Growing Jatropha curcas L. Improves the Chemical Characteristics of Degraded Tropical Soils

Intensive agriculture in tropical regions is the main cause of soil impoverishment, reducing its productivity. Studies based on soil restoration methods are being implemented, including the use of plants such as Jatropha curcas L., which could have the capacity to improve the agronomic properties of degraded soils in the tropics. The aim of this study is, therefore, to demonstrate that J. curcas L. can improve the characteristics of degraded tropical soil. Between October 2019 and November 2022, we evaluated the effect of spacing, planting material type and age, as well as their interactions, on carbon (C) and nitrogen (N) concentrations and pH at two depths (i.e., 0–10 and 10–20 cm) in the soil. The results reveal that after three years of J. curcas L. growth, C concentration and soil pH increased significantly (p < 0.001) at both depths, while N concentration increased significantly between 0 and 10 cm only. Plants grown from cuttings improved soil pH at 10–20 cm depth more (p = 0.012) than those grown from seeds. Three years after planting, soil N concentration under J. curcas reached a value comparable to that of undisturbed adjacent soil. Overall, our results indicate that J. curcas is a plant that can contribute effectively to restoring degraded tropical soils, therefore contributing to limiting the deforestation of natural forests.