Viabilidade técnica e econômica de modelos de produção agrícola em longo prazo

Abstract

The general objective of the present work was to identify superior production models in terms of technical and economic viability in southwestern Paraná and to understand their benefits and limitations in agronomic and economic aspects. The study was conducted at the experimental station of the Federal Technological University of Paraná, Campus Dois Vizinhos, on Distroferric Red Latosol, during the 2018/2019, 2019/2020 and 2020/2021 harvests. This is an experiment with four production systems, in a 4x6 factorial scheme, in a randomized block experimental design with subdivided plots and three replications, with two crop succession systems (corn-soybeans/beans and cover crops, and soy-corn/beans and cover crops) and two crop rotation systems (including beans in harvest and wheat in winter). Factor A refers to the strategies for using the plots in the 1st summer crop and factor B, in the subplots, the management of the 2nd summer crop and off-season, totaling 24 models. In relation to cover crops cultivated in the 2nd summer crop, Panicum glaucum showed the highest precocity and productivity, being indicated for soil cover in short periods between harvests, when sowing is positioned in summer and autumn. The total dry matter of all cover species is reduced as the sowing period lasts from February to March. Urochloa brizantha and Crotalaria juncea are more viable for off-season periods longer than 90 days. The productivity of cover crops is influenced by the predecessor crop, being more productive in succession to soybeans in the summer. Dolichos lablab showed the lowest biomass productivity in relation to cover species when grown in succession to maize. The biomass of the arrangement of P. glaucum in the second harvest + Raphanus sativus in the winter (19,489.87 and 20,615.44 kg DM ha-¹ harvest 2019 and 2020 respectively) points to superiority in relation to the other species, both in the succession of soybean and corn first crop, still, in terms of total biomass, considering the biomass accumulation of the three crops (summer, autumn and winter) the arrangement of corn, P. glaucum and Avena strigosa + R. sativus was the treatment that stood out, totaling 32.6; 35.5 and 26.2 t DM ha-1 in the 2018/19 seasons; 2019/20 and 2020/21 respectively. Based on the productivity factor, basically the 1st harvest proved to be more productive and profitable compared to the 2nd harvest in most production models, showing a greater contribution to profitability. In the three years of cultivation, the profitability index (IL%) of the cover species showed economic results similar to those obtained with cultivations only of plants with a commercial bias, however, when taking into account the operating profit (LO R$ ha-¹ ), the use of cash crops in the second summer crop becomes more profitable than cover crops alone. Dealing with profitability, P. glaucum and C. juncea were the species that stood out among the others. In economic terms, the production model with the best performance (LO of R$ 29,601 ha-¹) was the bean-corn-soybean rotation in the 1st summer crop with soybean-soybean-corn in the 2nd summer crop, respectively, more oats+radish in sequence over the three agricultural years. The highest IL (62.20%) was presented in the succession system with soy-corn-oats. In general, the ideal is to seek a productive balance, adopting part of the area with cover crops, protecting the soil and the other part with commercial crops.