44 - BULLETIN 1173, U. S. DEPARTMENT OF AGRICULTURE. 
but as conditions become more favorable and moisture is more 
abundant nitrate nitrogen in particular should receive increasing 
attention. 
HARROWING THE GROWING CROP. 
RESULTS AT MORO. 
Experiments to determine what effect the harrowing of winter 
wheat in the spring has on yield were carried on at Moro, Lind, and 
Nephi. This is a practice that has been quite widely followed by 
farmers in the West, but one on the value of which there has been 
considerable dispute. At Moro there were adjacent plats of winter 
wheat, one harrowed in the spring and the other not harrowed on 
land plowed for summer fallow on several dates and by different 
methods, as shown in Table 24. This experiment, therefore, was 
repeated nine times at Moro in each year since 1913. The yields 
shown in Table 24 are averages for nine years, 1913 to 1921, for the 
spring-plowed and summer-plowed plats and for eight years, 1914 to 
1921, for the fall-plowed plats. 
TABLE 24.—Average yields of Turkey winter wheat from plats harrowed in the spring and 
not harrowed, at Moro, Oreg., in the nine years, 1913 to 1921, inclusive, for the spring- 
plowed and summer-plowed and in the eight years, 1914 to 1921, inclusive, for the fall- 
plowed plats. 
_ Average yields per 
acre (bushels). 
Date and method of plowing. 
Har- | Not har- 
rowed. rowed. 
lowed eAprilél«(early Spring?) ses osse ce -eigee sotto Yam ects a thst arate ele eos 30. 1 
Biowed- May. (ate'sprimg)!.: Stes. Je. se reac oee ns soc se ee nese easels aes = 26.8 
lowed une: (early summer) a.6c5 5-5 eo hss Leste ase eo oe est eaaa, cee tor Cee 22.8 22.9 
Pelomeduml- Carly fall (ALY) coco oe.c obo cicim Sie ae ye cae detec ayers lots te eco ee en ee arate 28. 1 
Plowed in late fall (wet) 25.5 
IANVGEAROS SoS tos cas besa ER Ce ee nthe oe ini atote eh stoioe Mae ote Pe sin Milne ts Rese hai 4 26.6 27.6 
The results shown in Table 24 justify the conclusion that harrow- 
ing winter wheat in the spring at Moro decreases yields. The har- 
rowing was done at a time when it was thought it would do the most 
good and the least damage to the plants. The surface of the soil at 
Moro gets very hard in the spring and contains numerous shrinkage 
cracks. Harrowing apparently would put the land in better condition 
by creating a light mulch and closing the shrinkage cracks, but the 
yields have nearly always been decreased by the harrowing. Usually 
the stands were not appreciably reduced, but harrowing frequently 
set back the wheat so that it was two or three days later in heading 
and sometimes a day or two later in ripening than that not harrowed. 
This delayed maturity probably was caused by covering the wheat 
plants with small clods turned up by the harrow. Occasionally 
weeds in the grain can be killed by harrowing, but as a general rule 
the number of weeds that can be killed by spring harrowing of winter 
wheat is negligible. 
RESULTS AT LIND. 
At Lind during the period of these experiments fall conditions were 
so unfavorable that it was impossible to get winter wheat up and into 
the winter with a vigorous growth. As a result, in the spring all 
eis 
