Inokulasi Jamur Pengoksidasi Belerang pada Pupuk Fosfat Alam untuk Meningkatkan Fosfat dan Sulfat Tersedia bagi Tanaman

Abstract

Title : The Inoculation of Sulfur Oxidizing Fungi on Phosphate Rocks Fertilizer to Increase Their Available Phosphate and Sulfate. Phosphate rocks as an alternative sources of P fertilizer are cheaper than SP-36. The main problem was their low of total and available P that must be increased to make them more effective source of P for plants. Inoculate them with S oxidizing fungi will increase their available-P. The research aim was to study the potency of two S oxidizing fungi Aspergillus japonicus and Penicillium nalgiovensis to increase available-P of phosphate rocks. Experimental research done at the Lab. of Soil Biology and Lab. of Soil Chemistry and Fertility, Department of Soil Science, Faculty of Agriculture, UNS, Surakarta, at March – Mei 2008. The experiment arranged in completely randomized design with four factors i.e. the origin of elemental sulphur (from G. Welirang, East Java and from USA), the origin of phosphate rocks (Christmas Island, Ciamis and Madura), kind of inoculums fungi (A. japonicus and P. nalgiovensis) and inoculums densities (0; 106 and 107 spore/g of phosphate rock). Each treatment combinations were replicated three times. Fifty grams mixture of phosphate rocks, cassava solid waste, tapioca and rice bran was poured in 250 ml Erlenmeyer, sterilized with autoclave at 121 oC for 30 minutes, three times alternately in 5 days, then inoculated with fungus spores and incubated at field capacity in room temperature for 3 months. Samples were taken at 1, 2 and 3 months after incubation time for analysis of water soluble-P, soluble sulphate, pH and total fungus. Data analyzed statistically with F test and Duncan Multiple Range Test at 5% of level significance. The result show that the two of S oxidizing fungi Aspergillus japonicus and Penicillium nalgiovensis were be able to increases available-P of phosphate rocks, as well as soluble sulphate more than 200 % of control treatment. Penicillium nalgiovensis was more effective than Aspergillus japonicus. As P sources, phosphate rock from Christmas Island was better than from Ciamis and Madura, while elemental S imported from USA was better than local So from G. Welirang. The increase of inoculums densities and length of incubation times increase soluble P and sulphate. Keyword: phosphate rocks, S oxidizing fungi, soluble P and sulphate