Nutrient balances and present state of available nutrients in the soil

Abstract

A widely accepted approach to evaluate the sustainability of agricultural production concerning the nutrient status is to calculate nutrient balances (= input — output of nutrients). For this it is necessary to register all nutrient outputs (uptake by main product and by-product, leaching) and nutrient inputs (use of fertilisers, atmospheric deposition, use of sewage sludge, nitrogen fixation, use of seeds and planting material). Based on statistic data and results from field experiments decreasing nutrient balances of N, P and K were calculated for the Czech Republic for the period 1985 to 1998. This was mainly due to decreasing fertiliser input. Since 1992 negative balances are obtained for P and K, positive balances for nitrogen of more then 25 kg N ha⁻¹ year⁻¹ remained until 1998. Negative balances for P and K tend to correspond with decreasing P and K contents in soil.