Modelling resource competition and its mitigation at the crop-soil-hedge interface using WaNuLCAS

摘要

Agroforestry systems have a large potential to increase systems' productivity and provide soil conservation in hilly terrain but comprise complex interactions at the crop-soil-tree interface. Modelling can be an operational approach to unravel the later. We used the spatially explicit, dynamic Water Nutrient and Light Capture in Agroforestry Systems model to (i) predict maize above ground biomass (AGB) and interactions at the crop-soil-hedge interface, (ii) improve our understanding of trees' impact on crops in alley cropping, and (iii) identify mitigation strategies. A 2-year-data set from a soil conservation experiment in Western Thailand with maize farmers' practice (monocropping, tillage), maize-chili-hedgerow intercropping (+/- fertilization; minimum tillage) was used as model input. Model validation showed satisfactory results for maize AGB (R-2 = 0.76, root mean square error = 4.2, model efficiency = 0.69). Simulations revealed nitrogen (N) and phosphorus (P), rather than light and water, as main limiting factors at the crop-soil-hedge interface reducing maize AGB in rows close to hedgerows. Growth limitation by P was stronger than that of N while light competition was alleviated by four to six hedgerow prunings already. WaNuLCAS simulations clearly indicated that small-targeted additional N and P dressings to maize in rows close to hedges helped overcoming nutrient competition. Such strategic management options can be done for local farmers' and hence, foster adaptation of soil conservation techniques for sustainable crop production in future.