Fig. i. — Wheat plants from Rothamstecl plots 



1. Kroadbalk plot 9, complete artificial manure, including 46 lb. of nitrogen as nitrate of soda. 



2. Unmanured since 1839. 



3. Hoos field, wheat grown every other year only, no manure. 



4. Agdell field, wheat grown in rotation every fourth year only, no manure. 



p. 148] 



