Assessment of soil nutrient balance: Approaches and methodologies

The publication presents a state-of-the-art overview of nutrient-balance studies. It brings out the evolution of the various approaches and methodologies, provides for comparisons among them, and highlights the improvements made and the issues that are still to be addressed. It categorizes case studies into macrolevel, mesolevel and microlevel classes. The macrolevel is used for national, continental and global farming-system levels. The mesolevel coincides with the level of the province, district and agro-ecological zone. The microlevel is largely defined as the farm or village level. For each case, the study explains the methodological approaches, the elements of the nutrient balance, and the calculation of the nutrient flows.