Modelling soil water and nutrient dynamics under different irrigation techniques of onion production

Abstract

Irrigation remains important to meet the needs of the people by increasing agricultural productivity. However, its water productivity in developing countries is low due to inefficient irrigation water management. The main objective of this study was to evaluate soil water, crop growth and nutrient dynamics under different irrigation techniques. Hydrus-1D model was used to simulate soil water content (SWC), actual evapotranspiration (ETa) and soil leachates. The model performance was evaluated by comparing the measured and simulated treatment variables. The Hydrus-1D performance showed good agreement between the observed and simulated SWC (R2 = 0.55–0.81; NRMSE = 0.01-0.09; d-index = 0.95-0.99) and with a very good agreement for nitrate-nitrogen (NO3–N) leaching (R2 = 0.97, d index = 0.99 and NRMSE = 0.02). Similarly, performance in simulating PO4-P were acceptable (R2 = 0.88; d index = 0.99; NRMSE = 0.04). The value of SWC (cm3 cm−3) ranged from 0.30 to 0.38 at 10 cm and from 0.27 to 0.37 at 20 cm soil depths. The seasonal drainage water was reduced to 86%, 87%, and 54 %, respectively for AFI, FFI, and OHI treatments compared with CFI treatment. The NO3–N leaching was reduced by 41%, 71%, and 83% under AFI, FFI, and OHI compared with CFI while phosphate – P (PO4-P) leaching was 60%, 66%, and 79.6%, respectively, lower in AFI, FFI, and OHI than CFI. The highest seasonal ETa (421.95 mm) was found in CFI while the lowest (335.22 mm) was found in AFI treatment. Besides, the highest IWP (9.11 kg/m3) was obtained from AFI technique indicating that that AFI was the most efficient irrigation technique in saving both nutrient and water under onion production. Hydrus-1D could be a successful tool for predicting water and nutrient transport management decisions to improve water and nutrient management.

Keywords

• Soil water dynamic
• nutrient dynamics
• irrigation technique
• Hydrus-1D