Qualidade do solo de um sistema de plantio direto de hortaliças, sob produção orgânica em Seropédica (RJ)

Abstract

The no-till system is a practical management that aims to recover the productive potential of the soil and enable the sustainable use of agricultural land. It also presents principles equivalent to those used in organic production systems. It is believed that this management system, by keeping the vegetation cover (alive or dead), reducing soil overturning and recommending crop rotation, constitutes a strategic tool to enhance the sustainability of organic cultivation of vegetables. The general objective of the work was to evaluate the effect of the implantation of the no-tillage system on the productivity of vegetables under organic cultivation and on the quality of an Argissolo Vermelho-Amarelo (Ultisol), in Seropédica (RJ). The study was conducted at SIPA-Integrated System of Agroecological Production, located in Seropédica-RJ. Three soil management practices were evaluated: a) no-till system (PD) using straw shredder (Triton); b) conventional tillage of the soil, using the rotary hoe (PC-ER) and; c) conventional soil preparation, using a plow and two harrows (PC-AG). The planting of the vegetables was carried out after the pre-cultivation management that refers to the intercropping of corn with legumes (pork beans, crotalaria and mucuna). The experimental design used was a randomized block with three treatments and four replications. Vegetable productivity was assessed over five agricultural years. The deformed and undisturbed soil samples, in the 0-5 and 5-10 cm layers, were collected in 2018, four years after the implementation of the experiment for the evaluation of the following soil attributes: aggregation and organic carbon content in the aggregates, soil density, total porosity, soil resistance to penetration, gravimetric moisture, light fraction of organic matter, soil fertility, carbon and nitrogen stock, total organic carbon and edaphic macrofauna. The results showed that there was no significant difference between the means of the soil management systems for the evaluated physical attributes, except the resistance to penetration of the soil (15-25 cm). With regard to chemical and biological attributes, the carbon content in the soil aggregates, the free light fraction and the soil fauna were the most sensitive to organic soil management practices. The first two attributes were superior in the PC-ER (0-5 cm). The PD favored the greater density and richness of the soil fauna groups. As a conclusion, it is observed that the different management practices maintained the productivity of the vegetables at a level equal to the national average. The four-year period of implementation of soil management practices is a short period to verify significant differences between the evaluated soil attributes. However, in addition to soil resistance to penetration, the free light fraction, the organic carbon content in the macroaggregates and the soil fauna were the most sensitive to changes in land use and confirm the role of organic matter as a key indicator of the quality of the soil. soil in short term studies.