Good farmers for years have considered the manure produced on their farms a valuable fertilizer and many carefully conducted experiments have shown that these farmers have been right.
Cheney, H. B. and Englehorn, A. J.
"Manure- Valuable Soil Builder,"
Farm Science Reporter: Vol. 6
, Article 4.
Available at: https://lib.dr.iastate.edu/farmsciencereporter/vol6/iss4/4