32 THE PLANT FOOD SUPPLY 



If commercial fertilizers are used exclusively the soil becomes 

 deficient in organic matter, and therefore loses its friable texture 

 and its ability to resist drought. Commercial fertilizers are often 

 valuable to supplement, but never to. supplant, animal and green 

 manures. If one form of fertilizer alone must be depended upon 

 in the growing of vegetables, that form should be stable or barn- 

 yard manure. 



TIME AND METHOD OF APPLICATION 



For early spring crops or when coarse manure is to be used, 

 even for a late crop, it is advisable to apply the manure and plow 



Fig. 15. — Applying manure to melon hills. 



it under in the fall. This gives it a chance to decay and become 

 incorporated with the soil by the time the plants are started in 

 the spring. Fine, rotted manure may be applied just before 

 plowing immediately preceding the planting of any crop, whether 

 the season is spring, summer, or autumn. It may also be applied 

 as a top dressing after plowing or even after planting, under cer- 

 tain conditions; but its application previous to plowing is usually 

 the more satisfactory method (Fig. 14). 



Commercial fertilizers are usually applied after plowing. They 

 may be sown broadcast and then thoroughly mixed with the soil 

 by repeated disking and harrowing, or they may be drilled in with 

 a fertilizer attachment on the seed drill at the time the crop is 



