For the past several years we have been calling attention to the increase in yields obtained with corn, soybeans and other crops planted on the contour on sloping land as compared with yields from adjacent areas farmed the up-and-down hill way.
Browning, G. M.
Iowa Farm Science: Vol. 1
, Article 9.
Available at: https://lib.dr.iastate.edu/farmscience/vol1/iss3/9