Composition of Poultry Litter in Southern Brazil

Determining the chemical composition of poultry litter is important in order to apply this waste as soil fertilizer without causing negative environmental impacts. The aim of this study was to evaluate the average and variability of some chemical parameters of 165 samples of poultry litter produced from confined animal production facilities located in the states of Santa Catarina and Rio Grande do Sul, Southern of Brazil. Samples of approximately 5.0 L were collected on 20 points from the truck at the time the material was unloaded into the application sites. Subsequently, they were oven-dried at 65 °C and analyzed. Values of pH in water, dry matter, N, P and K were determined in all samples; N soluble in water (soluble-N), ammonium (NH+4-N) and nitrate (NO−3-N) were quantified in 50 samples; organic carbon (organic-C) and C/N ratio were assessed in 20 samples. There was large variation in the contents of N, P2O5 and K2O among samples, with the average accounting for 2.2, 3.0 and 2.9 %, respectively; these nutrients correlated with each other. More than 90 % of the N was in the organic form, into which the fraction soluble in water accounted for 21.8 % of the total. Inorganic N was predominantly in the form of ammonium (NH+4-N), and nitrate (NO−3-N) was absent. Average dry matter was 64.3 %, with a median of 66.5 %; pH was always alkaline (average of 7.8), with a low variation coefficient (7.4 %), and was negatively correlated with NH+4-N. The average of organic C and C/N ratio in dry matter was 28.3 % and 11.2, respectively, which results in the immediate release of N to the soil, with no microorganism immobilization. The chemical composition of poultry litters produced in confined systems in Southern Brazil is widely variable. Thus, to be successfully used as soil fertilizer, it is essential to know their composition, mainly in terms of moisture N, P2O5 and K2O contents.