Estimating nitrogen budgets for soil-crop systems

Abstract

Nitrate nitrogen (NO3-N) losses from agriculture into groundwater are a continuing concern for society. The agricultural community must begin to reduce these losses to be responsible stewards of soil and water resources, to improve crop N-use efficiency and farm profitability, and to respond to society’s expectations. A general feature common to many agricultural watershed N budgets is that the largest N03-N losses are associated with sites that receive excess N inputs. This chapter reviews N budget concepts and develops a N-screening model that will estimate field-scale N budgets to quickly identify N-rich sites where potential NO3-N losses to groundwater may be extensive. The first step in constructing a N budget is a clear statement of goals. Specific N budget goals may be to identify knowledge gaps, to identify dominant processes, or to study the interaction of specific N cycle processes.