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Phosphorous (P) contents in many soils are varies highly along with their ability to provide available P to plant growth. Soils may contain very high in total P, but low in available P due to high P adsorbed by soil matrix and all their adsorbing agents. This research which using natural materials was aimed to increase P availability in some high-P absorption soils. The natural materials utilized for extracting P were organic matter, P extracting bacterial, and rock phosphate. Those materials were interacted to high P absorption soils which were: Oxisol, Inceptisol, and Andisol. The detail objectives of this research were: (1) to study the potential of P-extracting agents (organic matter, and P-extracting bacteria) in releasing P of three high P- absorption soils; (2) to quantify the -age of P coming from the treatments; (3) to calculate the efficiency of P utilization by plant; and (4) to quantify Residual P in soils. The P mobility was analyzed by radioisotope technique using KH232PO4 carrier free solution. The results showed that adding soil organic matter increased the available P by 15.24% in Oxisol, 40.18 in Inceptisol, and by 7.34% in Andisol. Plant sorption toward P from % P used efficiency(%-PUE) up to 60 days was still very low, 0.65 to 9.34%. This was in accordance with the residual P in soils which were still quite high ranging from 94% to 96% in Andisol, 91%97% in Inceptisol, and 96%-98% in Oxisol. The implication of the results of this research, however, is that the application of natural materials in improving soil P availability provides a longtimeresidual effect which could give benefit to the following crops.Keywords: Andisols; Inceptisol; Oxisols; P. diminuta; PUE;  rock phosphate[How to Cite: Mudjiharjati A, TC Setiawati and MH Pandutama. 2012. Improving Phosphate Efficiency by Phosphate Solubilizing Bacteria and Organic Matter Estimated by Radio Isotop (32P) Technique in Some Soils. J Trop Soils, 17 (3) : 245-252. doi: 10.5400/jts.2012.17.3.245][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.3.245]

Organic matter is able to bind heavy metals. Soil enrichment with organic matter can reduce the availability of metal species as a result of the complexing of heavy metal free ions. This research examined the chelation of lead (Pb) and cadmium (Cd) waste-source heavy metals by organic matter, and the utilization of hyperaccumulator plants to remediate contaminated lands. The study was aimed to (a) analyze the influence of guano organic matter application to reduce heavy metals, Pb and Cd, and the combined effectiveness with plants; (b) to identify the capability of three plants as hyperaccumulator plants. Guano was used as an organic matter source in soils artificially contaminated with Cd and Pb from industrial solid waste. The research was conducted in two phases. The first research phaseused a combination of artificial Pb and Cd with guano. The second Research phase involved two dosages of guano and three concentrations of waste. Three plants were used as hyperaccumulator plants: elephant grass (Pennisetum purpureum), chinese cabbage (Amarantus tricolor), and water spinach (Ipomoea aquatica). The study results indicated that guano had the capability to chelate more than 90% of Pb and a maximum of 61% of Cd, hence reducing the concentration of Pb and Cd. Other results showed that the three hyperaccumulator plants generated different responses toward the addition of heavy metals (Pb and Cd). From the calculation of the Bio-Accumulation Factor (BAF), the value for Cd showed that P. Purpureum and A. Tricolor had good potential as hyperaccumulators. Only P purpureum had the capacity as a hyperaccumulator for Pb, while I.aquatica was not a hyperaccumulator plant for Cd or Pb. Keywords: heavy metals; hyperaccumulator; guano; bioaccumulation factor

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