Distribution of Various Forms of Phosphorus in Flue-cured Tobacco Grown Soils of Khammam District in Andhra Pradesh

Abstract

Phosphorus fractionation studies in Flue-cured Virginia (FCV) tobacco growing areas of Khammam district revealed that a wide variation exhists in concentration of different P-fractions in the three major soil groups. Saloid bound-P was less in Aswaraopet, Malkaram and E.Bayyaram soils, while Al-P is high in E.Bayyaram and Narasapuram soils where Al-P varied from 45-499 mg kg-1. The Fe-P ranged from 6.2-47.9 mg kg-1 and was high in E.Bayyaram soils. Among all the fractions studied, Fe-P was the lowest in all the tobacco soils of the district. The calcium-P varied from 6.9-438.2 mg kg-1 which was very low in Aswaraopet, Malkaram and E.Bayyaram red soils. The reductant soluble P or R-P varied from 31-644 mg kg-1 and it was low in Aswaraopet and Malkaram soils, whereas it was highest in Kunavaram soils. The total P concentration in Khammam soils varied between 91 to 1487 mg kg-1. It was observed that the total P content was low in Aswaraopet and Malkaram. In contrast, the total P content was high in Narasapuram, Kunavaram and Velerupadu. Available P status ranged from 2.81 mg kg-1. In Ananthapuram soils to 42.2 mg kg-1 in Narasapuram soils. Significant positive correlation was observed between pH and S=P, Ca-P and R-P wilt content of soil showed significant positive relation with total-P. Significant positive relation was observed between S=P, Ca-P and total-P. As there was no significant response to phosphorus application in high P soils, requirement of phosphorus being low (4-6 kg ha-1) for a yield level of 1600-1800 kg ha-1, phosphorus application can be minimized for FCV tobacco wherever soils are high in phosphorus content in Khammam district.