108 Practical Farming 



Commercial We often hear men, who have seen the 



Fertilizers |^^^ results that have come through the 

 injudicious use of commercial fertihzers, say that they 

 are only stimulants, and that they do the soil harm. 

 The ^fact is that the only real stimulants used are, as 

 we have seen, hme and plaster. The commercial fertil- 

 izers consist of the various plant foods that have been 

 found from experience to be most commonly used up and 

 made deficient in our old cultivated soil, in a readily 

 available and concentrated form. They contain when 

 complete fertiUzer mixtures, all the plant foods that are 

 contained in animal manures, but in a more concentrated 

 and more readily available form, and hence are more 

 quickly used by crops. 



The main difference between the commercial fertilizers 

 and stable manure lies in the fact that the stable manure 

 carries with it a large amount of organic matter that in- 

 creases the humus content of the soil, and thus renders 

 it more mellow and more retentive of moisture, while the 

 commercial fertilizers only furnish readily available plant 

 food. Therefore, if the use of commercial fertihzers is 

 continued year after year, without any effort to restore 

 and maintain the humus-making matter in the soil, the 

 final result will be the starving out of the nitrifying bac- 

 teria and the souring of the soil, while the absence of humus 

 will cause a heavy soil to run together after rains and bake 

 hard and dry out quickly. Under such conditions hilly 

 clay soils are made more incUned to wash. This result 

 can be seen all over the South, where cotton has been 

 grown year after year with simply an annual application 

 of commercial fertilizers in small amount in connection 



