FERTILIZERS, ROTATIONS FOR COTTON 91 



Plot 5. No fertilizer. 



Plot 6. 20 pounds each of acid phosphate and cotton-seed meal. 



Plot 7. 20 pounds of cotton-seed meal and 8 pounds of kainit. 



Plot 8. 20 pounds of acid phosphate and 8 pounds of kainit. 



Plot 9. 20 pounds each of acid phosphate and cotton-seed meal and 



8 pounds of kainit. 

 Plot 10. No fertilizer. 



When the cotton is well up it should be thinned, special 

 care being exercised to see that the stand is uniform for 

 all plots; otherwise the results will not be comparable. 

 Likewise the cultivation and in fact all treatment except 

 the fertilizer treatment should be the same for all plots. 

 At harvest time the seed cotton from each plot should be 

 carefully weighed. By comparing the yield of each ferti- 

 lized plot with that from the nearest unfertilized plot one 

 can determine the effectiveness of the various treatments. 

 A test of this nature should be repeated for several years 

 as it is known that seasonal conditions influence somewhat 

 the action of fertilizers. 



101. Judging fertilizer needs by appearance of 

 plants. In general, a rank growth of stalks and leaves 

 associated with a rich green color indicate an abundance 

 of nitrogen in the soil. On the other hand, small growth 

 and pale color are not necessarily indicative of nitrogen 

 starvation as any kind of malnutrition will produce imper- 

 fect growth. It is thought that phosphoric acid is closely 

 associated with the fruiting process and that poorly 

 fruited plants indicate a deficiency of phosphorus. While 

 these indications are often correct, they do not constitute 

 a safe criterion of fertilizer needs. It is not possible to 

 give accurate directions whereby one can tell from the 

 appearance of the crop what plant-food is lacking in the 

 soil. 



