초록
본 연구에서는 화학비료와 퇴비를 과다하게 투입하여 인산의 집적 및 유출 위험성이 높은 양파-벼 재배지와 시설재배지의 인산 집적 특성과 인산가수분해효소를 이용한 집적 인산의 수계에서의 생물이용가능성을 평가하였다. 수용성 인산 중 많은 부분의 유기태 인산이 주변 수계에 유출될 위험성이 높았지만 그동안 제대로 평가되지 못했다. 본 연구결과에서 alkaline phosphomonoesterase와 phosphodiesterase에 의해 이모작토양에서 DUP의 12, 24%가 시설재배지 토양에서 DUP의 18과 44%가 분해되는 것으로 나타났다. 토양에 축적된 유기태 인산중 orthophosphate monoester와 diester가 주로 인산분해효소에 의해 분해되어 농경지 주변 수계로 유출시 생물 이용 가능성이 큰 것으로 평가되었다. 따라서 수계에서 인산의 거동을 이해할 때 유기태 인산에 대한 충분한 고려가 필요할 것이다.
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.