Assessment of Soil Properties in Proposed Botanical Garden Site at FCE Gidan Madi, Sokoto State

Abstract

Soils of the Sudan Savanna are exposed to wide range of threats from human interference, weather fluctuations, precipitation deficit and are characterized by poor vegetation cover. The soils at Gidan Madi in Sokoto State, Nigeria are predominantly sandy (> 87% sand), slightly acidic (pH 6.13) and generally low in available phosphorus (0.99 mgkg-1), organic carbon (0.16%), organic matter (0.29%) and nitrogen (0.04 mg/g). The vegetation in the region hardly survives the longer dry seasons and the soil is seasonally exposed. The proposed garden site was deliberately stratified into dense woody, dense herbaceous, sparse woody, sparse herbaceous, more woody than herbaceous and more herbaceous than woody plots. The ANOVA experiment comprised of the six (6) plots replicated four times in a randomized complete block design (RCBD) with four blocks. Soil samples (0-20 cm depth) were collected and analyzed. The results show that dense woody and herbaceous plots had more silt content (20.52%) than the plots with sparse vegetation (9.25%). Clay increases (2.50%) & sand decreases (87.85%) in dense vegetation. Additionally, low bulk density (1.69gcm³) & moisture content (1.25%), higher particle density (2.24 & 2.25 g/cm³) were found in woody and herbaceous vegetation respectively. Soil pH was slightly acidic (5.90), slightly basic (6.13), and moderately basic (6.47) in soils under sparse vegetation cover, dense herbaceous cover and dense woody cover respectively. Organic carbon (0.29%) and organic matter (0.55%) were higher in herbaceous vegetation while nitrogen was higher (0.05gkg^-1) in the woody than in the herbaceous forms (0.04gkg^-1) and with higher P values in the dense cover (0.88 to 0.93gkg^-1) than in the sparse cover (0.56 to 0.76 mg/kg). Higher exchangeable bases: Ca²⁺ (0.62 cmolkg^-1), Mg²⁺ (0.71 cmolkg^-1) and K⁺ (1.09 cmolkg^-1) were obtained in the woody forms while higher Na⁺ (0.82 to 0.85 cmolkg^-1) were recorded in the herbaceous forms. The CEC values are higher in mixed (woody & herbaceous) vegetation (3.45 and 3.55 cmolkg^-1). The soils at Gidan Madi thus demonstrate a significant potential to sustainably house the proposed botanical garden in the college premises.