Regional application of a cropping systems simulation model: crop residue retention in maize production systems of Jalisco, Mexico

To ensure the productivity of smallholder maize production systems in Central America, increased attention must be paid to conserving soil and water resources. Various stakeholders from national agricultural research services (NARS), networks, non-governmental organizations (NGO's) and research institutes seek to develop and target productivity enhancing resource conserving management practices such as crop residue retention systems. To support this process, a methodology with explicit spatial and temporal dimensions using the DSSAT crop simulation models was developed and applied to the case study of residue retention in maize production systems of Jalisco, Mexico. Systems where crop residues were partially or totally retained were compared with systems with no residue retention. Variables considered included crop production, soil surface runoff water, soil organic carbon and soil organic nitrogen content. Gridded climate surfaces and a range of soil profile scenarios formed the basis of the regional input. Three levels of nitrogen application (0, 150 and 235 kg ha-1) were selected to represent current agronomic practices. Simulation models for maize and fallow were run in sequence for 12 consecutive years. Results demonstrated that soil water holding capacity and topography affected benefits of residue retention much more than nitrogen management. Benefits to maize production from residue retention were found mainly in areas in the northeast of Jalisco and surrounding regions, where low precipitation limits maize production. Reductions in soil surface runoff due to residue retention were most evident in high rainfall areas in the central-east of Jalisco and surrounding regions. Although the effect of soil loss is not accounted for in DSSAT, areas of pronounced soil surface runoff reduction are hypothesized to be areas of productivity gain in the longer term. The assessment provided insight in the regional potential for and the soil and climate conditions under which successful introduction of residue retention in maize cropping systems in Jalisco may be achieved. In combination with socio-economic assessment studies and experimental work, the approach and its results contribute to targeted introduction of new production technologies.