Study of mineralization of phosphorus and sulphur from various sources of green manures incorporated in entisol

Abstract

The laboratory experiment was carried out for 120 days in ambient condition to study mineralization of nitrogen from various sources of green manures, added on the basis of carbon content. Among the various sources of greenmanures the highest amount of total N, P and Fe contents were observed in the Cow pea while the lowest amount of total N, P, K, S, Mn, Zn and Cu contents were recorded in Subabul. The lowest C:N ratio (11.97) was recorded in Glyricida. However, the highest C:N ratio (20.89) was noticed in Sunnhemp. The available phosphorus was increased with increase in days after incubation in all the treatments. The maximum cumulative increase of available phosphorus was observed in cowpea while the lowest cumulative available phosphorus was recorded in control treatment. The slightly increased the available phosphorus content with increase in days after incubation in control treatment. The results of sulphur mineralization showed that the soils amended with all the sources of organic manures also increased available sulphur with increase in days after incubation. However, the slightly decrease in available sulphur was noticed in control treatment. A more or less available sulphur content was recorded at 60 and 90 days after incubation. The soils properties viz., pH, EC, calcium carbonate, Ex. Ca, Ex. Mg and all the DTPA extractable micronutrients were significantly not affected due to the incorporation of all the sources of organic manures. However, the addition of all the sources of organic manures significantly improved the organic carbon, available nitrogen and potassium content as compared with control treatment.The results concluded that the addition of Glyricidia is beneficial for improving the sulphur content while cowpea is helpful for improving the available phosphorus content of soil.