Foliar fertilization: a valid alternative for olive cultivar

From 1997 to 2000 a nutrition experiment was conducted to test the effects, on olive trees (cv. Carolea), of different fertilizers quantities and application methods. The fertilization to soil was made once, at bud break in spring, whereas foliar treatments were repeated four times: before flowering; after fruit set; at pit hardening and at the end of summer, before veraison. Parameters determined include the following: growth rate; percentages of flower bud differentiation; percentages of ovary abortion; fruit set; summer fruit drop and yield at harvest. In order to evaluate the nutritional status of trees, samples of leaves were analysed in April, July and November From the first two years, the trees fertilized with foliar sprays showed an increase in vegetative parameters and yield. From the third year, applications of only foliar fertilizers gave worse results than the fertilization to soil, demonstrating the necessity of fertilizer application to roots. The foliar application of macro-elements increased the productivity of trees, both as an addition to the fertilization to soil and, to a lesser extent, as alternative to it. This suggests that foliar fertilization can be used as a cheap and viable alternative for olive production.