A Systematic Review of the Effects of Fecal Sludge Derived Amendments on Crop Growth and Soil Health

The use of human excreta in agricultural settings hasthe potentialto meet crop nutrient requirements and improve soil health, whilealso providing a sustainable end use for fecal material. Previousreviews have focused on sewage sludge biosolids from wastewater treatmentplants, but with on-site sanitation systems overtaking sewers as theleading sanitation system worldwide, greater attention to fecal sludgeis warranted. This systematic Review is the first to compile the resultsof crop trials which utilized fecal amendments from on-site sanitationsystems and includes 47 experiments. Overall, fecal amendments increasedcrop growth compared to unamended control plots and also producedcomparable yields to synthetic fertilizers. Biological and physicalsoil parameters were underrepresented in the literature, which madea holistic assessment of soil health impossible. However, some improvementsin chemical characteristics were observed, most notably for soil organiccarbon. Inconsistent experimental design made aggregation of resultsand detailed statistical analysis difficult, highlighting the needfor a more standardized approach for testing the efficacy of amendmentsand reporting results. Regardless, this Review compiles our collectiveexisting knowledge to provide tentative results for the effect offecal amendments on crop growth and soil health and offers recommendationsfor future work.