L'importanza della sostanza organica nella gestione sostenibile del suolo per una frutticoltura efficiente

For its beneficial effect on soil chemical, physical and biological characteristics, organic matter (OM) is the factor most tightly related to soil fertility. Moreover, soil the repeated incorporation of OM over time allow the sequestretion of a considerable amount of organic C, with benefit for the agroecosystem. The first aim of a correct and strategic tree nutrient management is the increase of soil OM. The best way to achieve this goal is the use of: 1. raw or stabilized manures (i. e. compost obtained from the controlled biological decomposition of organic material); 2. floor permanent grass management; 3. mulches; 4. abscised leaves, and pruned wood, etc. Attention must be paid when fresh OM is incorporated into the soil, because it may create anoxia conditions. OM should be tilled into the soil to achieve not only a net release of N, but also an improvement of soil physical and biological fertility. If OM with a C:N ratio > 30 is incorporated into the soil, microbes use available soil N to break down organic residues and a soil N depletion is expected as well as an increase in soil humus content. With a C:N ratio < 20 a release of N is expected, although the timing depends on the chemical composition of organic material. A potential effect of the addition of OM is the ‘priming effect’ that is a sudden increase of microbial activity with a release of nutrients in their mineral form that promote both root uptake and shoot growth.