Modelling soil thermal regime in wheat using HYDRUS-2D under diversified maize-wheat-mungbean cropping system

Abstract Although conservation agriculture (CA) practices are being promoted, there is insufficient information on how these activities affect soil thermal regimes. An experiment was conducted in the long-term CA condition to compare soil hydrothermal environment with conventional agriculture under wheat crop. Two different tillage practices viz. zero tillage with residue retention (ZT + R) and conventional tillage with residue incorporation (CT + R), were followed. Soil temperature was observed at 2, 10 and 20 cm soil depths at 2 h interval using platinum resistance digital soil thermometer during three simulation periods, 33–52, 77–93, 106–125 days after sowing (DAS). Simultaneously, soil moisture content at 0–5, 5–15 and 15–25 cm were measured by gravimetric method to compute heat parameters. It was observed that maximum soil temperature (ST) was under CT + R than ZT + R. Maximum ST was 17.3, 13.9 and 13.6 °C at 2, 10 and 20 cm, respectively under ZT + R, on 85 DAS while it was 18.1, 14.6 and 14.1 °C, respectively under CT + R treatment. The amplitude of ST was high at depth of 2 cm than at 10 and 20 cm and it was also higher under CT + R than ZT + R. In this study modelling using HYDRUS-2D was carried out to simulate the ST. Soil thermal parameters were optimized using inverse solution approach and used for model. Accuracy of the simulation using HYDRUS-2D, was assessed by comparing the predicted values against observed. Results indicated a better performance of the model in predicting the ST for 2 and 10 cm depth with R2 between 0.66 and 0.87 and 0.71–0.85 for ZT + R and CT + R, respectively during all the three simulation periods. The performance was less satisfactorily for 20 cm depth with R2 between 0.47 and 0.55 and 0.53–0.69 for ZT + R and CT + R, respectively during all simulations.