The Bulletin 61 



gen compared to potash certainly justifies tlie assumption that the phos- 

 phoric acid and nitrogen supplies of this soil must be increased if large 

 crops are to be grown permanently on the soil. Such an assumption is 

 in accord with the chemical analysis of this soil which shows it to be 

 abnormally high in potash. The surface 6% inches contains enough 

 of this material for about 483 one hundred bushel corn crops, while it 

 is deficient in both phosphoric acid and nitrogen. Eighteen such crops 

 would require an amount of phosphoric acid equal to the total existing 

 in tlie top 6% inches, while six such crops would use up all the nitrogen. 



TREATMENT AND KESULTS ON FIELD E, IREDELL TEST FARM. 



The soil of this field is of the same character as that of all the other 

 fields at the Iredell farm. One-twentieth acre plats were laid off and 

 the experiments started in the spring of 1910. Corn was the first 

 crop grown in the following five-year rotation used on this field : 



First Year — Corn, with cowpeas. 

 Second Year — Cotton, with rye. 

 Third Year — Oats, with soy beans. 

 Fourth Year — Wheat, with red clover. 

 Fifth Year — Red clover. 



In this rotation the cowpeas, rye, soybeans and the last crop of red 

 clover are grown and turned into the soil for its improvement. As the 

 red clover seeded during the spring of 1913 failed, crimson clover was 

 seeded on the plats during the following fall, cowpeas in the spring, of 

 1914 and crimson clover again in the fall of 1914 in order to make the 

 conditions in the rotation as near as possible those of a successful clover 

 crop. The stand and growth of crimson clover and cowpeas were the 

 best on plats 14, 2, 8 and 5. The different fertilizer treatments received 

 by the several plats of this field with their results upon the yields of corn, 

 cotton, oats, wheat and red clover are contained in the following table: 



