Effect of irrigation uniformity on the profitability of crops

There are numerous models capable of simulating crop behavior under different water stress conditions. However, none of them takes into account the effect of irrigation water uniformity on yield. The model developed simulates the uniformity effect on yield and the repercussion on gross margin (GM). The application of the model to a maize crop in Albacete (Spain) indicates that for the same irrigation depth, an increase in uniformity of water in the soil (CU) corresponds to a 4% increase in yield for the common irrigation strategy in the area, and a 6.8% increase in yield for the optimal irrigation schedule established by the model. Values of percentage of adequately irrigated area (a) between 50 and 80% appear to be adequate for values of CU > 80%. This effect has special relevance on the GM mainly when designing the irrigation strategy of areas with limited water resources. This leads to improvement of CU from 75 to 95% for the common irrigation depth applied to maize and may increase GM up to 27%. For small irrigation depths, the effect of CU on GM is reduced. The maximum GM is reached at ETa/ETm < 1 and a <100%. The paper also describes a methodology for determining the most suitable irrigation schedule under regulated deficit irrigation conditions.

Research highlights▶ Area adequately irrigated (a) depends on the Coefficient of Uniformity (CU). Values of “a” between 50 and 80% appear to be adequate for CU > 80%. ▶ Irrigation uniformity modeling may support farmers and managers in the establishment of the appropriate irrigation strategy, mainly in areas with limited water resources. ▶ TIrrigation scheduling noticeably affect both crop yield and water productivity. This effect has special relevance on the gross margin obtained in irrigated farms. ▶ The model provides an option for selecting the optimal Regulated Deficit Irrigation that may support farmers in areas with water scarcity and/or high water price.