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

Adequate plant nutritional status and soil fertility preservation can be achieved through sustainable agricultural management techniques. The challenge of intensive orchard cultivation, besides the risk of nutrient decline, is to prevent the loss of soil fertility that could lead to soil degradation with a consequent negative impact on yield and fruit quality. The use of organic amendments could be a sustainable strategy to combine high plant performance with soil fertility improvement. This work aims at shedding light on the effects of compost addition with respect to an unfertilized control and a mineral fertilization treatment on macronutrient (K, Ca, Mg, and S) dynamics in plants and soil of a commercial nectarine orchard planted in 2001. In the first 0.15 m of soil, compost addition resulted in higher values (26–42%) of all the parameters. Both fertilization treatments induced a 28% increase in roots’ S content compared to the control but did not induce macronutrient content variation in plant skeleton, pruned wood, and thinned fruits. In autumn leaves, all the macronutrients resulted in higher values (24–45%) with both mineral and compost fertilization, and the same was observed in fruit at harvest (increases of 15–31%). In our study, the treatment with compost satisfied plants' nutrient demands as much as the mineral fertilizer. In addition, compost treatment also improved soil nutrient content while preserving yield. Our results show that it is possible to reconcile plant nutrient needs with the preservation of soil fertility with the aim of improving sustainability of agriculture.