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Background: In the era of precision agriculture, application of fertilizer based on soil testing is an essential tool to prescribe nutrient doses for crops to improve nutrient use efficiency and yield of hybrid castor. Methods: Field experiment was conducted in 2021 at the Tapioca and Castor Research Station, Yethapur, region near Salem city, Tamil Nadu, India (11°35'N, 78°29'E). By adopting inductive cum targeted yield model fertilizer prescription equation (FPEs) were developed for hybrid castor under irrigated condition for Alfisol soil order. Initially soil fertility gradient were established with respect to soil available N, P and K nutrients and twenty four treatment were imposed in three fertility strips under factorial randomized design. The basic parameters [nutrient requirement (NR) and nutrients contributions from soil (Cs), fertilizer (Cf) and farmyard manure (Co)] were calculated from the field experimental data. Result: 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) towards the total uptake was 21.40% of N, 10.35% of P2O5 and 26.06 % of K2O respectively. Using basic data, FPEs were developed for hybrid castor and ready reckoner were developed for operational range of soil test values for desired yield target under NPK alone and IPNS (NPK and FYM). [ABSTRACT FROM AUTHOR]

Thirty-four red kernel rice genotypes along with two check varieties were evaluated across three different locations of Tamil Nadu viz., Coimbatore, Paiyur and Aduthurai during Kharif 2022 to assess the stability of the genotypes for single plant yield. The AMMI and GGE models were used to study the interaction between the genotypes and the environment in order to select the stable genotypes. Significant differences among the genotypes and the environment revealed the existence of variations among the genotypes and also environmental influence over the genotypes for single plant yield. Considering the overall average single plant yield performances, the genotype Rangoon samba recorded the highest single plant yield over the check varieties, while the genotype Karuthakar had the lowest single plant yield. The genotypes G24 (Thooyala), G25 (Kothamalli samba) and G34 (IG74 Check) recorded higher stable single plant yield across locations. Based on AMMI and GGE stability models, these three genotypes were identified to be highly stable over environments with less G x E interaction and these genotypes can be recommended for cultivation across the environments to obtain a higher single plant yield. [ABSTRACT FROM AUTHOR]

Background: Considering the high cost of fertilizers and adverse effect of its overuse on environment and soil health, proper organic manure-fertilizer recommendations on the basis of soil test values, residual effect and yield targets of chilli becomes vital. Methods: Field experiment was carried out on Periyanaickenpalayam soil series of Inceptisol soil order at farmers holding, Dindigul, Tamil Nadu during 2021-2022 after establishment of marked fertility gradient with respect to soil available N, P and K by gradient experiment with fodder sorghum. The test crop experiment with chilli was laid out in a fractional factorial design comprising of 24 treatments with 4 levels of N (0, 50, 100 and 150 kg ha-1), 4 levels for both phosphorus pentoxide (P2O5) and potassium dioxide (K2O). Farmyard manure (FYM) levels were 0, 6.25 and 12.5 kg ha-1. From the field experiment data, the fundamental parametersnutrient requirement (NR) and nutrients contributions from soil (Cs), fertiliser (Cf) and farmyard manure (Co)-were determined. Result: The percentage of nutrients estimated from fertiliser (%Cf) that contributed towards the total amount of nutrients taken up by dry chilli was calculated to be 44.09, 39.29 and 76.91 per cent of N, P2O5 and K2O, respectively. K2O>N>P2O5 was seen as the order of the fertiliser nutrient per cent contributions to total nutrient uptake. Incase of nutrient contribution form soil (% Cs) the order is P2O5>N>K2O. FYM contributed (% Co) 29.42, 14.40 and 38.73 per cent of N, P2O5 and K2O. One quintal of dry chilli production was estimated to require (NR) 4.24 kg of nitrogen, 1.91 kg of phosphorus pentoxide (P2O5) and 4.80 kg of potassium oxide (K2O) as nutrients. Fertiliser prescription equations (FPEs) for dry chilli and ready reckoners for the operating range of soil test values for the intended yield target experiment under NPK alone and IPNS were built using basic data. [ABSTRACT FROM AUTHOR]

Soil test crop response (STCR's) soil fertility gradient approach is based on the idea that complex treatments are superimposed in a field to obtain crop responses for correlating with soil test values that are artificially created by differential fertiliser treatments prior to conducting the regular experiment, thereby providing a scientific basis for balanced fertilisation between applied and available forms of nutrients. The present study aimed to develop the fertility gradient with sorghum as test crop in the field concerning N, P, and K and also to evaluate its impact on sorghum nutrient uptake, and soil fertility. The experimental field was split into three equal strips. Strips I, II, and III each received three graded levels of fertiliser N (nitrogen), P2O5 (phosphorus pentoxide), and K2O (potassium oxide) as urea, single super phosphate, and muriate of potash, respectively. The green fodder yield of sorghum recorded at harvest in strip I, II & III was 16.4, 23.4 and 28.2 t ha-1, respectively. Whereas post-harvest soil available nitrogen in strip I, II & III was 155, 190 & 214 kg ha-1 respectively, for available phosphorus 12.5, 23.2 & 31.8 kg ha-1 respectively and for available potassium it is 332, 370 & 396 kg ha-1 respectively. Wide variations in green fodder yield and soil fertility were observed among the strips, establishing the influence of graded amounts of fertiliser treatment on these parameters and the formation of a soil fertility gradient. [ABSTRACT FROM AUTHOR]

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]

Background: Barnyard millet is one of the significant small millets cultivated in India. It has provided a good source of nutrients. Its production is low in low fertile soil. For that study undertaken into supplying balanced nutrition to achieve maximum yield by following soil test crop response-based fertilizer prescription equation. Methods: The Inductive methodology adopted in the field experiment for developing a scientific basis of fertilizer prescription for barnyard millet was performed on Periyanaickenpalayam soil series of Inceptisol soil order of Tamil Nadu during 2019-2020. The initial soil available nutrient status, grain yield, total nutrient uptake by barnyard millet and fertilizer N, P2O5 and K2O and FYM applied were taken into account for calculating four basic parameters for developing fertilizer prescription equation viz., nutrient requirement (NR) to produce 100 kg of barnyard millet grains, the contribution of nutrients from soil (Cs), fertilizer (Cf) and FYM (Cfym). Result: The fertilizer prescription equations and ready reckoner were developed to prescribe fertilizer dosage for a range of soil test values for specific yield target of barnyard millet on Inceptisol. It can be adopted on the Periyanaickenpalayam soil series of Tamil Nadu and also in regions with allied soil types. [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]

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]

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]