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In an agro-ecosystem, phosphorus (P) is found in organic and an inorganic form which includes soluble P, sorbed P and mineral bounded P. In soil, added P sources undergo various soil processes like mineralization, immobilization, precipitation, weathering, dissolution, sorption and desorption. For understanding the P dynamics in clay loam (Vertic Ustropept) soil, the present study was undertaken in P dynamics under rhizosphere and non-rhizosphere environment of maize in Long Term Fertilizer Experiment at Tamil Nadu Agricultural University, Coimbatore. The results revealed that the fractions of various pools of inorganic NaOH extractable Fe - P, H2SO4 extractable Ca- P, NH4F extractable Al- P, NH4Cl extractable Saloid P and Na citrate - Dithionate extractable Reductant soluble P were dominant in the non-rhizospheric soil than rhizospheric environment. The order of inorganic P fractions in the non-rhizospheric and rhizospheric region of the soil was found as Ca-P > Fe-P > Al-P > Reductant soluble-P > Saloid P and the knee-high stage of the non - rhizosphere soil recorded the highest inorganic as well organic P fractions. Irrespective of P fractions, Ca – P was recorded high (192.5 & 186.7 mg kg-1 ) followed by Fe - P (40.8& 34.9 mg kg-1) at a knee-high stage in non-rhizosphere and rhizosphere, respectively. Practising various nutrient management systems, application of 100% recommended dose of fertilizer along with FYM @ 10 t ha-1 (T8) recorded significant changes in all inorganic (Ca-P, Fe-P, Al-P, Reductant soluble-P, Saloid P), organic fractions and also Total P followed by 150% NPK (T3) in sandy clay loam soil. Nowadays, increasing demand for P fertilizer in India, judicious use of P fertilizer is important. Despite that, intensively cultivated soils have a lot of P reserves like organic and inorganic P pools and effective way of P transformation management could reduce the quantum of P fertilization in soil.

Secondary nutrient deficiency especially sulphur (S) in blackgram has imparted poor grain setting percentage and yield as well. Interest on S availability in soils has increased due to acute shortage production of quality blackgram. Therefore, an attempt was made to assess the three SO4-2- S sources (Gypsum, Ammonium sulphate and Potassium sulphate) and two S levels (10 and 20 kg S ha-1) under irrigated condition. This experimental trial was replicated three times along with randomized block design at farmer field of Thenamallur village, T. Kallikudi block, Madurai district. S treatments were also evaluated by two methods of fertilizer amendment such as, soil application (as basal dose) and foliar spray (0.5 % K2SO4) on 30th and 45th days after sowing and its combinations. Soil analysis is good method to assess the S nutritional status of soil under tropical areas. The results revealed that the S and micronutrient content was low in single soil application or foliar spray and irrespective of source and level. Foliar spray treatment plants recovered limited S concentration. We could found that the better higher S concentration among the combination treatments. Soil application of K2SO4 @ 20 kg ha-1 + foliar spray was increased the soil available S and DTPA - extractable Micronutrient (Zn, Fe, Mn and Cu) status. Our study explains that the treatment combinations had synergistic effect and it may be concluded that the combinations (soil + foliar spray) are increased soil available S and micronutrient status. Further, future studies are required to confirm the results of S fertilizers in alkaline soil.

Long term fertilizer applications and continuous cropping system of Maize - Finger millet (44 years of cropping sequence) has a significant impact on yield and nutrient balance on a soil system. The investigation assessed the effect of long term fertilizer usage on yield and nutrient balance through different treatments such as different doses of NPK (50%, 100% and 150%), NPK along with organic manure, omission of K, PK, addition of Zn along with NPK and omission of S from major nutrients. Application of inorganic NPK fertilizers at graded levels from 50 to 150% NPK increased the grain and straw yield of finger millet and maize. Under the integrated nutrient management practice (100% NPK+FYM),the percent increased grain yield was 17.08 in finger millet and 12.62 in maize over 100 % NPK indicating that INM is the best way of maximize the yield continuously in intensive cropping systems. Under this treatment, the soil available nutrient status was observed high. In INM treatment, possibly the added FYM, might have contributed directly in appreciable amounts of major and micronutrients to the soil and enhanced yields. The status of available N was highest under 100% NPK + FYM, followed by 100% NPK. Continuous addition of N alone did not influence available N, instead reduced available N when compared to NPK treatments. Addition of fertilizer P in progressive levels such as 50, 100 and 150% NPK levels has increased the soil available P (22.62 % in finger millet and 26.35 % in maize) over 100 per cent NPK. Also, addition of different levels of K has improved the soil available K (18.32 % in finger millet and 14.41 % in maize) when compared to 100 % NPK.