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On farm trials were conducted for two year to evaluate the effect of soil test based site specific nutrient management (SSNM) vis-a-vis other farmers practice on rice (Oryza sativa L.) and wheat (Triticum aestivum L.) productivity in villages of Ghaziabad (Uttar Pradesh) and Faridabad (Haryana). Results revealed that the SSNM led to significant increase in grain yield of rice and wheat crops in both the years as compared to the state recommended NPK fertilizer treatment and farmers practices. On an average, SSNM increased the grain yield of rice crop by 19.9% and 14.9% at Partapur and Badarpur said, respectively, over farmers practice. The corresponding increases in grain yield of wheat at Kumbhawas and Badarpur said were 13.9% and 15.4 %. The maximum net profits of Rupees 9 401/ha and Rupees 12 100/ha were obtained from rice under SSNM at Badarpur Said and Partapur, respectively. In wheat crop, the highest net profits of Rupees 6 346/ ha at Badarpur said and Rupees 4 346/ha at Kumbhawas were recorded under SSNM. The lowest yield and net profits from both the crops were obtained with farmers practices. The physicochemical properties (pH, EC and organic carbon) do not get deteriorated due to various nutrient management practices. Available major (NPK), secondary (S) and micronutrients (Zn and B) exhibited significant differences due to treatment variations. SSNM proved significantly superior in respect of buildup of these nutrients in soil.

Elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson] is an important tuber crop grown in many parts of India for its starchy corm and the average yield of this crop is far below the potential productivity of 100 tonnes/ha. One of the reasons attributed to the lower yield is the imbalanced application of essential plant nutrients. Site specific nutrient management (SSNM) is the application of plant nutrients based on the soil and crop need, yield target and developed with the aid of models such as QUEFTS. This paper gives the result of four year study conducted to calibrate and validate the QUEFTS model for elephant foot yam cultivation and the development of SSNM zonation maps and secondary and micronutrient fortified customised fertilizers for the crop in major growing environments of India. Data collected from different field experiments conducted in major elephant foot yam-production regions of India during 1968 to 2011 were used to calibrate the model. The derived parameters of minimum and maximum accumulation of N (130 and 460), P (900 and 2100) and K (100 and 170) are proposed as standard borderline values in the QUEFTS model for elephant foot yam. A linear increase in corm yield was suggested by the model with N, P and K uptakes of 3.97, 0.71, and 7.05 kg N, P and K/1 000 kg corm. The average NPK ratio in total plant dry matter was 5.56:1:9.88. Based on these results, the model was calibrated using historical data as well as by conducting field experiments. It can be observed that fertilizer best management practices by SSNM resulted in an average actual corm yield of 33.45 tonnes/ha, whereas, the model predicted a yield of 35 tonnes/ha. The results of the study showed good agreement between predicted and measured corm yields during the four years, which indicated that the calibrated model can be used to improve NPK fertilizer recommendations for elephant foot yam in India. Based on the results and using soil fertility maps and agro ecological unit maps, SSNM zonation maps and secondary and micronutrient fortified customised fertilizers were developed for major elephant foot yam growing environments of India.

Behaviour of crops and soils due to non-redressal of spatial variability in soil properties is not expressed uniformly within bigger orchard/field which has been the major triggering factor for not able to break yield barrier through conventional nutrient management strategy. Better response of site specific nutrient management (SSNM) over recommended doses of fertilizers (RDF) including those of farmers’ usual fertilizer practices (FFP) signals a wake-up call to address the fertilizer requirements on the principles of SSNM, if the full potential productivity of perennial crops has to be realized and sustain on any given soil type. The SSNM also warrants to tailor the fertilizer application on the basis of spatial variation in soil fertility and tree canopy size within an orchard/field through variable rate fertilizer application to minimize the gap between actual and potential productivity of crops. Application of geospatial tools like GPS and GIS coupled with DRIS- based nutrient diagnostics has substantially aided in developing rationale of fertilizer use using SSNM concept in crops like citrus, avocado, coconut, olive etc. which could well be expanded to other perennial crops.