Nitrogen in apple orchards under integrated and organic farming

The European Farm to Fork strategy demands a 50% reduction in nutrient losses, a 20% reduction in fertiliser use and the attainment of at least 25% of the European agricultural land under organic farming by 2030. The use of organic matrices in organic farming is a valid strategy to rationalise external inputs and reduce their negative impact on environment and the health of organisms. The aim of this study was to analyse nitrogen in a Gala apple orchard in Trentino over a five-year trial period (2018-2022), under two agronomic managements: integrated (INT) fertilised once a year with mineral products and organic (ORG) amended with mature manure every three years. During the growing cycle, the dynamics of mineral nitrogen in the soil was analysed colorimetrically after extraction in K2SO4. Total nitrogen in leaves and apples was determined by elemental method. Soil mineral nitrogen dynamics showed a higher average value in INT than in ORG, although the letter exhibited values equal to or above the apple tree requirement level. Furthermore, in INT, mineral nitrogen measured at different periods of the growing cycle was found to be in very high concentrations, exceeding the plants' needs and susceptible to leaching and pollution. Total nitrogen in leaves was higher in INT than in ORG from 2018 to 2021, whereas in 2022 was similar between the theses. However, over the five-year period, the leaf nitrogen content in both theses had values in the characteristic range for apple trees. The nitrogen in the fruit showed comparable values between theses after two e three years from the start of the trial. In contrast, in 2021 and 2022, INT and ORG differed in this parameter. Foliar fertilisation applied in INT probably led to an increase in nitrogen in the plant‘s storage organs. The use of organic matrices in organic farming, in addition to having an amendment effect, has also been shown to act as a fertiliser in apple orchards, reducing the impact on the environment.