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.

A field experiment was conducted to evaluate the impact of crop productivity and soil nutrient availability under continuous cropping and fertilization. A single nutrient application or omission of nutrient or mineral fertilizer alone can deteriorate the soil nutrient availability and yield in long run. The result revealed that soil pH and EC have not changed substantially even after the repeated application of fertilizers over five decades. The use of balanced fertilizers either alone or integrated with organic manure (FYM) has significantly increased the grain and straw yield of maize. The yield increment of maize was observed 13.9 percent higher than 100% NPK and 18.3 percent higher than without the addition of S (S free). Balanced fertilization can improve the soil nutrients (N, P, K & S) and soil organic carbon instead addition of FYM @ 10 t ha-1 could increase the SOC and soil nutrients in long run in a sustainable manner. Concerning nitrogen, single nutrient (N alone) plots received low available nutrients and yield also it’s deteriorated the soil nutrients over long period. A build-up of available soil P and S was observed due to its continuous addition through fertilizer but soil K has reduced because of intensive cropping and high-yielding cultivars. Hence, for sustainable  roduction, application of a recommended dose of mineral fertilization (100% NPK) along with FYM @ 10 t ha-1 may be used to achieve a higher yield, stable nutrient balance and soil quality over decades.