Phosphorus and trace metal dynamics in soils amended with poultry litter and granulates

Abstract

AbstractEnvironmental sustainability of animal agriculture is strongly dependent upon development of approaches to minimize the potential environmental impacts of applying animal manures. The excess manure and its nutrients (primarily phosphorus) in intensive animal production regions may need to be exported to other areas to comply with increased regulations on manure management. In our previous study we generated a variety of granulated products from poultry litter to achieve export of excess litter from the southwestern Ozarks, AR, USA. Our objective in the present study was to determine the effect of the application of poultry litter and granulated litter products on phosphorus (P), arsenic (As), copper (Cu) and zinc (Zn) dynamics in two Arkansas soils (Dewitt silt loam and Hector sandy loam). Poultry litter and granulated products were mixed with the surface horizon (0–15 cm) of soils at two application rates: P‐based (100 kg total P per hectare) and N‐based (160 kg plant‐available N per hectare). Soil–litter mixtures were incubated at 25 °C for 21 days. Sub‐samples were removed at 1, 7 and 21 days to determine the solubility and availability of P, As, Cu and Zn in soils. Results suggest that when litter was applied at 100 kg total P per hectare, contents of P, As, Cu and Zn were significantly greater in the soils amended with litter and granulated products than in the control (soil alone). However, the contents of P, As, Cu and Zn did not significantly differ in the soils amended with either normal litter or granulated litter products at total P or plant‐available N‐based application rates. This suggests that poultry litter granulation is a sound management practice that can be used to reduce concerns with fresh litter transport and potentially improve P and trace element balances in intensive poultry production regions, especially when applied on a plant‐available N basis.