Assessing the Impact of Land Use on Arbuscular Mycorrhizal Root Colonisation Rate, Phosphorus and Nitrogen Uptake in Ife Bimpe Cowpea

Abstract

Soil characteristics, microbial ecology and organic additions influence soil fertility and plant productivity. However, the effects of land use and organic amendments on arbuscular mycorrhizal fungi (AMF), which enhance nutrient uptake and tolerance to soil stress, remain insufficiently understood. This study examined the effects of land use and organic amendments on AMF spore abundance, root colonisation and nutrient uptake. Soils from African Star Apple (ASAR), Cassava (CRR) and Bush Fallow (BFR) collected from farms behind Babcock University stadium, Nigeria, were analysed for pH, organic carbon, total nitrogen and available phosphorus. AMF spore abundance was assessed at 3-week intervals over 9 weeks following application of poultry manure (5 t ha⁻¹), cow dung (10 t ha⁻¹), and poultry manure plus cow dung (5 t ha⁻¹ + 10 t ha⁻¹) before planting. Soil pH ranged from 7.00 (CRR) to 5.54 (BFR). ASAR had the highest organic carbon (5.46 g/kg) and total nitrogen (0.23%), while CRR had the highest phosphorus (4.727 mg/kg). CRR recorded the highest AMF root colonisation (48%) and Gigaspora spp. abundance, whereas ASAR had the highest total spore count (62%). Poultry manure increased root colonisation (44%) but reduced spore production, while cow dung maintained higher spore abundance (57%). Plant height and leaf development varied among land-use types, with ASAR soil supporting superior growth by Week 9. AMF parameters were positively related to soil fertility indicators. Overall, cow dung promoted AMF spore abundance, whereas poultry manure facilitated root colonisation; CRR soils favoured colonisation, while ASAR soils favoured sporulation.