Abstract
Abstract: The objective of this work was to evaluate the biomass (leaves and stems) production of annual and cover crops sown as second crop, and its effects on soybean yield in succession. The experiment was carried out in the 2014/2015 and 2015/2016 crop seasons. Soybean was sown in the crop season and in the second crop, in a randomized complete block design, in nine production systems (treatments) consisting of annual crops (corn, sunflower, and cowpea) and cover crops (Pennisetum glaucum, Crotalaria breviflora, C. spectabilis, Urochloa ruziziensis, Cajanus cajan, Stylosanthes sp., and U. brizantha), which were grown in monocropping or intercropping systems, besides fallow as a control. Monocropped P. glaucum and U. ruziziensis showed a faster establishment and growth of plants, higher-total biomass and soil cover rate in the 2014 crop season. In 2015, corn intercropped with U.ruziziensis and C.spectabilis, and sunflower with U.ruziziensis stood out for total biomass production during flowering and after harvesting of corn and sunflower grains. Biomass composition in the systems showed greater proportions of stems than of leaves, and C.spectabilis stood out after senescence. Sown as a second crop, C. spectabilis promotes yield increase of soybean grown in succession in the no-tillage system.
Highlights
Agricultural systems with soybean crops in Midwestern Brazil, in the Cerrado region, have contributed to the production of 99 million tonnes of grains every year, which has consolidated Brazil as the second largest grain producer worldwide (Acompanhamento..., 2016)
The cover plant C. breviflora showed a shorter cycle than C. spectabilis, which may be associated with the shorter photoperiod that occurs during the second crop, leading to a stronger induction of plant flowering and reduced potential to accumulate dry matter (DM) at that time (Menezes & Leandro, 2004)
The analysis of stem dry matter (SDM), leaf dry matter (LDM), and total dry matter (TDM) during corn senescence and grain harvest (Table 3), and the relation of total biomass in soil cover crops intercropped with the annual cultures after senescence (RBCC-S) (Table 4), showed that U. ruziziensis and C. spectabilis intercropped with corn have contributed significantly to the production of biomass due to the resumed development of the plants, favored by the solar radiation and final summer rains after corn senescence, which reinforces the findings reported by Pacheco et al (2013)
Summary
Agricultural systems with soybean crops in Midwestern Brazil, in the Cerrado region, have contributed to the production of 99 million tonnes of grains every year, which has consolidated Brazil as the second largest grain producer worldwide (Acompanhamento..., 2016). One of the greatest challenges in the use of this system in soybean crop areas is the assessment of option for the sowings of species that may favor biomass production and allow of increased soybean yield in succession planting. Considering that the succession planting of soybean in the crop season, and corn in the off-season, has been the production model in these regions, for economic reasons and because of the available infrastructure (Calegari, 2002), it is important to evaluate intercropping systems between annual grain-yielding crops and soil-cover plant species that produce biomass to promote the wide-spreading use of these systems
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