Interplanting Lentils Within Olive and Orange Trees Under Different Sources of Nitrogen Fertilizer in North Sinai

Background and Objective: Interplanting legumes with orchards is a popular practice on newly reclaimed soils. A field trial was conducted over two consecutive seasons in 2021/2022 and 2022/2023 at the newly reclaimed soils of East of Suez Canal Horticulture Research Station, Agricultural Research Center (ARC), North Sinai Governorate, Egypt. This study aimed to determine the optimal source of nitrogen (N) fertilizer for interplanting lentils within olive and orange trees to achieve high crop yields, efficient land use and financial benefits in sandy soil conditions. Materials and Methods: The treatments were two interplanting systems (interplanting lentils within olive trees and interplanting lentil within orange trees) and four sources of N fertilizer (mineral N fertilizer, bio+mineral N fertilizer, organic manure fertilizer and bio-N fertilizer). A strip design with three replicates was used for this experiment; the two interplanting systems were assigned in the vertical strips and the four sources of N fertilizer were distributed in the horizontal strips. Results: Compared to interplanting lentil within olive trees, interplanting lentil within orange trees increased number of branches/plant, seed yield/plant and seed yield/fad. Full dose of mineral N fertilizer had the highest number of branches/plant, seed yield/plant, 100-seed weight and seed yield/fad. The interaction has a dependent effect on plant height, number of pods/plant, seed yield/plant, seed yield/fad in both seasons and 100-seed weight in the second season. Once different sources of N were supplied, the significance between treatments for either olive or orange fruit production or trend disappeared. Conclusion: In sandy soil, high land usage and profitability were attained by growing two rows of lentil in six ridges with a full dose of mineral N fertilizer within the olive trees and two rows of lentil in six ridges with rhizobia and a starter dose of mineral N fertilizer within the orange trees.