Contribution of acacia species to the soil nitrogen in South-western Saudi Arabia

Abstract

The study revealed higher content of total soil nitrogen beneath the canopy compared to that outside the canopy of each Acacia sp., at different sites in the south-western region of Saudi Arabia, between 250 and 2500 m. Total soil nitrogen beneath and outside the canopy of A. ehrenbergiana, A. iragensis (syn A. gerrardii) and A. origena (syn. A. negrii) gave the following pairs of readings: 0.59,0.54; 0.56,0.52; 0.52, and 0.48 meq N per 100 g of air-dry soil, respectively. Lower soil pH and higher moisture content were recorded benpath the canopy compared with those recorded outside the canopy, for each of the Acacia species. No significant differences in soil nitrogen, pH, and moisture content were observed when comparing their values in lowlands (250 - 1500 m) and highlands (1750 - 2500 m).