Spatially explicit assessment of nutrient demands for promoting efficient regional fertilizer-use management in Vietnam
To transition to efficient fertilizer use for promoting food production, a wide range of stakeholders need to know nutrient demands for meeting crop yield potentials over an agricultural region. Knowledge about spatial patterns of these demands, however is often deficient in developing countries. This study (1) assesses the nutrient demands of potential crop productions in two intensive agricultural regions in Vietnam (Dong Nai and Bac Ninh provinces), and (2) provides public access to the output. We calculated the nitrogen (N), phosphorus (P) and potassium (K) demands for reaching crop yield potentials over the farmlands in the two provinces, taking soil nutrient balances into account. The balance calculations considered the effects of natural nutrient supplies (e.g., from soils), and different natural nutrient losses (e.g., by volatilization, erosion, leaching, runoff and crops’ uptake with different fertilizer use efficiencies). The results were spatially explicit, presented at a map scale of 1:100,000, and managed by a Web-based Geographic Information System (GIS). The web-based GIS allows lay users to query the results at different levels of aggregation (i.e., farm, commune, district and province) in a responsive and iterative manner.