LAUSR

To improve yield and nutrient absorption, the addition of fertilizers to provide nutrients in adequate quantities is recommended. An alternative substitution for soluble fertilizer is the use of Acidithiobacillus bacteria to produce rock biofertilizer that is then mixed with organic matter inoculated with diazotrophic bacteria (Beijerinckia indica) for N enrichment. This study evaluates the effectiveness of biofertilizer on nutrient uptake and its interaction with sugarcane filter cake in field-grown sugarcane on an Ultisol in the Brazilian rainforest region. The experiment used two NPK fertilizer treatments (biofertilizer and soluble fertilizer) applied at three rates (50, 100 and 150% of the recommended rate [RR]) and a control treatment of earthworm compost (20 t ha-1). The fertilizer treatments were applied with and without filter cake, in four replicates. Total C and N, available P and K, and exchangeable Ca and Mg in plants (upper shoots, leaves and stems) as well as soil samples were analyzed. The biofertilizer showed similar responses as did the soluble fertilizer in nutrient uptake in the different parts of sugarcane and in the soil samples. The effects of biofertilizer were enhanced by the interaction of the fertilizer treatments with sugarcane filter cake. We concluded that the biofertilizer enriched in N by inoculation with B. indica may be a viable alternative for the replacement of soluble fertilizers in sugarcane.