SEDIMENT LOSS AND NUTRIENT RUNOFF FROM THREE FERTILIZER APPLICATION METHODS

摘要

A localized compaction and doming (LCD) applicator has been shown to reduce nitrate leaching and increase nitrogen use efficiency in corn. The effects of LCD on sediment and nutrient losses in sloping fields are not well understood. During a two-year period (2003-2004), sediment and nutrient losses for each significant runoff event from corn plots were measured. A study was designed to compare losses from plots prepared using the LCD to those prepared using conventional no-till broadcast (NTB) and no-till coulter injection (NTC). These devices were used to apply recommended fertilizer rates (N-P ₂ O ₅ -K ₂ O = 143-116-67 kg ha -1 ) as well as a bromide tracer. Concentrations of nitrogen and bromide in the soil profile were also determined to quantify anion movement. For early rainfall events, there were significantly less runoff and soil erosion from LCD compared to the other treatments, but there was more sediment loss for later events in 2004. Total sediment loss for LCD was 1.6 Mg ha -1 , which was significantly greater than sediment loss for NTC (0.1 Mg ha -1 ) and NTB (0.2 Mg ha -1 ). Masses of bromide, nitrate, phosphate, total nitrogen, and total phosphorus in runoff for LCD were significantly less than the corresponding masses for NTB and NTC in 2004. Residual concentration profile values implied that nitrate applied by the LCD applicator was transported more slowly through soil compared with the other methods. These results showed that the LCD method can reduce phosphorus loss in runoff, although on sloping fields it appears to result in more soil erosion