Physico-chemical properties of soil under the canopies of Faidherbia albida (Delile) A. Chev and Acacia tortilis (Forssk.) Hayen in park land agroforestry system in Central Rift Valley, Ethiopia

Abstract

This study was conducted to evaluate the effect of Faidherbia albida and Acacia tortilis on soil physicochemical properties at Langano and Tuka in farm fields of Bora District where both trees are traditionally retained on the farm. At each site, four F. albida and four A. tortilis trees were purposively selected and soil sample collected from four directions at three distances (1.35, 3.35 and 26.35 m) from tree trunk and composite soil samples was taken for both physico-chemical analyses. Collected data was analyzed by two way ANOVA and mean separation with LSD (%). Mean moisture levels of all sites, 1.35 (14.32%) were significantly (p < 0.05) greater than that of openland (10.79%) at 26.35 m from tree trunk. Bulk density was also significantly affected by tree canopies (p<0.05). It increased from 1.20 g/cm 3 under canopy to 1.29 g/cm 3 in the openland. At both sites, pH was significantly lower (p < 0.05) under the canopy than out of the canopy (it was reduced from 6.05 under canopy to 7.00 at open land). Soil organic matter, total nitrogen available phosphorus, exchangeable calcium, exchangeable magnesium and cation exchange capacity were significantly higher (p < 0.05) under the canopy of trees as compared to openland. Apart from these, the recorded values of exchangeable sodium, potassium and electrical conductivity revealed statistically non-significant difference among the treatments. The research finding showed that trees have positive relation with availability of soil nutrient and to enhance these trees in the farm, farmers knowledge improvement and further research regarding tree age class should be conducted.

The limited potential of soil and vegetation in urban greenspace for nature‐based offsetting of institutional carbon emissions

“…This could be because most sampling points in urban lawn are in closer proximity to trees (the distance ranged from 3.3 to 15.4 m, average 7.6 m), while on average, the distance of soil points to the closest tree in Heaton Sports Ground is 31.6 m (nearest: 8.5 m, farthest: 75.3 m). The presence and abundance of soil microbes (Nacke et al, 2016), and soil chemical properties such as the concentration of metals (Desta et al, 2018), can be importantly influenced by the distance between soil sampling site and the tree trunk, which are all driving factors for soil carbon formation. As explained by Livesley et al ( 2016), tree roots not only modify soil compaction and improve nutrient cycling but also enhance organic input to the ground and strengthen soil carbon content.…”

Assessing Carbon Pools of Three Indigenous Agroforestry Systems in the Southeastern Rift-Valley Landscapes, Ethiopia

“…Another reason could be due to the lignified cells found in tree litter, branches, bark, roots, etc., which could lead to C stabilization and slower mineralization in the soil [82]. The slower oxidation rate of organic matter under tree shade [83], the addition of root exudates [84], and accumulation of more organic matter as a result of fine root degradation in the underground [85] may also initiate higher SOC stock. Similar results were reported by [75], who found higher SOC stock in homegarden AF than foodcrop monoculture land; [86] homegarden AF systems showed 114% greater SOC stock than rice paddies, and [79] observed increased soil organic C by 11-52% in AF systems compared to monocropped fields.…”