Are anthropogenic soils from dumpsites suitable for arable fields? Evaluation of soil fertility and biomass response to elements

Abstract

Background and purpose The fertility of anthropogenic soils developed from dumpsites used for arable fields is not well-studied. The study aimed to evaluate the fertility of soils from an abandoned dumpsite in Awotan, Nigeria, by measurable indicators and assess the bioaccessibility of elements of identified plant species. Methods The study adopted multi-analytical approaches to determine the signatures of the soils and further parameterized the bioaccessibility of elements to plants. Results The comparatively high content of Ca and Na in the anthropogenic soil contributed to the slightly alkaline soil reaction against the slightly acidic control. The high amount of organic matter is well-indicated by the enrichment of organic C and N in the anthropogenic soil. Waste deposition significantly contributed to the high accumulation of macronutrients (P, Ca, K, S) and micronutrients (Mn, Na, Fe) sufficient for maximum plant growth and yields, with an adequate C/N ratio supporting effective mineralization. The high cation exchange capacity of the anthropogenic soil contributed to cations binding. Indiscriminate deposition resulted in a high accumulation of potentially toxic elements (PTEs; Cu, Zn, As, Cd, Pb) above permissible limits in agricultural soils following WHO limits. Potential effects on lives are evident by the high PTEs accumulation in roots and leaves of Chromolaena odorata, Saccopetalum tectonum, Passiflora foetida, and Senna siamea. These plant species exhibited various PTEs accumulation, especially excluding Cd and Pb. Conclusion Although anthropogenic soils remained fertile, the bioaccessibility of PTEs by plants indicates potential threats to consumers of crops and herbs produced from such sites.