Energy demand for soil decompression and benefits in the establishment and productivity of soybean in the lowlands in the state of Rio Grande do Sul

The present study assessed soil preparation in terms of the advantages it provides in lowering the physical obstacles and their influence on soybean cultivation, with reference to its establishment, development and yield, apart from quantification of the energy demand for tractor performance. The experiments were performed in the field adopting the randomized block design with a two-factor scheme (6x2). Factor A included a variety of soil preparations performed during the off-season of the soybean crop. Sowing was accomplished using the same fertilizer deposition mechanism only, and the areas having no soil preparation done were sown using various other fertilizer deposition mechanisms from the seeder, namely: (A1) sowing without soil preparation (SSPS)+double disc in the seeder (DD); (A2) SSPS+turbo disc (DT); (A3) SSPS+furrowing rod (HS); (A4) plow harrow+DD; (A5) scarified+DD and (A6) subsoiled+DD. Soil preparations before sowing were done on days 52 and 98 days, respectively, during the first and second harvests. Factor B included two soybean cultivars, namely: (B1) Nidera 6601 and (B2) Brasmax Valente. No interaction was observed between the factors investigated. While the scarification+DD showed the need for higher fuel consumption, the results were increased productivity. For the seeder-linked mechanisms, the HS gives more extensive root development of the plants and grain yield. On the contrary, while DD and DT show the combination of the highest operational capacity and lower fuel usage, this is related to lower grain yield. RESUMO: O estudo teve por objetivo determinar os benefícios de preparos mecânicos do solo na redução dos impedimentos físicos e seus reflexos no estabelecimento, no desenvolvimento e na produtividade de grãos de soja, além de quantificar a demanda energética ao trator para as operações. O experimento foi conduzido a campo no delineamento de blocos ao acaso em esquema bifatorial (6x2). O fator A foi composto por diferentes preparos do solo realizados no período de entressafra da soja, semeando apenas com o mesmo mecanismo de deposição do fertilizante, e por áreas sem preparo do solo semeadas com diferentes mecanismos de deposição do fertilizante da semeadora, sendo eles: (A1) semeadura sem preparo do solo (SSPS)+disco duplo na semeadora (DD); (A2) SSPS+disco turbo (DT); (A3) SSPS+haste sulcadora (HS); (A4) grade aradora+DD; (A5) escarificado+DD e (A6) subsolado+DD. Os preparos do solo anteriores a semeadura foram realizados 52