Utilization of phosphate dissolving microorganism for Agriculture

This study included 5 activities; I) Isolation and identification of phosphate-dissolving microorganisms form upland soils, II) Studies the efficiency of the isolates in dissolving insoluble phosphate, III) Developing the process of mass production, IV) Study on the effect of soil inoculation with phosphate solubilizing organisms on plant growth and phosphorus uptake, and V) Economical evaluation of the project. One hundred and two phosphate-solubilizing microorganisms consisting of 76 strains of fungi and 26 strains of bacteria were isolated from rhizopheric soil in the central part of Thailand (Lop Buri, Sara Buri and Nakhon Sawan Province). Fungi were found to be more active in solubilizing phosphate than bacteria. Aspergillus sp. No. 001, Aspergillus sp. No. 501, Penicillium sp. No. 102 and Penicillium sp. No. 504 solubilized phosphorus from rock phosphate at the amount of 1804, 1790, 700 and 585 mg per 100 ml culture in 7 days, respectively whereas bacteria No. 401, No. 1102 and No. 1501 solubilized phosphorus at the amount of 350, 340 and 209 mg per 100 ml culture in 7 days, respectively. The bacterium No. 401 was identified to be Enterobacter sp. which could grow very quickly in 300 litre fermentor in which the cell number per miligram of culture reached 4.03 * 10*[8) in 12 hours. Aspergillus sp. No. 001 was found to be Aspergillus niger which could grow well in 300 litre fermentor giving 10.4 g (dry weight) per litre culture in 48 hours. Pot experiments on the effect of soil inoculation with phosphate solubilizers on growth and phosphorus uptake of plants showed that Aspergillus niger No. 001 was the most effective microorganism which significantly improved growth and phosphorus uptake of the plants. The dry matter of maize, soybean and chilli without inoculation were 217, 98 and 6.8 g/pot and the phosphorus uptake were 231, 217 and 33 mg/pot, respectively whereas the dry matter obtained from the inoculated plants were 307, 121 and .3 g/pot; and the P-uptake in inoculated plants were 353, 304 and 52 mg/pot, respectively. Field experiments conducted at the National Corn and Sorghum Research Center, Nakhon Ratchasima Province showed a satisfactory results. Growth and yield of corn and soybean inoculated with the phosphate solubilizers were improved compared to the controls. The experiments at Sakon Nakhon Province showed a significant increase in yield of tomato of up 400 kg/rai when the soil inoculated with the phosphate dissolvers at the rate of 20 kg/rai. This amount of increasing yield could raise the farmer's income by 1,105 baht/rai.