Efeito de consórcios de plantas de cobertura de verão na temperatura do solo, na população de plantas espontâneas e na produtividade em SPDH

Abstract

The no-tillage vegetable system (NTS) is a sustainable alternative for vegetable production, aiming to restore ecological balance by developing an environment rich in organic matter, balanced and biodiverse, capable of reducing losses resulting from climate change. In this sense, the objective was to evaluate the effect of combinations of summer cover crops, in the adoption of no-till farming, on the input of biomass and nutrients, variation in soil temperature, suppression of spontaneous plants, and productivity of vegetables. The experiment was conducted in DBA, with 4 repetitions in the municipality of Pato Branco, Paraná, and the treatments (T) were: T1 – control (no cover crop and with soil management simulating the SPC of vegetables); T2 – spontaneous occurrence plants; T3 – soybean + corn + millet intercropping; T4 – dwarf pigeon pea + corn + millet intercropping; T5 – crotalaria ochroleuca + corn + millet intercropping; T6 – soybean + corn + buckwheat intercropping; T7 – crotalaria juncea + sorghum + millet intercropping (commercial mix RX250®). Before the management of the first cycle (2023/2024) of the cover crops with the roller-knife, black oat overseeding was carried out. At the end of the cycle, the oat management was carried out, and evaluations of spontaneous plants and temperature above and below the mulch were performed. Then the second cycle (2024/2025) of summer cover crops was sown: first, corn was sown, and after 30 days the other species of each combination were sown. Ninety-five days after corn sowing, the production of green corn in the intercropping systems was evaluated, and after the end of the cycle of the other species in the intercropping systems, the cover crops were managed. Following this, spontaneous plants were evaluated, and lettuce seedlings were planted to assess production. During the lettuce cycle, soil temperature above and below the mulch was evaluated. In addition to the aforementioned evaluations, in both cycles the biomass production, N, P, K, and C/N ratio of the plant tissue of the summer cover crop combinations and oats were evaluated. The intercropping systems of sunn hemp + sorghum + millet and sunn hemp + corn + millet stood out for simultaneously meeting dry matter production and nutritional requirements. The intercropping system with soybean + corn + buckwheat showed less effectiveness in this aspect. The treatment without cover crops presented the highest soil temperatures, reaching 54.69 °C, while the RX250 intercropping system (sunn hemp + corn + millet) and the dwarf pigeon pea + corn + millet stood out with temperature reductions of 15.05 to 19.71 °C, 15.40 to 15.80 °C, and 11.57 to 19.41 °C, respectively, on the hottest days. The intercropping systems of crotalaria-ochroleuca + corn + millet and dwarf pigeon pea + corn + millet showed the lowest importance values for spontaneous plants, with 50% and 60%, respectively. The intercropping system of crotalaria-juncea + sorghum + millet stood out for promoting the lowest indices of species richness, diversity, and evenness. No significant differences were observed in green corn productivity among the intercropping systems. For lettuce production, the intercropping system with crotalariaochroleuca + corn + millet showed the best performance. It is concluded that the intercropping systems with the presence of crotalaria-ochroleuca, dwarf pigeon pea, and sorghum were the most outstanding in the evaluated attributes; the control without cover did not provide environmental and agronomic benefits.