The impact of native trees, Cordia africana and Ficus sur, and the economically valuable Manihot esculenta on soil chemical properties in an agroforestry system

Native trees in agroforestry systems sustain soil properties by building up and recycling nutrients in a sustainable manner. This manuscript aimed to assess the impact of different agroforestry species on soil chemical properties. Soil samples were collected from within and outside the canopy zones of native tree species (Cordia africana, Ficus sur) and a perennial tuber crop (Manihot esculenta) in agroforestry systems at three different elevations. The results showed that, the soil chemical properties were significantly better within the canopy zones of all agroforestry species compared to outside. However, there was insignificant difference in pH between the soil inside and outside the canopy of Manihot esculenta. With a few exceptions, the evaluated soil chemical parameters exhibited minimal variations between Cordia africana and Ficus sur. Interestingly, Manihot esculenta had the least positive impact on soil chemical properties in the agroforestry system, indicating that native tree species enhance soil chemical properties more effectively than the tuber crop. The influence of agroforestry species on soil chemical properties remained consistent across all elevation ranges, suggesting that elevation does not alter the effects of agroforestry species on soil properties. In general, native trees, Cordia africana, and Ficus sur, positively contribute to soil chemical properties, while Manihot esculenta has a negative impact, particularly on cation exchange capacity, soil pH, and available potassium in comparison to the native tree species. These findings highlight the importance of using native tree species in agroforestry systems to promote healthy soil chemical properties and enhance the resilience of forest ecosystems.