SOILS AND FERTILIZERS 463 



obtained, standard-grade commercial fertilizers may be used. These 

 should contain in the mixture 8 to 10 per cent of available phosphoric 

 acid, 2 to 3 per cent of nitrogen, and l 1 /^ to 2 per cent of potash, or 

 on some lands a high-grade acid phosphate, 14 per cent, may be 

 used. On black waxy land the best practice is to have the cotton fol- 

 low a crop of cowpeas. 



The question as to how fertilizers should be applied is somewhat 

 difficult to answer because it depends on a number of conditions, es- 

 pecially the kind of fertilizer and the amount to be used. Phosphoric 

 acid and potash, even in water soluble forms do not leach out of the 

 eoil to any appreciable extent. On the contrary, they do not dis- 

 tribute themselves well enough, and therefore should be applied to 

 some depth. Nitrogen, on the other hand, finally leaches out of the 

 soil unless taken up by the roots of plants. In some materials, how- 

 ever, it is much less readily soluble than in others. Tankage, for 

 example, should be applied deep, and it is well to mix cotton-seed 

 meal and blood with the soil; but nitrate of soda and ammonium 

 sulphate should nearly always be applied as surface dressings. Only 

 one application is advised for ammonium sulphate, but when large 

 quantities, over 200 pounds to the acre, of nitrate are to be used, two 

 applications of 100 pounds each are often made to advantage, one 

 when the plants are first coming up and the other two or three weeks 

 later. Potash salts when used in quantity, 100 pounds or more to the 

 acre, are well applied in the fall, so that the winter rains may take 

 out the chlorine, which when combined with either lime or magnesia 

 acts in a detrimental manner to plant growth. Lime is also well 

 applied in the fall. Acid phosphate when used as a top dressing may 

 be applied either in the fall or in the early spring. When a small 

 amount of fertilizer is to be used it is best applied as the seed is sown 

 or as the plants are set out, in the row or in the hill or, when prac- 

 ticable, drilled with crops which are drilled. As a general rule only 

 a heavy application of a complete fertilizer, say 1,000 pounds or more 

 to the acre, is recommended to be applied broadcast and worked into 

 the soil for crops which are planted in rows. 



The most profitable fertilizer to apply depends upon the charac- 

 ter of the soil, and the kind of crops to be grown. The previous treat- 

 ment to which the soil has been subjected is also of influence. There 

 are such variations in soils that each user of fertilizers must, to a 

 large extent, be guided by his own experience. Based on the fer- 

 tilizer experiments which have been made, and knowledge of the 

 composition and properties of soils, suggestions for the fertilizers to 

 be applied to different crops in different localities may be made, and 

 the application of fertilizers as suggested will prove profitable in many 

 cases, if judgment is used. More profitable results, however, may be 

 often produced with a somewhat different formula, and it is in this 

 respect that the experience of the individual must be applied. The 

 best results with fertilizers are obtained when thorough cultivation 

 is given. 



The user of fertilizer should distinguish between a large increase 

 of crop and a profitable increase. With many crops it is possible to 



