FERTILIZER EXPERIMENTS WITH COTTON ON THE 



SANDY LOAM SOILS (NORFOLK SANDY 



LOAMS) OF THE COASTAL PLAIN 



Being a Report of Work with Cotton on the Edgecombe 

 Test Farm in 1903-1909, Inclusive 



By B. W. Kilgoke, C. B. Williams, G. M. MacNider, and R. W. Scott, Jr. 



GENERAL SUMMARY OF RESULTS OF FERTILIZER TESTS 



1. The proper fertilization of cotton pays large profits, larger ones 

 than any other staple crop generally grown in the State. What this 

 fertilization should be on these and similar soils is shown by the results 

 of our experiments as given on the following pages. 



2. In the production of cotton on this land with only two constituents 

 used nitrogen combined with potash afforded the largest net returns per 

 acre, while a mixture of nitrogen and phosphoric acid gave the smallest 

 profit. The use of phospphoric acid and potash averaged $4.06 more 

 profit per acre than phosphoric acid and nitrogen, but it' was not so great 

 by $6.24 per acre as that secured on an average by the use of a mixture 

 carrying nitrogen and potash. 



The experiments as a whole show nitrogen to be the dominant or con- 

 trolling constituent of plant-food for increasing yields and adding the 

 greatest profit per acre in growing cotton on this type of soil. 



3. The results show that lime alone has been used on an average at 

 a small profit. In combination with nitrogen, phosphoric acid and 

 potash to make a complete fertilizer it has shown an annual increased 

 profit of $6.17 per acre above the net returns secured from the use of 

 the complete fertilizer alone. 



The results show that for cotton growing on this type of land the use 

 of moderate quantities of lime particularly in connection with a com- 

 plete fertilizer will prove quite profitable. 



4. The amount of nitrogen used in the normal fertilizer (400 pounds 

 per acre), applied in these cotton experiments, was 2% per cent, or 10 

 pounds to the acre. This amount was varied so as to give 5, 10, 20 and 

 30 pounds of nitrogen per acre. The yields and profits per acre were 

 increased as the applications of nitrogen were made larger. As an 

 average of all the results on the two fields, both increase in the yield 

 due to fertilizer and in profit per acre were almost tripled by the use of 

 30 pounds of nitrogen with normal amounts of phosphoric acid and 

 potash over what they were where only 5 pounds of nitrogen was used 

 ^^?ith normal amounts of phosphoric acid and potash. The former appli- 

 cation on an average gave a profit of $26.45 per acre over cost of ferti- 

 lizer applied. The increase of 25 pounds of nitrogen in the formula 



