Estabilidade de agregados de um latossolo vermelho degradado em recuperação com adubos verdes, calcário e gesso

Abstract

Inadequate land use and large buildings in rural areas are causing damages to the soilclimate environment, reducing productivity and thus expanding degraded areas. In view of this problem, this study evaluated the recovery of an Oxisol that had been treated with green manure, soil amendment, gypsum and pasture in the last 17 years. The quality of the structure was used as an indicator of soil recovery. The study was conducted in a completely randomized design with nine treatments and four replications. The treatments consisted of a control (mobilized soil) until 1999 and then planted with signal grass (Brachiaria decumbens); black velvet bean (Stizolobium aterrimum) (Piper & Tracy) until 1999, then replaced by B. decumbens; pigeon pea (Cajanus cajan (L.)) until 1994, then replaced by jack bean (Canavalia ensiformis (L.)); pigeon pea (Cajanus cajan (L.)) until 1994, then replaced by signal grass (B. decumbens); Lime + S. aterrimum until 1999 when replaced by B. decumbens; Lime + C. cajan until 1994, when replaced by C. ensiformis and after 1999 replaced by B. decumbens; Lime + Gypsum + S. aterrimum until 1999, when replaced by B. decumbens; Lime+Gypsum+C. cajan until 1994, when replaced by C. ensiformis and after 1999 replaced by B. decumbens, and two controls: bare soil (without recovery techniques) and native Cerrado vegetation (savannah). Water aggregate stability and soil organic matter were evaluated in the layers 0- 10; 10-20 and 20-40 cm. The soil is being recovered and the structure quality, compared to the native Cerrado, was most improved in the 0-10 cm layer; the results of the treatments with lime and gypsum were the best and soil organic matter in this layer was higher than in the others. Below the surface layer, the effect of the treatments was similar. The structure quality of the bare soil, measured by aggregate stability and mean weighted diameter, was poor in all layers.