Effects of a Short-term Introduction of an Agroforestry System in which Olive and Durum Wheat are Combined on the Growth of Both Crops and Soil Nitrogen and Carbon Content in Japanese Olive Orchards

Abstract

The agroforestry system (AF) is an agricultural system in which crops are cultivated, or livestock are raised among trees and is said to provide various advantages including improved land use efficiency and/or soil fertility. However, very few examples and research have been reported in Japan. In this study, we conducted a 2.5-year trial of AF in combination with olive and durum wheat to examine the effects of AF introduction on the growth of both crops and soil nitrogen and carbon content. Durum wheat yield was 129 to 268 g m^-2 in the 2021/22 crop season. Olive tree height and width remained similar regardless of the introduction of AF. Soil total nitrogen content, available nitrogen content, and organic carbon content did not increase after introducing AF for 2.5 years, irrespective of the soil depth. These results revealed that the main advantage of short-term introduction of AF in Japan is the improvement of land use efficiency due to harvesting crops between trees without affecting the fruit trees. On the other hand, this study also showed some issues in olive groves with AF, such as an increased risk of damage to crops by animals and weeds. Although soil nitrogen and carbon did not increase with the short-term introduction of AF, some items showed a tendency to improve. These results suggest the need for continued verification of AF in Japan.