DECOMPOSITION AND MINERALIZATION OF N,P AND K OF CATTLE MANURE AND POULTRY LITTER ISOLATED OR MIXED

The use of organic residues in the crop fertilizations demand information about the dynamics of decomposition and release of nutrients contained therein. This study aimed to evaluate the decomposition and release of N, P and K from organic residues cattle manure and poultry litter isolates or mixed, using the method of decomposition bags (litterbag) in Alfissol of Coast Tableland in Paraiba State. The experiment was conducted in randomized block with treatments arranged in a factorial 3 × 2 × 5 refers to three organic residues [(cattle manure (CM), poultry litter (PL) and the mixture of these residues in the ratio of 1: 1, called mixed manure (MM)], the incorporation of two layers (0-10 and 10-20 cm) and six evaluation periods (0, 30, 90, 150, 210 and 270 days after application) and three replications. From the results it was observed that the depth did not affect the decomposition of organic residues CM and MM and that it was more rapid in PL (0.0035 g day−1), more slow in CM (0.0010 g day−1) and occurred at a speed intermediate in MM (0.0020 g day−1). It was release more faster of N in MM (0.0011 g day−1), of P in CM (0.0040 g day−1) and K on PL (0.0025 g day−1), with an upward trend in the release of N in the PL and P in all residues with the incorporation at 10-20 cm. After 270 daa, it was estimated that the release of nutrients in the residues CM, PL and MM in relation to the initial content was 5.0, 15.0 and 28.0% for N; 80.0, 68.0 and 47.0% for P; and 20.0, 53.0 and 32.0% for K. In absolute terms, these percentages represented, respectively, 19.0, 103.0 and 149.5 kg ha−1 N, 28.0, 18.0 and 15.0 kg ha−1 P, and 75.0, 493.0 and 209.0 kg ha−1 K. The organic residues proved inadequate to meet the demand alone nutritional short cycle crops in these soils. © 2014, Revista Brasileira de Ciencia do Solo. All rights reserved.