Environmental critical limit of phosphorus (LCA-P) in soils used for the distribution of swine manure

Abstract

The aim of this study was to evaluate the phosphorus levels in soils used for apply swine manure and to identify possible factors that predispose them to exceed the Environmental Critical Limit for P (LCA-P).  Phosphorus levels were assessed in 191 soil samples taken over eight years from 26 properties (two samples per property, three to four years apart). Half of the properties practiced pig production and the other half belonged to third parties who gave up their land to incorporate manure. Only 7.32% of the samples showed an LCA-P above 20% in relation to the limit established by the legislation, 2.09% showed up to 20% above the LCA-P and 90.59% were below this limit. The further the pigsty from the soil sample collection site, the lower the phosphorus content (P ? 0.05), and the greater the number of pigs on the farm, the higher the phosphorus content in the soil samples inherent to the farm owner (P ? 0.05). In the region, the soils that receive pig manure are generally within the LCA-P limits set by the environmental agency.