COMMERCIAL FERTILIZERS 



71 



amount of fertilizer that can be profitably used. This principle is well 

 illustrated in an experiment with fertilizers used in different amounts on 

 cotton at the Georgia Experiment Station. In this experiment a fertilizer 

 valued at about $20 per ton was applied in amounts valued at $4, $8 

 and $12 per acre respectively. As an average of three years with these 

 applications the increase in lint and seed, respectively, resulting from the 

 applications were valued at $10.11, $15.69 and $21.17, the percentage of 

 profit on the investment in fertilizers being 153, 96 and 76 for the three 

 amounts respectively. These results coincide with the principle above 

 stated. In the above experiment the increase in yield of seed cotton for 

 400 pounds of fertilizer was 281 pounds. The increase for 800 pounds 

 was not twice 281, which would be 562, but was only 436 pounds. The 

 increase for 1200 pounds was not three times 281, which would equal 843, 

 but was only 588 pounds. The smallest amount of fertilizer produced 

 the largest return on the capital invested in fertilizer, although the largest 

 amount made the largest aggregate profit. In this case each $4 invested 

 brought a return greater than the actual investment, and it is evident 

 that it might have been possible to add another $4 worth of fertilizer 

 and still further increase the total profit per acre, although the percentage 

 return on the investment would have been reduced still further. The 

 fertilizer, however, is only part of the investment, since the rent of land 

 and cost of labor and seed are comparatively large items. 



If a planter has $1400 to invest in the growing of cotton and the rent 

 of land, seed, labor and every expense connected with the cost of culti- 

 vation and picking aggregated $28 per acre, he can plant fifty acres. If 

 his profit without fertilizer is $3 per acre, it will aggregate $150, or lOf 

 per cent on the investment. On the basis of the above experiment and 

 with the same capital, how much will he be justified in reducing his acre- 

 age in order to purchase fertilizers? 



By inspection we find: 



The increased cost per acre represents the addition of fertilizers to the 

 amount of $4, $8 and $12 and is justified up fco the $12 limit where the 

 maximum profit of $425 is secured. By growing 35 acres well fertilized, 

 his percentage profit on capital invested is 30J instead of lOf where no 

 fertilizer was to be used. 



When to Apply Fertilizers. The time at which to apply commercial 

 fertilizer will be determined by the needs of the crop, kind of fertilizer, 



