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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]

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]

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]

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]

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]

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]

Following Inductive methodology (fertility gradient concept), a field experiment was conducted to study the effect of initial soil fertility and Integrated Plant Nutrition System (IPNS) on the yield of brinjal (var. CO 2) on Typic Rhodustalf of Tamil Nadu. In the first phase of the experiment, variations in soil fertility with reference to soil available N, P and K was established among the three fertility strips with the addition of fertilizers at graded levels and by growing fodder sorghum as gradient crop. In the second phase viz., the test crop experiment with brinjal, consisted of four levels each of fertilizer N, P2O5 and K2O and three levels of farm yard manure (FYM). The highest yield of 35.8 t ha-1 was recorded with 150:75:75 kg ha-1 of fertilizer N, P2O5 and K2O along with 12.5 t ha-1 of FYM in strip III with initial soil available NPK status of 203, 34 and 500 kg ha-1 respectively. The fruit yield as well as NPK uptake by brinjal had increased with increase in initial soil fertility and with increase in the levels of fertilizer N, P2O5 and K2O and FYM. [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]

A field experiment was conducted with maize hybrid NK6240 at Tamil Nadu Agricultural University, Coimbatore during rabi 2010-2011 on an Inceptisol to evaluate the effect of biochar on yield, NPK uptake and fertility status of the soil. The experiment was laid out in a randomized block design (RBD) with 12 treatments and replicated thrice. The results revealed that Integrated Plant Nutrition System (IPNS) i.e. application of biochar @ 10 t ha-1 along with the recommended dose of NPK (250:75:75 kg ha-1) + FYM @ 12.5 t ha-1 and Azospirillum @ 2 kg ha-1 had recorded significantly higher yield and NPK uptake with sustained soil fertility. Further, the study clearly broughtforth the fact that for increased productivity of maize with sustained soil fertility, application of biochar must be coupled with either IPNS or recommended dose of NPK fertilisers. [ABSTRACT FROM AUTHOR]