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Biological N2 fixation by soybeans grown with or without liming on acid soils in a no-till integrated crop-livestock system

2021; Elsevier BV; Volume: 209; Linguagem: Inglês

10.1016/j.still.2020.104923

1879-3444

Lucas Aquino Alves, Vítor Gabriel Ambrosini, Luiz Gustavo de Oliveira Denardin, João Pedro Moro Flores, Amanda Posselt Martins, Dionata Filippi, Carolina Bremm, Paulo César de Faccio Carvalho, Gustavo Duarte Farias, Ignacio A. Ciampitti, Tales Tiecher,

Plant nutrient uptake and metabolism

Soil acidity can impair biological N2 fixation (BNF) and increase soybean (Glycine max L.) reliance on soil N to satisfy its plant N demand. This study aimed to evaluate the effect of liming, fertilization strategy, and grazing on: i) the N supplied via BNF process, ii) partial N-balance, and iii) soybean yield, in an integrated crop-livestock system under a non-tilled sandy and acidic Acrisol. Initial soil conditions were soil pH of 4.0 and Al saturation of 50%. Limestone was applied to rise soil pH to 6.0 and a control area was kept with the initial soil conditions. Soybean was grown in the summer and Italian ryegrass (as a cover crop or grazed by sheep) in the winter. Fertilization strategies consisted in applying P and K prior to soybean or ryegrass. Partial N-balance was calculated by the difference between N derived from BNF and N removed in soybean seeds. Contribution of N from the atmosphere to soybeans was on average 62 and 66% in plots without and with liming, respectively. The fixed-N was 27% greater under low soil acidity due to lime. Partial N-balance was positive in both treatments, but 57% greater in the limed- relative to the non-limed (+58 kg ha−1) soils, resulting in 11% soybean yield increase when lime was added. The most relevant soil chemical properties influencing N fixation were soil pH and Al saturation. Grazing and fertilization strategies had no effect on soil acidity properties, N supply, and soybean evaluations. Further research should explore the long-term effect of grazing, fertilization strategies, and liming.