SWEET-POTATO STORAGE STUDIES. 6 
strations and object lessons, with the result that thousands of similar 
houses are now in use. 
OBJECTS OF THE EXPERIMENTS. 
Many problems arose relative to the management of storage houses 
built according to the plans as originally made and as modified from 
time to time. It became apparent that more information was 
needed on the problems involved. These were — 
(1) The factors which hasten the decay of sweet potatoes in storage. 
(2) The best methods of reducing the losses due to decay and to excessive 
shrinkage. 
(3) The effects on shrinkage and decay of different methods of handling 
sweet potatoes. 
(4) A comparison of varieties of sweet potatoes with reference to loss in 
storage from shrinkage and decay. 
(5) The effects on the keeping quality of sweet potatoes of temperature and 
humidity in the storage house. 
METHODS OF PROCEDURE. 
Experimental work on sweet-potato storage was begun in 1912 
and has been continued every year since. During the first four years 
all the experiments were conducted in houses owned and controlled 
by farmers or commercial firms, and the management was not en- 
tirely under the control of the investigators. During the five years 
1916-17 to 1920-21, inclusive, the work was carried on in a storage 
house erected for this purpose on the Arlington Experimental Farm 
at Rosslyn, Va. This house has been under the complete control of 
the investigators. 
In all of the experiments it was the aim of the investigators to have 
all the conditions identical, with the exception of the particular one 
being studied. Where the conditions were not alike the results are 
not considered in this bulletin. 
In all the experiments conducted in storage houses the sweet 
potatoes were subjected to a curing process for a period of two or 
three weeks, the length of time depending upon the weather and 
the condition of the potatoes. The curing consists of reducing the 
moisture content of the potatoes by means of artificial heat with 
thorough ventilation. The temperature during the curing period 
was usually maintained between 80° and 90° F. by means of 
heating apparatus until the potatoes were cured, as evidenced by 
the " feel " when handled or by the appearance of sprouts. When 
the potatoes were cured the temperature was gradually lowered to the 
desired point. The average temperature maintained in the different 
rooms in the experimental house is shown in figure 1. 
Ventilation was provided by means of openings in the floor and 
through the ceiling and roof, as illustrated in figure 2, and by means 
