• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.97-102
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• 2007

The present investigation deals to achieve an accurate determination of the phosphorous present in the wastewater samples using the membrane reactor. The study may enable to quantify the dissolved (DP) and adsorbed phosphorous (AP), also the adsorbed phosphorous categorically identified as inorganic coupled phosphorous (DRP) and organic coupled phosphorous (NRP). Moreover, the study has been conducted separately in anaerobic and aerobic chamber. The results obtained showed that dissolved phosphorous only can occur in anaerobic chamber with ca. 25%. The study conducted for adsorbed phosphorous showed that the DRP has the percent composition in anaerobic and aerobic chamber respectively 33% and 40% i.e., 7% more in aerobic chamber. The similar values obtained for NRP was found to be 42% and 60% i.e., 18% more in aerobic chamber. On the other hand while comparing the results for NRP and DRP, it has to be noted that NRP has 9% and 20% more percent composition than DRP respectively in anaerobic and aerobic chamber. Further, the adsorbed phase showed the species Al-P, Fe-P in the aerobic chamber with the quotient of 7.73 mg/g TS (total solid) whereas in the anaerobic chamber it showed the species Fe-P and $Fe(OH)_3$-P with the 7.16 mg/g TS.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.66-71
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• 2008

Phosphorus transfer from agricultural soils to surface waters is an important environmental issue. Fly ash and phospho-gypsum which are industrial by-product were investigated as a means of reducing dissolved phosphorus in arable soil. To determine the optimum mixing ratio of fly ash(FA) and phospho-gypsum(PG) for reducing dissolved reactive P(DRP) in soil, various mixture ratio of FA and PG were mixed with two soil. The DRP content and pH in soils were analysed after 3 weeks incubation under flooding condition. Although DRP content in soils was significantly decreased by FA-PG mixture compared with control, there were no significant difference among the FA and PG mixture ratio of 75:25, 50:50, and 25:75. The mixture of 75% FA and 25% PG was selected for field test. A field experiment was carried out to evaluate the reducing DRP content in paddy soil to which 0(NPK), 20(FG 20), 40(FG 40), and 60(FG 60) Mg $ha^{-1}$ of the mixture were applied. The DRP content was reduced by 31% at the application rate of 60 Mg $ha^{-1}$. In contrast to deceasing DRP, Ca-P content increased significantly with the mixture application rate. After rice harvesting, available $SiO_2$, P, and exchangeable Ca content in soil increased significantly with application rate due to high content of Si, P, and Ca in the mixture. Mixtures of fly ash and gypsum should reduce P loss from paddy soil and increase soil fertility.

• Korean Journal of Environmental Agriculture
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• v.31 no.4
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• pp.293-299
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• 2012

BACKGROUND: Soil utilization pattern can be the main factor affecting soil physico-chemical properties, especially in soil phosphorus (P). Understanding the distribution and bioavailability of P is important for developing management to minimize P release from arable soils to environment. This study was conducted to evaluate the potential bioavailability of soil organic P by using phosphatase hydrolysis method. METHODS AND RESULTS: Twenty-four soils from onion-rice double cropping and 30 soils from plastic film house were selected from Changyeong and Daegok in Gyeongnam province, respectively. The P accumulation pattern (total P, inorganic P, organic P, residual P) and water soluble P were characterized. Commercial phosphatase enzymes were used to classify water-extractable molybdate unreactive P from arable soils into compounds that could be hydrolysed by (i) alkaline phosphomonoesterase (comprising labile orthophosphate monoesters), (ii) a combination of alkaline phosphomonoesterase and phosphodiesterase (comprising labile orthophosphate monoesters and diesters), and (iii) phytase (including inositol hexakisphosphate). Available P was highly accumulated with 616 and 1,208 mg/kg in double cropping system and plastic film house, respectively. Dissolved reactive P (DRP) and dissolved unreactive P (DUP) had similar trends with available P, showing 24 and 109 mg/kg in double cropping and 37 and 159 mg/kg in plastic film house, respectively, indicating that important role of dissolved organic P in the environments had been underestimated. From the result of phosphatase hydrolysis, about 39% and 66% of DUP was evaluated as bioavailable in double cropping and plastic film house, respectively. CONCLUSION(S): Orthophosphate monoester and orthophosphate diester accounted for high portion of dissolved organic P in arable soils, indicating that these organic P forms give important impacts on bioavailability of P released from P accumulated soils.