48 BULLETIN 1301, U. S. DEPARTMENT OF AGRICULTURE 
it, which interferes with the uniformity of the yields. The main 
field contains 225 tenth-acre plats and the south field 60 tenth-acre 
plats. The plats are 132 feet long and 33 feet wide. They are 
separated along the sides by 4-foot alleys, and along the ends by 
20-foot roadways and are divided into blocks of 12 plats each by 20- 
foot roadways. The alleys and roads are cultivated and kept free of 
vegetation. 
The methods of cultural treatment under trial are spring plowing, 
fall plowing, disked corn ground, summer fallowing, subsoiling, list- 
ing, and green manuring, el plowing except for special treatments 
is done to a depth of 6 inches. Corn ground to be sown to spring 
grain is disked once with a double cutaw ay disk shortly before seed- 
ing. Summer fallow is plowed the first week in June and kept free 
from weeds the rest of the season by cultivation. All subsoiled plats 
are fall- plowed to a depth of 6 inches, and the subsoiler is run in the 
bottom of each furrow to a further depth of 8 inches, loosening the 
soil to a total depth of 14 inches. Subsoiling is done for two years 
in succession and then omitted for two years. Listing is done to a 
depth of 6 to 8 inches in the fall for all small-grain crops that re- 
cele this treatment. Winter rye, peas, and sweet clover are grown 
and plowed under for green manure. This treatment is a modifica- 
tion of summer fallow, differing from it in the kind and quantity of 
the green matter that is turned under and the time ot plowing. 
The green-manure plats are plowed from four to six weeks later than 
summer fallow. 
Table 15 shows the crops that are regularly grown in the rota- 
t ons, the varieties used, the rate of seeding, and the number of plats 
of each crop seeded annually. The varieties used are those that are 
considered well adapted to the locality. The same variety of a 
given crop is seeded in all plats. 
TABLE 15.—Crops, varieties, seeding rate, and number of plats seeded annually in 
the crop rotation and cultivation experiments at the Northern Great Plains Field 
Station 
Numupes 
; Jariety S Saya of plats 
Crop Variety Seed per acre eeedce 
annually 
Scin cemiheate semen ee eee Kubankse vee soe S| ATCC lc oe 67 
WAMTEernwhea bs ees eh ee. Ce Eee ei Turkeyjon Kharkofes = 232 | 4 pecksie= Sie ee 5 
Onis a See eS ee ere Sixty. aye eee 6: pecks: sso s eae 64 
RAT Cy aos meee eer Bae ene ee 2 Hann chen sess se 5 a eee Lek OPCCKSeas eee eee 22 
CONS ate. ae eae Daw Se SS ee North westenmel) Grits a eee 64 
1D piven oe see ee ee eS ee North Dakota Wilt Resistant_| 20 pounds_________ 12 
I OUALOCS Se Se ae es ee Ae Barly Ohio =a 10 bushels_-________ 2 
AT Fat ey errs eee Se Se ee ei ee Grim sesabnet Ss) 2 aie | 6 to 8 pounds______ 1 
STO TMC TASS peers ere oo te sa ata oe BromuSinenniisa =e === eee el pOUn USE 1 
SWwechclovers-22--=- See Oe ee Be Whites: es eee eer dh ae i TOspounds==ae 2 
Win Gergry.Cs sem oe oe ee ae een ae eee Common essa hee | 50 pounds__----__- 2 
TP CASS as ee en ae Set ee ae Canadianghield ===. = aaee 2) bushels=s==o=-== 2 
3 MEER 1 
SOLLO 2 ae ees sans tere ee ree EEE: DakotagAumipe rs = anaes eae 8 pounds 
Spring-plowed and fall-plowed plats that are seeded to spring 
small grains are harrowed twice in the spring. Fall-plowed plats 
are left rough over winter. Spring-plowed plats to be seeded to 
corn are harrowed twice before seeding. Fall plowing for corn is 
harrowed once at the time the plats for small grain are harrowed 
and again when the spring-plowed plats for corn are harrowed. 
q 
