Organic fertilization and crop load in yield and quality of organic nectarines in Italy

Abstract

Organic fertilization in orchards aims at increasing soil fertility, at impacting plant productivity and environmental sustainability. This study aimed at verifying the effects of organic fertilization and fruit load on two nectarine cultivars with high and low fruit loads. The experiment was carried out in an orchard under organic management in Fratta Terme, Po valley, in northeastern Italy. Nectarine cultivars Big Top and Carene, implemented in 2017 and grafted onto GF677, were used. Three levels of compost (0, 20 and 40 t dw ha-1) were combined with two fruit loads (low and high) to set up a factorial experimental design with two factors and four randomized replicates. Compost was incorporated at 20 cm depth. The following parameters were evaluated: nitrate- and ammonium- N concentrations in soil at 20 - 40 cm depth, macro and micronutrients in leaves, tree yield, number of fruits, fruit mass and diameter, soluble solids and pulp firmness. The supply of compost enhanced nitrate-N release in soil. In both cultivars, macro- and micronutrient concentrations in leaves were not affected by organic fertilization or fruit load, except for iron, which increased as a consequence of the compost supply. Low crop load induced higher fruit size in both varieties, a fact that was observed after pit hardening. However, the organic fertilization rate did not influence tree yield, fruit mass and soluble solids.

Compost improves plant and soil macronutrient content in a 14-years orchard

“…In addition, the application of organic matter is able tocan improve soil physical properties (Chatzistathis et al, 2020) as, for example, bulk density reduction and aggregate stability and water holding capacity increase (Adugna, 2016), positively affecting soil microbial community (Fawzi et al, 2010;Safaei Khorram et al, 2019) and increasing macro-and micro-nutrient availability (Baldi et al, 2021a;Fawzi et al, 2010). Organic amendments thus represent not only a source of N, phosphorus (P), and potassium (K) but also of calcium (Ca), magnesium (Mg), and sulphur (S) that which are equally considered as essential plant macronutrients (Barreto et al, 2021;Shiwakoti et al, 2020). In the study of Shiwakoti et al (2020), the farmyard manure long-term (approximatively 64 years) addition of farmyard manure (at the rate of 11.2 Mg ha -1 year -1 ) evidenced higher macronutrient (K, S, and Mg) content in soil than the other treatments (pea vine and wheat residues, with and without N addition) mainly due to the high amounts of these nutrients that directly contribute to soil chemical fertility.…”