Ciclagem e liberação de potássio por plantas de cobertura na cultura da soja no ecótono Cerrado-Amazônia Mato-Grossense

Abstract

The use of cover crops has shown to be a promising practice in potassium cycling for subsequent crops, leading to a reduction in the use of fertilizers, which are essential for obtain high yields in grain production. Thus, the aim of this study was to evaluate the accumulation of potassium (K) by the cover crops, the decomposition dynamics and the rate and time of nutrient release, as well as the potassium utilization in the soybean crop, in transition CerradoAmazonia mato-grossense. The design was a randomized complete block design with split plot in a factorial scheme (7x9), composed of seven cover crops in the main plot and nine evaluations in subplots with four replications. Cover crops were: Crotalaria spectabilis, Fagopyrum esculentum, Mucuna aterrima, Urochloa brizantha, Urochloa ruziziensis, Eleusine coracana and Pennisetum glaucum. The evaluation of the remaining potassium in the biomass was performed: 0, 15, 30, 45, 60, 90, 120, 150 and 180 days after the management desiccation. Potassium presents a high rate of release to the soil, in addition to high accumulation by cover plants evaluated mainly by Urochloa brizantha. The largest grain yield was observed with cultivation on straw of Urochloa brizantha. It is a kind of great potential to be recommended for the K cycling in transition Cerrado-Amazonia.