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In the era of precision agriculture, the fertilizer prescription based on the soil fertility status is much required. Analyzing the soil after each crop is necessary for fertilizer recommendation and developing an alternative technique to forecast the soil available nutrient value rather than analyzing the soil. Multiple linear regression (MLR) equation was developed using filed experiment data to predict the soil available nutrient in castor cropping sequence. The post-harvest soil available nutrient was considered as the dependent variable and the initially available soil nutrient values, fertilizer added, yield and nutrient uptake of castor as an independent variable. In general, the post-harvest soil nutrient model's prediction accuracy was notable and had a coefficient of determination of less than 0.90. By calculating the RMSE (root means square error), R2 value, the ratio performance to deviation (RPD) and, RE (relative error) the performance of the MLR model was confirmed.Using the validated model, post-harvest soil available nutrients were predicted and compared with laboratory tested soil available nutreints. It turned out that the established model is more precisely effective and equally precise. Fertilizer recommendation could be made to subsequent crop after hybrid castor using the predicted soil available nutrients. [ABSTRACT FROM AUTHOR]

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]

The fertilizer prescription equations were developed for rainfed Bt cotton on Pielamedu series (Typic haplusterts) by adopting the inductive cum targeted yield model, and fertilizer requirements were quantified for Bt cotton based on soil test and yield target. The validity of fertilizer prescription equations was done by conducting test verification trials at four locations in Perambalur district of Tamil Nadu developed for rainfed Bt cotton. The fertilizer prescription equations were used to calculate the fertilizer doses for STCR treatments. The percent achievement of the targeted yield was within ±10% variation in all the locations for both the yield targets under nitrogen, phosphorus, and potassium (NPK) alone and IPNS, proving the validity of the equations. STCR-IPNS based fertilizer recommendations for a yield target of 32 q/ha has recorded the highest yield, nutrient response ratio, and percent yield achievement in all the locations. [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]

A field experiment was conducted on a Typic Ustropept (Irugur soil series) soil of Western Zone of Tamil Nadu to refine the existing fertilizer prescription equation for rainfed maize adopting the inductive-cum-targeted yield model, and fertilizer requirements were quantified for rainfed maize based on soil test and yield target. The basic parameters viz., nutrient requirement (NR) and contributions of nutrients from soil (Cs), fertilizer (Cf) and farm yard manure (Cfym) were computed from the field experimental data. Using the basic parameters, fertilizer prescription equations were developed based on integrated plant nutrition system (IPNS), and nomograms were formulated for the desired yield target of rainfed maize for the given soil test values. The extent of saving of inorganic fertilizers for rainfed maize was computed using the fertilizer prescription equations under IPNS with the application of FYM @ 12.5 t/ha (32% moisture and 0.50, 0.21 and 0.49% of N, P and K, respectively, was 22, 17 and 20 kg of fertilizer N, P2O5 and K2O, respectively, when applied along with the N, P and K fertilizers as per soil test and desired yield target. To validate the fertilizer prescription equations developed for rainfed maize under IPNS, field experiments were carried out during 2013-15 in three locations. The per cent achievement of the targeted yield of all the three verification trials was within ±10% variation proving the validity of the equations for prescribing integrated fertilizer doses for rainfed maize. [ABSTRACT FROM AUTHOR]

Field experiments were conducted on a Typic Rhodustalf (Palaviduthi soil series) soil of Southern Zone of Tamil Nadu by adopting the inductive-cum-targeted yield model, and fertilizer requirements were quantified for glory lily based on soil test and yield target. The basic parameters viz., nutrient requirement (NR) and contribution of nutrients from soil (Cs), fertilizer (Cf) and farm yard manure (Cfym) were computed from the field experimental data. Using the basic parameters, fertilizer prescription equations were developed based on integrated plant nutrition system (IPNS), and nomograms were formulated for desired yield target of glory lily for a range of soil test values. The extent of saving of inorganic fertilizers for glory lily was computed using the fertilizer prescription equations under IPNS. The estimates showed that for the application of FYM @ 12.5 t/ha with 25% moisture and 0.528, 0.261 and 0.501% of N, P and K, respectively, when applied along with the N, P and K fertilizers as per soil test and desired yield target, the saving was 35, 22 and 30 kg of fertilizer N, P2O5 and K2O, respectively. [ABSTRACT FROM AUTHOR]

Soil test crop response (STCR) based fertilizer prescription for desired yield target of wheat was developed under Integrated Plant Nutrition System (STCR-IPNS) on Periyanaickepalayam soil series (Vertic 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 in six locations to evaluate the model through field experiments in Western Zone of Tamil Nadu. The treatments included control, blanket recommendation, soil test crop response (STCR) based fertilizer dose for an yield target of 3.0 and 4.0 t/ha, STCR-IPNS based fertilizer dose for an yield target of 3.0 and 4.0 t/ha and farmer's practice. Based on the initial soil test values of available N, P and K and the quantities of N, P and K contributed through farm yard manure (FYM), fertilizer doses were calculated and applied for STCR and STCR-IPNS treatments for the respective yield targets. The treatments were imposed and cultivation practices were carried out periodically and the grain yield was recorded at harvest. Using the data on grain yield and fertilizer doses applied, per cent achievement and response ratio (RR) were worked out. Post-harvest soil samples were collected and analyzed for available N, P and K status. The results of the experiments indicated that in all the six locations, the per cent achievement of the targeted yield was within±10% variation proving the validity of the equations for prescribing integrated fertilizer doses for wheat. The highest mean per cent achievement was recorded in the yield target of 4.0 t/ha (101.2) under STCR-IPNS followed by STCR-NPK alone 4.0 t/ha. The highest mean yield was recorded in STCR-IPNS-4.0 t/ha (4047 kg/ha) recording an increase of 62.1% over blanket recommendation. Among the treatments, STCR-IPNS recorded relatively higher RR than other treatments and the highest mean RR of 6.90 kg/kgwas recorded under STCR-IPNS 4.0 t/ha. The highest benefit : cost ratio (1.81) was also recorded in STCR-IPNS 4.0 t/ha. 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 wheat under IPNS can be recommended for mixed black calcareous soils of Tamil Nadu (Vertic Ustropept) for achieving an yield target of 4.0 t/ha 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]

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]

Field experiments were conducted on a Typic Haplustalf soil of Tamil Nadu by adopting the inductive cum targeted yield model, and fertilizer requirements were quantified for beetroot based on soil test and yield target. The basic parameters [nutrient requirement (NR) and contributions of nutrients from soil (Cs), fertilizer (Cf), and vermicompost (Cvermi)] were computed from the field experimental data. Using these basic parameters, we developed fertilizer prescription equations under the integrated plant nutrition system (IPNS), and nomograms were formulated for the desired yield target of beetroot for a range of soil test values. The quantity of fertilizers that could be contributed by vermicompost at 5 t ha-1 was evaluated as 40, 21, and 30 kg nitrogen (N), phosphorus pentoxide (P2O5), and potassium oxide (K2O), respectively, when applied along with the NPK fertilizers as per soil test and desired yield target. [ABSTRACT FROM AUTHOR]