824 EXPERIMENT STATION RECORD. [Vol. 41 



Tlie effect of potatoes in the rotation was siujilar lo lluit <iL' corn. Fallowing 

 also produced much tlie same effect, except that the lirst wheat cx'op yielded less 

 and the third one more than when grown in a similar place in the rotation with 

 corn or potatoes. There was a greater growth of straws when wheat was grown 

 on fallow land than occurred on potato land, and more on potato land than on 

 corn land. In specially favorable years more grain was produced with the 

 greater growth of straw, but the results arc held to indicate that ordinarily 

 more grain is produced on corn land than on potato or fallow land for the con- 

 ditions under which this work was carried on. 



St)il moisture determinations in 1912 and 1913 showed that German millet 

 and broom coni millet used similar amounts- of water from the top 3 ft. of soil. 

 More ^vater was used in producing a bushel of wlieat in the crop following 

 millet than was used by the second, and more by the second than by the third 

 crop of wheat following millet. AVheat was produced with less loss of water 

 from the top 3 ft. of soil when it followed corn than when grown after millet. 

 As an average of three crops, a bushel of wheat was produced with 1S.4 tons less 

 water than in the German millet rotation and 14.8 tons less than in the broom 

 corn millet rotation. The first wheat crop following corn required less water 

 than the second and the second slightly less than the third. More water was 

 used from the top 3 ft. of soil for the p]-oduction of a bushel of wheat when 

 potatoes took the place of corn in the rotation, but less than was used in the 

 millet rotations. The first wheat crop following the potatoes was produced 

 with the least w^ater, the amount increasing v/ith each succeeding wheat crop. 

 Wheat grown on fallow required more water for each bushel produced than 

 when grown on corn or potato land, but less than when grow-n on millet ground 

 if no account was taken of the loss during the year in which it was fallowed. 

 As an average of two years this loss amounted to approximately 6 in. of rainfall. 



The grov/ing of millet seemed to favor the accumulation of nitrates more 

 than the growing of wheat, but the heavy demands of the millet crop sometimes 

 reduced the nitrate content of the soil to a low point. Nitrates accunuilated 

 more rapidly in corn, potato, and fallow land than wdiere millet was grown. 

 When measured by the amount of nitrogen used by the crop and the amount 

 remaining in the soil in the form of nitrates, there was less available nitrogen 

 produced in the wheat land the first year following millet than there was the 

 second year. The amounts produced the third year following millet were prac- 

 tically the same as for the second season. The available nitrogen produced in 

 soil growing the first crop of wheat after corn or potatoes was greater than 

 when either the second or third crop was grown. 



Finally it is concluded that, " for the black clay soil of the Red River Valley, 

 the beneficial effect of corn and potatoes in the rotation is due largely to the 

 greater amount of nitrogen made available during the growing season of suc- 

 ceeding crops and greater economy in the use of plant food and soil moisture. 

 The better soil structure after a cultivated crop has been grown probably favors 

 nitrification and permits a more complete and uniforn) distribution of the crop 

 roots through the soil mass. The eradication of weeds is an important factor 

 in the improvement of soil structure and the economy of plant food and soil 

 moisture." 



[Report of field crops work at the Hettinger, N. Dak. substation, 1913— 

 1918], W. R. I.ANxoN, A. J. Ogaard. and U. J. Downey (North Dakota Stn. 

 Bui. 130 (1919), pp. 9-12, U-20, 21-28, 25-28, S6-/,9. 50-58, 55. 56').— This com- 

 prises a report on variety, rotation, and cultural lests with wheat, oats, barley, 

 potatoes, flax, and corn, and field tests with buckwheat, alfalfa, sweet clover, 

 red clover, brome grass, millet, Sudan grass, field peas, soy beans, chick-peas, 

 kaoliang, emmer, hemp, and Dakota amber sorghum. 



