Abstract
More than 2 million hectare of soil at the soybean-wheat offseason remains on fallow in Brazil. Therefore, this research studied a suitable cover crop and its herbicide management to be adopted is this period as well as its influence on wheat yield at the 2017/18 and 2018/19 growing season. Experiment was laid out as a randomized block design in a factorial scheme composed of four cover crops (Fagopyrum esculentum, Crotalaria juncea, Pennisetum glaucum and Urochloa brizantha) and two herbicide management [Anticipated Desiccation (17 days before) and Desiccation at the wheat Sowing day] with four replications. Fallow without cover crops was used as a control. The tradeoff between the additional biomass produced by millet and brachiaria between herbicide desiccation periods does not pay the wheat grain yield reduction, suggesting that its herbicide management should be anticipated. In the other hand, C. juncea showed a linear increase in biomass along the periods without wheat yield effects and its herbicide dissection at the wheat sowing day appears to be the best management. F. esculentum showed the fastest development cycle and can be recommended for shorter offseason periods. P. glaucum showed rapid growth and the highest biomass yield at both years, standing out as the best option for offseason periods from 70 to 80 days, although, anticipated herbicide management before wheat sowing resulted in higher grain yield at the second year of study. Further studies should consider other cover crop benefits as weed suppression, physical and chemical soil traits improvements and erosion reduction.
Highlights
Among several cropping arrangement and soil use management options, soybean/wheat rotation under no-till are the most common adopted cash crop system in southern Brazil
Experiment was laid out as a randomized block design in a factorial scheme composed of four cover crops (Fagopyrum esculentum, Crotalaria juncea, Pennisetum glaucum and Urochloa brizantha) and two herbicide management [Anticipated Desiccation (17 days before) and Desiccation at the wheat Sowing day] with four replications
C. juncea showed a linear increase in biomass along the periods without wheat yield effects and its herbicide dissection at the wheat sowing day appears to be the best management
Summary
Among several cropping arrangement and soil use management options, soybean/wheat rotation under no-till are the most common adopted cash crop system in southern Brazil. Soybean is harvested between February and March and wheat is sown between May and June, generating an offseason that ranges from 70 to 120 days These areas remain most of the times on fallow. In the other hand, according to Rosolem et al (2016), selection of a suitable cover crop for rotation with grain crops is important and essential for the success of no-till, in tropical soils In this away, cover crops growth in the soybean-wheat offseason could reduce these problems, besides improving the physical, chemical, and biological soil traits, which may result in higher yields of subsequent crops (Pacheco et al, 2011; Rosolem et al, 2016; Posse et al, 2018; Büchi et al, 2018)
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