ype and
characteristics of the stock on his farm.

To improve the county's stock, farmers were urged to breed their
livestock with purebred animals whenever possible, and keep accurate
records of milk and egg production. An especially successful tool was
the establishment of Dairy Herd Improvement Associations which tested
the yield and butter fat content of each cow's milk. The aim of these
organizations was to identify the high and low producers in a herd so
that poor producers could be sold and breeding done to best advantage.
Agricultural Agent H. B. Derr moved quickly to establish these groups in
the county. By 1920 two of the fourteen Dairy Herd Improvement
Associations in Virginia were in Fairfax County, and the result was a
continual improvement in the stock owned by Fairfax farmers. Derr
reported with pleasure that within the first year of the program 15% of
the cows were eliminated and replaced by better stock and that "one
dairyman said the first month's test paid for the year's work."[109]

Similar improvements were taking place in the grading and
standardization of seed. When Derr first arrived in Fairfax County in
1917, he complained that it was "the dumping ground of about as bad a
lot of seed as he had ever seen."[110] Old or genetically mixed seed
yielded poor crops and Derr organized volunteer farmers to help test new
strains as well as established varieties in the area's soil. The
experimentation for crop return and quality and controlled breeding done
at the Virginia Polytechnical Institute and similar institutions
increased the variety of seed available and made for highly predictable
returns. An additional help was the increased dependability of seed
distributors. Holden Harrison recalled that Southern States Cooperative
was particularly conscientious in this regard. "Other seed companies had
begun to improve their seed stocks, but Southern States put the emphasis
on it. The seed wheat we got from Southern States outproduced any other
that we could find."[111] Whereas traditionally many had merely been
saving the most likely ears of corn or a random bushel of wheat for
seed, the farmer now demanded certified seed of a variety most
responsive to his area's soil type and weather.

Agriculturalists were also making huge strides in understanding the
physical needs of animals and disease prevention. The discoveries about
bacterial and viral infections made by medical researchers during the
1920s and