SRINIVASAMURTHY, C. A.CHANDRAKALA, M.2017-07-062017-07-062014-10-05Th-10960http://krishikosh.egranth.ac.in/handle/1/5810024424An investigation on available soil phosphorus status, P fractions, requirement of P for finger millet and maize in EDZ of Karnataka and revalidation of soil test ratings for phosphorus was taken at UAS, Bangalore. Soil samples from EDZ were analysed for P status and randomly collected samples were analysed for P fractions. Response of finger millet and maize to graded levels of P was studied in the field by creating five phosphorus fertility gradients viz., P0 (Very low), P1 (Low), P2 (Medium), P3 (High) and P4 (Very high) (< 15: 16-30: 31-45: 46-60: > 60 kg P2O5 ha-1, respectively). Critical limits and soil P ratings was determined by conducting pot culture experiment in 24 soils from six different locations from each VL, L, M and H categories, using maize as test crop applied with graded levels of P. Results revealed that, application of 125% RDP with rec. NK&FYM recorded higher finger millet (31.66 and 55.32 q ha-1grain and straw, respectively) and maize (78.26 q ha-1 grain) yield in high P strip. PUE was higher with lower levels of P application. There was a build-up of P in soil with graded levels of P application to gradient strips, which was reflected by increase in total P and P fractions. Critical limit for available P2O5 was 17.00 kg ha-1 and for plant 0.12 per cent. The proposed fertility ratings for available P2O5 are <15.50, 15.51-28.00, 28.10-48.50 and >48.50 kg ha-1; VL: L: M: H, respectively. Available P2O5 in soils of EDZ ranged 10.22 to 98.32 kg ha-1. Percentage of soil samples under different category are Low (30.80) > Medium (27.20) > High (21.20) > Very low (20.80). Total-P, organic-P, reductant soluble-P, occluded-P and Ca-P increased as the soil phosphorus fertility increased and reverse trend was noticed for saloid-P, Al-P and Fe-P fractions.ennullThesis