Fertilization, cover cropping and measurement period: Their effects on the annual growth of trees in an olive farm in Southwestern Buenos Aires

Abstract

The objective of this study was to determine the effect of fertilization in areas with or without a cover crop on the annual growth of irrigated olive trees (Olea europaea L.) during two growing seasons (2020/2021 and 2021/2022) in southwestern Buenos Aires Province, Argentina. Fertilization treatments included (1) organic fertilizer applied to the soil beneath the tree trunk; (2) inorganic fertilizer applied to the soil or (3) to the leaves of the olive trees; and (4) an unfertilized control. Vetch (Vicia sativa L.) and oats (Avena sativa L.) sown between the tree rows constituted the cover crop areas. Unsown areas corresponded to the control treatment. Annual growth variables were height, trunk circumference, and canopy area and volume. There were no significant differences (p>0.05) between fertilization treatments or areas with or without cover crops for any of the annual growth parameters studied. However, the annual growth of these variables was greater (p<0.05) in 2020/2021 than in 2021/2022. Furthermore, the difference in annual growth between the 2020/2021 and 2021/2022 periods was greater (p<0.05) in the organic and inorganic soil fertilization treatments than in the inorganic foliar fertilization treatment. Moreover, this difference was greater (p<0.05) in areas without cover crops compared to those with. This study determined that the annual growth of irrigated olive trees was not affected by different fertilization treatments in areas with or without inter-row cover crops in the studied region.