Virtual nitrogen as a tool for assessment of nitrogen management at the field scale: A crop rotation approach

摘要

The efficient management of nitrogen (N) requires accurate quantification of the critical components of the N balance. N budgeting was conducted on a production farm at Gorzno, Poland during the 2004-2007 growing seasons for 17 crop sequences: ten oil-seed rape and winter wheat, six maize grown for grain or silage, and one onion monoculture. The measured N components were: i) soil N mineral content measured at 0.0-0.3, 0.3-0.6, and 0.6-0.9 m depths in the soil profile prior to spring growth and immediately after harvest, ii) applied N from fertilizer and farmyard manure, and iii) N content in the harvested crop products and crop residues. Two budgeting procedures, soil surface balance (SSuB), and soil system balance (SSyB), were used to evaluate the impact of cropping sequences on N management. The total N input ranged from 223 to 313 kg N ha(-1), primarily derived (40-50%) from the soil mineral N (N-min). The N output depended on the N content in the harvestable crop component (R-2 = 0.93).