Dec. 2. 1918 Effect of Farm Manure on Irrigated Field Crops 497 



Table I. — Effect of manure on the yields of Irish potatoes at the Scottsbluff, Nebr., Belle 

 Fourcke, S. Dak., and Huntley, Mont., field stations, IQ12 io igiy — Continued 



HUNTLEY 



" No manurial effect on this crop. 



T-he results given in Table I, which refer to the total yield of potatoes, 

 show that in 8 of the 9 cases the application of manure was followed by 

 increased 5delds, and it should be remembered that these crops were 

 produced on new land, where good yields are obtained even without 

 manuring. 



Each year since 191 3 it has been the practice in connection with these 

 experiments to sort the potatoes in the field at the time of digging. This 

 sorting has been done by means of a wire screen with 2-inch meshes. The 

 smaller potatoes that pass through this screen are classed as unmarket- 

 able, while those passing over the screen are classed as marketable. It 

 has been observ^ed at Scottsbluff and at Belle Fourche not only that the 

 manured crops have been larger than those not manured, but also that 

 the proportion of marketable potatoes has been larger on the manured 

 land. This has not so far proved to be the case at Huntley. The yields 

 of marketable potatoes at the three stations for the three pairs of rota- 

 tions for five years are given in Table II, together with the annual differ- 

 ences and the mean yields and the mean of the annual differences. 



