46 The Bulletin 



As a result of three years' tests with com and one year's test with 

 cotton, it is quite evident that the chief plant food deficiencies of the 

 soil of this field are nitrogen and phosphoric acid. The use of phos- 

 phoric acid alone yielded on an average above the unfertilized plat an 

 increase of 8.0 bushels of corn and 541 pounds of stover, and 67 pounds 

 of seed cotton; and of nitrogen alone 6.9 bushels of corn and 121 pounds 

 of stover, and 172 pounds of seed cotton per acre. Potash alone and 

 lime alone produced 4.3 and 7.0 bushels of corn ; 381 and 366 pounds of 

 stover; and 67 and 127 pounds of seed cotton increases respectively per 

 acre. On this field, the greatest gains for each of the plant food con- 

 stituents were secured when they were used alone. 



The average gain for each element, given in the lower section of the 

 table, has been computed from the figures in the main table. For ex- 

 ample, there are four plats, each one of which received exactly the 

 same treatment as some other plat except that nitrogen was applied in 

 addition. In each case the gain for nitrogen may be determined. Plat 

 2 for instance, yielded on an average at the rate of 6.9 bushels of corn 

 and 121 pounds of stover, and 172 pounds of seed cotton more than plat 

 6 ; plat 'No. 5 yielded at the rate of 1.5 bushels of com and 100 pounds 

 of stover, and 8 pounds of seed cotton more than plat 2 ; plat 7 at the 

 rate of 0.1 bushel of corn and minus 40 pounds of stover and 188 pounds 

 of seed cotton more than plat 4 ; and plat 9 at the average rate 4.7 bushels 

 of com and 210 pounds of stover, and 120 pounds of seed cotton more 

 than plat 8. The average of these four are the average gains, as will 

 be seen in Table 1, of 3.3 bushels of corn and 98 pounds of stover, and 

 122 pounds of seed cotton per acre. The average gains for phosphoric 

 acid, potash and lime with each crop are secured in the same manner. 



On an average, the gain with com is greater from the phosphoric 

 acid applications but with cotton the nitrogen applications produced 

 the larger increases. Taking the results as a whole nitrogen at the 

 present time seems the more essential constituent for this soil, particu- 

 larly so for the growth of cotton. Lime next to nitrogen and phos- 

 phoric acid seems to be more essential than potash for the growth of 

 such crops as corn and cotton. The marked benefits of applications of 

 nitrogen and phosphoric acid compared with potash certainly justifies 

 the assumption that the nitrogen and phosphoric acid must be increased 

 if maximum crops are to be produced permanently on this soil. Such 

 an assum^jtion is in accord with the chemical analysis of this soil which 

 shows it to be high in potash. The surface 6% inches contains enough 

 of this material for nearly 124 one hundred bushel corn crops, while it 

 is deficient in both phosphoric acid and nitrogen. Twenty-seven such 

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

 existing in the top 6% inches, while less than one-third this number 

 would use up all the nitrogen. 



TREATMENT AND RESULTS ON CHARLOTTE FIELD NO. II. 



The soil of Charlotte field No. 2 is typical Iredell loam, high phos- 

 phoric acid phase. This type occurs quite widely over the Piedmont 

 section of the State, and is generally known as "black-jack" soil. The 

 ex]jeriments at this farm were started at the same time as those on 

 Charlotte Pield No. 1. The plats are one-twentieth acre in size. The 



