Mineralization of Carbon and Phosphorus in Soil as Affected by Soil Moisture Regime and Incorporation of Crop Residues

摘要

Crop residue is important for conserving and sustaining soil productivity. It is the primary substrate for replenishment of soil organic matter and can efficiently arrest the decline in soil organic matter (SOM) content. Upon mineralization, crop residues also supply essential plant nutrients (Walters et al. 1992). Additionally, residue incorporation improves physical and biological conditions of the soil and prevents soil degradation (Nyborg et al. 1995). The value of organic manures is determined by their content of nutrients available for plant growth. Organic matter greatly influences the transformation and availability of N, P, K and several other essential plant nutrients through its impact on the chemical and biological properties of soils. Organic acids formed during the course of decomposition of green manures interact with soil components, thereby considerably enriching the pool of available P (Bin 1983). In green manure-treated soils, active biodegradation and resultant extensive production of CO_2 can lead to the dissolution of Ca and Mg carbonates, thereby influencing the availability of P in soil. Manipulating the soil biological environment can help in enhancing the release of nutrients from these sources. Information on release pattern of nutrients of different organic sources as affected by different water regimes is not well understood. Therefore, this study was undertaken with the objective to evaluate the pattern of release of CO_2 and P from the soil amended with Sesbania aculeata, mungbean and wheat straw under different moisture regimes.