94 
Journal of Agricultural Research 
Vol. XI, No. 4 
watered in all cases with the same amount of distilled water. When the 
plants were about 3 inches in height, they were thinned to 6 plants of 
average size in each jar. After the pods had matured, which took place 
at different times, according to the soil, the plants were cut close to the 
ground, air-dried, and weighed. They were cut on the following dates: 
No. 894 and 895 on December 31; No. 892 and 893 on January 9; and 
the remainder on January 19, 1915. 
Series 11 : clover. —After the plants in Series I had been cut, the soil 
in each jar was sifted, and 25 inoculated red-clover seeds (Trifolium 
pratense ) planted. After germinating, these were thinned to 15 average¬ 
sized plants in each jar. The plants were allowed to grow until they 
had attained a height of about 10 inches. Four cuttings were made at 
a distance of about 2 inches from the crown. When cut in this manner 
and not allowed to blossom, the plants grew faster, and this procedure 
was followed until July 14, when the weather became too warm for 
greenhouse experiments. 
Series in: oats. —The soil in each jar of Series II was pulverized 
and stirred to a depth of 6 inches, and on December 23, 1915, 36 Burt 
oat seeds (Avena sativa) were planted in each. Two weeks later they 
were thinned to 25 average-sized plants in .each jar, and potassium 
nitrate was then added in solution at the rate of 100 pounds per acre 
and repeated on February 15. On May 12, 1916, after the seed had 
matured, the plants were cut close to the ground, air-dried, and weighed. 
SERIES iv : alfalfa. —Similar jars of the same soils used in Series I to 
III were prepared, and, in addition, jars representing 200 pounds of 
sulphur per acre were included in triplicate. Thirty-five inoculated 
alfalfa seeds (Medicago sativa) were planted on October 14, 1914, in each 
of the jars containing soil from Warren, Mason, Muhlenburg, and 
McCracken Counties, and a like number on November 6 in the remainder. 
On November 17 the plants were thinned to 15 average-sized plants, and 
cuttings were made at intervals—whenever the plants attained a height 
of about 10 inches—just as was done in Series II. Five cuttings were 
made from the Lawrence, Barren, Madison, and Jefferson County soils, 
and six from the remainder. Final cuttings on all were made on July 9, 
1915, when the experiments were stopped. 
Series v: wheat. —The soils in Series IV were stirred and pulverized 
to a depth of 6 inches and on December 23, 1915, were planted with 36 
Jersey Fultz wheat seeds (Triticum aestivum) in each jar. The plants 
were thinned to 25 averagersized plants, and potassium nitrate was 
added in the same amounts and at the same time as in Series III. On 
June 13, 1916, after the seeds had matured, the plants were cut close 
to the ground, air-dried, and weighed. 
The weight in grams of the total air-dry materials in Series I-V, 
together with the percentage gains or losses are given in Table II. 
