Toward Zero Hunger Through Coupled Ecological Sanitation-Agriculture Systems

Abstract

Ecological sanitation (EcoSan) systems capture and sanitize human excreta and generate organic nutrient resources that can support more sustainable nutrient management in agricultural ecosystems. An emerging EcoSan system that is implemented in Haiti and several other contexts globally couples container-based household toilets with aerobic, thermophilic composting. This closed loop sanitation system generates organic nutrient resources that can be used as part of an ecological approach to soil nutrient management and thus has the potential to contribute to Sustainable Development Goals 2 (zero hunger), 6 (clean water and sanitation for all), and 13 (climate change solutions). However, the role of organic nutrient resources derived from human excreta in food production is poorly studied. We conducted a greenhouse experiment comparing the impact of feces-derived compost on crop production, soil nutrient cycling, and nutrient losses with two amendments produced from wastewater treatment (pelletized biosolids and biofertilizer), urea, and an unfertilized control. Excreta-derived amendments increased crop yields 2.5 times more than urea, but had differing carry-over effects. After a one-time application of compost, crop production remained elevated throughout all six crop cycles. In contrast, the carry-over of crop response lasted two and four crop cycles for biosolids and biofertilizer, respectively, and was absent for urea. Soil carbon concentration in the compost amended soils increased linearly through time from 2.0 to 2.5%, an effect not seen with other treatments. Soil nitrous oxide emissions factors ranged from 0.3% (compost) to 4.6% (biosolids), while nitrogen leaching losses were lowest for biosolids and highest for urea. These results indicate that excreta-derived compost provides plant available nutrients, while improving soil health through the addition of soil organic carbon. It also improved biogeochemical functions, indicating the potential of excreta-derived compost to close nutrient loops if implemented at larger scales. If captured and safely treated through EcoSan, human feces produced in Haiti can meet up to 13, 22, and 11% of major crop needs of nitrogen, phosphorus, and potassium, respectively.

Metagenomic Insights Into the Changes of Antibiotic Resistance and Pathogenicity Factor Pools Upon Thermophilic Composting of Human Excreta

“…However, due to sanitation systems that treat human excreta as waste, they usually remain unused in many countries that use water-based sanitation systems. Ecological sanitation using thermophilic composting can serve as a treatment to convert human excreta into a humus-rich material with low pathogen contents that nurtures plants and increases soil fertility of agricultural fields ( Dalzell et al, 1987 ; Amlinger et al, 2007 ; Rose et al, 2015 ; Reid, 2020 ; Ryals et al, 2021 ). The possible spread of human pathogens or ARGs is one concern toward the usage of composted human excrements ( Schönning and Stenström, 2004 ).…”

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

“…Estimates of the readily available inorganic N (N i ) within organic amendments vary greatly, depending on the form of the amendment and its treatment conditions and duration, but some studies assume a single value for N i for simplicity (e.g., N i = 10% of N T in the case of Chirere et al). In addition to the N i contained within organic amendments, it is also hard to predict how much of the organic N becomes mineralized into N i during the course of the growing season, and different equations for this exist. , In summary, under comparable N T loading rates, fecal amendments would supply significantly lower plant-available N as compared with synthetic fertilizers. This should be considered when interpreting the results.…”

“…In addition to the N i contained within organic amendments, it is also hard to predict how much of the organic N becomes mineralized into N i during the course of the growing season, and different equations for this exist. 61,62 In summary, under comparable N T loading rates, fecal amendments would supply significantly lower plant-available N as compared with synthetic fertilizers. This should be considered when interpreting the results.…”

Organic Waste Generation and Its Valorization Potential through Composting in Shashemene, Southern Ethiopia

“…Introducing a waste management system that produces compost from human excreta, manure from urban livestock, and other organic wastes could therefore not only reduce the costs for MSW management, but also decrease environmental pollution and mitigate climate change [30,93]. Furthermore, the resulting higher availability of humus-and nutrient-rich compost could be a chance for smallholder farmers to access organic fertilizer and a soil fertility, restoring soil amendment [94]. Applying compost in agriculture could thus close urban-rural nutrient cycles and reduce the dependency on mineral fertilizer, while simultaneously improving soil structure and fertility, crop yields, and food security [29].…”