26 BULLETIN 1094, U. S. DEPARTMENT OF AGEICULTUEE. 



in the yield of spring-sown barley as a result of its following kafir, 

 which is very contrary to the effect of kafir on fall-sown wheat, as 

 shown in rotations Nos. 149, 150, 349, and 350, which have been 

 considered. 



WHEAT IN 3-YEAR ROTATIONS OF KAFIR, FALLOW, AND WHEAT. 



In 1913 two series of ten 3-year rotations were started. These 20 

 rotations are all fallow, winter wheat, and kafir. The first series, 

 niunbered from 501 to 510, inclusive, was planned primarily to study 

 methods of raising kafir on wheat stubble, but two of the rotations, 

 Nos. 501 and 502, vary from the others in the method of fallow. 

 The cultivation for fallow in rotation No. 501 is started in the fall 

 by plowing to a depth of 12 to 14 inches with a deep-tillage machine. 

 The plat to be fallowed in rotation No. 502 is dynamited before listing 

 in the fall. A half stick of dynamite is shot at a depth of 3 feet in 

 holes 16 feet apart. The first year 20 per cent dynamite was used, 

 but since then 40 per cent has been used. This plat and the plats to 

 be fallowed in rotations Nos. 503 to 510, inclusive, are listed in late 

 fall. During the spring the lister ridges are leveled by such cultiva- 

 tion as may be necessary to prevent weed growth. About midsummer 

 the plats are all plowed. Enough cultivation is given after plowing 

 to prevent weed growth and to prepare a good seed bed for winter 

 wheat. The fallows are seeded uniformly to wheat in the usual man- 

 ner, with no special treatment. 



These rotations are so arranged that the fallow, wheat, and kafir 

 each occupy a solid block of 10 plats side by side, arranged from north 

 to south in numerical order. The wheat stubble is prepared for 

 kafir in the several rotations as follows: 



Rotation 501: Fall list, cultivate ridges down in early spring, list at planting time 



(deep tilled for fallow). 

 Rotation 502: Same as No. 501 except dynamited for fallow instead of deep tilled. 

 Rotation 503: Double-disk in July or August, fall Ust, cultivate ridges down in 



early spring, list at planting time. 

 Rotation 504: Fall list, cultivate ridges down in early spring, Ust at planting time. 

 Rotation 505: Fall list, ridges untouched until planting time, then split ridges. 

 Rotation 506: Fall Ust, work with harrow in spring, Ust in same furrows at planting 



time. 

 Rotation 507: Fall list, work with harrow in spring, spUt ridges at planting time. 

 Rotation 508 : Early spring list, ridges untouched until planting time, plant in same 



furrows. 

 Rotation 509: Double-disk in spring, Ust at planting time. 

 Rotation 510: Untouched until planting time, then Ust. 



The yields of both wheat and kafir in these 10 rotations for the 

 7-year period from 1914 to 1920, inclusive, are given in Table 11. 



Careful study of the data from these and the 10 companion rota- 

 tions shows the plat variation or experimental error to be so high 



