Interaction between P and Zn on the Changes in Different Inorganic Phosphorus Fractions under Waterlogged Soil Treated with and Without Organic Matter

Background: Phosphorus and zinc are two essential nutrients which are required for normal plant growth. These nutrients are mutually antagonistic in certain circumstances which can cause yield reductions in many crops due to either P or Zn deficiencies. Organic matter causes soil to clump and form soil aggregates, which improves soil structure. With better soil structure, permeability improves, in turn improving the soil’s ability to take up and hold water. The addition of organic manure may reduce the mobility of Zn in soil by forming stable chelates thereby may affect the formation of Zn-P complexes in soil. Thus, the present study was undertaken to find the interaction between P and Zn on the changes in different inorganic phosphorus fractions under waterlogged soil treated with and without organic matter. Methods: An incubation experiment has been conducted in the laboratory of Department of Agricultural Chemistry and Soil Science, University of Calcutta to find the interaction between P and Zn on the changes in different phosphorus fractions under waterlogged soil treated with and without organic matter. Treatments details: P0Zn0 - No Phosphorus + No Zn, P0Zn1 - No Phosphorus + Application of Zn at 2.5 mg/kg soil, P0Zn2 - No Phosphorus + Application of Zn at 5 mg/kg soil , P1Zn0 - Application of P at 10 mg/kg soil + No Zn, P1Zn1 - Application of P at 10 mg/kg soil + Application of Zn at 2.5 mg/kg soil,P1Zn2 - Application of P at 10 mg/kg soil + Application of Zn at 5 mg/kg soil, P2Zn0 - Application of P at 15 mg/kg soil + No Zn, P2Zn1 - Application of P at 15 mg/kg soil + Application of Zn at 2.5 mg/kg soil, P2Zn2 - Application of P at 15 mg/kg soil + Application of Zn at 5 mg/kg soil. The same treatment combination was studied with application of organic matter where organic matter was applied @1% by soil weight basis and another set of treatment combination were conducted in absence of organic matter. After application of all treatments, maintaining waterlogged condition, the soils were allowed to incubate at room temperature (30±2)°C for a period of 10, 20, 30, 40, 50 days interval and analyzed for different fractions of P. Result: The amount of Soluble and Loosely bound P fractions has been recorded highest (47.50 mg kg-1) in the treatment P2OM2 at 30 days of incubation in presence of organic matter. As regards to the interaction effect between P and organic matter it was observed that the amount of Al-P was recorded enhanced, being highest with their highest level of application. The individual application of P increased the amount of Fe-P content, being highest (56.96 mg kg-1) at 30 days of incubation with its highest level, while the application of organic matter at its highest level recorded highest amount of Fe-P (55.30 mg kg-1) content. The absolute amount of Reductant soluble P was recorded a lower value than Fe-P. The results suggest that Ca-P fraction was the dominant inorganic P fraction among other fractions and there is a synergistic effect was found between P and organic matter where there is an antagonistic effect found between P and Zn.