The Influence of Oxisol Physics Parameters on Dry Matter Production in Grasses of Brachiaria Genus

Abstract

The aim of this study was to assess the correlation between physical attributes of a Yellow Oxisol and the shoot dry matter production in grasses from the Brachiaria genus in the Brejo region, in Paraíba. The experiment has been conducted since 2005 in an experimental area of the Center of Agricultural Sciences of the Federal University of Paraíba, Areia-PB (6°58’12’’ S; 35°41’15’’ W and 573 m altitude). The experimental design adopted was that of randomized complete blocks (RCB) with 4 treatments and 4 replications. T1- Brachiaria decumbens Stapf.; T2- Brachiaria brizantha (Hochst) Stapf.; T3- Brachiaria humidicola (Rendle) Schwnickerdt Vr.; T4- Brachiaria brizantha MG5 cv. Vitória. The soil in the experimental area was characterized as Dystrophic Yellow Oxisol with clay-sandy texture. Soil samples with disturbed and undisturbed structure were collected within the 0.0-0.10 m layer. The shoot dry matter of grasses was collected in october of 2018. The analyzed variables were: bulk density (BD), compaction degree (CD), total porosity (TP), macroporosity (Ma), microporosity (Mi), field capacity (θ_FC), permanent wilting point (θ_PWP), available water content (θ_AWC), soil aeration capacity (SAC), mean weighted diameter of wet and dry aggregates (Wet and Dry MWD), aggregate stability index (ASI) and saturated hydraulic conductivity (K_θ). The Student’s t-test and Pearson's correlation analysis (p <0.05) were performed. It was concluded that dry matter production was positively influenced by θ_FC and θ_PWP. And the increase of the average values of BD, CD, Wet and Dry MWD favored the increase of shoot dry matter production by grasses.