Establishing a scientific basis for fertilizer recommendations for wheat in China: Yield response and agronomic efficiency

The inappropriate application of fertilizer has become a common phenomenon in wheat production systems in China and has led to nutrient imbalances, inefficient use and large losses to the environment. However, defining an appropriate fertilization rate remains the foundation to science-based nutrient management. This paper described a new fertilizer recommendation method for wheat in China based on yield response and agronomic efficiency using datasets from 2000 to 2011. The results showed that the mean yield responses of wheat to N. P and K were 1.7, 1.0 and 0.8 t/ha, respectively. Nitrogen was the nutrient most limiting yield, followed by P and then K. The soil indigenous nutrient supplies were 122.6 kg N/ha, 38.0 kg P/ha, and 120.2 kg K/ha. The mean agronomic efficiencies were 9.4, 10.2 and 6.5 kg/kg for N, P and K, respectively. There was a significant negative exponential relationship between yield response and indigenous nutrient supply, and a significant negative linear correlation between yield response and relative yield. It was also demonstrated a quadratic equation between yield response (x) and agronomic efficiency (y) (P < 0.05). The relationship between yield response (x) and agronomic efficiency (y) for N was y(N) = 0.3729x(N)(2) + 6.1333x(N) + 0.1438 (R-2 = 0.76, n = 601), for P was y(p) = 0.5013x(p)(2) + 8.3209x(p) + 2.3907 (R-2 = 0.65, n = 288), and for K was y(K) = 1.6581x(K)(2) + 9.099x(K) +0.7668 (R-2 = 0.58, n = 379). These equations were all incorporated as part of the Nutrient Expert for Wheat fertilizer recommendation decision support system. The results of multiple field experiments helped to validate the feasibility of the recommendation model and concluded that Nutrient Expert for Wheat could be used as an alternative method to make fertilizer recommendations in China. (C) 2012 Elsevier B.V. All rights reserved.