Biomassa vegetal, atributos físicos do solo e microclima em sistemas silvipastoril com louro-pardo (Cordia trichotoma (Vell.) Arrab. ex Steud) e (Panicum maximum) cultivar Aruana

Abstract

Global awareness of the need to attend the increase in world demand for food sustainably has generated collective efforts in the search for efficient, ecologically correct and economically viable productive models. Thus, silvipastoral systems are increasingly emphasizing and creating space in the crop areas, becoming an alternative capable of maximizing natural resources and diversifying the income of the property. However, there are still many questions and doubts about the behavior of the system as a whole, since different components are inserted in the same area and at the same time. The lack of information increases even more when it comes to a system composed of native species such as the Louropardo, since there is little research on the behavior of this specie in intercropping systems. Thus, the objective of this work was to compare the effect of the cultivation of the Louropardo tree (Cordia trichotoma (Vell.) Arrab. ex Steud) on Aruana productivity (Panicum maximum), the soil physical attributes and the local microclimate. For this, we considered four longitudinal bands allocated between the lines and in the tree lines in a silvipastoral system composed of Louro-pardo and Aruana, an area of pasture with Aruana growing in open sunlight, both pastured by sheep. Soil samples were collected before and after grazing, at depths of 0-5; 5-10; 10-20 cm, for determination of density, microporosity, macroporosity and total soil porosity. The analysis of the mechanical resistance to penetration was performed at depths of 0-5; 5-10; 10-20, 20-30, 30-40 and 40-50 cm. The Aruana production evaluation was carried out in five different moments, with intervals of 21 days between each collection, in the spring / summer of 2016/2017. Data on tree component productivity were collected in April 2017, with the evaluation of total height, crown height, DAP and crown radius. The microclimatic variables analyzed were: mean air temperature (° C), soil temperature (ºC), turf temperature (ºC), photosynthetically active radiation and wind speed (ms-1) performed in three periods of the day (09: 00, 12:00 and 15:00 hours) in 4 days. The experimental design was a randomized block with three replications and five treatments.The results showed that the short grazing period exerted little influence on soil density and porosity. The highest changes were recorded for soil resistance to penetration, with a significant increase in the 0-20 cm layer after grazing. The tree component caused a reduction in the available radiation to the pasture near the tree lines, a decrease in the average wind speed and a small reduction in the air and soil temperature, which resulted in a decrease of pasture production in those bands close to the tree lines. However, it contributes to improve thermal comfort for animals in the adopted silvipastoral system.