EFFECT OF MINERAL AND ORGANIC FERTILIZATION ON SOIL CHEMICAL, BIOLOGICAL AND PHYSICAL FERTILITY IN A COMMERCIAL PEACH ORCHARD

In this paper the effect of organic matter supply as an alternative to mineral fertilization in a commercial peach orchard is investigated through the comparison of the following treatments: 1. unfertilized control; 2. mineral fertilization; 3. compost at planting; 4. cow manure at planting; 5. compost (5 t DW ha^-1 year^-1) and 6. compost (10 t DW ha^-1 year^-1). Nitrate-N concentration, microbial biomass, root growth, leaf and fruit nutrient concentrations were evaluated from 2001 (planting) to 2003 (beginning of bearing stage). The organic fertilization increased soil organic matter, total N and nitrate-N, but did not affect the nutritional status of the trees. New root production was observed from May to June and white absorbing roots had a life span of several months, reaching the end of the season.