Quantificação de coprólitos de minhocas nativas em latossolo amarelo cultivado com braquiárias na ausência e presença de adubação mineral

Abstract

In the formation of soils, aggregates formed occur because of natural factors of soil formation and aggregates sourced from alternative genetic processes, these are aggregated biogenic originate of the activity from soil macrofauna. The objective of this study was to evaluate the production and the quality of native earthworm coprolites "geófaga" in Oxisol, located in Areia - Paraíba, pastures with Brachiaria in the absence and presence of mineral fertilizer with nitrogen-phosphorus-potassium (NPK). The experiment was conducted at the "Farm Tea Garden", belonging to the Center of Agrarian Sciences, Federal University of Paraíba. It was used the randomized block design in split plot design with four replications. In the plots had been the Brachiaria species (B. decumbens, B. brizanta, B. humidicola ruziziensis B., B. MG-5) and the subplots the presence or absence of fertilization. Samples were collected in coprolites produced by earthworms, every 35 days, thus totaling ten collected, being five in the rainy season and the five dry season for a year. Besides the quantity of coprolites produced, were made to determine the quality of the coprolites through physical analysis (aggregation, size and aggregate stability). From the results, there was the largest production of coprolites in the wet season and the two fertilization conditions in the presence of mineral fertilizer and cover crops tested. Besides the quantity of coprolites produced, were made to determine the quality of the casting from their physical analysis (aggregation, size and aggregate stability). From the results there was the largest production of coprolites in the wet season and the two fertilization conditions in the presence of mineral fertilizer and brachiarias tested. The largest production of coprolites was obtained by Brachiaria decumbens, which distinguished than the other grasses. There was, still, a significant interaction between grasses and fertilizing. As to the physical quality (biogenic aggregates) there was that these aggregates gave the best pedogenic. The higher soil moisture provided higher production of coprolites of earthworms, giving the latter, greater resistance to deformation. The higher soil moisture produced higher coprolites of earthworms, giving the latter, greater resistance to deformation. The largest production of coprolites by native earthworms occurred in the rainy season and under mineral fertilizer with NPK, among the species of Brachiarias utilized, the B. decumbens stood out for presenting higher production coprolites of earthworms. The biogenic aggregates produced in areas fertilized, presented more resistant to the disintegration, wherein the greater resistance to the deformation as the casting was provided by mineral fertilizer. Biogenic aggregates (coprolites) were more resistant than pedogenic aggregates (soil aggregates) want under dry sieving or under wet sieving.