Assessing the effectiveness of mycorrhizal inoculation and soil compost addition for enhancing reafforestation with Olea europaea subsp sylvestris through changes in soil biological and physical parameters

A field experiment was carried out in a semiarid area to assess the influence of mycorrhizal inoculation and soil compost addition on establishment of Olea europaea seedlings. Associated changes in soil biological and physical parameters were observed. One year after planting, both reafforestation. methods had significantly improved the soil structure. Thus, mycorrhizal inoculation increased soil aggregate stability (AS) and composted residue addition decreased soil bulk density (BD). A significant correlation (P < 0.05) was found between BD and several biochemical parameters (dehydrogenase, protease and P-glucosidase activities), indicating that soil biological agents play an important role in improving soil structure. The growth of O. europaea was significantly enhanced by both composted organic residue addition and mycorrhizal inoculation treatment. The increase in mycorrhizal. O. europaea seedling growth may be due to the positive influence of mycorrhiza on soil AS. The combination of high fertility levels and low BD also favoured the growth of O. europaea in compost-amended soils. Finally, the positive interaction between the two methods in relation to seedling height growth could be related to the capacity of the fungus to increase nutrient uptake from the composted residue. (C) 2002 Elsevier Science B.V. All rights reserved.