Wheat yields in many parts of India are stagnant. The main reason for this is conventional blanket fertilizer recommendation, lower fertilizer use efficiency, and imbalanced use of fertilizers. Estimation of fertilizer requirements based on quantitative approaches can assist in improving wheat yields and increasing nutrient use efficiency. We used the QUEFTS (QUantitative Evaluation of Fertility of Tropical Soils) model for estimation of nitrogen (N), phosphorus (P), and potassium (K) requirements and fertilizer recommendations for a target yield of wheat. The model considers the interactions of N, P, and K, and climate adjusted potential yield of the region. Published data from several field experiments dealing with N, P, and K conducted during the years 1970 to 1998 across wheat-growing environments of India, covering a wide range of soil and climatic conditions, were used to reflect the environmental variability. The relationships between indigenous N, P, and K supply and soil organic carbon, Olsen P, and ammonium acetate-extractable K, respectively, were established. The required N, P, and K accumulation in the plant for 1 tonne grain yield was 23.1, 3.5, and 28.5 kg, respectively, suggesting an average NPK ratio in the plant dry matter of about 6.6:1:8.1. The constants for minimum and maximum accumulation (kg grain kg-1) of N (27 and 60), P (162 and 390), and K (20 and 59) were derived as the standard model parameters in QUEFTS for fertilizer recommendation for irrigated wheat in the tropical and subtropical regions of India. Relationships of apparent recovery efficiencies of fertilizer N, P, and K with levels of their application were also determined. The observed yields of wheat with different amounts of these nutrients were in good agreement with the values predicted by the model, indicating that the model can be used for fertilizer recommendations.
- nitrogen-use efficiency
- lowland rice systems