Propriedades físicas do solo e níveis de palha de azevém na produtividade da soja em plantio direto com integração lavoura pecuária

Abstract

Brazil has been standing out in soybean production, currently being the largest exporter and producer of the grain. A significant part of these results is attributed to the cultivation of the crop in a conservationist system called No-Till Farming (NTF). The objective of this study was to evaluate the effect of straw quantities on the soil surface on soybean grain yield in a no-till system. The experimental design adopted was completely randomized, with three treatments and eight replications, in plots measuring 2.5 x 2 m. The treatments consisted of: 1) Cultivation of ryegrass Lolium multiflorum with removal of the surface straw; 2) Cultivation of ryegrass without removal of the surface straw; 3) Cultivation of ryegrass with the addition of the straw removed from treatment one, corresponding to twice the quantity of ryegrass straw. In 2020, desiccation was carried out with herbicide in May, and 40 kg ha-¹ of ryegrass was sown using a broadcast spreader without incorporation, with no grazing. In June, 4.5 t ha-¹ of limestone with 70% PRNT (Effective Neutralizing Power) was applied on the soil surface. On September 27, 2020, herbicide was applied to control weeds. On December 8, 2020, soybean seeds, BMX raio IPRO variety, with early maturity, were treated, inoculated, and sown in all treatments using a no-till seed drill, with a spacing of 0.50 m between rows and 18 seeds per meter. Fertilization was carried out according to the recommendation (CQFS-RS/SC, 2016). At harvest, the weight of 100 seeds and grain yield were evaluated in an area of 1.5 m², with moisture adjusted to 13%. The soil of the site showed surface compaction, so allied the irregular rainfall were factors that contributed to the non-achievement of an even higher productivity, being the straw essential for the increase of productivity, so the irregular distribution of precipitation allied to the superficial compaction of the soil were factors that determined the productivity of the cultivar, however, in the treatments where there was straw on the surface, an increase of 21% was obtained of productivity when compared to the treatment where the superficial straw was removed.