Influência da adubação nitrogenada na Sabiá (Mimosa caesalpiniifolia Benth) em sistema integrado , no ecótono de transição Amazônia - Cerrado

Abstract

In the Amazon-Cerrado transition ecotone region, there are high rainfall, temperature and soils with low nitrogen (N) availability, as nitrogen fertilizers burden production costs, it becomes necessary to ensure their maximum efficiency, through doses suitable. The introduction of tree legumes in agrosilvopastoral systems is a possible approach to the intensification of integrated systems, which, in addition to contributing to symbiotic N fixation, provides an increase in forage production. The objective of this research was to evaluate the chemical composition, dendometric, the effect of tannin on larval unsheathing and soil moisture under levels of nitrogen fertilization, in an Agrosilvipastoral System, in the Amazon-Cerrado transition ecotone. The experiment was conducted at the ICLF Technological Reference Unit -URT of the Brazilian Agricultural Research Corporation (Embrapa), Cocais unit, located in the municipality of Pindaré-Mirim/MA. A randomized block design with four treatments and three replications was used. Each block had 1 ha and was divided into 12 plots of 0.25 ha. The treatments were: no nitrogen fertilization (0 N); application of 100 kg of N ha-1 year-1 (100N); application of 200 kg of N ha-1 year-1 (200 N); application of 400 kg of N ha-1 year-1 (400 N). Two test animals were used per paddock, while the adjustment animals were used based on the DM forage offer per kg of animal live weight. For sabiá evaluation, two collects were carried out with an interval of eight months and 72 trees were selected per collect to determine the plant stand per plot, stem length (SL), density, volume, height of Lorey (hL), diameter in the breast height (DBH), base diameter (BD) and total aerial biomass (leaves and branches). For the chemical composition of total biomass (leaves and branches), crude protein (CP), dry matter (DM), mineral matter (MM), nitrogen (N), in addition to BNF (leaves) were determined. Statistical analyzes were performed using the ProcMixed program from INFOSTAT. The means of each treatment were compared using the Tukey test, at the 5% probability level. The results found, in relation to the thrush dendrometric variables, there was no significant difference (P<0.05) between the evaluation levels for the variables Dry Matter (DM), mineral matter (MM), crude protein (CP) Fiber in Neutral Detergent (FDN) and Fiber in Acid Detergent (FDA) however, the treatment with 200N had a greater increase in all variables, with an average DB of 9.03 cm, average DBH of 7.78 cm and average height of 6.66 m, for Lorey's height, an estimated average height of 6.66 m was found at 5 years of age. The estimated average volume of sabiá wood was 0.5 m³. Regarding the chemical composition, in the leaf and branch fraction, there was no significant difference (P>0.05) between the evaluation levels for the variables Dry Matter (DM), Mineral Matter (MM), Crude Protein (CP) Fiber in Neutral Detergent (FDN) and Fiber in Acid Detergent (FDA). As for larval unsheathing, the ketonic leaf extract of the 100 N (kg ha-1year-1) treatment of M. Caesalpinifolia Benth showed the most effective result, inhibiting larval unsheathing by 100% at a concentration of 1.2 mg mL -¹. Regarding soil moisture, there was no significant difference (P>0.05) between treatments and evaluated distances. Thus, it is concluded that, regarding the different levels of nitrogen fertilization, the dendrometry and chemical composition of thrush were not influenced in the agrosilvopastoral system. However, the leaf extract of Mimosa caesalpinifolia Benth fertilized with different levels of nitrogen obtained satisfactory results in the inhibitory activity of larval unsheathing.