Development and Evaluation of an Integrated Water, Salinity, and Nitrogen Model: ENVIRON-GRO.

Salinity in irrigated cropland significantly affects food and fiber production. Thus it is imperative to understand the interaction between soil water salinity and crop yield. A simulation model was developed to evaluate the integrated effects of water, salinity, and nitrogen on crop growth. The model can be used to evaluate: (1) response of plant to water, salinity and N stresses; (2) water, salt, and nitrogen dynamics in the soil profile; and (3) balances of water, salt and nitrogen to improve water and fertilizer use efficiency and assess salt and nitrate leaching. The simulated relative yields of cotton and salt distribution from the ENVIRO-GRO model were compared with measured yields and salt distribution from a three-year field experiment in Xinjiang, China. A good agreement between simulated and observed cotton relative yield and average electrical conductivity of saturated extract (ECe) in root zone was observed. Both simulated and measured data showed that salt accumulation in the soil profile increased as irrigation water salinity level increased, depending on irrigation water salinity and irrigation scheduling. Cotton yield was not influenced by water salinity in the first year, but decreased significantly as the salinity level of the irrigation water increased in the second and third year. A comparison between ENVIRO-GRO (transient-state model) and WATSUIT (steady-state model) reveals that the WATSUIT predicted higher average EC_e values in the root zone, which often overestimated the negative impact of saline water irrigation. Our results showed that the ENVIRO-GRO model can be used with confidence in simulating the consequences of irrigation management options under saline conditions.