Phosphorus transformation in root zone environment under semi tropical agro ecosystem in sandy clay loam soil

Abstract

A field experiment was carried out during 2021, at the existing long term fertilizer experiment of TNAU which is in operation since 1972 at Coimbatore, Tamil Nadu with a cropping system of finger millet-maize at field no: 36 F, Eastern farm, TNAU, Coimbatore, Tamil Nadu to evaluate phosphorus transformation in root zone environment under semi tropical agro ecosystem in sandy clay loam soil under long term fertilization in finger millet-maize cropping sequence. The treatments were established in ten treatments namely T 1 -50% NPK, T 2 -100% NPK, T 3 -150% NPK, T 4 -100% NPK+ Hand weeding, T 5 -100% NPK+ZnSO 4 , T 6 -100% NP, T 7 -100% N, T 8 -100% NPK+FYM, T 9 -100% NPK(-S), T 10 -Control replicated thrice in a Randomized Block Design. The available P reported a 5.8 percent increased availability in the rhizosphere soil over the non-rhizosphere and followed a decline in plant growth was highest in the 100% NPK+FYM plot, while the total P revealed the same percent rise in the non-rhizosphere soil. Saloid P, Fe-P, Al-P, Ca-P and Reductant soluble P each contributed about 7. 18, 10.05, 11.27, 61.38, 10.12 percent to the total inorganic P pools. For the total P, the organic P contributed about 61.19% and inorganic fractions contributed about 38.81%. The competence among the P fraction exhibited the pattern of Ca-P > Al-P > Fe-P > Reductant soluble P > Saloid P in their share in the root zone soil. The results revealed that the fractions of various P pools were dominant in the non rhizospheric soil than rhizospheric environment and followed a declining trend when the crop proceeded towards maturity. Practising various nutrient management system, application of 100% recommended dose of fertilizer along with FYM @ 10 tha -1 (T 8 ) was recorded significant changes in all inorganic (Ca-P, Fe-P, Al-P, Reductant soluble-P, saloid P), organic fractions, available P and also Total P followed by 150% NPK (T 3 ) in sandy clay loam soil. Phosphorus dynamics in soil are critical for careful phosphorus fertilisation management in order to achieve sustainable agricultural development.