BALANCE OF NITROGEN FLOWS IN FARMS FOR ESTIMATION AND OPTIMISATION OF FERTILIZING STRATEGIES

Abstract

Nitrogen surplus in farms which can be assessed by balance-methods uncontradictedly represents a key indicator for the estimation of nitrogen efficiency as well as for environmental load caused by agricultural management. Different methods for nutrient balance are evaluated concerning their reliability and usability.

Farm- and field-balance according to farm gate-method - in combination with a weak-point analysis via “balance at the field scale” for optimisation of fertilization strategies - are predominantly suited for intra-farm and external utilization of balance results. A long-time experiment shows that prediction of nitrogen loss potential by nitrogen balance only works when changes in soil-N-pool are considered. The revised fertilization regulation for Germany contains benchmarks for N-surpluses determined by field-balance. Those and further in domains of agriculture and environmental protection published valuation standards are discussed.