IMPACT OF ROCK PHOSPHATE ENRICHED COMPOST AND PHOSPHORUS SOLUBILIZING BACTERIA ON MAIZE GROWTH AND NUTRIENT UPTAKE.

Present study was carried out at Department of Soil Science and Soil Water Conservation, PMAS-Arid Agriculture University, Rawalpindi, Pakistan to obtain phosphorus (9) enriched compost from municipal solid waste (MSW) including rock phosphate (RP) solubilized with phosphate solubilizing bacteria (PSB) and to evaluate this compost for enhancing maize growth and nutrient uptake. The MSW composting treatments were RP (5 and 10% by weight of MSW) and PSB strains (Burkholderia-cepacia and Klebsiella-pneumoniae) in different combinations, incubated for 120 days. Combined addition of RP (10%) and both PSB strains resulted in the highest contents of total P (2.05%) and soluble P (120 mg/kg). This compost was selected for growing maize as test crop in the greenhouse. Treatments included application of P-enriched compost (PEC) for 50, 100, 150 and 200 percent of recommended P rate for maize and a combination of compost and SSP (75:25), half and full rate of SSP fertilizer. The highest dose of PEC (200%) caused higher concentration (mg/kg) of macronutrients (nitrate-N 18.2; available P 7.8; extractable K 162) in soil. Contents of N P and K in maize plants were 2.9, 0.47, and 1.72 percent, respectively being also higher under this treatment. The PEC (200%) yielded the highest fresh and dry weight (123.6 and 32.3 g/pot followed by that with full rate of SSP. Mixture of PEC and SSP (75:25) also gave results comparable to those obtained from 200% PEC and SSP. Therefore, use of PEC and P-fertilizer mixture is suggested as an economic and efficient way of P input to soil for having sustainable maize yield. [ABSTRACT FROM AUTHOR]