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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]

In the advent of precision agriculture, applying fertilizer based on soil testing is a crucial tool to prescribe nutrient levels for crops, to increase nutrient use efficiency and production. A field experiment was conducted in a farmer's field in the Dindigul district, Southern agro-climatic zone of Tamil Nadu to ascertain the effect of artificial soil fertility gradient method on soil fertility, green fodder production of sorghum (Sorghum bicolor (L.) Moench) (var. CO 30) and nutrient absorption. A fertility gradient technique has been investigated to produce fertilizer recommendations for location-specific in red soils (Alfisols, Typic Rhodustalf). The experimental field was separated into three equal strips: strip I, II, and III, which received applications of the three graded levels of ertilizer N0P0K0, N1P1K1, and N2P2K2, respectively. Urea, single super phosphate, and muriate of potash fertilizers, respectively, were used to apply NPK. As a gradient crop, S. bicolor was raised. The N1 level was set based on the general fertilizer recommendation of feed sorghum, while the P1 and K1 values were set based on the soil’s ability to fix 100 kg ha-1 of phosphorus and 100 kg ha-1 of potassium, respectively. Plant samples were taken at harvest time, and their NPK content and nutrient uptake were determined. With addition of graded doses of nitrogen, phosphorus and potassium fertilizer in Strip I, II & III increased the soil's available N, P & K status substantially in the order of Strip I

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]

The soil test value is based on the soil test-based fertilizer prescription/recommendation equation. Each crop harvesting after the next crop is necessary to analyze the soil. Therefore, it is necessary to develop an alternative technique to predict postharvest soil tests after the harvest of every crop. For that a study was conducted in mixed black calcareous soils at Tamil Nadu agricultural University, Coimbatore to develop the post-harvest prediction equations for available nitrogen, phosphorus and potassium in barnyard millet cropping sequence based on a multiple regression model by considering post-harvest soil test value as the dependent variable and initial available nutrients, fertilizer doses and crop yield or crop nutrient uptake as an independent variables. The developed model was validated by computing R2 value, RMSE (root means square error), RE (relative error), and the ratio of performance to deviation (RPD) and the developed model was found to be valid. Using the validated model, post-harvest soil test values were predicted. A fertilizer recommendation was made for blackgram based on predicted postharvest soil test values in the barnyard millet-blackgram cropping sequence. The predicted soil test values were compared with actual soil test values and it revealed that the developed model is fairly accurate and best-fitted with more precision. The predicted post-harvest soil test values of barnyard millet could be used in order to prescribe fertilizer for desired yield targets for subsequent crops. [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 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]