Palha de aveia em superfície, compactação do solo e crescimento de soja

Abstract

Brazil stands out among other countries in the production of soybeans, where it is currently the largest exporter and the second largest producer of the grain. Most of these results are due to the cultivation of the crop in a conservation system called Direct Sowing System. The aim of this study was to evaluate the effect of oats and surface straw quantities on soil compaction and the relation with soybean growth in lowland soils. The experimental design was randomized with seven treatments, with four replicates. The treatments were: 1) Fallow in winter without compaction (PO); 2) Fallow in winter + compaction (POC); 3) Black oats and surface straw removal + compaction (0PC); 4) Oats and 50 % removal of straw + compaction (0.5PC); 5) Oats + straw permanence + compaction (1PC); 6) Oat + straw withdrawn from treatment 3 (2 doses straw) + compaction (2PC); 7) Oat + straw permanence, without compaction (1P). Black oats were sown at 0.17 m spacing between rows and 80 kg-ha-¹ of seed. At the end of the crop cycle, the black oats were cut at 0.03 m height, the quantities of straw were adjusted in the treatments, and the soil compaction was carried out in treatments 2 to 6. After the soybean cultivation, with BMX Magna RR and a spacing of 0.45 m between rows, 16 seeds per meter were sown. When the plants reached the phenological stage R2, 28 samples within a metal square of 0.3 x 0.3 x 0.15 m of depth were removed. The following were evaluated: dry mass of nodules, roots and shoot, height of plants and nitrogen in the dry mass of the shoot. The soybean crop presented greater growth in the treatments without compaction. The black oats straw levels were not sufficient to decrease the negative effects of compaction.