502 Journal of Agricultural Research voi. xv. no. 9 



combined weight of beets and tops for 46 plot-years is 26 per cent, with 

 a mean annual difference in favor of the manuring of 2.7 ±0.6. 



At Belle Fourche the yield of beets for 46 plot-years averaged 10.7 

 tons per acre, with a mean annual difference in favor of the manuring 

 of 1. 9 ±0.36. The size of beets from the same plots averaged 0.84 

 pound, with a mean annual difference in favor of the manuring of 

 0.08 ±0.035. The percentage of sugar in the beets, omitting 191 2, 

 averaged for 40 plot- years 19.6 per cent, with the mean annual difference 

 in favor of the manured plots of 0.3 ± 0.22. The record of the percentage 

 of tops is incomplete. 



At Huntley the yield of beets for 46 plot- years averaged 11.3 tons 

 per acre, with the mean annual difference in favor of the manuring of 

 2.6 ±0.33. The notes as to size of beets, percentage of sugar, and per- 

 centage of tops were not taken for 191 2. The size of beets for 40 

 plot-years averaged 0.92 pound, with the mean annual difference in 

 favor of manuring of 0.21 ±0.034. The percentage of sugar in the 

 beets averaged 16.8 per cent, with a mean annual difference in favor of 

 the manuring of 0.16 ±0.17, which is negligible. 



The proportion of the weight of tops to the combined weight of beets 

 and tops averaged 32 per cent, with a mean annual difference in favor 

 of the manuring of 3.2 ± 1.12. 



SUMMARY 



The effect of manure on the yields of Irish potatoes and sugar beets 

 under irrigation has been tested for six years in seven rotations at each 

 of three different stations in the northern Great Plains. Comparison>is 

 made between the yields of these crops when grown in rotations without 

 manure and when grown in the same sequence in other rotations in 

 which manure is applied at the rate of 12 tons per acre otice during the 

 cycle of the rotation. 



At Scottsbluff, Nebr., the effect of the manure has been to increase 

 the yield of potatoes about 40 bushels per acre, to increase the propor- 

 tion of marketable potatoes about 8 per cent, and to increase the yield 

 of sugar beets 4.3 tons per acre without materially affecting the sugar 

 content of the beets. 



At Belle Fourche, S. Dak,, the effect of the manure has been to increase 

 the yield of potatoes about 34 bushels per acre, to increase the proportion 

 of marketable potatoes about 7 per cent, and to increase the yield of 

 sugar beets 1.9 tons per acre without materially affecting the sugar 

 content of the beets. 



At Huntley, Mont., the effect of the manure has been to increase the 

 yield of potatoes about 26 bushels per acre without influencing mate- 

 rially the proportion of marketable potatoes, and to increase the yield 



