FIELD CEOPS. 37 



corn. The average profit for the P K application over cost of fertilizer was 

 $6.17 per acre. 



" On an average a fertilizing mixture carrying normal amounts of nitrogen 

 and potash was used with only a very small gain in yield and at a loss of 86 

 cts. per acre. Nitrogen, phosphoric acid, and potash combined in a complete 

 fertilizer yielded on an average slightly less than when the potash was left out 

 of the mixture. The experiments, as a whole, show that phosphoric acid and 

 nitrogen are the predominant or controlling plant food constituents for increas- 

 ing yields and adding to profits iu growing com on this soil." 



Lime alone was used at a very small profit, while in a complete fertilizer the 

 gain In yield was equal to a profit of 86 per cent. " Taking all the results as a 

 whole, the indications are that in growing corn on this soil under similar con- 

 ditions to those obtaining in these experiments, lime will generally be needed for 

 the largest yields and greatest profit per acre." 



The amount of nitrogen in the normal fertilizer applied w\as 3 per cent or 9 

 lbs. to the acre. When this amount was varied so as to give 4i, 9, IS, and 27 

 lbs., the larger the amount of nitrogen the greater was the yield and profit per 

 acre. The average yield of corn during eight years on the plats receiving three 

 times the normal quantity of nitrogen with normal quantities of phosphoric acid 

 and potash (NsP K) was 24.4 bu. per acre and the average increase over unfer- 

 tilized plats 15.2 bu. This fertilizer application cost $7.35 per acre, making the 

 cost of fertilizer per bushel of increase of corn 48 cts. 



The amount of potash in the normal fertilizer used was 1^ per cent or 4^ lbs. 

 per acre. This amount was varied so as to apply 2i, 9, and 13i lbs., respec- 

 tively. The results for the two fields were not in agreement, since in one the 

 half-normal potash and in the other the twice-normal application of potash were 

 indicated to be the most profitable amounts of this constituent to use. 



The amount of phosphoric acid in the normal fertilizer used was 7 per cent or 

 21 lbs. of phosphoric acid per acre. Tliis quantity was varied so as to apply 

 lOi, 42, and 63 lbs., respectively. The results show the largest yields, increases, 

 and profits per acre from the use of 42 and 63 lbs. 



Varying the amounts of the normal fertilizer application from 150 to 900 

 lbs. per acre gave increased yields and profits for all the applications, the most 

 profitable returns on an a^■erage resulting from 150 lbs. of fertilizer per acre. 

 After paying for the fertilizer itself the following respective profits were ob- 

 tained : With 150 lbs., $7.88 for corn and stover; with 300 lbs., $5.21; with 450 

 lbs., $6.94 ; wath 600 lbs., $6.49 ; and with 900 lbs., $5.64. 



In comparisons of dried blood and iiitrate of soda as sources of nitrogen, the 

 total yields and increased yields over unfertilized plats were quite uniform in 

 showing a slight advantage in favor of the latter. Better profits were secured 

 when the nitrate was divided, applying one half at planting with the acid 

 phosphate and manure salt and reserving the other half and applying as a side 

 dressing about July 1. Stable manure showed up particularly well on this soil 

 as a source of nitrogen for corn. 



Wheu 300 lbs. of fertilizer Avas applied in the drill at the ordniary depth; 

 in the drill about 4 or 5 in. below the seed; broadcast before planting; and, 

 divided into two equal parts, one half being applied in the drill before planting 

 and the other as a side dressing about July 1, the deep application and dividing 

 the applications gave the largest yields and profits per acre. 



Our soil analyses of the various soils of the State indicate that these results 

 will apply to the red (Cecil) clay loams, red (Cecil) clays, and valley soils of 

 the Piedmont, and in like manner the soil analyses and experiments on the moun- 

 tain soils indicate that the results will apply to this section of the State also. 



