Acúmulo e liberação de potássio por culturas anuais e de cobertura em sucessão a soja

Abstract

The insertion of cover crops by direct drilling system promotes nutrient cycling, being able to benefit the subsequent crop. Thus, potassium (K) corresponds to the macronutrient most found in this system, being one of the most important for crops, since it guarantees their full development. Thus, the objective of this work is to evaluate the performance of annual crops and cover crops under direct drilling system, in the accumulation and release of potassium, in the region of Rondonópolis-MT. The experiment was carried out at the experimental station of the Federal University of Mato Grosso in a dystrophic Oxisol, in DBC design, with nine production systems and four repetitions, that being: S1: fallow in DDS; S2: fallow in CP; S3: C. spectabilis; S4: Corn + C. spectabilis; S5: P. glaucum; S6: U. ruziziensis; S7: Sunflower + U. ruziziensis; S8: V. unguiculata; S9: Corn + U. ruziziensis. Phytomass evaluations of cover crops during the harvest were made immediately before the desiccation in October 2015, and repeated at 15, 30, 60, 90 and 120 days after management desiccation (DAD). It was observed that there was statistical difference between treatments, in which all consortia resulted in significant effects regarding the accumulation and release of potassium. Sunflower consortium + U. ruziziensis presented the best performance as K cycling on the aerial parto f plants, with greater accumulation at the time of desiccation and higher rate of release to soybeans in succession. All treatments show increased accumulation of K in succession, except for fallow in DP. The higher productivity of soybean was not in the treatment that obtained greater K cycling on the aerial parto f plants. C. spectabilis promotes greater influence on productivity of soybean in succession.