Interactions between N, P and K fertilizers affect the environment and the yield and quality of satsumas

The balance between crop yield, quality and soil nutrient status can be manipulated by exploiting nutrient interactions. Field experiments were conducted in citrus orchards in Danjiangkou, Hubei Province to assess the effects of N (0, 0.3, 0.6 and 0.9 kg plant (-1)), P (0, 0.1, 0.2, 0.3 kg plant (-1)), K (0, 0.15, 0.30, 0.45 kg plant (-1)) and their interactions on residual nutrient content in soils, and the yield and quality of satsumas. The results showed that the effects of N and K fertilizers on the yield and quality of satsumas were greater than those of P fertilizers. Appropriate application rates of N (0.6 kg plant (-1)), P (0.3 kg plant(-1)) and K (0.15 kg plant(-1)) significantly improved yield and quality. Lack or excess or inappropriate ratios of N, P and K fertilizer can affect the absorption and utilization of nutrients and reduce yield and quality. The best fertilizer combination, determined by comprehensively considering yield, quality and environment, was N0.3P0.2K0.3, which delivered moderate yield, high fruit quality and low potential risk of pollution. The amount of fertilizer in this case was 0.3 kg N, 0.2 kg P, 0.3 kg K per plant, which is lower than the current recommended application rates (0.5-0.8 kg N, 0.2-0.5 kg P, 0.25-0.64 kg K, respectively). The economic benefit did not decrease because of a decline of yield, but increased slightly because of the improved fruit quality and the reduction in fertilizer input, compared with the treatment with the highest yield. Therefore, we suggest that it is necessary to consider the quality of agricultural products and environmental protection when applying fertilizer and to reduce N and P fertilizer input and appropriately increase the proportion of K. (C) 2019 The Authors. Published by Elsevier B.V.