Viabilidade do sistema de cultivo intercalar trigo-soja e milho em sucessão

Abstract

Wheat-soybean is one of the most used crop arrangements in the southern of Brazil. Even thought, Brazil produces less than 50% of its wheat demand, the crop has been losing cultivation area in many regions of the country. In this context, relay cropping allows the overlapping of soybean on wheat for a period of time, reducing wheat productive risks and allowing gains in terms of anticipation soybean sowing and harvest. This study aimed to evaluate the technical and economic feasibilityof wheat-soybean relay crop and the growthof corn as a third crop in the same agricultural year. Experiment was carried out at the UTFPR, câmpus Dois Vizinhos-PR in a randomized blocks design with in 6x3 and 4x3factorial scheme, with 3 replications at the 2019/2020 and 2020/202 growing season. Factor A was represented by the wheat inter-row spacing, with arrangements of 17 and 22 centimetersin single rows, in-between (17A and 22Aperformed only in the 1styear) and double rows (17D and 22D), resulting in soybean row spacing of 45 cm for the single rows and 34, 44, 51, and 66 cm for the other treatments respectively. Factor B was composed of 2sowing periods of soybeans (BMX Zeus), in relay double cropping, where soybean was sown on standing wheat at milk and drought grain before crop maturity and1 in contrast to sequential cropping where soybean is sown after wheat harvest. The best wheat-soybean relay cropping arrangement was 17D, where wheat produced 2,812 and 2,267 kg ha-1, or 69.41 and 64.82% of the total produced by the control treatment in the 1stand 2nd year respectively. At the first year, soybean at the 51 cm arrangement, (same 17D as wheat) at the 2ndsowing season (09/23/19), produced 6,029.42 kg ha-1(32.5% higher than 1stseason on 09/13/19 and 11.8% lower than control 10/3/19). At the 2ndyear, the same treatment sowed at September 29thyielded 4.235,00 kg ha-1(12.58% more than the 1stsowing period which was on September 14thand 7.4% lower than the control sowed on October 23rdof 2020. Even its yield being 1,239 kg ha-1less thanthe control (17S), intercropping anticipated corn sowing in 15 days what resulted in a grain yield increase of 1,956 kg ha-1when compared to the corn sowed post-soybean harvest in the conventional system. The tradeoff between wheat yield losses and corn yield gains indicated that wheat-soybean relay cropping has a positive balance and can be used as a management strategy to reduce crop risks and obtain higher grain yield per area. Further, wheat-soybean at the conventional system do not allow corn crop adoption inside sowing zoning calendar. Wheat-soybean relay cropping provides grain yield gains per area and contributes to the productive system, reducing risks for the three crops and bringing higher economic gainsin both studied years. Futurestudies mayevaluate wheat grown after corn grown as a 2ndsummer crop since it may result in a longer relay cropping period of soybean into wheat resulting in even greater economic gains for the production systems, besides reducing production risks.