Efeito da cobertura com resíduos vegetais na umidade e temperatura do solo

Abstract

The Direct Planting (PD) (no-till) is the predominant type of management in the Southern Region of Brazil, being different from the Direct Planting System (SPD), which is the most recommended for Brazilian soils, as this system uses various conservationist management and maintenance practices to reducing degradation and increasing soil preservation. The SPD is supported by three fundamental pillars, being, not disturbing the soil, crop rotation and permanent soil cover; In certain situations, there is a need to add a fourth pillar, with conservation practices being complementary. Permanent soil coverage promotes a reduction in evaporation, increases water retention by increasing infiltration, in addition to reducing the intensity of solar radiation on the soil, resulting in milder temperatures for the development of plants and organisms. The objective of this work was to evaluate the effects of different amounts of plant residue in the cover on soil temperature and humidity in a corn crop for cover. The study was carried out in the experimental area of the Universidade Federal da Fronteira Sul, Campus Cerro Largo – RS, where a Oxisol from the Santo Ângelo Mapping Unit is located. The design used was randomized blocks, where bare soil was used, and soils with 2, 4, 8 and 12 Mg ha-1 of plant residue. Were evaluated the production of corn dry biomass, soil density (Ds), total porosity (PT), macroporosity (Mac), microporosity (Mic), aeration porosity (Par), volumetric humidity (UV) in the first 20 cm of the soil and temperature in the first 5 cm of soil. The results were subjected to analysis of variance (ANOVA), where the means were compared using the Tukey test at 5% significance. The physical attributes of the soil, evaluated in the 0 - 10 and 10 - 20 cm layers, did not differ significantly. The greatest water availability was obtained by the treatment with 12 Mg ha-1 of plant residue, with an average of 34.8 mm, being , 8.13 mm more than the treatment without plant residue coverage. Soils with plant residue coverage above 8 Mg ha-1 provided the lowest thermal amplitudes during the study, with an average temperature reduction of 1.3ºC in relation to bare soil. The highest corn biomass production was obtained in treatments with greater coverage. The use of permanent soil coverage with quantities above 8 Mg ha-1 is essential for preserving the soil, in addition to maintaining humidity and maintaining milder temperatures for plant development.