Effectiveness of rock biofertilizers with sulfur and <i>Acidithiobacillus</i> on melon in the San Francisco Valley

Abstract

Biofertilizers with phosphate rock (PR) and potash rock (KR) plus sulfur and Acidithiobacillus (S+Ac) were compared with triple superphosphate (TSP) and potassium chloride (KCl) fertilizers on melon in an Argisol of the San Francisco Valley. A factorial 32+3 in randomized blocks design with phosphate  biofertilizer (PB) and potassium biofertilizer (KB) applied in levels 50%, 100% and 200% based on recommendation to TSP and KCl. Additional treatments were: a) rocks (PR+KR+S-Ac), b) fertilizers (TSP+KCl) and c) control treatment (P0K0). Response of P and K fertilization on fruit weight, fruit yield, and nutrient in leaves were observed with best results obtained applying TSP+KCl, PR+KR+S-Ac and PB and KB. Total P, K and Mg in leaves showed best results when applied P biofertilizer in PB200 and PR+KR+S-Ac. Uptake of SO^-4 in leaves increased with BK biofertilizers and lowest results were obtained in the control treatment. No effects of PK fertilization were observed in biomass of leaves, brix, vitamin C , fruit texture and ATT. Biofertilizers BP and BK with S+Ac and P and K rocks with S-Ac may be used as alternative to P and K fertilizers.