Microclima em diferentes modelos de sistemas silvipastoris

Abstract

Agriculture in Brazil represents a good part of the country's economy, thus, the Silvipastoral Systems (SSP) help to intensify the agricultural system, in addition to promoting environmental benefits, contributing to the recovery of degraded areas, increasing carbon and nitrogen stocks in the soil, contributing to the cycling of nutrients, helping to increase water infiltration into the soil and also favoring animal thermal comfort. The study aimed to evaluate how the tree component influences the microclimate, in different models of silvopastoral systems, in the rainy season (summer) and in the dry season (winter). Therefore, the study was carried out in a rural area located in the municipality of Jerônimo Monteiro, ES (Latitude: 20°50'27"S; Longitude: 41°22'22"W and Altitude: 141m, located at 45º northeast (NE ) on a slope with an inclination of 17, which consists of an area of initially recovered pasture, where three models of silvopastoral systems were adopted: pasture intercropped with eucalyptus (E. urophila x E. gradis), pasture intercropped with eucalyptus and leucaena (Leucaena leucocephala ), a forest legume and, finally, pasture intercropped with arariba (Centrolobium tomentosum) and two monocultures: eucalyptus and brachiaria pasture (Urochloa brizantha), totaling five treatments. The treatments were delimited in a width of 34x50 in length. performed by means of sensors that were coupled to automatic meteorological stations through a datalogger, measuring the following variables: radiation balance, global solar radiation, radiation photosynthetically active, air temperature, relative air humidity, surface temperature and soil temperature at 2, 5, 10 and 20 cm depth. From the temperature and relative humidity data, it was possible to determine the vapor pressure deficit. Leaf area index was determined using a model canopy analyzer. Data were analyzed using descriptive statistics and linear regression. The results showed that the volume of rain influences the partition of the energy balance and the microclimatic variations between seasons. The radiation regimen between treatments differed significantly due to the presence of the arboreal component in the Silvipastoril System. Among the three silvopastoral systems, eucalyptus with pasture, eucalyptus with leucaena and arariba with pasture, the photosynthetically active radiation varied considerably, showing that the type of tree component that constitutes a given SSP directly influences the incidence and radiation regime on the system, affecting the soil surface temperature and soil profile, the temperature and the relative humidity of the air within the system. As the canopy of the arboreal component increases, there are changes in the microclimatic variables in the system, as it changes the energy regime within the system, thus affecting the soil surface temperature between treatments, when compared to seasons, rainy and dry. The maximum soil surface temperature of the SSP when compared to the monoculture treatments of pasture and arariba with pasture, reduced in both seasons, which can benefit livestock production, providing greater animal thermal comfort.