Integrated sensing device for irrigation scheduling: field evaluation and crop water stress index estimation of wheat

Abstract

An integrated sensing device for irrigation scheduling (ISDI) was developed to assess the soil–plant–atmosphere continuum for irrigation scheduling. In the present study, a field experiment was carried out to evaluate the performance of ISDI. ISDI was used to determine crop water stress index (CWSI) across various irrigation regimes in wheat crop at the WTC farm, ICAR-IARI, New Delhi, India. The experiment considered were full irrigation (FI) and various deficit irrigation levels (DI-15, DI-30, DI-45, and DI-60), receiving 15, 30, 45, and 60% less water in comparison to FI, respectively. The calibration and performance of the ISDI sensor probes in the field was done with gravimetric methods along with time domain reflectometry (TDR) and a handheld infrared thermometer. The field calibration of the ISDI's soil moisture probe and TDR gave promising results, with R² values ranging from 0.76 to 0.81 and 0.81 to 0.86, respectively, for soil depths up to 45 cm. ISDI's infrared sensor probe also demonstrated strong alignment with a handheld infrared thermometer (R2: 0.95), indicating reliable methods. Furthermore, a regression equation for estimating the lower baseline and upper threshold for CWSI computation was derived as (Tc − Ta)ll = 1.97 × VPD − 1.43 with R2 of 0.86 and 1.93 °C, respectively. It was also recommended to initiate irrigation when CWSI was ≥0.35 for wheat to achieve optimal crop yields.