Indicators of the Biological Quality of the Soil in Agroforestry Systems: A Case Study in the Amazon- Brazil

In Brazil, especially the Amazon region, it is characterized by presenting environments with natural forests and extensive areas in agricultural use, with great concern about soil degradation due to increased deforestation and inadequate management of pasture areas, causing changes in biological properties from soil. AFS have been suggested as good alternatives because they promote greater biological diversity with sustainability in the soil, due to the advantages of interleaving different species in the same area. In this context, the objective of this work was to evaluate the biological attributes of the soil in the oil palm cultivation systems with intercropping. The experimental area is located of São João da Baliza, Vicinal 26, km 12, with geographic coordinates of reference 00º.51'13.3''N and 60º00'19.8''W, the altitude of 100 masl and, distant to 352 km from the capital Boa Vista, state of Roraima realized in 2016. The experimental design used was completely randomized with four repetitions and six treatments: Oil palm (Elaeis guineense Jacq.) interspersed with pineapple (OPi), bean (OBe), banana (OBa), yucca (OYu) and Brachiaria humidicola (OPa), as well as adjacent area only with Brachiaria humidicola as a witness (Pa). The Tukey test was used at a level of 5% probability in samples analyzed at a depth of 0-0.10 m, to compare the means of the variables evaluated. The TOC presented values between 4.70 and 9.45 g kg-1, being the highest values found in the interim systems OYu, Pa, OBa, highlighting the intermediate system OPi that presented the lowest levels. The highest basal respiration values of the soil (RBS) (23.50 mg C-CO2 kg-1 soil h-1) and carbon from microbial biomass (C-BMS) (116.0 mg C microbiano kg-1 soil) were verified in the pasture system. Likewise, for the urease and acid phosphatase activity, the grass system stands out as a control with values of (148.42 g NH4+ g-1 soil 2h-1) y (230 μg de p-nitrofenol g-1 soil h-1) followed by palm with grass and yucca systems. However, the β-glucosidase activity (51.22 μg p-nitrofenol g-1 h-1) it was positively influenced by the oil palm system with yucca. On the other hand, the system interspersed with pineapple showed a higher metabolic coefficient (qCO2) (0.36 mg C-CO2 g-1 C-BMS h-1). It can be concluded that the pasture system (Pa) is presented as a more stable environment, followed by interspersed systems of oil palm with grass (OPa) and yucca (OYu).