238 EXPERIMENT STATION RECORD. 



this is taken as the standard of comparison for the different rotations. The average 

 yield of oats was 48.64 hu. of grain and 2,281 lbs. of straw, and of barley 37.25 bu. of 

 grain and 1,968 lbs. of straw. In these average results the ratio of grain to straw for 

 wheat, oats, and barley was 1:2.65, 1:1.58, and 1:1.15, resjiectively. 



The best average yields were obtained from wheat following sunnner fallow, but 

 the difference in yield as compared with wheat following corn amounted to only ^ of 

 a bushel per acre, and for this reason the rotations containing corn crops are regarded 

 as much more ])rolitable than those with summer fallow. The lowest yields of grain 

 and straw were obtained where wheat followed oats. The yields of wheat after 

 millet were below the general average, and on account of this fact millet is regarded 

 as having but little value as a restorative crop. Wheat after peas also yielded less 

 than the general average, and where the peas were plowed under for green manure 

 the yields were not as good as where corn had been grown the previous year. Con- 

 tinuous cropping with wheat resulted in an average yield of al)out 1.5 bu. per acre 

 below the standard. Wheat after roots gave about the same x-esults as after corn, and 

 when grown after vetch the yields were slightly Ijetter than when following ])eas. 



The value of l)rome grass in the rotation is jaointed out, and directions for its use 

 and treatment in this connection are given. 



The effects of growing corn on succeeding crops are summarized as follows: 



"The soil is kept in the best condition for the growth of nitrifying and other bene- 

 ficial bacteria. 



"Chemical changes, in part dependent upon, and in part independent of, the 

 growth of bacteria are induced; thus reducing the unavailable plant food to forms in 

 which it can be readily assimilated by the growing plants. 



"The soil moisture is conserved and kept stored in the soil for the use of the suc- 

 ceeding crop instead of being evaporated from the surface. 



" A less amount of moisture is used by the corn crop than by any of the other crops 

 under consideration; and, therefore, a larger store of soil water is available for the 

 succeeding crop." 



The seasons of 1900 and 1901 represented unfavorable and favorable conditions, 

 respectively, and a comparison is made of the effects upon the yields of wheat and 

 oats produced by the immediately j^receding crop during these seasons. In 1900 the 

 average yield of wheat from 30 plats was only 9.15 bu. ])er acre, while in 1901 from 

 the same plats and in the same rotations it was 16.38 bu. The average A'ield of oats 

 from 8 plats was 20.69 bu. per acre in 1900 and 47.87 bu. in 1901. An increase in 

 yield of 8.04 bu. per acre was obtained where wheat followed summer fallow, corn, 

 potatoes, or peas plowed under, and an increase of 16.12 bu. of oats where this crop 

 was grown after corn instead of after wheat. The yields of both crops in 1901 were 

 quite uniform, and there was no apparent advantage in growing wheat on summer 

 fallow or corn land during this favorable season. 



In observing the effects of the frequency of croi:)ping with wheat the author found 

 that where wheat was grown only once in 5 years the average yield was 15.27 bu., 

 and where grown every 2 years, 15.33 bu. per acre. The yields in the other groups 

 differed from each other by less than 1 bu. per acre, and were considerably less than 

 for the 2 and 5 year periods. The failure to detect any relation between the length 

 of the interval between wheat crops and the yields strengthens the author's former 

 conclusion that the yields depend almost entirely upon the crop immediately preced- 

 ing the wheat crop. 



In addition to the report on the rotation tests the results of experiments in the 

 api)lication of manure to wlieat are given. The quantities of inanure applied ranged 

 from 4,000 to 9,600 lbs. per acre. In 1897 the average increase on the manured plats 

 was 1.9 bu. and in 1S9S 2.99 ])u. These results proved ])rofitable. 



Industrial progress in plant work, B. T. Galloway ( U. S. Dej)t. Agr. Yearbook 

 190^, 2)p. 219-230). — This paper briefly reviews the progress made in the improve- 



