4 BULLETIN 214, U. S. DEPARTMENT OF AGRICULTURE. 
where winter rye had been turned under the year before. In 1915 
A will be in wheat, B in winter rye, C in oats, and D in corn. 
In the present stage of development of the work, the effect of the 
immediately preceding crop and of the method of handling its stubble 
in preparing the seed bed greatly overshadows the effects of the rota- 
tions considered as units. Some of the rotations are calculated to 
conserve or to accumulate fertility and organic matter in the soil, while 
others may perhaps deplete it, but on the naturally fertile soils of the 
Plains such results are not strongly evidenced in the first years of 
treatment. The controllable factors that exert the greatest influence 
on production are water supply, physical condition of the seed bed, 
and a recognized if not understood effect of the immediately preceding 
crop. The crop of a single year brings the land back so near to uni- 
Asj>. ^ 
A SJ>. U 
A LATE PP.U 
AS,. 
A S.P y. 
A s.P. 
A COP/I, S.P. 
A CORN, S.P 
B pp. \ 
B p.p. ^ 
Bp.p. -% 
B PP. 5 
B pp. ¥ 
B p, I 
B WHEAT, mM 
DC. 74 
3 WHEAT „ 
d.c. 76 
C cork, s.P. 
C WHEAT, 
S.P. 
C WHEAT S.P. 
C oats, s.r. 
C BARLEY, 
s.r. 
C FLAX, S.P 
C W. RYE, 
P.P. 
C PEA S f F.P. 
D fallowed 
D FALLOW EO 
D FALLOWEO 
D FALLOWED 
O FALLOWEO 
D FA l LOWE O 
D OATS, 
CM 
D OATS, 6.M. 
£ subsoileo 
£ SUB SOI LED 
£ sue SOILED 
£ SUB SOIL ED 
£ SUBSOILED 
£ SUBSOILED 
£ CORN, 5. P. 
A CORN, S. P. 
F LISTED 
F L/STED 
F LISTED 
F listed 
F LISTED 
F LISTED 
B OATS, ' 
D.C. 75 
B OATJ, 
d.c. 77 
6 LISTED 
6 l/steo 
A corn, F.P. 
A FALLOHFO 
A CORH, 
p.p. 
F.P. 
C W.RYE, 
C F>EAS t F.P. 
A OATS 
d.c. 40 
A CORN, ^ 
B BARLEY, „ 
D.C 6 
B wheat, _ 
FAL. S 
B WHEAT, _ 
r./>. 3 
B WHEAT, 
D.C. 7 
D WHEAT, 
CM. 
P WNEAT f 6.M. 
O CORN 
8 WHEAT, 
D.C. 
r OATS, PR 
C OATS, P.P. 
r OATS, f.P. 
£ OA TS, F. P. 
A o*»,** 
£ CORN, S.P. 
A OATS 
F.P 
A FALLOWED 
A corn r. p. 
4 CORH, S.P. 
A CORN, S. P. 
A\ COR rt, S.P. 
"oT r '/9 
*VZ* 78 
B CORH 
m&s. p. 68 
B OArs - o 
° fal. 8 
g OATS, D.C. 
* w J!%1 r ' z 
8 ??> 7 
* f.P 3 ' 9 
r FALLOWED 
C FALLOWED 
C WHEAT, DC 
C WHEAT 
F.P. 
C WHEAT, F.P. 
C. OATS, S.P 
C BARLEY, 
S.P. 
p OATS, FAL. 
Q WHEAT, FAL. . 
A L ,. ■? N, f P 
1 W WHEAT, 
OR RYE 
A °* TS - P p - 
j BROKE 
A CLOYER 
^ ba?ome 
4 afio/ie. 
£ ALFALFA] 
B WHEAT, 
* Z%* 64 
B ^"w 305 
B °'< r - i 
3 OATS, 
On sod 
g OROME 
a °*r s 
g OATS 
C OATS, 
Mir. P. 
r W.PYE, 
r. f. 
r WHEAT, 
OHEALLOW 
C CORN. 
<- S.P. 70 
S. P. // 
c r soo' 72 
b s.p. 47 
c Tp"' 42 
a CORN, 
A f.P 
A Mts'.P. 
A conn, r. R. 
n WHEAT, 
D-C. 
n WHEAT 
D.C. 
OATS, F. P. 
° D.C. ' 
WHEAT, D.C. 
*"/!.*■ 4S 
° 82* 67 
" ftg%w 
£ SROnC 
£ CLOVER 
£ CORN, S. P. 
£ 3ROMF 
£ ALFALFA, 
C OATS, SOD. 
f WHEAT 
C OAT J, CM. 
£ INN PAT, 
D.C ' 
p aROMc 
yC ALFALFA. 
Fig. 2.— Diagram of the dry-land rotation field at the Judith Basin Field Station. The lettering shows the 
cropping practiced in 1914. The explanation of abbreviations used is as follows: D. C = disked (corn 
land), Fal.,or S.T.=summer tilled, F. P.=fall plowed, G. M.=green manured, M.=manured, S. P.= 
spring plowed. 
formity in these factors that their probable residual effect is not great 
enough in the work in hand to introduce serious error into a study as 
here made. 
It seems advisable at the present time to prepare a series of bulletins 
discussing in each the results secured with one crop, as determined by 
the treatment of the land in only the one year preceding its growth. 
CLIMATIC CONDITIONS. 
The annual precipitation at the various stations varies from about 
15 to 21 inches. The average increases from north to south and from 
west to east. An increase in the average daily evaporation from north 
to south prevails. The rainfall is fluctuating in character. Years of 
heavy rainfall may follow years when it is deficient, and vice versa. 
