40 BULLETIN 1173, U. S. DEPARTMENT OF AGRICULTURE. | 
RESULTS AT LIND. ' 
Weed growth has such an important bearing on yield in the por- 
tion of the Columbia Basin lying in central Washington that tillage 
of some sort for weed control can not be omitted in maintaining the 
fallow. It simply is a question of whether tillage should be given 
immediately after plowing or whether the tillage should be delayed 
until weeds start growth. The results obtained are given in 
Table 22. 
From these data it is seen that so long as moisture conditions are 
favorable, as at the earlier dates of plowing, immediate cultivation 
may or may not have advantages. As the soil becomes more dry, . 
as in the June plowing, there is nothing to be gained by immediate 
tillage. In other words, the more dry the general conditions, the less 
“he possible advantages to be gained through immediate cultivation 
Fic. 22.—Plats in the tillage experiments at Moro, Oreg., July, 1922. At left, plat given frequent culti- 
vation; at right, plat harrowed once immediately after plowing and not cultivated thereafter. The 
furrows in the plat cultivated frequently are made by the rod weeder. This weeder is sometimes fol- 
lowed immediately with a spike-tooth harrow to smooth the ground, but usually the fallow is left as 
shown until seeding time, the ground being smoothed just before sowing. 
following the plow. Taken alone these data would not justify such 
a conclusion, but in conjunction with those from two other stations 
they tend to point in that direction. 
TABLE 22.—Average and annual yields of wheat after fallow cultivated immediately and 
not cultivated immediately after the plowing, at Lind, Wash., in the years 1918 to 1921, 
mnelusive. ~ 
Annual and average yields per acre (bushels). 
Date of plowing and subsequent treatment. SSS Se 
1918 1919 | 1920 | 1921 Average. 
March plowing (early spring): 
LIMITS CT ALCICUIGIV ATION. 5c. % onc: sens won ccivscoawep ee 
DWelavedeulnvatlOw =. <2 .400%05..0% wae cess ec=pe 
April plowing (late spring): 
Immediate cultivation............... Sao eee 
Welayed cultivalOns. <se- ~s- sac ode acoso geese ce 
June plowing (early summer): 
immediate cultivation<-...-..2-...s.-.-deses+--c0 
WelavedicultivaiOns nesasa-- =. s a6 socerceceeeeoee 
aioe 
gr ID 
mw lop a>) 00 tO 
