Validation of a New Scheme for Determination of Irrigation Depths Using a Numerical Model of Crop Response to Irrigation and Quantitative Weather Forecasts.

A scheme to determine irrigation depths using weather forecasts was incorporated into a numerical model of crop response to irrigation and quantitative weather forecasts. A concept of net income as a function of cumulative transpiration over an irrigation interval was used to optimize an irrigation depth. The objective of this paper was to validate the effectiveness of such scheme on irrigation amounts and net income as compared to automated irrigation method. A field experiment was carried out in Arid Land research Center, Tottori, Japan in 2016. It consisted of two treatments 1) treatment A was automated irrigation and 2) treatment S was the proposed scheme. The soil was sand and the crop was sweet potato (Ipomoea batatas (L.), cv. Kintoki). Results showed that the proposed scheme achieved higher net income 1.5 times compared to treatment A. It also could save irrigation water and increase yield production by 18% and 47% compared to treatment A, respectively. Observed values of water content agreed well with the measured ones. Obtained results emphasized that proposed scheme can be altered with automated method if appropriate parameter values for soil and crop are used.