Journal
AGRICULTURAL WATER MANAGEMENT
Volume 150, Issue -, Pages 18-34Publisher
ELSEVIER
DOI: 10.1016/j.agwat.2014.11.009
Keywords
Wheat modeling; Grain yield; Water and nitrogen application; Evaporation; Transpiration
Categories
Funding
- Shiraz University Research Council [92-GR-AGR 42, 92-GR-AGR-40]
- Drought National Research Institute
- Center of Excellence
- Higher Education Ministry of IR Iran
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Model WSM (Wheat Simulation Model) was developed based on the previous model (MSM, Maize Simulation Model). The planted cultivar was Shiraz with five irrigation treatments (1.2, 1.0, 0.8, and 0.5 ratios of the potential irrigation requirement under surface irrigation system and rain-fed) and four applied nitrogen treatments (0, 46, 92, 136 kg N ha(-1)). The irrigation water requirements were estimated by measuring the differences between soil field capacity and measured soil water content at root depth in the full irrigation treatment before irrigation. In the WSM model, dynamic flow of water, nitrogen, and heat through the soil were simulated numerically in an unsteady state condition at soil profile. Water and nitrogen transfer in the soil are governed by the Richard's equation and the diffusion convection equation, respectively. Emergence time of seed after sowing was simulated using soil water content, temperature, sowing depth, and soil particle diameters using beta function. Plant growth stages were simulated considering photoperiod, vernalization and air temperature. Hourly simulation of actual evaporation from soil surface and transpiration were simulated using the Penman-Monteith method based on atmospheric conditions and soil water content at root depth. Nitrogen uptake was simulated through mass flow and diffusion processes during the growing season. Produced dry matter was simulated as a function of hourly corrected intercepted radiation (based on air temperature) by plant leaves, maximum and minimum plant top N concentration and the amount of N uptake. Wheat grain yield was simulated by the ratio of grain N uptake and grain N concentration that were estimated by an empirical equation as a function of simulated top N uptake. Obtained experimental data in 2009-2010 were used to calibrate the model. The experimental results from 2010 to 2011 validated favorably the proposed model. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.
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