52 AGRICULTURE 



mustard and rape than after preliminary 

 treatment with vetches. This rather un- 

 expected result is probably to be explained 

 by the fact that decomposing mustard or 

 rape has greater power of absorbing and 

 retaining moisture than vetches, and as 

 moisture is quite as important as nitrogen in 

 the growth of crops, the former has proved 

 to be the more powerful determining factor 

 at this particular station. It may be, also, 

 that rape and mustard bring the soil into 

 superior physical condition. 



While green-manuring is doubtless some- 

 times justifiable, it pays better, as a rule, to 

 consume crops by stock than to cultivate 

 them exclusively for fertilizing purposes. 

 Thus, in the case of crimson clover, it will 

 usually be more profitable to feed off the 

 crop with sheep, and to depend for an increase 

 of humus on the roots that are left in the 

 soil, and on the excreta dropped on the surface 

 by the animals. Of course, a considerable 

 proportion of the organic matter is dissipated 

 by the consumption of the crop by animals, 

 and therefore the amount of humus added to 

 the soil is correspondingly reduced ; but the 

 advantages to the live stock, as a rule, out- 

 weigh the disadvantages of reducing the 

 available supply of humus, and, consequently, 



