Intercrop of olive trees with cereals and legumes in Chalkidiki, Northern Greece

It is estimated that olive groves cover an area of 700,000 ha in Greece, with 124,311 ha forming agroforestry systems combined with various crops or pasture, established in the understory of the trees. A lush understory grows under the olive trees, consisting mostly of herbaceous vegetation for animal grazing, vegetables and various crops such as cereals and legumes. The aim of this study was to produce quantitative information about the intercropping of olive trees and leguminous crops or cereals in northern Greece, where olive agroforestry is a traditional practice. For this reason, a controlled experiment (1.08 ha area) was established in 2014 and was composed of olive trees, in a density of 100 trees/ha, intercropped with barley and a mixture of barley and common vetch. The latin square design involved three treatments (olive trees and barley, olive trees and a mixture of barley and common vetch, and olive trees as control), with three replications for three years and fertilized by N–P–K. Soil, tree and crop parameters were measured since plant germination to harvesting. Based on the results, barley and common vetch plant density and height were higher in the middle of the alleys than in the proximity of the trees. On the contrary, the number of grains per spike was higher close to the trees. Above ground biomass of the mixture (barley and common vetch) was higher in the middle of the alleys for the duration of the experiment. Total grain yield of barley was close to 80% of the average barley in monocultures.