COW-PASTUEES AND COW-PATHS 53 



lutely nothing either in theory or practice to justify 

 this belief. It is true that the total quantity of 

 plant-food in all good soils is very great; yet it is 

 not unlimited and it cannot be subtracted from 

 every year for generations without some day ap- 

 proaching the end of abundance. There are perma- 

 nent pastures where in many cases for a century 

 the cows have been carrying away everything that 

 grew and where there has never been any pretense 

 of returning either fertility or grass-seed. The 

 owner now wonders vaguely why that old hill does 

 not seem to feed as many cows as it used to in 

 grandfather's time. Of course, the argument is 

 that while the cow takes everything off the land, 

 she immediately returns her manure in liquidation 

 of the debt. This line of reasoning is very faulty 

 because some of this fertility is permanently lost 

 to the farm and some of it is redistributed to other 

 areas. Mere pasturing does not constitute soil con- 

 servation. When we remember that each ton of 

 milk contains, say, twelve pounds of nitrogen, four 

 pounds of phosphoric acid and four pounds of 

 potash, and that these old pastures have been fur- 

 nishing scores of tons of milk annually for genera- 

 tions, and when we add to this the much more 

 serious loss due to other causes, we see that our old 

 pastures present a very serious problem in soil 

 depletion. 



In general, these old worn fields are to be treated 

 in one of three ways. Those reasonably free of 



