Verifying the nitrification to immobilisation ratio (N/I) as a key determinant of potential nitrate loss in grassland and arable soils Elizabeth A. Stockdale, David J. Hatch, Daniel V. Murphy, Stewart F. Ledgard and Catherine J. Watson Agronomie, 22 7-8 (2002) 831-838 DOI: 10.1051/agro:2002060