Tropentag, September 10 - 12, 2025, Bonn "Reconciling land system changes with planetary health"

Interaction of legume tree and legume crop for improved crop productivity and soil fertility

¹Mekelle University, Land Resources Management and Environmental Protection, Ethiopia
²Tigray Land Administration Bureau, Land Administration, Ethiopia
³Mekelle University, Food Science and Post harvest Technology, Ethiopia

Abstract

Legume tree-based agroforestry systems play a crucial role in enhancing crop productivity and soil health, particularly in low-input agricultural systems. However, the amount of nitrogen (N) derived from atmospheric fixation is highly variable among different tree species resulting in differences in the effect of the tree-crop interactions. Our study focuses on examining the legume tree-legume crop interaction and their effect on crop yield and soil fertility. A field experiment was conducted in Tigray, Ethiopia (13º38’ N, 39º10’ E; elevation: 1350–2835 m) taking Vachellia seyal-Cicer arietinum (chickpea) as test tree-crop. Three Vachellia seyal trees were selected for the experiment. Soil fertility status and grain yield under and outside the tree canopy were evaluated from 24 plots arranged in four directions per tree, spaced 1 m apart. Results showed a 200% increase in total nitrogen (N) and 180% in soil organic carbon (SOC) near the Vachellia seyal tree compared to the outside tree canopy along with a 123% chickpea yield increment. The soil moisture content near the tree was also 162% higher, with an 81% reduction in bulk density. These all factors resulted in 119% increase in above-ground biomass and 211% increase in root biomass of the chickpea. However, phosphorus (P) and potassium (K) declined by 66% and 61%, respectively. This could likely be due to the combination of factors including high P and K demand of the legume crops, the vigorous crop growth effect from the biological nitrogen fixation and increased P solubility. These findings suggest that legume tree-legume crop interaction significantly improved N, SOC and crop yield which could benefit the subsequent cropping season especially with P and K supplemental fertilisation to sustain long-term productivity.

Keywords: Biomass, chickpea, crop harvest index, root biomass, soil chemical properties, vachellia seyal

Contact Address: Tigist Araya Gessesse, Mekelle University, Land Resources Management and Environmental Protection, Mekelle, Ethiopia, e-mail: tigst.arayamu.edu.et