How does pig slurry fertilization influence percolated water and runoff erosion? A study of the soybean cycle in Brazilian Cerrado soil

Abstract

The objective of this study was to evaluate the effects of pig slurry (PS) and chemical fertilizer (NPK 02–20–20) applications on soil water infiltration; sediment, water and nutrient losses by runoff; and soybean yield during a soybean (Glycine max L.) cropping cycle. A field study was carried out in Rio Verde, Goiás, Brazil on a Cerrado Oxisol managed with no tillage. The experiment was arranged as a randomized block design with three replications and treatments. The treatments consisted of two doses of PS, 25 and 100m3ha−1, and chemical fertilization at 370kg ha−1 (NPK 02–20–20) applied to the soil surface in a single application. After the occurrence of rainfall events, the volume of percolated water in lysimeters and the sediment and water losses in plots was measured. To determine the macro and- (Ca, Mg, K, P) micronutrients (Fe, Mn, Cu, Zn), runoff water was collected. We also assessed the dry biomass and productivity of soybean production at the end of the experiment. Treatment with 25m3ha−1 of PS resulted in higher amounts of (106mm) percolated water in the soil (p>0.05). Neither losses of water, sediment and nutrients or biomass production and soybean productivity were significantly affected by the PS treatments compared with chemical (NPK) fertilization (p>0.05). A trend of higher sediment and water losses was observed in the 25m3ha−1 PS treatment (249.86kg ha−1 and 20.58mm, respectively) compared with the 100m3ha−1 PS and chemical (NPK) treatments; the 25m3ha−1 PS treatment showed ~10% and ~43% higher values of sediment losses, respectively, and ~43% and ~23% higher values of water losses, respectively. Regarding soybean productivity, the 25m3ha−1 PS treatment showed a tendency of low productivity (3405kg ha−1) that was ~15% and ~20% lower than that of the 100m3ha−1 PS and chemical (NPK) treatments, respectively. The low values of sediment and water required per kilogram of soybean produced in the chemical fertilization and 100m3ha−1 PS treatments indicate that these management regimes are more sustainable.