Distribution of nutrients in the active root area of olive trees under a drip irrigation system in a sandy soil

Abstract

A study was carried out on the root distribution of mature olive trees (olea europaea, L., var. manzanillo) grown on a sandy soil, irrigated by means of drip irrigation, and on the nutrient distribution in the soil and plants. Soil was sampled at a distance of 20-160 cm from the tree trunks at depths of 0-80 cm. Leaves were also analysed for nutrient content. The roots were concentrated in the area 80-140 cm from the trunk at a soil depth of 20-60 cm, i.e. in the zone with the highest soil water content. In the horizontal layer, magnesium, iron, manganese, zinc and copper mostly decreased at the ends of the wet area, while in the vertical layer, the 0-20 cm surface soil layer was the richest in potassium, calcium, manganese, zinc and copper. Phosphorus concentrations fluctuated. The average values of potassium, magnesium, iron, manganese, zinc and copper concentrations in olive leaves were significantly higher in bearing years than in non-bearing ones. For this reason it is important to increase the doses of fertilizers containing these elements after bearing years to replace the high removal.