Atributos físicos do solo e produtividade de alface em sistema plantio direto com diferentes plantas de cobertura

Abstract

The Conventional Tillage System of vegetables is an activity that uses intensive techniques of soil revolving in the surface layers, affecting the physical features of soil. The No-till System of vegetables represents a more viable alternative for more sustainable management in vegetable production, searching for a more conservative approach to soil and water. Therefore, the aim of this study was to evaluate the physical attibutes of the soil under a direct planting system with different species of cover crops, and analyze the impacto n lettuce productivity. This study was developed at Universidade Federal da Fronteira Sul- campus Cerro largo, and consisted of twenty 8 m2 experimental units. Randomized block design with five treatments and four replications, the following were used as cover: millet, sudan grass, guandu beans and pork beans, and fallow. We analyzed the dry mass production of the cover crops and concentration of nutrients in the aerial part, soil density (DS), total porosity (PT), degree of compaction, macroporosity, microporosity, soil temperature measured three times a day (8:00 am, 11:00 am and 2:00 pm), volumetric humidity and lettuce productivity. The results were submitted to analysis of variance and the means were compared using the Tukey test at 5% significance. Sudan grass had a higher C/N ratio and biomass production compared to the other cover crops, In terms of N and Ca, pork beans and guandu beans had higher concentrations. Sudan grass had the highest concentrations of P, S and Zn. The soil features, density, total porosity, macroporosity, microporosity, and degree of compaction, assessed in the 0-5, 5-10 and 10-15 cm, were not influenced by cover crops. In relation to volumetric soil moisture, total soil water capacity, available water capacity and porosity and aeration, there was no significant difference, but grasses stood out in these evaluated atributes. Temperatures differed significantly between treatments, with the fallow treatment showing the greatest temperature range at 2 p.m. Millet and sudan grass had the lowest soil temperatures during the experiment. The sudan grass cover provided greater lettuce productivity. Thus, sudan grass is an excellent soil cover in No-till Vegetable Systems.