Nutrient Budgets And Their Implication On Soil Fertility In Organic Farming Across Europe

Knowledge of nutrient budgets of organic farms and their effect on soil nutrient contents across Europe is relatively limited. Therefore, a meta-analysis was conducted to investigate the nutrient supply of organic farms as affected by budgeting method, farm type and studied country. Further, an assessment was performed relating nutrient budgets with soil nutrient contents across five countries. We found an average surplus of N, an almost balanced budget for P and a deficit for K. Yet, nutrient budgets varied over a wide range. Farm type, more than the studied country or budgeting method, was able to explain some of the variations, with vegetable farms having higher surpluses, especially for N, than dairy farms, followed by mixed or stockless farms. Soil nutrient contents showed also considerable differences among farms and countries. A relationship between soil nutrient content and budget was found only for P, which indicates negative P budgets as a real risk for soil P depletion