All human waste originally came from the earth. And all human waste will eventually be converted back into the earth. If this process is properly controlled then the harmful microorganisms inside human waste will be destroyed and the resulting compost can be safely used to replenish the nutrients in garden soil. Compost is one of nature's best mulches and soil enhancements. It may also be successfully used instead of fertilizer. Compost helps to aerate and loosen clays soils. It also helps sandy soils retain their moisture.