Ciclagem do magnésio por culturas de cobertura sob plantio direto

Abstract

In the long term, conservationist systems generate positive results in the use of soil nutrients, where they become available for the next crop in succession, as these are returned by the decomposition of the straw. This protection mechanism also benefits the population of microorganisms and fungi that are part of the organic matter. Magnesium is a secondary macronutrient present in plants, being essential for its development, specifically in the participation of the photosynthesis process. The objective of this study was to evaluate the accumulation and release of magnesium from cover crops and their effects on soybean productivity in succession under notillage in Rondonópolis-MT. The experiment was carried out during the 2015/16 agricultural year, at the Experimental Station of the Federal University of Rondonópolis, in a dystrophic Red Latosol, in a randomized block design with nine production systems and four replications in 7m x 9m experimental units. The treatments being: S1: Fallow PD; S2: Fallow PC; S3: C. spectabilis; S4: Maize + C. spectabilis; S5: P. glaucum; S6: U. ruziziensis; S7: Sunflower + U. ruziziensis; S8: V. unguiculata; S9: Maize + U. ruziziensis. To describe the release of Mg that occurred in cover crops, after desiccation, the data collected at 0, 15, 30, 60, 90 and 120 days after desiccation (DAD). The soybean productivity in the harvest was evaluated by means of collections in two lines of two meters, expressed in kg ha-1. Regarding the greater accumulation of magnesium at flowering, it was observed at T7 (Sunflower + U. ruziziensis) (Figure 2). This result is justified by the combination of these crops, which offer not only a greater amount of dry matter and soil cover, but also an increase in the C / N ratio for the sunflower. It was found that the consortium of Girassol + U. ruziziensis offers better performance in Mg cycling during flowering and senescence. With the exception of fallow, all treatments show an increase in Mg accumulation in the succession of cultures. C. spectabilis shows higher soybean productivity under no-tillage in the Cerrado.