Estimating Crop Yield and Production Changes as a Function of Irrigation Deficit Based on Watershed and County Level Data PDF Download
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Author: Priscila Darakjian
Publisher:
ISBN:
Category : Crops and water
Languages : en
Pages : 224
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Book Description
Response of agricultural crops to irrigation water deficit is well-understood at the field scale. Broader scale (watershed and county levels) studies have been less frequently performed. Data collection at the field level for extensive areas is time consuming and expensive. The importance of studies at a broader scale for evaluating future scenarios of agricultural land use justifies exploring alternative approaches that produce reasonable results in a faster and more economical manner. The objective of this study was to verify the ability of coarser level data to provide general trends of changes in agricultural cropping patterns as a function of water use management in the Willamette basin. In this study, watershed and county level data were used to analyze broader scale crop water relationships, since these data are abundant and easily accessible. Further, future estimates of crop water use, based on estimates of yield and acreage changes, were attempted for a study period spanning current conditions (2000) through 2050. FAO Yield Response to Water Model was used to relate crop yield and production to applied irrigation water. Assumptions made to apply this model at the basin level related mostly to climatic factors and dynamic change of the system. Changes in maximum crop yield for all important crops grown in the Willamette basin were estimated using a logistic function parameterized with historic and current datasets. It was important to consider the dynamic system response when modeling the system to incorporate environmental, technological and socio-economic factors not reflected in the original model. The results for crop yield showed a decrease through time for sweet corn, stable yield for cherries, ryegrass, and grapes, and increasing yield for alfalfa, strawberries and raspberries. Crops showing higher sensitivity to water deficit included snap beans, winter and spring wheat, oats and filberts. Production estimates showed 3 groups of crops: predominantly successful (filberts, cherries, ryegrass, oats and spring wheat), stable (strawberries, alfalfa, orchardgrass, mint and fescue) and predominantly unsuccessful crops (winter wheat, sweet corn, snap beans and berries). County level and watershed level data proved helpful in developing a more comprehensive view of crop production and its irrigation deficit response, using models incorporating information from finer spatial scale experiments. Socio-economic, technologic and environmental variables that might influence agriculture over time should be investigated in further studies.
Author: Priscila Darakjian
Publisher:
ISBN:
Category : Crops and water
Languages : en
Pages : 224
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Book Description
Response of agricultural crops to irrigation water deficit is well-understood at the field scale. Broader scale (watershed and county levels) studies have been less frequently performed. Data collection at the field level for extensive areas is time consuming and expensive. The importance of studies at a broader scale for evaluating future scenarios of agricultural land use justifies exploring alternative approaches that produce reasonable results in a faster and more economical manner. The objective of this study was to verify the ability of coarser level data to provide general trends of changes in agricultural cropping patterns as a function of water use management in the Willamette basin. In this study, watershed and county level data were used to analyze broader scale crop water relationships, since these data are abundant and easily accessible. Further, future estimates of crop water use, based on estimates of yield and acreage changes, were attempted for a study period spanning current conditions (2000) through 2050. FAO Yield Response to Water Model was used to relate crop yield and production to applied irrigation water. Assumptions made to apply this model at the basin level related mostly to climatic factors and dynamic change of the system. Changes in maximum crop yield for all important crops grown in the Willamette basin were estimated using a logistic function parameterized with historic and current datasets. It was important to consider the dynamic system response when modeling the system to incorporate environmental, technological and socio-economic factors not reflected in the original model. The results for crop yield showed a decrease through time for sweet corn, stable yield for cherries, ryegrass, and grapes, and increasing yield for alfalfa, strawberries and raspberries. Crops showing higher sensitivity to water deficit included snap beans, winter and spring wheat, oats and filberts. Production estimates showed 3 groups of crops: predominantly successful (filberts, cherries, ryegrass, oats and spring wheat), stable (strawberries, alfalfa, orchardgrass, mint and fescue) and predominantly unsuccessful crops (winter wheat, sweet corn, snap beans and berries). County level and watershed level data proved helpful in developing a more comprehensive view of crop production and its irrigation deficit response, using models incorporating information from finer spatial scale experiments. Socio-economic, technologic and environmental variables that might influence agriculture over time should be investigated in further studies.
Author: Food and Agriculture Organization of the United Nations
Publisher: Food & Agriculture Org.
ISBN: 9789251047682
Category : Technology & Engineering
Languages : en
Pages : 116
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Book Description
In the context of improving water productivity, there is a growing interest in deficit irrigation, an irrigation practice whereby water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. Under conditions of scarce water supply and drought, deficit irrigation can lead to greater economic gains than maximizing yields per unit of water for a given crop; farmers are more inclined to use water more efficiently, and more water-efficient cash crop selection helps optimize returns. However, this approach requires precise knowledge of crop response to water as drought tolerance varies considerably by species, cultivar and stage of growth. The studies present the latest research concepts and involve various practices for deficit irrigation. Both annual and perennial crops were exposed to different levels of water stress, either during a particular growth phase, throughout the whole growing season or in a combination of growth stages. The overall finding, based on the synthesis of the different contributions, is that deficit or regulated-deficit irrigation can be beneficial where appropriately applied. Substantial savings of water can be achieved with little impact on the quality and quantity of the harvested yield. However, to be successful, an intimate knowledge of crop behavior is required, as crop response to water stress varies considerably.
Author:
Publisher:
ISBN:
Category : Hydraulic structures
Languages : en
Pages : 68
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Book Description
Author: Brian Clifford Nakamura
Publisher:
ISBN:
Category : Irrigation efficiency
Languages : en
Pages : 222
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Book Description
Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits affect yields and the interaction of the deficits with the scheduling of irrigations. A field experiment was conducted during the 1981 irrigation season to investigate the effects of high and low frequency deficit irrigation on yields of winter wheat. Yield and water use data were used to construct three production functions. The relationship between the level of water use and the resulting yield were determined for three irrigation frequency regimes. Field plots under daily (high frequency), weekly (normal frequency), and stress (reduced frequency) regimes were included in the field experiment as well as two dryland production plots. The relationships derived from this project were characterized by a large degree of scatter in the results. Highly favorable weather conditions offset the effects of irrigation deficits on plant yields throughout the irrigation season. At this time, a second year of data is in the process of compilation. The results of a regression analysis showed no statistically significant difference in the water use-yield relationships of the three irrigation frequency regimes. The effect of frequency did not lead to any readily apparent differences in the three production functions. The efficiency of water use of the different irrigation frequencies increases with decreasing amount of applied water for the 1981 crop year. The most efficient treatment, i.e., least water use per unit of yield, was the pre-plant irrigated, dryfarmed plots. The density of the wheat, a measure of crop quality also increased with decreased water use in this experiment. The optimal irrigation treatment (measured by production and quality) was the two-week frequency set.
Author: Gaylord V. Skogerboe
Publisher:
ISBN:
Category : Corn
Languages : en
Pages : 210
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Book Description
Author: Daniel Bucur
Publisher: BoD – Books on Demand
ISBN: 1789858119
Category : Science
Languages : en
Pages : 142
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Book Description
Since the beginning of its formation approximately three billion years ago, the hydrosphere - as an envelope of the terrestrial ellipsoid - has remained constant from a quantitative point of view. The hydrosphere modifies only the ratio of the stretches of the planetary ocean and land, including the proportion of the states of water aggregation: gaseous, liquid, and solid.The hydrological cycle transports only a portion of the hydrosphere, repeats itself annually, and presents itself as a huge planetary plant that for billions of years has operated uninterruptedly on the basis of solar energy and gravity, providing freshwater resources for the maintenance and perpetuation of life beyond the planetary ocean.Water resources are highly influenced by the hydrologic cycle and play a role in agricultural economic development. However, as is shown by the Intergovernmental Panel on Climate Change report, the phenomena of changing climate and land use are set to exacerbate an already serious situation of water supply for various users. In this context, scientific investigations into the issue of the sustainable use of water are timely and important. Improvement of water management involves the accurate estimation of consumptive uses. The purpose of this book is to show the achievements of scientists and academicians all over the world in promoting and sharing new issues on various topics related to evapotranspiration.
Author: Craig L. Mapel
Publisher:
ISBN:
Category : Field crops
Languages : en
Pages : 48
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Book Description
Author: Charles Faye Sarle
Publisher:
ISBN:
Category : Agricultural estimating and reporting
Languages : en
Pages : 152
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Book Description
Author: United States. Bureau of Reclamation
Publisher:
ISBN:
Category : Crops
Languages : en
Pages : 320
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Book Description
Representing agricultural systems explicitly in Earth system models is important for understanding the water-energy-food nexus under climate change. In this study, we applied Version 4.5 of the Community Land Model (CLM) at a 0.125 degree resolution to provide the first county-scale validation of the model in simulating crop yields over the Conterminous United States (CONUS). We focused on corn and soybean that are both important grain crops and biofuel feedstocks (corn for bioethanol; soybean for biodiesel). We find that the default model substantially under- or over-estimate yields of corn and soybean as compared to the US Department of Agriculture (USDA) census data, with corresponding county-level root-mean square error (RMSE) of 45.3 Bu/acre and 12.9 Bu/acre, or 42% and 38% of the US mean yields for these crops, respectively. Based on the numerical experiments, the lack of proper representation of agricultural management practices, such as irrigation and fertilization, was identified as a major cause for the model's poor performance. After implementing an irrigation management scheme calibrated against county-level US Geological Survey (USGS) census data, the county-level RMSE for corn yields reduced to 42.6 Bu/acre. We then incorporated an optimized fertilizer scheme in rate and timing, which is achieved by the constraining annual total fertilizer amount against the USDA data, considering the dynamics between fertilizer demand and supply and adopting a calibrated fertilizer scheduling map. The proposed approach is shown to be effective in increasing the fertilizer use efficiency for corn yields, with county-level RMSE reduced to 23.8 Bu/acre (or 22% of the US mean yield). In regions with similar annual fertilizer applied as in the default, the improvements in corn yield simulations are mainly attributed to application of longer fertilization periods and consideration of the dynamics between fertilizer demand and supply. For soybean which is capable of fixing nitrogen to meet nitrogen demand, the reduced positive bias to 6.9 Bu/acre (or 21% of the country mean) was mainly attributed to consideration of the dynamic interactions between fertilizer demand and supply. Although large bias remains in terms of the spatial pattern (i.e. high county-level RMSE), mainly due to limited performance over the Western US, our results show that optimizing irrigation and fertilization can lead to promising improvement in crop and soybean yield simulations in terms of the mean and variability especially over the Mid-west corn belt, and subsequent evapotranspiration (ET) estimates. Finally, this study demonstrates the CLM4.5 capability for predicting crop yields and their interactions with climate, and highlights the value of continued model improvements and development to understand biogeophysical and biogeochemical impacts of land use and land cover change using an Earth system modeling framework.
