1916.] PUBLIC DOCUMENT — No. 31. 41a 



(twelve years), potatoes (twelve years), corn, grain (seven 

 years), sweet corn, ears (one year), cabbages (ten years), soy 

 beans (four years), alfalfa (four j'ears), crimson clover (one 

 year), common red and alsike clover (one year), and mammoth 

 red clover (one year). 



North Corn Acre. 



For twenty-six years there have been under comparison on 

 this field two fertilizer mixtures. In one, the percentage of 

 potash is high and that of phosphoric acid low; in the other 

 (which represents about the average analysis of the commercial 

 corn fertilizers offered on our markets), the percentage of phos- 

 phoric acid is high and that of potash low. For twenty years 

 the rotation on this field has been two years grass and two 

 years corn. The seed (a mixture of timothy, red top and clover) 

 has usually been sown in the standing corn the latter part of 

 July. The soil has not had the benefit of a green manure crop 

 nor an application of manure during the twenty-six years of the 

 experiment. The turf and corn stubble which have been plowed 

 under have been the only source of humus. The crop this year 

 was corn. The yield was somewhat smaller than in previous 

 years, but it is believed that the abnormally wet season was 

 more responsible for the lower yield than the lack of fertility. 

 Judged on the basis of crop production, it would seem that the 

 fertility of the soil had been maintained by the use of commer- 

 cial fertilizer alone. 



The yield of crib-dried corn obtained this year was at the 

 rate of 46 bushels per acre on the combination rich in phos- 

 phoric acid, and the stover on this plot was at the rate of 

 5,420 pounds per acre. On the plot receiving the combination 

 richer in potash, the yields were at the following rate: crib- 

 dried corn, 35.1 bushels; stover, 5,060 pounds. 



North Soil Test. 

 This experiment began in 1890 and has for its object a study 

 of the effect of the continued use of fertilizers containing single 

 plant-food elemeats and different combinations of plant-food 

 elements for different crops; also the effect of lime added to 

 each fertilizer under comparison. 



