4 BULLETIN 320, U. S. DEPARTMENT OF AGRICULTURE. 
ditions with reference to farm labor and farm capital are the prin- 
cipal factors in determining differences in practice. In the prepara- 
tion of the seed bed the soil type is also an important factor, while 
in intertillage the types of weeds to be dealt with have much to do 
with prevailing practices. The reason why greater variation in re- 
sults is not shown for the different methods and amounts of inter- 
tillage is that, in the main, all the practices studied were adequate 
for weed control in the growing crop in the regions where these 
practices are employed. (Table I.) 
Previous investigations have shown that if weeds are eliminated, 
any sort of intertillage becomes of minor consideration. 1 The whole 
subject, therefore, is far more largely of economic than of agronomic 
importance. What the farmer wants to know concerning seed-bed 
preparation is: What is the cheapest method of making an adequate 
seed bed under his conditions? An adequate seed bed may be de- 
fined as land free from weeds and surface trash, sufficiently mellow to 
permit easy penetration of the plant roots, sufficiently compact to 
hold moisture and to be free from large air spaces, and sufficiently 
fine in texture to bring many soil particles in contact with the seed 
and thus to supply an abundance of moisture to the germinating 
plant. Land so prepared is also in good condition for subsequent 
tillage. What he wants to know concerning intertillage is: What is 
the cheapest method of controlling weeds which infest his growing 
crops ? 
Table I. — Summary of tillage practices with corn, showing the averages of depth 
of plowing, number of cultivations, price of land, commercial fertilizer used, 
and normal yields per acre in twenty-one regions of the United States. 
Region covered (fig. 1} 
Key 
letter, 
County and State. 
Depth 
of 
plow- 
ing. 
Workings 
after 
plowing 
and 
• before 
planting. 
Cultiva- 
tions 
after 
planting. 
Price 
of land 
per acre. 
Commercial fertil- 
izer used. 
Farms 
applying. 
Applied 
per acre. 
Normal 
yield. 
Tipton, Ind 
Montgomery, Ohio 
Mercer, N. J 
Moultrie, 111 
Tama, Iowa 
Kalamazoo, Mich 
Maury, Term 
Hartford, Conn 
Bradford, Pa 
Christian, Ky 
Hamilton, Nebr 
Rockwall and Grayson, 
Tex 
Scotland, N.C 
Augusta, Va 
Waushara, Wis 
Bates, Mo 
Alexander, N.C 
Oklahoma, Okla 
Pike, Ala 
Holmes, Miss 
Russell. Kan^ 
Inches. 
6.7 
7.1 
6.3 
5.4 
5.1 
6.7 
7.7 
7.4 
6.1 
7.1 
5.8 
6.4 
7.0 
8.0 
5.5 
5.9 
6.0 
2.8 
3.6 
3.5 
3.2 
3.0 
3.3 
2.7 
2.4 
2.5 
3.0 
2.5 
1.5 
2.3 
3.0 
1.8 
2.3 
1.1 
1.5 
.6 
1.4 

5.5 
4.0 
5.9 
4.4 
5.3 
5.0 
5.4 
3.8 
4.4 
5.1 
5.1 
3.9 
4.3 
4.1 
5.4 
4.8 
5.1 
3.9 
4.7 
4.7 
3.8 
S209. 48 
146. 96 
101.87 
198.30 
196. 40 
101.40 
110.38 
138. 80 
51.20 
69.04 
158.38 
103.41 
113.50 
71.80 
48.27 
95.00 
39.14 
50.00 
36.50 
22.40 
43.20 
Per cent. 
3.4 
31.0 
78.1 




88.0 
28.6 
3.8 


100 
42.9 


78.9 

90.5 
4.0 

Pounds. 
200.0 
217.2 
331.7 
727.3 
178.1 
125. 
575.7 
161.3 
366.8 
200.0 
Bushels. 
57.4 
52.3 
51.1 
49.5 
46.6 
41.5 
40.9 
39.9 
38.2 
36.9 
35.0 
33.6 
33.0 
33.0 
30.4 
29.3 
25.2 
23.9 
23.1 
22.0 
20.4 
1 See Bureau of Plant Industry Bulletin No. 257, already mentioned. 
