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Precision application of nutrient based on soil test value is important for improving nutrient use efficiency and yield of hybrid castor. Field trial was conducted during 2021 at Tapioca and Castor Research Station, Yethapur, Salem District, Tamil Nadu, India (110 ∘ 35' N, 780 ∘ 29' E). Fertilizer prescription equations (FPEs) were developed for hybrid castor by adopting inductive cum targeted yield model approach under irrigated condition on Alfisol. Initially, soil fertility gradients were established with respect to soil available N, P and K nutrients, and 24 treatments were imposed in three fertility strips under factorial randomized design. Principle component analysis revealed that all the variables accounted for developing the FPEs of hybrid castor are present at the positive quadrant which mean that all the variables are highly important toward the castor seed yield production. From the field experimental data, the basic parameters [nutrient requirement (NR) and nutrients contributions from farmyard manure (Co), fertilizer (Cf), and soil (Cs)] were computed. The nutrient required for producing one quintal of hybrid castor seed yield was evaluated as 3.20 kg of nitrogen, 1.23 kg of phosphorus pentoxide (P2O5), and 3.28 kg of potassium oxide (K2O). The study revealed that soil nutrient contribution was high in case of available phosphorus (41.87%), available nitrogen (21.56%), and available potassium (19.12%), respectively, toward P, N, and K nutrient uptake by hybrid castor. The nutrient contribution from farmyard manure (Co) toward the total uptake was 21.40% of N, 10.35% of P2O5, and 26.06% of K2O, respectively. FPEs for hybrid castor and a ready reckoner of fertilizer dosages were developed using basic data for operational range of soil test values for intended yield target under inorganic fertilization alone and Integrated plant Nutrient System (IPNS) (NPK and FYM). [ABSTRACT FROM AUTHOR]

Soil test crop response (STCR) correlation studies under Integrated Plant Nutrition System were conducted in the western agroclimatic zone of Tamil Nadu during 2020-2021 to devise the fertilizer prescription equations for tomato (Solanum lycopersicum L.) under drip fertigation on an alfisol. The equations were derived by following Ramamoorthy's Inductive cum targeted yield model. The nutrient requirement of N, P2O5 and K2O for producing one quintal of tomato fruit was found to be 0.22, 0.11, 0.27 kg respectively. The per cent contribution of nutrients were 37.93, 46.73 and 29.53 of N, P2O5 and K2O from soil (Cs) and 47.84, 31.12 and 74.13 of N, P2O5 and K2O from fertilizers (Cf) respectively. Two organic sources were applied viz., FYM (Farm Yard Manure) and Biocompost and the per cent contribution of nutrients from FYM were 38.36, 13.22 and 52.17 of N, P2O5 and K2O and from biocompost were 43.34, 10.90 and 57.00 of N, P2O5 and K2O respectively. Fertilizer adjustment equations were formulated for STCR-NPK alone, STCR-IPNS (FYM) and STCR-IPNS (Biocompost) by applying the basic parameters such as NR, Cs, Cf, Cfym, Cbiocompost. A ready reckoner of fertilizer doses for a set of soil test values at yield targets 80 and 90 t ha-1 was computed. The findings also showed that the adoption of STCR-IPNS could save more fertilizers. [ABSTRACT FROM AUTHOR]

An insight into the balanced crop nutrition and efficient irrigation will be rewarding to attain profitable bulb yield of shallow-rooted and high nutrient requiring aggregatum onion. To develop fertilizer prescription equations(FPEs) for aggregatum onion under drip fertigation by encompassing the Soil Test Crop Response approach (STCR), a field experiment was conducted in Palaviduthi soil series with 15 treatments viz., Absolute control (T1), Blanket recommendation (60:60:30) + Farm Yard Manure (FYM) @ 12.5 t ha-1(T2), STCR based NPK fertilizer recommendation (STCR-NPK) for the targeted yield of 14 (T3),15 (T4),16 t ha-1 (T5), FYM @ 6.25 (T6), 12.5 t ha-1 (T7), STCR-NPK+FYM @ 12.5 t ha-1 for the targeted yield of 14 (T8),15 (T9),16 t ha-1 (T10), Biocompost @ 2.5 (T11), 5 t ha-1 (T12) and STCR-NPK+Biocompost @ 5 t ha-1 for the targeted yield of 14 (T13),15 (T14),16 t ha-1 (T15). The results revealed that T10 was more supercilious than others. The basic parameters were deliberated from the experimental data on total nutrient uptake, initial soil fertility status, applied fertilizer doses. The aggregatum onion (variety CO 4) required 0.43, 0.32, 0.45 Kg of N, P2O5, K2O to produce one quintal of bulb yield. The percent contribution of nutrients from soil and fertilizer was 14.01, 54.57 for N, 35.11,50.50 for P2O5 and 12.69, 70.12 for K2O, respectively. The contribution of N, P2O5, K2O from FYM and biocompost were 41.02, 16.23, 41.53 and 47.98, 15.87, 49.56 percent sequentially. Based on the above parameters, the fertilizer prescription equations were formulated for aggregatum onion under drip fertigation in Palaviduthi soil series. [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]

A study on Soil Test Crop Response based Integrated Plant Nutrition System (STCR - IPNS) were conducted adopting an Inductive cum Targeted yield model in non-calcareous sandy loam soils of Lithic Haplusteptat Regional Research Station, Tamil Nadu Agricultural University, Paiyur, Tamil Nadu during Kharif 2013 in orderto develop fertilizer prescriptions equation (FPEs) through IPNS for the desired yield targets of rice under SRI technique. A ready reckoner of fertilizer doses at varying soil test value, for attaining 6 to 9 t ha-1 target grain yield of rice has been worked out. Using these equations a validation trial was conducted on Kharif 2014 at this station. The grain yield of rice ranged from 2.54 t ha-1 in absolute control to 8.65 t ha-1 in STCR-IPNS-9 t ha-1. The STCR-IPNS @ 8 t ha-1 was effective and economical as compare with any other treatments. The deviation recorded in the achievement of targets aimed was within the range of ± 10 per cent (90 - 110 %) proving the validity of the FPEs. The STCR treatments recorded relatively higher response ratio (RR) and benefit-cost ratio (BCR) over blanket and farmer's practice and STCR-IPNS treatments recorded relatively higher RR and BCR over STCR-NPK alone treatments. Post-harvest soil tests for NPK revealed that there was maintenance of soil fertility. The STCR-IPNS @ 8 t ha-1 was effective and economical as compare with any other treatments. Thus, the Inductive cum Targeted yield model used to develop fertilizer prescription equations provides a strong basis for soil fertility maintenance consistent with high productivity and efficient nutrient management for sustainable and enduring Agriculture. [ABSTRACT FROM AUTHOR]