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Alternative models for predicting the foliage—Air temperature difference of well irrigated wheat under variable meteorological conditions. I. Derivation of parameters II. Accuracy of predictions (1986)

Smith, R. C. G. ; Barrs, H. D. ; Steiner, J. L.

Springer

Irrigation science 7 (1986), S. 225-236

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ISSN: 1432-1319

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary One means of using infrared measurements of foliage temperature (T f ) for scheduling irrigations requires the use of meteorological data to predict the foliage-air temperature difference for a comparable well-watered crop (T f * − T a ). To determine the best method for making this prediction, parameters for models of increasing complexity for predicting (T f * − T a ) were derived for wheat using two sets of field data collected in 1982 and 1983. The simplest model with vapor pressure deficit (VPD) as the sole predictor accounted for 64% of observed variance in (T f * − T a ). The next model with both VPD and net radiation (R n ) as predictors accounted for 74%. The most complex model predicted (T f * − T a ) from the crop energy balance. In addition to VPD and R n it included parameters for the effects of air temperature (T a ), aerodynamic resistance (r a ) and the canopy resistance of a well-watered crop (r cp ) and accounted for 70% of the variance. Accuracy of these alternative models was tested against an independent set of field data collected in 1984. The single variable model with VPD as sole predictor accounted for 17% of the variance in observed values of (T f * − T a ). This increased to 47% when the effect of R n was included by using the two variable model and was increased further to 65% when the additional variables of T a , r a and r cp were included by use of the energy balance model. When the complexity of the model was measured by its number of variables there was a close relationship between complexity and the accuracy of the predictions. Reasons for the residual variability are discussed. The need for improved instrumentation for meteorological measurements was indicated.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00270432

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2

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Role of transpiration suppression by evaporation of intercepted water in improving irrigation efficiency (1995)

Tolk, J. A. ; Howell, T. A. ; Steiner, J. L. ; [et al.]

Springer

Irrigation science 16 (1995), S. 89-95

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ISSN: 1432-1319

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Sprinkler irrigation efficiency declines when applied water intercepted by the crop foliage, or gross interception (Igross), as well as airborne droplets and ponded water at the soil surface evaporate before use by the crop. However, evaporation of applied water can also supply some of the atmospheric demands usually met by plant transpiration. Any suppression of crop transpiration from the irrigated area as compared to a non-irrigated area can be subtracted from Igross irrigation application losses for a reduced, or net, interception (Inet) loss. This study was conducted to determine the extent in which transpiration suppression due to microclimatic modification resulting from evaporation of plant-intercepted water and/or of applied water can reduce total sprinkler irrigation application losses of impact sprinkler and low energy precision application (LEPA) irrigation systems. Fully irrigated corn (Zea Mays L.) was grown on 0.75 m wide east-west rows in 1990 at Bushland, TX in two contiguous 5-ha fields, each containing a weighing lysimeter and micrometeorological instrumentation. Transpiration (Tr) was measured using heat balance sap flow gauges. During and following an impact sprinkler irrigation, within-canopy vapor pressure deficit and canopy temperature declined sharply due to canopyintercepted water and microclimatic modification from evaporation. For an average day time impact irrigation application of 21 mm, estimated average Igross loss was 10.7%, but the resulting suppression of measured Tr by 50% or more during the irrigation reduced Igross loss by 3.9%. On days of high solar radiation, continued transpiration suppression following the irrigation reduced Igross loss an additional 1.2%. Further 4–6% reductions in Igross losses were predicted when aerodynamic and canopy resistances were considered. Irrigation water applied only at the soil surface by LEPA irrigation had little effect on the microclimate within the canopy and consequently on Tr or ET, or irrigation application efficiency.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00189165

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3

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Microclimatic and crop responses to center pivot sprinkler and to surface irrigation (1983)

Steiner, J. L. ; Kanemasu, E. T. ; Hasza, D.

Springer

Irrigation science 4 (1983), S. 201-214

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ISSN: 1432-1319

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary Over 1 million hectares are irrigated with center pivot sprinklers in the Great Plains, USA. Microclimatic conditions under center pivot systems will be affected somewhat by periodic sprinkling, but the extent of microclimatic modification to be expected from sprinkling in the High Plains region and the physiological implications have not been reported. We compared the leaf temperature, canopy air temperature, vapor pressure deficit, vapor pressure, soil temperature, and soil heat flux in a corn (Zea mays L.) canopy under center pivot sprinkler and surface irrigation. The crops were grown at Garden City, Kansas, in 1980, a hot, dry year, and in 1981, a relatively cool, wet year. Leaf and air temperatures in 1980 were significantly cooler undder sprinkler irrigation than under surface irrigation. Maximum, minimum, and mean daily leaf temperatures were reduced by 2°, 2°, and 1° C, respectively; and maximum, minimum, and mean canopy air temperatures were reduced by 3°, 1.5°, and 1.5° C, respectively. Leaf and minimum canopy air temperature reductions were significant at the 1 % level. Shorter irrigation intervals may explain the reduced stress on the sprinkled plots. We observed small, nonsignificant temperature reductions under the sprinkler in the 1981 season. No significant effects of irrigation type on vapor pressure deficit or on vapor pressure in the canopy were observed in 1980 or 1981. Analysis of the 1981 data indicated that most of the day-to-day variability in leaf and canopy temperatures is related to ambient air temperature and that canopy vapor pressure deficit and vapor pressure are related to both ambient temperature and ambient vapor pressure deficit. Soil temperatures were significantly reduced and soil heat flux increased under sprinkler irrigation. The diurnal response to sprinkler irrigation cycles was pronounced during early stress periods of the 1980 growing season. Leaf and canopy air temperature and vapor pressure deficit were all significantly lower throughout the day in recently irrigated areas compared to areas that were sprinkled one or two days earlier. Responses to sprinkling during nonstress periods of 1980 and 1981 only persisted while the leaves were wetted; after, conditions returned to levels found in the rest of the field.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00285526

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4

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Influence of season to season variability in weather on irrigation scheduling of wheat: A simulation study (1985)

Smith, R. C. G. ; Steiner, J. L. ; Meyer, W. S. ; [et al.]

Springer

Irrigation science 6 (1985), S. 241-251

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ISSN: 1432-1319

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary There is an increasing demand from farmers for irrigation scheduling advice. Where rainfall and evapotranspiration vary little from year to year, advice on a fixed irrigation schedule based on mean climatic data can be given. However where significant year to year variability in weather occurs a more flexible approach using actual weather data to predict the current level of soil water and mean climatic data to forecast the future rate of depletion and hence irrigation date may be needed. A technique for deciding the most appropriate scheduling approach was tested by using a simple model of crop growth combined with a soil water balance model to simulate year to year variability in scheduling advice. This technique was applied to irrigated wheat using a set of climatic data from 1968 to 1978 for Griffith in the Murrumbidgee Irrigation Area of New South Wales, Australia. A typical sowing date in early June was used and simulated irrigations were scheduled at an allowable soil water depletion (ASWD) of 62 mm for maximum yield and 93 mm for 80% of maximum. The analysis predicted that weather variability between years would cause the number of irrigations to vary from 2 to 7 for ASWD=62 mm and 1 to 4 for ASWD=93 mm. The interval between irrigations varied from 12 to 30 days, for ASWD=62 mm and from 16 to 28 days, for ASWD=93 mm. The first irrigation occurred between 76 and 131 days from sowing for ASWD=62 mm and from 100 to 140 days from sowing for ASWD=93 mm. The date of the last irrigation was similarly variable. This high degree of variability in the times and frequency of irrigations indicated that in south-eastern Australia accurate irrigation scheduling advice can only be given by using a flexible model using both actual and mean climatic data. A fixed schedule based on mean climatic data would lead to an inefficient use of water caused by the mistiming of irrigations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00262469

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5

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Nutrient Dynamics of Crop Residues Decomposing on a Fallow No-Till Soil Surface (1999)

Schomberg, H. H. ; Steiner, J. L.

Springer

Soil Science Society of America journal 63 (1999), S. 607-613

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ISSN: 1435-0661

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Medicago sativa L.), corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], spring and winter wheat (Triticum aestivum L.). Residues (20 g) in 10 by 10 cm, 1-mm mesh bags were placed on a Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls) at Bushland, TX, in August 1991 and collected monthly until August 1992. Water regime did not influence mass, N, or P dynamics but did affect K. Mass declined exponentially with decomposition coefficients (-r) of 4.4, 1.5, 2.0, 1.7, and 1.1 g kg-1 d-1 for the five crop residues listed above, respectively. Potassium loss was first order with -r ranging from 29.3 to 4.4 g kg-1 initial K d-1, depending on crop and water. Averaged across water regimes, -r equaled 25, 9, 8, 12, and 7 g kg-1 initial K d-1 for the respective crops. The water effect indicated 150-mm water removed 500 g kg-1 initial K from residues. Residue N declined from 38.7 to 16.0, 10.9 to 5.1, 12.2 to 6.4, 9.5 to 4.5, and from 7.6 to 3.4 g kg-1 during the first 34 d for the respective crop residues, after which nonlegume residues accumulated N (0.21 to 0.96 g kg-1 initial N d-1), while alfalfa lost N (-0.37 g kg-1 initial N d-1). Corn and winter wheat residue P increased from 0.7 to 1.2 and 0.5 to 1.0 g P kg-1, respectively, during the first 34 d, after which all residues lost P (-1.4, -2.1, -1.3, -2.0, and -2.8 g kg-1 initial P d-1, respectively). Nutrient dynamics were not directly related to mass loss. Water regime effects were small, so nutrient availability from residues should be similar in irrigated and dryland systems in the southern High Plains.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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6

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Impacts of crop residue at the earth-atmosphere interface: Introduction (1996)

Steiner, J. L. ; Schomberg, H. H.

Springer

Theoretical and applied climatology 54 (1996), S. 1-4

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ISSN: 1434-4483

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Summary Crop residues have been an under-valued resource in many agricultural systems. This collection of papers presents a sampling of new research and applications of new knowledge to improve our understanding of crop residue properties and impacts. Development and implementation of improved crop residue management offers opportunities to manipulate hydrologic, radiative, and energy balance processes. I hope the readers of Theoretical and Applied Climatology will be stimulated with new ideas. Collectively our new ideas can advance understanding of crop residue management and help us achieve sustainability in agricultural systems.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00863553

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7

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Climatic influence on residue decomposition prediction in the Wind Erosion Prediction System (1996)

Schomberg, H. H. ; Steiner, J. L. ; Evett, S. R. ; [et al.]

Springer

Theoretical and applied climatology 54 (1996), S. 5-16

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ISSN: 1434-4483

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Summary The effectiveness of crop residues to protect the soil surface and reduce soil erosion decreases as residues decompose. The rate of residue decomposition is directly related to the temperature and moisture regimes of the residues. Predicting changes in residue mass, orientation, and soil cover requires the use of functions that relate changes in decomposition rates to changes in the temperature and water regimes. Temperature and water functions used in the residue decomposition submodel of the Wind Erosion Prediction System (WEPS) were evaluated for their effects on predictions of residue decomposition. A precipitation function (PC) was found to produce relatively more accurate estimates of decomposition than a near surface soil water content function (SWC) for describing water regime effects. The estimated accuracies of the two functions were similar when bias in the estimation was considered. Predictions made with PC had estimated accuracies of ± 11.4, 14.5, 13.5% for alfalfa, sorghum and wheat, respectively, while those made with SWC had estimated accuracies of ± 13.8, 16.2, and 16.9%, respectively. Three temperature functions were compared for use in predicting residue decomposition over a range of locations and crops. There was little difference between the temperature functions over all the locations but, for several locations, one function overpredicted decomposition more often than the other two functions. Accuracies ranged from ±4 to ±51% of the observed values. The highest values were obtained at one location, and all three temperature functions produced similar high values. Over most of the data, estimated accuracies were generally between ± 15 and ± 25%. The prediction intervals were similar to those observed for decomposition of surface-placed residues. This evaluation indicates that the temperature and water functions used in the WEPS decomposition submodel will give reasonable estimates of mass loss from surface residues using easy-to-obtain weather data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00863554

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8

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Measuring crop residue cover using remote sensing techniques (1996)

Daughtry, C. S. T. ; McMurtrey, J. E. ; Chappelle, E. W. ; [et al.]

Springer

Theoretical and applied climatology 54 (1996), S. 17-26

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ISSN: 1434-4483

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Summary Crop residues are managed under conservation tillage programs to leave as much as possible on the surface for minimization soil erosion and for improving water quality. Because current methods for measuring crop residue cover are tediuous and somewhat subjective, there is a need for new methods to measure residue cover that are rapid, accurate, and objective. We discuss the potential for discriminating crop residues from soils using reflectance and fluorescence techniques and examine experimentally the changes in wheat residue fluorescence during weathering. The fluorescence of crop residue was a board band phenomenon with emissions extending from 420 to 600 nm for excitation of 350–420 nm. Soils had low intensity broad band emissions over the 400–690 nm region for excitations of 300–600 nm. We found that the fluorescence intensities for the crop residues were much greater than the fluorescence of the soils, but as the crop residues decompose, their blue-green fluorescence intensities approach the fluorescence of the soils. We conclude that fluorescence techniques are less ambiguous and better suited for discriminating crop residues from soils than the reflectance methods. However, the potential problems, that must be addressed to implement the fluorescence technique, are (i) adequate excitation energy must be supplied to induce fluorescence and (ii) the fluorescence signal is small relative to normal, ambient sunlight. Nevertheless, if properly implemented, we believe that the fluorescence techniques can be used to quantify crop residue cover in the field.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00863555

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