Indicadores de qualidade do solo em sistemas de manejo para produção de hortaliças

Abstract

The measurement of soil quality (SQ) indicators makes it possible to assess the sustainability of agricultural management systems. This work aimed to evaluate the effect of different soil management systems for vegetable production on SQ indicators, in order to indicate alternative ways for a more sustainable and balanced management. The experiment was carried out under field conditions in the experimental area of the Universidade Federal da Fronteira Sul, campus Cerro Largo, RS, in a Hapludox. Historically the area was cultivated with Secale cereale, Crotalaria juncea, Brassica oleracea var. capitata and Lactuca sativa L. in the last two years prior to the implementation of the present study. The treatments were: Vegetable No-Till System (SPDH); No-tillage without vegetation cover (PDsc); Conventional Cultivation System with vegetation cover (SCc); and Conventional Cultivation System without vegetation cover (SCsc). The ground cover crop was rye. The experiment was designed in randomized blocks with five replications and the analyzed crops were Lactuca sativa L. succeeded by Brassica oleracea var. capitata. The soil parameters analyzed were physical indicators: density (Ds), total porosity (PT), microporosity (Mic), macroporosity (Mac), degree of compaction (GC), volumetric moisture (UV) and aeration porosity (PA); chemical: pHH2O, SMP index, H+Al, MO, CTCefet., CTCpH70., Al, P, K, Ca, Mg, Zn, Cu, S and B contents and V% and m% contents; and biological: β-glucosidase and arylsulfatase enzymes. The data obtained were submitted to normal distribution and analysis of variance (ANOVA) and the means were compared by Tukey's test (p < 0.05) using the Statistical Analysis System (SAS) program. Higher values of Ds, Mic and GC were observed, as well as lower values of PT and Mac for the PDsc treatment, mainly in the 0.00-0.05 m layer. Higher UV values were found in PDsc, SPDH and SCc. Lower PA values were observed in PDsc. Soil chemical parameters and lettuce and cabbage yields showed similar behavior between SCc, SCsc and SPDH treatments. The enzymatic activity of β-glucosidase was higher in SPDH and of arylsulfatase was higher for SPDH and SCc, which did not differ from SCsc. It is concluded that the cultivation of lettuce and cabbage under SPDH improved the physical, chemical and biological characteristics of the soil and enabled high crop productivity, being a viable and more sustainable system when compared to conventional production systems.