It's a mixture of decaying organic substances, such as dead leaves, used to fertilize soil
[DOC] [TLE] Sustainable Table | Soil Quality [PAR] Though healthy soil is invaluable, industrial agricultural practices degrade this 
natural ... such as conservation tillage, crop rotation, and organic fertilization in 
order to ... of manure, it's too costly to transport it to other cropland for use as 
fertilizer.