Nutrient inputs and outputs in commercial clingstone peach orchards in Greece based on conventional or sustainable fertilization practices

Clingstone peach production is important in Greece as large amounts of processed peaches are being exported throughout the world. Fertilization of peach farms is still conducted empirically with substantial amounts of N, P and K applied in late winter with basic composite fertilizers rarely followed by additional N and K or Ca applications in spring and summer. A more sustainable fertilization program was followed using <50% N, minor quantities of P, and similar or higher quantities of K than that applied with the local regime and with a different schedule compared to local practices in a number of farms and commonly grown cultivars. Inorganic nutrients were measured in fruits and prunings after two years of sustainable fertilization practices. Fruit yield and prunings volume were measured. The macronutrient inputs in the sustainable program were (in kg/ha): in 2019 <70 N, < 30 P2O5, <100 K2O, and in 2020 <85 N, <40 P2O5, <155 K2O. Outputs with fruit normalized for 40 Mg ha(-1) (most farms during the two years had lower yield) in 2020 were (in kg ha(-1)): <50 N, <11 P2O5, <4.3 CaO, <4.4 MgO, <80 K2O. Outputs with prunings in 2020 were (in kg ha(-1)): <25 N, <4 P2O5, <30 CaO, <3 MgO, <11 K2O. The balance between inputs and outputs was improved using the sustainable fertilization program, while fertilizer cost was variably affected and the possible environmental and economic burden due to nutrient losses decreased.