194 DRY-FARMING 
ent conditions as to soil and climate, have developed 
practically the same system of dry-farming. In all 
these places the best dry-farmers practice deep plow- 
ing wherever the subsoil will permit it; fall plowing 
wherever the climate will permit it; the sowing of 
fall grain wherever the winters will permit it, and the 
clean summer fallow every other year, or every third 
or fourth year. H.W. Campbell, who has been the 
leading exponent of dry-farming in the Great Plains 
area, began his work without the clean summer fal- 
low asa part of his system, but has long since adopted 
it for that section of the country. It is scarcely to be 
believed that these practices, developed laboriously 
through a long succession of years in widely separated 
localities, do not rest upon correct scientific prin- 
ciples. In any case, the accumulated experience of 
the dry-farmers in this country confirms the doctrines 
of soil tillage for dry-farms laid down in the preceding 
chapters. 
At the Dry-Farming Congresses large numbers of 
practical farmers assemble for the purpose of ex- 
changing experiences and views. The reports of the 
Congress show a great difference of opinion on minor 
matters and a wonderful unanimity of opinion on the 
more fundamental questions. For instance, deep 
plowing was recommended by all who touched upon 
the subject in their remarks; though one farmer, who 
lived in a locality the subsoil of which was very inert, 
recommended that the depth of plowing should be 
