No. 4.] KEEPING UP FERTILITY. 87 



in soils poor in available nitrogen, and should not apply 

 nitrogenous fertilizers to them in any considerable amounts. 

 Beyond a supply sufficient to give these crops a start, 

 nitrogen placed before legumes is practically thrown away. 



The withdrawal of nitrogen from the air through the 

 agency of the legumes may be made an important factor in 

 the maintenance of the fertility of our farms. This is true 

 whether we plough under such crops, or feed them, carefully 

 saving and applying the resulting manure ; and I regard the 

 latter plan as generally preferable. Every crop we grow has 

 two values, — a food value and a manurial value. Plough 

 the crop in, and we get the entire manurial value. Feed it 

 wisely, we get the full food value, and besides, in the ex- 

 creta, four-fifths of the manurial value. Food value plus 

 four-lifths the manurial value minus the cost of handling 

 crop and manure under conditions prevailing in Massachu- 

 setts will generally be greater than the full manurial value ; 

 hence the wisdom of feedino- rather than turninty under a 

 crop which farm stock will relish. There are of course, 

 exceptions ; but as a general rule I would pasture or cut and 

 feed green crops grown either for nitrogen conservation or 

 as nitrogen gatherers. 



It should be remembered also, that the manurial effect of 

 the roots and stubble of a green crop is always considerable. 

 In the case of red clover it has been found that we may 

 under favorable conditions cut and carry off hay crops which 

 may contain two hundred pounds of nitrogen, and still there 

 will be more nitrogen in the surface soil (including clover 

 roots and stubble) than was present before the clover was 

 planted. This seems very much like " eating one's cake and 

 having it too." 



Manures. 



In taking up that part of my subject dealing more 

 particularly with the use of manures and fertilizers as agents 

 for the maintenance of soil fertility, — on the whole by far 

 the most important part, — it seems appropriate to speak 

 first of manures, as these constitute a home resource upon 

 most of our farms. As farmers f have no doubt you all 

 appreciate at their full value the various forms of manure, 

 and it may seem in a measure unnecessary to spend valuable 



