To do so requires an evaluation of the response to increasing the effectiveness of the mycorrhizal symbiosis relative to increasing yield with addition of phosphorus fertilizer. Thus field experiments should be designed to measure the response to phosphorus addition with the existing mycorrhizal population as well as with the more effectively managed population. In this paper we discuss changes that may be induced in mycorrhizal fungi by management to increase their effectiveness in promoting plant growth. We then suggest an economic analysis approach to assessing the potential benefits of this increase in effectiveness. We conclude with a discussion of research approaches needed to determine, in a more objective manner, the role of mycorrhizas in managed ecosystems.
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  • 9
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    Hydrobiologia 275-276 (1994), S. 359-369 
    ISSN: 1573-5117
    Keywords: agriculture ; blue-green algae ; eutrophication ; internal loading ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of agriculture was estimated on two shallow, eutrophic lakes, Lake Kotojärvi and Lake Villikkalanjärvi in southern Finland. The main emphasis was on phosphorus and nitrogen budgets and on the phytoplankton dynamics. Special attention was paid to internal P loading and blue-green algal blooms. The mean Tot-P load from agricultural land was 1.2 kg ha-1 a-1 in both basins and Tot-N loads were 19 kg ha-1 a-1 in L. Villikkalanjärvi and 12 kg ha-1 a-1 in L. Kotojärvi. The Tot-P input to L. Kotojärvi was on an average 0.62 g m-2 a-1 (per lake surface area), and the Tot-N input 9.1 g m-2 a-1. The corresponding inputs to L. Villikkalanjärvi were 3.1 and 57 g m-2 a-1, respectively. The annual variation followed the runoff volumes. About half of the Tot-P and one third of the Tot-N load was retained in L. Kotojärvi. In L. Villikkalanjärvi the retention was only 24% for Tot-P and 19% for Tot-N. The difference was very probably due to a longer theoretical retention time in L. Kotojärvi. In L. Villikkalanjärvi the mean concentration of Tot-P was 120 µg 1-1 and that of Tot-N 1700 µg 1-1 and the corresponding figures in L. Kotojärvi 67 and 990 µg 1-1, respectively. The mean chlorophyll a concentration was, however, higher in L. Kotojärvi (26 µg 1-1) than in L. Villikkalanjärvi (20 µg 1-1). This was probably due to an internal P load in L. Kotojärvi: in 1988 the internal load of dissolved P was estimated to be as much as twofold the external load. In L. Villikkalanjärvi the internal dissolved P load was only up to 50% of the external input. In L. Kotojärvi the high internal P load coupled with a low DIN:DIP ratio resulted in a strong blue-green algal bloom in the summer of 1988. In L. Villikkalanjärvi blue-green algae were observed only in small amounts. Even in August 1990, when the DIN:DIP ratio was low enough to favor the occurrence of blue-green algae, they contributed only up to 10–15% of the total phytoplankton biomass.
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  • 10
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    Hydrobiologia 287 (1994), S. 179-194 
    ISSN: 1573-5117
    Keywords: agriculture ; phosphorus ; bioavailability ; bioassays ; isotherms ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The potential bioavailability of phosphorus in agriculturally loaded rivers of southern Finland was determined by an algal bioassay and the release of the potentially bioavailable particulate P was estimated by sorption studies. According to the bioassay 0 to 13.2 per cent (mean 5.1%) of the particulate P in river water samples was potentially bioavailable. Dissolved reactive P (DRP) in river waters appeared to be totally bioavailable whereas the dissolved unreactive P appeared not to be utilized by algae. In addition to river waters two lake sediment samples were also assayed. In these samples 0 and 2.6% of the P was bioavailable. The potential bioavailability of particulate P in agriculturally loaded rivers obtained in this study was lower than that reported in studies from other countries. The difference was assumed to arise partly from methodological factors and partly from the nature of the Finnish soils. The EPC (equilibrium phosphate concentration) values indicated that during the period when most of the agricultural loading enters the lakes in Finland, potentially bioavailable P is not released from the particles because of the relatively high DRP concentration in the receiving waters. However, during the algal production period the DRP concentration in lakes decreases below the EPC and potentially bioavailable particulate P is desorbed. The increase in pH during this period may further enhance the desorption of P.
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  • 11
    ISSN: 1573-5117
    Keywords: particulate organic matter ; storage ; organic processing ; agriculture ; longitudinal patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An agriculturally-impacted stream in northern Idaho was examined over a two-year period to determine seasonal and longitudinal patterns of the storage and decomposition of particulate organic matter. Biomass of benthic organic matter (BOM) was considerably less than values reported in the literature for comparable, undisturbed streams. Coarse, fine, and total benthic particulate organic matter were not correlated with parameters pertaining to stream size (e.g., stream order), but were correlated with sample site and amount of litterfall. The association of BOM with site and litterfall suggests that storage of particulate organic matter is a function of local characteristics rather than stream size. Low biomass of stored organic matter is a response to the low input of terrestrially-derived organic matter resulting from removal of climax vegetation. Leaf packs of alder, Alnus sp., were placed in the stream seasonally for 30 and 60 d. While there were significant differences for months, there was no significant difference among sites for leaf packs exposed for 30 d. Significant differences were observed among both sites and months for leaf packs exposed for 60 d; however, differences among sites accounted for only 5% of the variance. The absence of differences in decomposition of organic matter along the gradient of Lapwai Creek, despite heterogeneity of the drainage basin and availability of organic matter, may be in response to the overall low biomass of stored benthic organic matter. This study demonstrates that agricultural activity can substantially influence instream heterotrophic processes through reduced availability of organic matter and can shape community structure and ecosystem dynamics of streams flowing through agricultural drainage basins.
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  • 12
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    Environmental and resource economics 1 (1991), S. 313-332 
    ISSN: 1573-1502
    Keywords: Manure problem ; nutrient policy ; nutrient surplus ; regulatory levy ; sustainability ; agriculture ; intensive livestock sector ; acidification ; groundwater pollution ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract Rapid increases in livestock production in the Netherlands have changed manure from a valuable input into a mere waste product. This is especially true for the southern and eastern parts of the country, where specialized pig and poultry farms have concentrated on sandy soils. As these farms generally own very little land, they largely depend on imported feedstuffs. As a consequence, manure is applied to the land in such large quantities that serious environmental problems have resulted: (1) eutrophication of surface water by phosphate emissions; (2) pollution of groundwater by nitrate emissions; and (3) acidification by ammonia emissions. In the last few years the Dutch government has developed a manure policy to counteract these effects. Our analysis of that policy has revealed at least three fundamental defects, which render the manure policy ineffective and inefficient. In this paper proposals are made to remove the defects in current manure policy. Much attention is paid to the problem of designing a mixture of policy instruments which is both effective as well as efficient in limiting the environmental problems caused by manure. It is shown that the use of financial incentives in regulation can substantially improve the efficiency of the manure policy. Finally, the main economic consequences of the proposed policy are examined for the public sector as well as for the agricultural sector.
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  • 13
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    Environmental and resource economics 3 (1993), S. 285-296 
    ISSN: 1573-1502
    Keywords: Pollution control ; nitrogen taxation ; agriculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract Amongst possible economic incentives to encourage reduced nitrate contamination of water, this paper emphasizes a nitrogen tax as a possible solution. This finding is based on models estimated from panel data for 100 intensive livestock farms. For each farm a threshold is established (nitrogen units which can be spread per hectare without damage) above which there is an excess of nitrogen. The 100 farms can consequently be classified into two subsamples. The demand for nitrogen is derived for each sub-sample using the dual approach. Both categories are pooled together and a tobit model is estimated. This is used to derive total nitogen demand if all farms were under the threshold. A mineral nitrogen tax would lead to a reduced nitrate concentration in water supplies, because of a more efficient use of organic nitrogen together with a reduction in the use of mineral nitrogen in crop production.
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  • 14
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    Nutrient cycling in agroecosystems 36 (1993), S. 79-90 
    ISSN: 1573-0867
    Keywords: agriculture ; Sahel ; Sudan ; Mali ; cotton ; fertilization ; nutrient ; soil ; soil degradation ; depletion ; nutrient ; nutrient balance ; nitrogen ; phosphorus ; potassium ; calcium ; magnesium ; acidification ; sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given. The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur. Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits. The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.
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  • 15
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    Nutrient cycling in agroecosystems 36 (1993), S. 177-184 
    ISSN: 1573-0867
    Keywords: diffuse nutrient loss ; management ; agriculture ; fertilizer ; soil testing ; water and erosion control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eutrophication problems in waterbodies in south-western Australia are primarily caused by inputs of nutrients from diffuse sources within the agricultural catchments of these waterbodies. To reduce the algal growth and seagrass decline caused by these inputs, it is essential to modify land management to minimise nutrient losses. Permanent reduction in nutrient losses from agricultural catchments should involve voluntary changes in farm management practices based on improved land management. Specifically, these include on-farm nutrient management such as soil testing, fertilizer management, the use of perennial plants, and water and erosion control measures to reduce nutrient loss from rural land. This paper describes the management of nutrient loss from the catchment of Oyster Harbour on the south coast of Western Australia using a co-operative approach.
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  • 16
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    Human ecology 20 (1992), S. 145-167 
    ISSN: 1572-9915
    Keywords: agriculture ; development ; diversity ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This paper reconsiders two widely held hypotheses about the effects of the green revolution, that it led to biological simplification and instability. The hypothesis of biological simplification (genetic erosion) is tested with evidence from Andean agriculture, where farmers maintain a significant degree of crop diversity even as they adopt modern crop varieties. The hypothesis of increased instability is tested with evidence from Asia where wheat and rice yields show no general pattern of increased instability. Neither of these hypotheses is confirmed. The conventional wisdom about the green revolution should be reconsidered with emphasis on resilience and variation in modernizing farming systems.
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  • 17
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    Human ecology 18 (1990), S. 105-130 
    ISSN: 1572-9915
    Keywords: agriculture ; forest farming ; social history ; Appalachia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This research uses aggregate statistical sources to describe agricultural diversity in a 31 county area of Appalachian Kentucky over the period 1880–1910. In particular, it considers the distribution and duration of forest farming in this region. It examines the causes of agricultural diversity by testing a series of hypotheses conceptually based in ecological theory. For 1880, counties differed in the degree to which they had the characteristics expected for forest farming. This variation was geographically patterned. While there was still geographical variation in county agricultural characteristics in 1910, sufficient change had occurred so that none of the counties continued to closely conform to the pattern expected for forest farming. Variation and change in county agricultural characteristics were found to be related to population density and growth, soil quality, the presence of railroads, and the development of commercial coal mining.
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  • 18
    ISSN: 1572-9915
    Keywords: land use ; land cover ; Amazon ; estuary ; flooded forest ; aÇai ; palms ; agriculture ; pastures ; swidden ; slash-and-burn agriculture ; succession ; remote sensing ; GIS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract Landsat TM scenes for 1985 and 1991 are used to produce a georeferenced map of land cover and land use for an area of the Amazon estuary inhabited by three populations of caboclos with distinct patterns of land use. This information is combined in a geographic information system with ethnographic and survey research carried out over the past 5 years to develop representative spectral “signatures” which permit measurement and differentiation of land uses and the detection of change even between small areas of managed floodplain forest and unmanaged forest, and between three distinct age/growth classes of secondary succession following deforestation. Implementation of these procedures permit the scaling up or down of research at different resolutions. Three distinct patterns of land use are examined with differential impact on the environment. Mechanized agriculture at one site has eliminated virtually all the mature upland forest and is now dominated by secondary successional vegetation. The more traditional system of diversified land use at the next site shows a subtle cycling of flooded forest to managed palm forest through time in response to the price of palm fruit and cycling in the use of fallow land. A third site, based on palm fruit extractivism, shows minimal changes in land cover due to persistent specialization on management of flooded forest extraction. There is little evidence that the community with the greatest impact on forest cover is any better off economically than the two communities which have minimal impact on the landscape. This study suggests how a balance between use and conservation in Amazonia may be achieved in floodplain and estuarine areas, and the effectiveness of monitoring these types of land cover from satellite platforms.
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  • 19
    ISSN: 1573-5117
    Keywords: agriculture ; algae ; lake ; littoral ; macrophytes ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We are studying present conditions and consequences of material movement from land to water in the Lake Titicaca basin, and how fluxes are affected by human activities. The principal objective of this research is to describe and explain the variability in the Andean Altiplano of (a) water, nutrient and sediment fluxes from land and (b) composition, nutrient limitation and other important features of nearshore lake communities, and compare the effects of different agricultural practices (especially traditional and modern) on these factors. We are focusing on a comparison of the impacts of two forms of agriculture in this region: ancient raised fields currently under rehabilitation, and flat pastures and fields, which are more common. Results of the first year of study indicate there is substantial variability in nitrogen and phosphorus dynamics in relation to ecotone complexity (simple vs. intermediate vs. complex). Raised field sites have the beneficial effect of reducing high available nutrient concentrations (nitrate and soluble reactive phosphorus) and sediment load (measured as turbidity) as the water passes through them enroute to the lake. Aquatic vegetation (algae and macrophytes) reflect well ambient total nitrogen and phosphorus concentrations. Experimental nutrient limitation bioassays indicate that nitrogen is the most important limiting nutrient, though there is important spatial variability within the landscape, and phosphorus as well as nitrogen can be limiting.
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  • 20
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    Journal of agricultural and environmental ethics 6 (1993), S. 75-88 
    ISSN: 1573-322X
    Keywords: biotechnology ; education ; agriculture ; socio-economic issues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract An interdisciplinary course was designed as an introduction to the applications of, and the socio-economic issues associated with, biotechnology. College students enrolled in the course were surveyed prior to the first formal lecture, and again upon completion of the course. Assessment was made of the impact of the educational materials on the attitudes and perceptions of the students toward the applications of biotechnology to agriculture. Data were collected for the first three semesters in which the course was offered. Answers to survey questions were analyzed on a before and after basis. It was found that students were very accepting of biotechnology prior to taking the course, despite a generally low level of exposure to this type of technology. The course was effective in increasing the knowledge base of the students, but not as effective in allaying their perceptions of risks associated with biotechnology.
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  • 21
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    Environmental and ecological statistics 1 (1994), S. 21-36 
    ISSN: 1573-3009
    Keywords: agriculture ; economic index ; statistical tests ; total factor productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract An agricultural system is sustainable if productive output is maintained economically over time when assessed in relation to environmental concern. This paper considers ways of statistically evaluating measures of sustainability illustrated by reference to extensive data from the Classical Experiments at Rothamsted.
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  • 22
    ISSN: 1573-3017
    Keywords: striped bass ; opossum shrimp ; agriculture ; toxicity ; bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The striped bass (Morone saxatilis) population of the Sacramento-San Joaquin Delta has declined approximately 80% since the mid-1970s. This decline has been attributed to factors such as water diversions, pollution and reduced abundance of food organisms. One source of potential pollutants is agricultural return water. The Colusa Basin Drain discharges water from over 150 000 acres and can account for over 20% of the flow of the Sacramento River. Because discharge occurs at the same time striped bass are spawning, early developmental stages could be adversely affected. Toxicity studies conducted over a 3 year period consistently demonstrated acute toxicity to striped bass larvae and to opossum shrimp (Neomysis mercedis), an important food organism for juvenile striped bass. Acute toxicity was also demonstrated with striped bass embryos. In addition, a model based on pesticide use more effectively predicted striped bass recruitment during the period of decline than did a model based on historically important river flows and delta diversions. These studies indicate that agricultural return water should not be disregarded when considering potential causes of the decline of striped bass.
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  • 23
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    Journal of agricultural and environmental ethics 6 (1993), S. 1-19 
    ISSN: 1573-322X
    Keywords: agroecosystems ; agriculture ; ecology ; sustainability ; biodiversity ; competition ; succession ; culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract In the final analysis, sustainable agriculture must derive from applied ecology, especially the principle of the regulation of the abundance and distribution of species (and, secondarily, their activities) in space and time. Interspecific competition in natural ecosystems has its counterparts in agriculture, designed to divert greater amounts of energy, nutrients, and water into crops. Whereas natural ecosystems select for a diversity of species in communities, recent agriculture has minimized diversity in favour of vulnerable monocultures. Such systems show intrinsically less stability and resilience to perturbations. Some kinds of crop rotation resemble ecological succession in that one crop prepares the land for successive crop production. Such rotations enhance soil organic processes such as decomposition and material cycling, build a nutrient capital to sustain later crop growth, and reduce the intensity of pest buildup. Species in natural communities occur at discrete points along the r-K continuum of reproductive maturity. Clearing forested land for agriculture, rotational burning practices, and replacing perennial grassland communities by cereal monocultures moves the agricultural community towards the r extreme. Plant breeders select for varieties which yield at an earlier age and lower plant biomass, effectively moving a variety towards the r type. Features of more natural landscapes, such as hedgerows, may act as physical and biological adjuncts to agricultural production. They should exist as networks in agricultural lands to be most effective. Soil is of major importance in agroecosystems, and maintaining, deliberately, its vitality and resilience to agricultural perturbations is the very basis of sustainable land use.
    Type of Medium: Electronic Resource
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