Nutrient losses are influenced by the soil tillage system. In general, nutrient concentrations in runoff are higher in soil conservation tillage systems, whereas the total nutrient losses are higher in conventional soil tillage. The NH4+ and NO3- losses in water and mineral nitrogen in runoff sediment were determined under natural rainfall in the following tillage systems: six years of no-tillage (NT6), nine years of no-tillage (NT9), nine years of chisel plow plus disking cultivation (CD9), nine years of plowing plus double disking (PD9) and nine years of plowing plus double disking without crop planting (BS9). The experiment was conducted on an Inceptisol (Haplumbrept) with a mean slope of 0.102 m m-1 from November 1999 to October 2001. In the treatments with soil cultivation a rotation of crops including bean, vetch, maize, and oat was used and, in crop succession, soybean, wheat, soybean, and wheat was adopted. Soil and water losses were higher in the conventional soil tillage than under soil conservation tillage systems. The NH4+ and NO3- concentrations in the runoff water from conventional soil tillage were lower than from soil conservation tillage, while the mineral nitrogen concentration in runoff sediment from the soil conservation was lower than from the conventional tillage treatments. Total NH4+ and NO3- losses through runoff water and nitrogen losses through the sediment were lower in the soil conservation than in the conventional soil tillage system.
nutrients losses; sediments; runoff
