| Abstract | The effect of the application of lime and fertilizers (N, P, K) on the rehabilitation of a degraded pasture of Brachiaria brizantha cv. Marandu, grown on a dystrophic Yellow Latosol of clayey texture, was studied under field conditions at the Empresa Brasileira de Pesquisa Agropecuária (Embrapa-Rondônia) in Porto Velho, Brazil, over a 3-year period. A randomized block design was used, arranged in a 2 x 2 x 2 x 2 factorial for levels of liming (base saturation of 20% and 40%) and doses of nitrogen (50 and 100 kg N/ha as urea), phosphorus (50 and 100 kg P2O5/ha as triple superphosphate) and potassium (30 and 60 kg K2O /ha as potassium chloride) and in a 3 x 2 x 2 x 2 factorial for fertilization frequencies (annual, biennial, and triennial) and levels. The lime and fertilizers were applied after native vegetation was controlled and light plowing. Soil samples were taken at a depth of 0-15 cm and 15-30 cm to determine the effect of the treatments on soil physical properties. Cations and exchangeable Al decreased significantly, while soil pH and exchangeable
bases increased. At both depths, total P increased with the P doses applied fractionated every 2 years. When lime was applied to correct bases up to 20%, the best responses to P in samples taken between 0 and 15 cm were found when 60 kg K2O /ha were applied, which did not occur at 40% base saturation. Treatments did not affect K or OM contents. P content was only affected by frequency of application. Under these study conditions, it is recommended that lime be applied to increase base content to 40% and NPK fertilization rates of 100, 50, and 60 kg/ha at a minimum frequency of 2 years. |
