Nitrogen and Phosphorus Losses with Drainage Runoff and Field Balance as a Result of Crop Management

Abstract

Two high‐input and two low‐input crop‐management systems, one reference treatment with field crop rotation, and one long‐term moderately treated pasture were studied and compared in respect to nitrogen (N) and phosphorus (P) flow and balance. The experiment was conducted on tile‐drained plots covered by Endocalcari‐Endohypogleyic Cambisols. The least Nmin (mineral nitrogen) leaching losses were registered in the pasture. The high‐input management systems did not consistently result in larger losses of Nmin mainly nitrate (NO₃)‐N] and Ptot (total phosphorus) in the drainage water. The leaching of Nmin depended more on amount of the drainage water leaving the site, soil organic matter/humus, and soil Ntot content (positive correlation) as well as the content of water‐stable aggregates (negative correlation). The higher concentrations of Ptot in drainage runoff in the organic (ORG1) treatment and pasture during the second rotation might be conditioned of ley root system impact. Ptot leaching was positively correlated to the available P₂O₅‐AL in the topsoil. Negative N field balance was determined in all the treatments, except ORG2 and LTP in 1995–1999, whereas it was negative only in the reference plots (REF) in the 2001–2003 rotation because of the increased crop residues and drier climatic conditions. Phosphorus balance was slightly negative in the ORG1 and reference treatments during both rotations.