RED CLOVER 379 



as on similar plots that had received a fair amount of 

 fertilizer containing nitrogen each year. At the Rhode 

 Island Experiment Station potatoes yielded 294.5 bushels 

 after clover and 259.7 bushels after corn. At the Pennsyl- 

 vania Experiment Station the fertility of the soil was 

 fully maintained for 25 years on certain plots where clover 

 was grown every fourth year in the rotation and only the 

 stubble plowed under. No. barnyard manure was used, 

 but each alternate year 48 pounds of phosphoric acid and 

 100 pounds of potash per acre was added. 



The results at the Ohio Experiment Station show that 

 in general a good crop of clover will leave enough nitrogen 

 in the roots and stubble for the succeeding crop, but the 

 nitrogen supply cannot be maintained by clover alone 

 even if planted every third year. At the Illinois Experi- 

 ment Station the yield of corn grown continuously for 7 

 years averaged 35.7 bushels to an acre. In a rotation of 

 corn, oats, clover, the average yield of corn for the 5 years 

 immediately after clover was 55.1 bushels, and after clover 

 cropped two years 46.8 bushels to an acre. At the Minne- 

 sota Experiment Station it was found that 6 pounds of red 

 clover sown with wheat in continuous wheat culture in- 

 creased the average yield of wheat for 10 years 3J bushels 

 to an acre. The results at this station taken as a whole 

 show that the nitrogen content of the soil is preserved if red 

 clover is grown two years in a five-year rotation. At the 

 Canebrake, Alabama, Experiment Station, oats yielded 

 52 bushels an acre after four-year-old clover stubble, 

 while a yield of 54 bushels was obtained by using 200 

 pounds of nitrate of soda to an acre. 



446. Volunteer crops. A good stand of red clover is 

 sometimes secured by the scattering of barnyard manure 

 which happens to contain sufficient viable seed. 



