Physicochemical Properties of an Alfisol Under Fallow and Adjacent Forest Lands and Their Suitability for Cocoyam, Pigeon Pea and Sweet Potato Production in Nsukka, Southeastern Nigeria

Forest land provides a wide range of ecosystem services such as reducing the impact of raindrops on the soil and maintenance of soil fertility, whereas fallowing is one method used in restoring the fertility status of degraded farmlands. This study evaluated the physicochemical properties of an Alfisol under fallow and adjacent forestland, and their suitability for cocoyam, pigeon pea, and sweet potato. The fallow plots were brought into cultivation in the year 1998 under the IITA-UNN long-term collaborative research. Soil samples were collected from 0-20 cm depth in triplicates using an auger and cylindrical core from the seven representative fallow plots previously grown to sole cassava from the year 1998–2003 and under fallow till the year 2016 as well as the adjacent forest land. The result obtained showed that the fallow land had higher fertility nutrients than the forest land in the year 2016. The fallow land gave the highest values of SOC, total nitrogen, percentage base saturation, total exchangeable bases (Ca2+, Mg2+, Na+, K+) and exchangeable acidity when compared with the forest land. Using the FAO’s principle of limiting conditions as guide, both fallow and forest soils are marginally suitable (S3) for cocoyam production but highly suitable (S1) for both pigeon pea and sweet potato production.