MANURES AND MANURING 3I 



makes an excellent growth, which is, however, killed 

 down by the first severe weather. 



Even though the need of these crops is more par- 

 ticularly felt as a source of humus, their growth for 

 cover crop purposes is of great value everywhere 

 and under all conditions. Some rapidly growing 

 crop coming in at the very last of the season catches 

 and holds a large amount of the plant food rendered 

 available by the various soil agencies during the 

 previous summer. Some of these materials, par- 

 ticularly the nitrates, would doubtless be leached 

 out of the soil and lost entirely by the following 

 spring unless taken up and held by the cover crops. 

 The cover crop during the winter catches and holds 

 the moisture, preventing a rapid run-off and direct- 

 ing it into the soil, where it may be properly held 

 and conserved for the coming season's crops. If 

 the soils have become greatly impoverished, it is 

 often necessary to make liberal applications of com- 

 mercial fertilizers to the crops grown for green 

 manure purposes in order to stimulate a sufficient 

 growth to be of any particular value in this respect. 

 The combination of commercial fertilizers, together 

 with the humus derived from the cover crop 

 turned back into the soil, very quickly and 

 satisfactorily builds up and restores the fertility 

 of any soil. The proper time to turn under green 

 manure crops is again a question that must be de- 

 termined by good judgment. If plowed under too 

 early less organic material is returned to the soil and 

 the ultimate results from the addition of humus is 

 not so marked. If plowed under too late, the ma- 

 terial decays slowly and in seasons of drouth may 

 interfere with the movement of soil moisture. A 

 happy medium between the two extremes will be 



