Effect of different spring and summer fertilization proportions on fruit yield, quality, and nutrient use efficiency of Newhall orange (Citrus sinensis Osbeck) orchard in Ganzhou province

The amount and time of fertilization play an important role in the quality and yield of citrus. Moreover, twice fertilization in the spring (March) and summer (July) are generally applied in citrus orchards, of which the appropriate proportion is unclear, especially in Ganzhou. Therefore, the two-year field experiment containing three proportions (60/40, 80/20, 100/0) of spring and summer fertilization was carried out with a 15-year-old Newhall orange orchard to recommend the optimum fertilization proportion for orchard. Results showed that variations of soil available N, P, K concentrations resulting from different spring and summer fertilization proportion significantly affected orange fruit quality and yield. The soil available nitrogen (N), phosphorus (P), and potassium (K) concentrations fertilized with a proportion of 80/20 spring and summer were higher overall the year. The spring and summer fertilizer application with 80/20 increased fruit yield by 35.14%, and had higher total soluble solids and lower titrated acid. Moreover, the only one-time fertilization exhibited almost the same fruit yield, fruit N, P, K removal, but lower fruit titrated acid content and higher solid acid ratio. The present study results demonstrated that increasing the proportion of spring fertilization particularly the proportion of 80/20 could be a recommended dose for obtaining higher fruit yield and quality.