Compost can successfully replace mineral fertilizers in the nutrient management of commercial peach orchard

The objective of this experiment was to evaluate in the long-term (9 years), the suitability of compost as a fertilizer in commercial peach orchard. The experiment was carried out on nectarine trees (Prunus persica var.nectarina), Stark RedGold grafted on GF677 peach x almond (P. amygdalus L.) hybrid. The treatments were: (1) unfertilized control; (2) mineral fertilization including phosphorus (P at 100 kg/ha) and potassium (K at 200 kg/ha) applied at planting and nitrogen (N at 70-130 kg/ha/yr) split in two applications at 40 days after full bloom (60%) and in September (40%); (3) cow manure supplied at planting [10 t dry weight (dw)/ha] and then, from the forth year at the rate of 5 t dw/ha/yr in spring; (4) compost supplied at planting (10 t dw/ha) and then, from the forth year at the rate of 5 t dw/ha/yr in spring; (5) compost supply at a rate of 5 t dw/ha/yr, and (6) 10 t dw/ha/yr, both treatment 5 and 6 split as described for treatment 2. Nitrate-N soil concentration was usually not affected by treatments. Soil microbial carbon, organic matter, total N, P, K were increased by application of organic fertilizers. SOM and total N were positively correlated to soil microbial biomass. Aggregate stability, humic and fulvic acid concentration were not affected by fertilization treatment. Only the application of compost at 10 t dw/ha/yr (6) increased fruit production.