Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web.
Agricultural manure in liquid form, known as slurry, is produced by more intensive livestock rearing systems where concrete or slats are used instead of straw bedding.
Green manures are crops grown for the express purpose of plowing them in, thus increasing fertility through the incorporation of nutrients and organic matter into the soil.
Other types of plant matter used as manure include the contents of the rumens of slaughtered ruminants, spent grain (left over from brewing beer) and seaweed.
Due to the relatively lower level of proteins in vegetable matter, herbivore manure has a milder smell than the dung of carnivores or omnivores.
In intensive agricultural land use, animal manure is often not used as targeted as mineral fertilizers, and thus, the nitrogen utilization efficiency is poor.
Animal manure can become a problem in terms of excessive use in areas of intensive agriculture with high numbers of livestock and too little available farmland.
[citation needed] Manure can emit the greenhouse gas nitrous oxide, contributing to climate change.
[11] In 2007, a University of Minnesota study[12][13] indicated that foods such as corn, lettuce, and potatoes have been found to accumulate antibiotics from soils spread with animal manure that contains these drugs.