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Field experiments were conducted during 2016-17 at Manickapuram village of Theni District, Southern Zone of Tamil Nadu to study the impact of Inductive approach (artificial gradient)on soil fertility, nutrient uptake and fodder yield of sorghum (var CO30) and further,Soil Test Crop Response correlation studies under Integrated Plant Nutrition System (STCR-IPNS) for desired yield targets of maize on Vertisol. The profile study of the experimental site has been described in detail. The artificial fertility gradient was developed by dividing the field into three equal strips and graded levels of fertilizers were applied in the form of Urea, Single Super Phosphate and Muriate of Potash, respectively to strip I (N0P0K0), II (N1P1K1) and III (N2P2K2). The N1level was fixed based on the blanket recommendation of fodder sorghum and P1 and K1 levels were fixed based on the phosphorus (100 kg ha-1) and potassium (80 kg ha-1) fixing capacities of the soil.Sorghum (var.CO30) was grown as gradient crop and green fodder yield was recorded at harvest and plant samples were collected and analyzed for N, P and K contents and their uptake was computed. The results confirmed that the application of graded levels of fertilizer N, P2O5 and K2O significantly influenced soil fertility status, N, P and K uptake and green fodder yield of sorghum. Subsequently, the STCR-IPNS studies on maize (hybrids) revealed that the requirement of N, P2O5 and K2O for maize (NR) was found to be 2.08, 0.73 and 1.38 kg q-1respectively. The per cent, nutrient contribution from soil (Cs) was 43.01, 44.03 and 9.17; from fertilizers (Cf) was 55.00, 49.83 and 76.99, and from organic manure (Co) was 49.01, 19.71 and 39.83 for N, P2O5 and K2O, respectively. Using the basic data viz., NR, Cs, Cf and Co, fertilizer prescription equations (FPEs) have been developed and ready reckoner of fertilizer doses was formulated for desired yield targets of maize for a range of soil test values on Vertisol. The findings also brought forth the fact that when farm yard manure (FYM) was applied @12.5 t ha-1 (with 25 per cent moisture and 0.54, 0.26 and 0.53 per cent NPK, respectively), 45, 22 and 32 kg ha-1 of fertilizer N, P2O5 and K2O could be reduced from the recommended fertilizer doses for Maize. Using the nomograms, critical levels of soil available N, P and K were fixed. [ABSTRACT FROM AUTHOR]

Field experiments were conducted based on Inductive cum targeted yield concept on Typic Haplustert soils (Pilamedu series - black calcareous) to predict the post-harvest soil test values for prescribing soil test crop response based fertilizer doses under Integrated Plant Nutrition System (STCR-IPNS) for maize based cropping sequence. The experiment comprised of 24 treatments with four levels each of N (0,100,200 and 300 kg ha-1), P2O5 (0,40,80 and120 kg ha-1) and K2O (0,40,80 and120 kg ha-1) and three levels of FYM (0, 6.25 and 12.5 t ha-1) for the test crop maize (TNAU Maize hybrid CO 6) laid out in fractional factorial design. Making use of the experimental data on initial and post-harvest soil test values, fertilizer doses and the grain yield obtained or uptake of N,P and K by maize, Post-Harvest Soil Test Values (PHSTVs) prediction equations with high R2 values (>0.90) were developed, which could be used with confidence for the prediction of post-harvest KMnO4-N,Olsen-P and NH4OAc-K. Using the predicted PHSTVs after kharif maize, soil test based fertilizer prescription for desired yield target of succeeding crop viz., cotton could be prescribed. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during rabi season of 2017-2018 on a mixed black calcareous soil (Typic Ustropept - Periyanackenpalayam soil series) at Eastern Block, Tamil Nadu Agricultural University, Coimbatore to refine the existing fertilizer prescription equations under Integrated Plant Nutrition System (IPNS) for hybrids to suit pearl millet variety. The experiment comprised of eleven treatments with three replications in Randomized Block Design. The experimental results revealed that there was a progressive increase in response from lower target to higher targets and the magnitude of response was higher under STCR-IPNS than under STCR-NPK alone treatments. Using the experimental data, the basic parameters viz., nutrient requirement (NR), per cent contribution of nutrients from soil (Cs), fertilizers (Cf) and FYM (Cfym) towards total N,P and K uptake by pearl millet (var. CO 10) were computed based on targeted yield model. It was found that pearl millet variety requires 2.81, 1.33 and 2.53 kg of N, P2O5 and K2O, respectively to produce one quintal of grain. The contribution of nutrients from soil, fertilizers and FYM for N was 26.36, 45.44 and 27.55 per cent; for P2O5 it was 38.51, 44.14 and 16.04 per cent and for K2O it was 10.33, 87.45 and 40.15 per cent respectively. Making use of the refined basic parameters, Fertilizer Prescription Equations (FPEs) were developed under NPK alone and IPNS for pearl millet variety. Ready reckoner of fertilizer doses (nomograms) were formulated for a range of soil test values and for desired yield target viz., 3.0, 3.5 and 4.0 t ha-1. For an average soil test value of 180:24:460 kg ha-1 and yield target of 4.0 t ha-1, 105, 51 and 25 kg of fertilizer N, P2O5 and K2O is to be appiled along with FYM @ 12.5 t ha-1. The extent of saving of inorganic fertilizers for pearl millet with the application of FYM @ 12.5 t ha-1 (with 21% moisture, 0.64, 0.27 and 0.46% N, P and K respectively) was 38, 22 and 25 kg of fertilizer N, P2O5 and K2O respectively. [ABSTRACT FROM AUTHOR]

Geo referenced surface soil samples were collected from 79 villages of Cuddalore district, Tamil Nadu and about 474 soil samples were analysed for twelve chemical parameters. The fertility status revealed that the soils were acidic to alkaline in soil reaction, non - saline and low in organic carbon content. The macronutrient availability showed low available N (82.3%), high available P (61.8%), medium to high available K (49.3&31.8%) and sufficient in available S (84.4%). With regard to micronutrients, the soils were predominantly deficient in Zn (76.4%) followed by Cu (38%), B (10.6 %), Fe (1.8 %) and Mn (1.4 %). Using the geocoordinates, thematic maps for all the parameters were prepared,, which also indicated that major area of the district was acidic to alkaline in soil reaction, non-saline, low in OC, low, high and medium in available N, P and K, respectively. Zinc was predominantly deficient among the micronutrients, while all others were in sufficient status. [ABSTRACT FROM AUTHOR]

Soil Test Crop Response based fertilizer prescription equations for desired yield target of rainfed maize were developed under Integrated Plant Nutrition System (STCR-IPNS) on Irugur soil series (Typic Ustropept) of Tamil Nadu. On farm testing of fertilizer prescription equations are essential to demonstrate the effectiveness of technology delivery to the stake holders in need. The present study was undertaken to evaluate the targeted yield model through field experiments at six locations in Dindigul district, Western Zone of Tamil Nadu. The treatments included control, blanket recommendation, soil test crop response (STCR) based fertilizer dose for the yield targets of 4.0 to 6.0 t ha-1, STCR-IPNS based fertilizer dose for the yield targets of 4.0 to 6.0 t ha-1 and farmer's practice. In all the six locations, the per cent achievement of the targeted yield was within ± 10 per cent variation proving the validity of the equations for prescribing integrated fertilizer doses for rainfed maize. The highest mean grain yield was recorded in STCR-IPNS - 6.0 t ha-1 (5013 kg ha-1) recording an increase of 52.2 per cent over blanket recommendation. The highest per cent achievement, response ratio and B:C ratio of 97.2,17.47 and 2.28, respectively were recorded in the yield target of 5.0 t ha-1 under STCR-IPNS. The post-harvest soil available NPK indicated the build up and maintenance of soil fertility due to soil test based fertilizer recommendation under IPNS. The fertilizer prescription equations developed for rainfed maize under IPNS can be recommended for red non calcareous soils of Tamil Nadu for achieving the yield target of 5.0 t ha-1 with sustained soil fertility and it can be extrapolated to other agro-climatic zones of Tamil Nadu on similar and allied soil types. [ABSTRACT FROM AUTHOR]

Delineation of available macro and micronutrients was carried out by collecting 318 geo referenced surface soil samples from 53 villages in 14 blocks covering nine taluks of Tiruchirapalli district, Tamil Nadu using Global positioning system (GPS) by following multistage stratified random sampling approach. The soil samples were analyzed for 12 chemical parameters and georeferenced data were used for the preparation of soil fertility maps using GIS. Results from the analytical data of 318 soil samples revealed that a major per cent of the samples was neutral to alkaline, non-saline, low to high in OC, low in available N, medium in available P and medium to high in available K. With regard to available S and micronutrients, Zn is predominantly deficient; B is moderate to sufficient while S, Fe, Cu, and Mn were in sufficient status. Based on Nutrient Index Value, the over all fertility rating is medium OC, low, medium and high and very high N, P, K and S, respectively; marginal Zn, high Fe, Cu and B and very high Mn. Making use of the analytical data and GPS readings the thematic soil fertility maps were generated by krigging in Arc-GIS software version 9.3. The maps clearly revealed that, a major area of the district was alkaline, non-saline, medium in OC, low, medium and high in available N,P and K, respectively with regard to available S and micronutrients, Zn was predominantly deficient, B was moderate while S, Fe, Cu and Mn were in sufficient status. [ABSTRACT FROM AUTHOR]

Soil Test Crop Response correlation studies were carried out in maize under Integrated Plant Nutrition System (STCR-IPNS) on Typic Rhodustalf of Tamil Nadu, adopting "Inductive cum Targeted yield model". The basic parameters for the "Targeted yield model" viz. nutrient requirement (NR), contribution of nutrients from soil (Cs), fertilizer (Cf) and farmyard manure (Cfym) were computed from field experimental data. Using these parameters, the fertiliser prescription equations were developed under IPNS and ready reckoner of fertiliser doses were formulated for desired yield target of maize for a range of soil test values. The quantity of fertilizer nutrients that could be saved due to the application of FYM @ 12.5 t ha-1 was assessed to the tune of 40, 20 and 26 kg fertilizer N, P2O5 and K2O respectively, when applied along with the NPK fertilizers. The per cent reduction in fertilizer N, P2O5 and K2O under IPNS increased with increasing soil available NPK. [ABSTRACT FROM AUTHOR]

Soil test based fertilizer prescriptions for desired yield target of wheat were developed under Integrated Plant Nutrition System (IPNS) for Ooty soil series (Typic Haplohumult) of Tamil Nadu. To validate the equations, experiments were conducted in Salem and Namakkal districts at farmers holding on similar soil series. The results revealed that the per cent achievement of the aimed yield target was within ± 10 per cent variation confirming the validity of the equations. STCR treatments recorded significantly higher yield, Response Ratio (RR) and BCR over blanket while STCR - IPNS treatments recorded relatively higher yield, RR and BCR over STCR-NPK alone treatments. The highest mean yield of 41.63 q ha-1 was recorded with STCR-IPNS 40 q ha-1 with an increase of 55.8 per cent over blanket. Post - harvest soil fertility with respect to available N, P and K revealed that there was sustainability of soil fertility in STCR treatments. Therefore soil test based fertilizer prescription can be recommended to hilly and foothill areas of Tamil Nadu for achieving 40 q ha-1 of wheat. [ABSTRACT FROM AUTHOR]

Field experiments were conducted in Southern and Western Zones of Tamil Nadu to evaluate the Soil Test Crop Response based fertilizer prescription model under Integrated Plant Nutrition System (STCR-IPNS) for desired yield targets of radish on red calcareous soils (Palathurai series-Typic Rhodustalf). The treatments include control, blanket recommendation, soil test crop response (STCR) based fertilizer dose for an yield target of 40 t ha-1 and 50 t ha-1, STCR-IPNS based fertilizer dose for an yield target of 40 t ha-1 and 50 t ha-1 and farmer's practice. The results of the experiments indicated that, in all the six trials, the per cent achievement of the targeted yield was within ± 10 per cent variation proving the validity of the equations for prescribing integrated fertilizer doses for radish. The highest mean per cent achievement was recorded with STCR - IPNS - 50 t ha-1 (101.3) followed by STCR-NPK alone 50 t ha-1. The highest mean yield was recorded in STCR-IPNS - 50 t ha-1 (50.6 t ha-1) recording an increase of 56.7 per cent over blanket recommendation and 69.0 per cent over farmer's practice. Among the treatments, STCR-IPNS-50 t ha-1 recorded relatively higher RR (81.3 kg kg-1) and BCR (2.24) than other treatments. Post-harvest soil available NPK indicated the build up and maintenance of soil fertility due to soil test based fertilizer recommendation under IPNS. [ABSTRACT FROM AUTHOR]