Abstract
Sustainable food production to achieve food security and increased access to safely managed sanitation are major global challenges. Treating human excreta and producing safe nutrient-rich soil amendments is an effective way of creating an incentive to tackle these two challenges. This research analysed the quality of fertilisers produced from human excreta and evaluated their acceptability within the local market. Antananarivo (Madagascar) was the field site for crop trial and three different fertilisers derived from human excreta were used to grow maize: digestate, compost and vermicompost, each derived from the previous one. The three fertilisers had different characteristics: nutrients were more concentrated in compost (23 g/kg) and vermicompost (11 g/kg) and mineralisation stages varied between them but did not cause any detrimental effect to crop yield. When compared to chemical fertilisers, the three human excreta derived fertilisers resulted in comparable yield which is encouraging. A series of 81 interviews were also carried out with farmers of the peri-urban area of Antananarivo, which highlighted the importance of characterising the market, identifying users’ perceived needs and developing a product responding to these. The majority of local farmers perceived human excreta derived fertilisers as acceptable and gave great importance to their texture and general appearance. In this study, both the field trials and interviews suggest that there is a good potential to produce fertilisers from human excreta, which have a positive effect on crops and can be adopted in the local market.
Highlights
Food Security ChallengesGlobal food security is recognised as one of the major challenges for sustaining 9 billion people on Earth by 2050
This study aimed to demonstrate the efficacy of three different types of fertilisers derived from human excreta compared to inorganic fertilisers and investigate their acceptability amongst farmers in the peri-urban area of Antananarivo
The total N content increased from 0.88 g/L in the digestate to 23 g/kg in compost, due to the addition of rice straw and the concentration phenomenon that occurs during composting through the degradation of organic carbon compounds [51]
Summary
Food Security ChallengesGlobal food security is recognised as one of the major challenges for sustaining 9 billion people on Earth by 2050. Considering the current rate of population growth it is predicted that the demand for food will double by 2050, putting unprecedented pressures on natural resources [1] This resonates with the concept of the ‘Perfect Storm’, introduced by Sir John Beddington in 2009 [2] to illustrate the pressures of increasing demand of food, water and energy worldwide on our finite resources on Earth. In recent years the concept of a circular economy has gained interest and the need for shifting from linear to circular production processes where waste streams become input streams into new processes has been recognised [3] This is especially true in agriculture where the predicted increase in fertiliser demand is combined with finite mineral nutrient reserves creating an urgent need to close nutrient loops by returning waste nutrients into soil [4, 5]
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