Mineral Nitrogen and Phosphate Cycles in Different Agroecosystems

Abstract

The current investigation compared various intensive crop rotations (Norfolk, row crops, cereals, short-term grass) grown on Cambisols. The results showed significant effects of N fertilization on the agroecosystem and N balance, and on the mineral N concentration in drainage water and its leaching process. The highest N concentration in drainage water and leaching was determined in the cereals and row crops rotations. No major impact of the crop rotation on the P-PO 4 3Ϫ concentration in drainage water was determined. The average leaching of P-PO 4 3Ϫ by drainage did not exceed 100-140 g ha Ϫ1 within a seven-year study period. A rational and well-considered fertilization regime ensures high crop productivity and profitable farming as well as a steady, close-to-neutral N balance, which is the main condition for reducing the non-point source pollution of water.

Sustainable Agriculture

“…This analysis also revealed that the fertilisation rate was not higher than the plant requirements (considering plant-available nutrient storage in the soil) and that minimal tillage systems are more effective in reducing leaching than changes in crop rotation. In other studies on Cambisols where different crop rotations were compared, the highest average DIN (dissolved inorganic nitrogen) concentration in drainage water and total leaching was determined in cereals and row crop rotations (Aksomaitienė et al, 2004), but there was no major impact of these crop rotations on phosphate concentration in drainage water and leaching. Green manure crops or leys before winter cereal sowing will not always catch the available soil mineral nitrogen, as in wet autumns it might migrate to deeper horizons and leach with drainage runoff (Romanovskaja and Tripolskaja, 2003).…”