Large-scale impacts of nutrient management on soil acidification and cadmium mobilization in Chinese croplands

Samenvatting (Engelstalig)

Elevated nitrogen (N) fertilizer application has largely increased food production in China but also enhanced soil acidification of croplands, causing crop yield decrease and cadmium (Cd) accumulation in crops. This thesis amis to develop a sustainable management strategy to avoid acidification-induced crop yield decrease and Cd accumulation in crops, simultaneously minimizing N and phosphorus (P) surpluses. Mitigation management mainly focus on replacing mineral fertilizers by manure, applying fertilizers based on balanced crop nutrient demands and adding lime for remaining soil acidification. The variations in land use, soil properties and climate were taken into account to assess site-specific impacts. Models were used to assess soil acidification (VSD+) affecting crop yield and soil Cd accumulation (mass balance approach), affecting Cd uptake and crop Cd contents. Critical values for pH and crop Cd contents, in view of crop yield and crop quality, were used to assess site-specific optimal fertilizer, manure and lime applications.