"When the rains arrive, his pits pit collect more water that feeds down to the seeds, increasing crop yields by up to 500%, according to the U.N. Environment Programme (UNEP).
The adoption of zai and similar soil and water conservation methods across the West African nation over the past 30 years has improved food security, groundwater levels, tree cover and biodiversity, according to a 2018 study in the journal Sustainability."
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I believe China is also working on this idea. Let's hope it works in many places.