Modelling crop residue mulching effects on water use and production of maize under semi-arid and humid tropical conditions

A key principle of direct seeding mulch-based cropping systems is the retention of crop residues on the soil surface to preserve soil water for crop growth. In this study the impact of surface crop residue on water use and production risk associated with rainfall variability is analysed for two contrasting tropical sites. The two sites are La Tinaja in semi-arid Mexico and Planaltina in humid Brazil. The crop growth model STICS, version 3.0 was updated with a simple empirical module, incorporating the following effects of surface residue on soil water balance: (1) rainfall interception and subsequent mulch evaporation; (2) radiation interception with associated reduction of soil evaporation and (3) reduction of surface water runoff. The results of the model simulations showed that the effect of radiation interception at both sites was much more important than the effect of intercepting rain.[...]