N. Khalili; K. Davary; A. Alizadeh; M. Kafi; H. Ansari
Abstract
Modeling of crop growth plays an important role in evaluation of drought impacts on rainfed yield, choosing an optimum sowing date, and managerial decision-makings. Aquacrop model is a new crop model that developed by Food and Agriculture Organization (FAO), that is a model for simulation of crop yield ...
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Modeling of crop growth plays an important role in evaluation of drought impacts on rainfed yield, choosing an optimum sowing date, and managerial decision-makings. Aquacrop model is a new crop model that developed by Food and Agriculture Organization (FAO), that is a model for simulation of crop yield based on “yield response to water“ with meteorological, crop, soli and management practices data as inputs. This model has to be calibrated and validated for each crop species and each location. In this paper, the Aquacrop has been calibrated and evaluated for rainfed wheat in Sisab station (Northern Khorasan). For this purpose, daily meteorological data and historical yield data from two cropping season (2007-2008 and 2008-2009) in the Sisab station have been used to calibrate this model. Next, meteorological data and historical yield data of five cropping season (2002-2003 to 2006-2007) are used to validate the model. The result shows that the Aqucrop can accurately predict crop yield as R2, RMSE, NRMSE, ME, and D-Index are achieved 0.86, 0.062, 5.235, 0.917 and 0.877, respectively.
A. Shabani; Gh. haghnia; Ali reza Karimi; M.M. Ahmadi
Abstract
Topographic characteristics are considered as important factors for growth and yield of rainfed crops because of the impact on the water distribution and consequently effects on soil physical and chemical properties. No information is available on this subject for North Khorasan province of Iran. The ...
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Topographic characteristics are considered as important factors for growth and yield of rainfed crops because of the impact on the water distribution and consequently effects on soil physical and chemical properties. No information is available on this subject for North Khorasan province of Iran. The purpose of this study was to investigate the effect of soil and topographic characteristics on the rainfed wheat yield in Sisab region of North Khorasan province. Surface soil samples and wheat yield data were taken from 100, 1×1 m2 plots on different slope positions from 800 ha of rainfed farms. Sand, silt, clay, gravel, calcium carbonate equivalent, soil organic matter, pH, EC, total nitrogen, available potassium and phosphorus were measured. Primary and secondary topographic derivatives including elevation, slope, aspect, plan curvature, topographic wetness index, sediment transport index and stream power index were calculated from a 30m grid cell size digital elevation model. Multiple regression models were developed between soil and topographic characteristics and yield components. 20 out of 100 samples were used to validate the model prediction. Coefficients of correlation matrix showed that elevation and calcium carbonate equivalent have the strongest correlation with wheat yield components. Soil factors including calcium carbonate percentage and organic matter and topographic indices such as elevation, slope and stream power index were entered into the regression models. Because of non-linear and complex interrelation, the regression models explained only 43% and 40% of total and grain yield variations, respectively. The results of this study showed that although Sisab is located on the border of arid and semiarid climate, the topographic characteristics could affect soil properties and wheat yield components.
