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A 36 Thirty—F0urth· Annual Report
l used alone, while on the Campbellsville field, rock phosphate
on unlimed ground produces very large results, but limestone k
and rock phosphate used together scarcely function at all.
1 Soil Surveys. The field work on the Garrard County
soil survey was finished during the year and a report is being
i prepared upon it. Reports are in preparation upon Logan and
Muhlenberg Counties, the field work on which was finished
, prior to this year. This work is in cooperation with the Bureau
  of Soils of the United States Department of Agriculture.
i { Sulfur in Plants and Soils. ln the study of sulfur in
° plants and soils and its significance to permanent soil fertility,
also the determination of the best sulfur compound for correct-
ing sulfur deficiency in soil, a series of pot experiments with
wheat has been carried on on four soils to compare Dr. Lip-
11121117% "bacsul phosphate" with acid phosphate, and a similar
series with oats is now under way. The results show distinct;
. benefit in yields from the bacsul phosphate. This material is a
mixture of ground rock phosphate with sulfur which has been
I inoculated with the bacteria which oxidize sulfur.
The Occurrence and Distribution of Manganese in Plants.
_ The phase of this study which concerns the function of mang-
,' anese in plants and soils has occupied attention during most of
{ the year. Pot experiments with carefully prepared sand and
, chemicals as nearly as possible free from manganese were car-
  ried on with garden peas, soybeans, cowpeas, corn and buck-
‘ wheat, under conditions in which the manganese present was
I very little, if any, more than that contained in the seeds of the
% plants which were grown. Controls to which small amounts of
manganese had been added were carried on at the same time.
_ The growth of the plants in the pots to which no manganese
. had been added was arrested before they attained the size of
' the controls and the plants showed signs of malnutrition,
whereas the plants which received manganese continued
thrifty. These experiments seem to show that manganese in
plants performs an important function in connection with the
_ assimilation of carbon and the production of chlorophyl.
1