Modelling soil water dynamic in rain-fed spring maize field with plastic mulching

Abstract

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two different approaches to represent the rainfall infiltration in irrigated field with plastic mulching: ‘BP’ – an approach comprised by bare strip boundary and plastic strip boundary without consideration of film side infiltration;‘BP + ’- an approach comprised by bare strip and plastic strip with integrating the process of film side infiltration by increasing the rainfall infiltration amount in bare strip. Nevertheless, the performance of these approaches has not yet been evaluated in rain-fed fields. Considering much more dominant role of rainfall infiltration in rain-fed agriculture, we tested an additional approach which comprised a bare strip, plastic strip and planting hole (BPH) to take into account the effect of the rainfall canopy redistribution and film side infiltration, and we compared its performance to the two existing approaches. Results suggested BP completely failed to reproduce the soil water content (SWC) in all soil layers of plastic strip and in the deep soil layers of bare strip. BP+ overestimated the SWC in 0–20 cm of the bare strip, while the performance of BPH was acceptable in different positions. After that, we compared the soil water distribution between no-mulched field (NM) and plastic mulched field (PM) with approach BPH. Our simulation showed that the highest SWC in PM occurred near the planting hole, SWC in the center zone of plastic strip was lower, while SWC in the bare strip was lowest. PM improves the soil water availability not only in the plastic strip but also in the bare strip as compared to NM.