Physical Quality Indicators of an Oxisol Under Grass in the Agreste Region of Paraiba, Brazil

The aim of this study was to evaluate the influence of different grass cultivars on physical attributes of an Oxisol in the Agreste region of Paraíba. The experiment was set up in 2005 in experimental areas of the Center of Agricultural Sciences of the Federal University of Paraíba, Areia-PB. The experimental design adopted was that of randomized complete blocks (RCB) with 5 treatments and 4 replications, in experimental plots of 50 m2. The treatments were the following: I. Brachiaria decumbens Stapf., II. Brachiaria brizantha, III. Brachiaria humidicola (Rendle) Schweickvr., IV. Brachiaria brizantha cv. MG5-Vitória and V. Brachiaria ruziziensis. In October 2018 samples of soil with disturbed and undisturbed structure were collected at the center of each experimental plot in the depth of 0.0-0.10 m for the determination of the following variables: soil porosity (total, macro and micro), bulk density, compaction degree, saturated hydraulic conductivity, field capacity, permanent wilting point, available water content, soil aeration capacity, clay dispersed in water, flocculation degree and aggregate stability index. The analysis of variance was performed and the means were compared by Tukey’s tests, principal component analysis and Pearson’s correlation analysis (p < 0.05). It is concluded that after the 13-year period, Brachiaria brizantha promoted improvements to the field capacity of the Oxisol. The other attributes were not physically altered. Main component analysis showed that the correlation values were more significant for the Brachiaria brizantha component. Pearson’s correlation was significant between field capacity and soil aeration capacity.