ISHS Acta Horticulturae 868: VI International Symposium on Mineral Nutrition of Fruit Crops
NUTRITIONAL IMPLICATIONS OF ORGANIC MANAGEMENT IN FRUIT TREE PRODUCTION |
| Author: | M. Toselli |
| Keywords: | C:N ratio, compost, cover crop, grass, iron chlorosis, manure, nutrients, organic matter |
| DOI: | 10.17660/ActaHortic.2010.868.2 |
| Abstract:
The most distinctive feature of tree mineral nutrition in organic farming systems is related to the concept that the target of fertilization is the soil rather than the tree. The best way to achieve this goal is to increase soil organic matter (OM) content through 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, and 4) abscised leaves, and pruned wood, etc. Fresh OM, such as raw manure (animal and green), cover crop, mulch, etc. with a C:N ratio < 20 should be tilled into the soil to achieve a net release of N. If OM with a C:N ratio > 20 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. Attention must be paid when fresh OM is incorporated into the soil because it may create anoxia conditions. When nutrient deficiencies appear, fertilizers with a fast release of minerals such as blood meal (N = 5-12%), fish meal (N = 5%), natural guano (N = 16%), poultry manure (N = 3.7%) should be used. Stabilized manure and municipal solid waste (MSW) compost present a slower N release rate, but allow a complete ‘nutrient cycling’ (the breakdown of organic substances, release of energy and matter captured by life processes and their use to stimulate the new growth). In addition, by incorporating MSW composts into the soil there is a sequestration of C that otherwise would follow disposal processes with a potential release of CO2 in the atmosphere. Iron organic management of fruit trees is a major issue in calcareous soils, where prevention of leaf chlorosis might be achieved by appropriate agronomic techniques that include: introduction of tolerant rootstocks, increase of soil OM content, association with graminaceous such as Festuca spp. known to produce phytosiderophores (i.e. mugineic acid), that are natural Fe chelators, use of blood meal that contains the Fe chelator heme group. | |
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