lucio usobiaga sees the excrement that has been collected here as a resource. to give back to the earth what we've received in the shape of food. otherwise you get an imbalance, leading to pests and depleted soil. to feed the plants properly you need to return all that's left over back to the soil. reporter: right now, they're only fertilizing fruit trees with human dung. they want to first make sure they can reliably filter out any pathogens, residual hormones, and medication in the compost before they start using it for vegetables too. back to the ollin tlalli organic farm. tomÁs villanueva's customer know how his vegetables are grown, and they wholeheartedly approve. tomÁs: poop has a bad image in our society, but we know that this composting process makes it perfectly hygienic. and we always like to say that with poop you never lose a harvest. reporter: a cycle of giving and taking, eating and excreting. something that triggers revulsion elsewhere is seen here as the most natural thing in the world. ♪ dubi: hi. i'm dubi gawusas from sesfontein. i am a grade

lucio usobiaga sees the excrement that has been collected here as a resource. to give back to the earth what we've received in the shape of food. otherwise you get an imbalance, leading to pests and depleted soil. to feed the plants properly you need to return all that's left over back to the soil. reporter: right now, they're only fertilizing fruit trees with human dung. they want to first make sure they can reliably filter out any pathogens, residual hormones, and medication in the compost before they start using it for vegetables too. back to the ollin tlalli organic farm. tomÁs villanueva's customer know how his vegetables are grown, and they wholeheartedly approve. tomÁs: poop has a bad image in our society, but we know that this composting process makes it perfectly hygienic. and we always like to say that with poop you never lose a harvest. reporter: a cycle of giving and taking, eating and excreting. something that triggers revulsion elsewhere is seen here as the most natural thing in the world. ♪ dubi: hi. i'm dubi gawusas from sesfontein. i am a grade

lucio usobiaga sees the excrement that has been collected here as a resource. to give back to the earth what we've received in the shape of food. otherwise you get an imbalance, leading to pests and depleted soil. to feed the plants properly you need to return all that's left over back to the soil. reporter: right now, they're only fertilizing fruit trees with human dung. they want to first make sure they can reliably filter out any pathogens, residual hormones, and medication in the compost before they start using it for vegetables too. back to the ollin tlalli organic farm. tomÁs villanueva's customer know how his vegetables are grown, and they wholeheartedly approve. tomÁs: poop has a bad image in our society, but we know that this composting process makes it perfectly hygienic. and we always like to say that with poop you never lose a harvest. reporter: a cycle of giving and taking, eating and excreting. something that triggers revulsion elsewhere is seen here as the most natural thing in the world. ♪ dubi: hi. i'm dubi gawusas from sesfontein. i am a grade