A study on soil moisture model for agricultural water management under soil moisture stress conditions in Sikkim (India)

Soil moisture is a critical component of the earth system that impacts on the water, energy and bio-geochemical cycles. A soil moisture study was conducted for agricultural water management of selected crops in Sikkim (India). An effort was made to quantify extent of soil moisture stress and to develop a soil moisture model for estimating irrigation water requirement. In the study, it was observed that significant stress exists in Sikkim (ranging from 600 to 1620.21 kPa). It has been reported that soil moisture stress above 100 kPa constrains the water uptake capability of any plant and thus it needs to be replenished artificially through irrigation. For efficient irrigation water management, it is necessary to estimate the irrigation requirement. The irrigation requirement was estimated using the developed model for selected crops of Sikkim. The models were tested using various performance assessment parameters such as coefficient of determination (R²) (0.76, 0.66 and 0.63), root mean square error (RMSE) (3.00–6.5%) and mean relative error (MRE) (3–9.18%) for selected locations, viz., Mangan, Pangthang and Gyalshing. The estimated annual irrigation requirement for the selected crops varied from 31.7 to 185.06 mm at different locations, viz., Mangan, Pangthang and Gyalshing.