STCR, Integrated Nutrient Management, Soil Nitrogen, Phosphorus, Potassium, Wheat.

Wheat [Triticum aestivum L.] is one of the world's and India's most important staple food crop. It may be grown in a variety of soil and climatic conditions. It is a nutritious diet that contains around 78 percent carbohydrate, 12 percent protein, 2 percent fat and minerals, as well as a significant quantity of vitamins. At present nutrient mining is a major threat for agricultural soil as there is wide gaps between crop removal and fertilizer application have been created by irregular supplement use. The profitability of fertilizers over the past 35 years has shown a declining trend, from 48 kg of food grains per kg of NPK fertilizer in 1970-1971 to 10 kg of food grains per kg of  NPK fertilizer in 2007-2008 (Aulakh and Benbi 2008; Subba Rao and Reddy 2009). The use of the proper amount of fertilizer is essential for farm productivity and environmental assurance. Fertilizer is likely the most expensive component of the agribusiness. Farmers that apply inorganic fertilizers without knowledge of the soil's nutrient condition or the crop's need for the supplement have adverse effects on both the crop and the soil, including hazardous supplement quality and a lack of it due to misuse or inadequate application. Using the soil test crop response (STCR) approach, there is a great deal of potential to boost wheat productivity. This method uses fertiliser adjustment equations to prescribe fertiliser doses when a substantial correlation between the applied fertilisers and soil test results has been established. Because the STCR correlation idea combines soil and plant analysis to provide information on the actual balance between applied and accessible nutrients in the soil, its recommendations are more quantitative, accurate, and  significant (Sharma et al., 2016).

On the other hand, although organic manure is a useful and renewable source of nutrients, its application to soils alone is insufficient to satisfy the nutrient requirements of contemporary crop types, which leads to low crop yields. However, their ongoing use improves the soil's resistance and resilience capacity in addition to its biological activity, biomass, diversity, and physical characteristics (Sharma et al., 2015; Kumar et al., 2014). Therefore, integration of inorganic with organics may go long way in maintaining sustainable crop production and enhancing soil health through their complementary effects (Antil et al., 2011). Soil test crop response (STCR) based integrated fertiliser use in combination with vermicompost and chemical fertiliser through soil test method is therefore necessary to improve the nutrient delivery system in terms of balanced nutrient management. Therefore, the goal of the current study was to evaluate the effect of soil test crop response based fertilizer recommendations for wheat crop.

A field experiment was conducted with wheat crop variety DBW-187 at Rajasthan College of Agriculture, Udaipur, Rajasthan in Rabi seasons of 2021-22 and 2022-23. The experiment was laid out in randomized block design with three replications and nine treatments. The following treatments were imposed viz., T1 : Control, T2: 100% RDF (120-60-40), T3:STCR based NPK Fertilizer dose, T4:75% RDF + Vermicompost (2 t/ha), T5:50% RDF + Vermicompost (4 t/ha),T6:75% STCR + Vermicompost (2 t/ha),T7:50% STCR + Vermicompost (4 t/ha),T8: 100% RDF through Vermicompost + Azotobacter, T9 : Integrated nutrient management (INM) - 50% of nutrients through organic (Vermicompost) + 50% of nutrients through inorganic Fertilizer + Azotobacter. Nutrients doses (kg/ha) were calculated from the fertilizer adjustment equations for targeting yield 50 q/ha of wheat crop. The fertilizer adjustment equations given below:

FN= 4.40T-0.40SN

FP2O5= 4.00T-5.73SP

FK2O= 2.53T-0.16SK

Where, (FN, FP2O5 and FK2O = Fertilizer doses  (kg  ha-1) and (SN, SP and SK = Soil test values (kg ha-1), T stand for Target Yield of the crop (q ha-1)

A calculated quantity of nitrogen was added in accordance with urea treatments. The wheat crop received a half dose of nitrogen as a basal at planting and the other half in two equal splits at tillering and heading.  At the time of wheat sowing, phosphorus and potassium were added in accordance with treatments using DAP and muriate of potash as a base dose. The required quantity of vermicompost was applied two weeks before sowing of the crop as per treatment. The sowing of wheat was done in the month of November during Rabi season 2021-22 and 2022-23. The irrigations were given as per need of the crop and two hand weeding were done for removing the weeds from experimental field. The yields (grain and straw of crop) were recorded at harvest. The soil samples collected after harvest of crop were analyzed for available nitrogen by alkaline permanganate method (Subbaiah and Asija 1956), available phosphorus (Olsen et al., 1954) and available potassium by ammonium acetate method (Richards,1954). Statistical methods Panse and Sukhatme (1985) were used for analyzing the data.

Yield. Application of 75% STCR + Vermicompost (2 t/ha) (T6) significantly increased the grain and straw yield of wheat as compared to other treatments (Table 1 and Fig. 1). Integrated use of fertilizer with 2 tonnes vermicompost/ha based on STCR recorded significantly higher grain and straw yield (5296 and 5346 kg/ha, mean 5321 kg/ha) and (7029 and 7066 kg/ha, mean 7048 kg/ha), respectively and it was remained at par with the treatment 75% RDF + vermicompost (2 t/ha) (T4) during both years of experiments as well as in pooled analysis. Other treatments, i.e., T9, T7 and T5 were found statistically at par with each other in respect of grain yield as well as straw yield of wheat, but these treatments recorded significantly higher grain as well as straw yield of wheat over the STCR based NPK Fertilizer dose (T3) and 100% RDF (120-60-40) (T2). Increased productivity may result from improved physical, chemical, and biological qualities, as well as from increased microbial activity and the transformation of inaccessible nutrients into available forms (Sharma et al., 2015). The higher yield of wheat seemed to be the cumulative effect of yield attributes which was boosted by balanced nutrient supply (Yaduvanshi et al., 2013).

Soil fertility. Application of 100% RDF through vermicompost + Azotobacter (T8) significantly increased the available N, P2O5 and K2O content in soil over STCR based chemical fertilizer and recommended dose of fertilizer (Table 2). The higher amount of available nitrogen (314.68 and 316.76 kg/ha, mean 315.72 kg/ha) was noted with 100% RDF through vermicompost + Azotobacter (T8) and it was found statistically at par with the application of treatments 75% STCR + vermicompost (2 t/ha) (T6) and 75% RDF + vermicompost (2 t/ha) (T4). However, rest of the treatments also significantly improved the available nitrogen status over control. Increase in available nitrogen content with 100% RDF through vermicompost + Azotobacter (T8) or with 75% STCR + vermicompost (2 t/ha) may be attributed to enhanced mineralization of vermicompost which might be helped in buildup of available nitrogen (Yaduvanshi et al., 2013). 

The available phosphorus content in soil (29.06 and 30.14 kg/ha, mean 29.60 kg/ha) increased with 100% RDF through vermicompost + Azotobacter (T8) as compared to STCR based chemical fertilizer and recommended dose of fertilizer. However, 100% RDF through vermicompost + Azotobacter (T8) did not differ significantly with 75% STCR + vermicompost (2 t/ha) (T6) and 75% RDF + vermicompost (2 t/ha) (T4) treatments in respect of available phosphorus. Application of 100% RDF through vermicompost + Azotobacter (T8) being at par with 75% STCR + vermicompost (2 t/ha) (T6) and 75% RDF + vermicompost (2 t/ha) (T4) recorded significantly higher available phosphorus over STCR based fertilizer and recommended dose of fertilizer. The increases in available phosphorus content in soil due to addition of vermicompost may be due to its solubilizing effect of native P. Similar results were reported by Sharma et al. (2015); Sharma et al. (2016). The maximum available K2O content (501.00 and 502.21 kg/ha, mean 501.61 kg/ha) was recorded with 100% RDF through vermicompost + Azotobacter (T8). Application of 100% RDF through vermicompost + Azotobacter (T8)being at par with 75% STCR + vermicompost (2 t/ha) (T6) and 75% RDF + vermicompost (2 t/ha) (T4) which were recorded significantly higher available K over STCR based fertilizer and recommended dose of fertilizer. Addition of vermicompost along with inorganic fertilizers had a beneficial effect in increasing the K availability. Similar results were reported by Sharma et al. (2015); Sharma et al. (2016).

Table 1: Effect of Integrated Nutrient Management on grain and straw yield of wheat.

Table 2: Effect of Integrated Nutrient Management on available N, P2O5 and K2O in soil after harvest of wheat.

Fig. 1. Effect of Integrated Nutrient Management on grain and straw yield of wheat.

Santosh Yadav and Dharm Pal Singh (2025). STCR-based Fertilizer Recommendation under Integrated Nutrient Management for Higher Productivity of Wheat Crop (Triticum aestivum L.). Biological Forum, 17(7): 14-17.