Agronomic potential of excreta-based biofertilizers made from treated human feces and urine for crop production

Abstract

The use of human excreta in agriculture is driven by water scarcity, degradation of water resources, and increased demand for food. This work investigated the agronomic potential of biofertilizers made from treated human feces and urine for crop production. In this regard, field research with 18 lysimeters (six treatments and three blocks) was conducted by applying four biofertilizers in the soil to grow Lactuca sativa var. Valentina. Treatments employed were negative control (T1), chemical fertilizer (T2), urea-treated feces (T3), composted feces with organic waste (T4), stored urine (T5), and struvite (T6). Plant development was assessed weekly by measuring the plant height and diameter. As main results, the use of the biofertilizers presented a higher growth than the negative control (T1) and lower than chemical fertilizer (T2), except for the stored urine treatment, which did not exhibit a significant difference from T1. Struvite treatment stood out, showing a height 98% higher than the negative control and final leaf numbers with no significant statistical difference from the chemical fertilizer. Therefore, treated human excreta presented a potential to fertilize the soil and plant uptake. Even though the initial nutrient concentration in the soil was very low, according to the fertilizing guide from southern Brazil, the plants could still grow and present a better development than the soil with no fertilizer. As nutrient availability in organic fertilization is slower than in chemical fertilization, sequential cultivation cycles should improve plant development.