Influência do resíduo vegetal na temperatura e umidade do solo e na produtividade da soja

Abstract

Rio Grande do Sul, with a subtropical climate and large thermal amplitude, benefits from mulch to regulate soil temperature and reduce evaporation, promoting plant growth and development. Soil thermal stability creates optimal conditions for plant physiological functions, root development, and nutrient absorption. This study evaluated the impact of different amounts of black oat residue on soil moisture, temperature, and soybean yield components.The study was conducted at the experimental area of the Federal University of Fronteira Sul (UFFS), Cerro Largo Campus - RS, located in the Missions region (-28.141183, -54.760799). The climate is categorized as Cfa, indicating a humid temperate climate with hot summers. The soil at the site is classified a Oxisol from the Santo Ângelo Mapping Unit. The experimental design used was a randomized block design (RBD) with five treatments and four repetitions. The treatments included different amounts of black oat straw distributed over the soil surface in each plot: Control (T1) with 0 Mg ha⁻¹; 2 Mg ha⁻¹ (T2); 4 Mg ha⁻¹ (T3); 8 Mg ha⁻¹ (T4); and 12 Mg ha⁻¹ (T5). The soybean cultivar used was TMG 7362 IPRO, with a density of 200,000 plants/ha. Soil temperature parameters were evaluated in the row and inter-row at depths of 0-5 cm and 0-10 cm, soil moisture at a depth of 0-20 cm, soil density, aeration porosity, macroporosity, microporosity, total porosity, as well as crop productivity. Based on the conditions under which the experiment was conducted, the parameters of soil density, total porosity, air porosity, macroporosity, and microporosity, evaluated at layers of 0–10 cm and 10–20 cm, showed no significant differences. However, the temperature parameter exhibited significant differences among treatments, with the treatment without plant residue recording the highest temperatures. For soil moisture, there were no significant differences among treatments; nevertheless, the treatment with 12 Mg ha⁻¹ achieved the highest values. Regarding productivity, the treatments showed significant differences, with the 12 Mg ha⁻¹ treatment resulting in the highest productivity. Thus, it can be concluded that the presence of plant residue on the soil surface reduces its temperature and acts as a protective barrier against intense heat. Furthermore, this practice leads to significant increases in productivity.