GROWTH-EQUATION CONSTANTS IN CROP STUDIES 1 
By W. L. Gaines, Chief in Milk Production, and W. B. Nevens, Assistant Chief 
in Dairy Cattle Feeding , Agricultural Experiment Station , University of 
Illinois 
INTRODUCTION 
The writers undertook, during the season of 1921, to obtain some 
experimental data as to the value of the sunflower crop for silage. 
There was at the time an increasing interest on the part of Illinois 
farmers in the sunflower as an alternative crop to corn for use as a 
silage crop. The investigation 2 was planned primarily for practical 
ends, and the proper stage of maturity for harvest seemed to be one 
of the questions on which information was needed. 
The Mammoth Russian variety of sunflower was used, and the 
date of planting was May 18, 1921. The crop was grown at Urbana 
on a 10-acre fidd 80 rods long. The crop in three parts of the field 
was harvested for silage at three stages of maturity—87, 107, and 
126 days after planting. The resulting silage was used in digestion 
and feeding trials in comparison with corn silage for milk production. 
This represented the limit of the facilities available for harvest and 
utilization of the crop as silage. 
Further data as to the progressive changes in the crop with advance 
in maturity were obtained by quantitatively sampling the growing 
crop in the field at eight periods—65, 75, 86, 96, 106, 117, 127, and 
138 days after planting. Four rows near the center of the field were 
reserved for this purpose. The plants for the field samples were 
selected in a systematic manner. The first plant for the sample at 
any period was taken at a preselected number from* one end of the 
row. With this plant as a starting point, every hundredth plant 
was taken at the first sampling period, every ninety-ninth plant at 
the second period, and so on to every ninety-third plant at the eighth 
sampling period. The number in the row of the first plant selected 
for any sample was varied at each sampling period so as to insure 
some distance between the plants entering into the various samples, 
and thus avoid, in the samples, the effect of thinning by removal of 
plants. The plants selected at each period were cut 6 inches above 
ground level and the combined lot of 58 to 60 plants was at once 
weighed and subsampled or analysis. Separate determinations were 
made on stalk and seed, commencing 86 days after planting. Analysis 
included the analysis customarily made of feed: Dry matter, crude 
protein, crude fat, crude fiber, nitrogen-free extract, and ash. The 
1 Received for publication Apr. 22, 1925—issued January, 1926. • 
2 More complete data than here given have been published in the following bulletins: 
Gaines, W. L., and Nevens, W. B. the sunflower as a silage crop, composition and yield 
at different stages OF maturity. Ill. Agr. Exp. Sta. Bui. 268: 407-455, illus. 1925. 
Nevens, W. B. the sunflower as a silage crop, feeding value for dairy cows; composition 
AND DIGESTIBILITY WHEN ENSILED AT DIFFERENT STAGES OF MATURITY. Ill. Agr. Exp. Sta. Bui. 253: 
185-225, illus. 1924. 
Journal of Agricultural Research, 
Washington, D. C. 
( 973 ) 
Vol. XXXI, No. 10 
Nov. 15, 1925 
Key No. Ill.-21 
