163 



The legumes increased the yield in every case as com- 

 pared with sweet potatoes, the excess ranging from 41 

 to 181 per cent. Among the non-leguminous plants 

 SAveet potatoes was most exhausting to the soil, and 

 chufas, when consumed on the land, the least. This 

 agrees with common observation. In this case the ex- 

 hausting effects of the sweet potatoes were not due to 

 leaching of the disturbed soil, for all plots were plowed 

 soon after the potatoes were dug. 



Among the legumes the greatest increase, 181 per 

 cent, was obtained on the plot where Spanish peanuts 

 had been consumed on the land by hogs. Since the 

 yield of peanuts here was not excessive, since the growth 

 of tops was only moderate, and since the vines of Span- 

 ish peanuts on an adjoining plot did not greatly in- 

 crease the yield, we can attribute the increase where 

 hogs had grazed, only to an assumed quicker nutrifica- 

 tion of the material that had passed through animals. 

 This view finds further support in the fact that chufas 

 consumed bv hogs on the land left the soil in better 

 condition than did either corn or sweet potatoes. 



Wherever the entire growth of the several legumes 

 was left on the land, with or without being utilized as 

 hog food, the succeeding yield of rye was more than 

 doubled. 



Cotton was grown in 1899 on a plot adjacent to the 

 legumes. The rye following cotton yielded 5,560 

 pounds per acre, but it is not fair to compare this yield 

 with that following the legumes, because the cotton 

 had been very heavily fertilized, and some of this fer- 

 tilizer probably remained in the soil to be utilized by 

 the rve. 



