Uso de biofertilizantes de rochas com enxofre e Inoculado com acidithiobacillus em Argissolo Acinzentado do Vale do São Francisco cultivado com melão.

Abstract

The production of biofertilizers from rocks is a practical process that may reduce the energy consumption and promote nutrients availability for plant growth. Nutrient content of P and K biofertilizers varied according to the methodology and the used material. Presently biofertilizers are known as fertilizers that are produced using different organic by-products. The aim of this work was to evaluate the potential of the biofertilizers from phosphate and potash rocks sources by addition of sulfur inoculated with Acidithiobacillus, compared to conventional chemical fertilizers, in Haploxeralf soil of the Valley of the São Francisco cultivated with melon. It was conducted a field experiment in the District of Petrolina (PE), in cooperation with Embrapa Tropical Semi-Arid, in soil with low available P and medium available K. Two fertilizers sources were applied: P biofertilizer (BP) and K biofertilizers (BK), in recommended level to melon, 50% and 200% of the recommended levels (kg ha-1) regarding the nutrient equivalent for triple superphosphate (TSP) and potassium chloride (KCl) chemical fertilizers. The following were additional treatments: a) mixture of conventional fertilizers in recommended level (SFT100 + KCl100); b) mixture of P and K rocks in 200% of recommended level (RA200 + RB200), and c) control treatment without P andK fertilization (P0 + K0). Melon (cv. AF-682) was grown spaced 2,00m x 0,50m, and the culture was cropped until the fruits harvest. In plants were determined: fruit yield and average fruits weight, dry biomass of the aerial part, and nutrients uptake (P, K, Mg, SO4-2); in soil were determined: pH, P, K, Ca, Mg, Na e Al, following Embrapa (1997) methodology. The fruits were qualified according to fruit texture, C vitamin, soluble solids content and total tritable acidity. The experiment was conducted in a factorial 32+3, with three replicates. Statistical analyses included analyses of variance, and the media were compared by test (p=0.05), using the software SAS version 8.0. Rocks and biofertilizers reduced soil pH comparing with conventional fertilizers and rocks plus sulfur. Available P and K were greater when applied biofertilizers (PB and KB) in higher levels. Magnesium and aluminum showed greater values with KB applied in higher level. Effect of fertilization on weight and yield of fruits, and on nutrient uptake in leaves was observed and it was not verified effects in leaves biomass, soluble solids content, C vitamin, fruit texture and in total tritable acidity. Best results on weight were obtained when applied TSP+KCl and rocks (RP+RK) with S and biofertilizers (BK) and (BP). The conventional mixture of rocks and fertilizershad gotten the biggest values of yield of fruits. For total plant P, K and Mg the bestresults were obtained with BP200. Total (SO4-) in leaves showed low values when applied TSP+KCl and the control treatment.