248 



Green Manuring. 



[June, 



and since the interval between wheat and roots in the ordinary 

 four-course rotation is the one in which green manuring with 

 catch crops can be most easily fitted, more attention should be 

 directed to the use of green manure for these crops. Green 

 manures for winter wheat appear also to be undoubtedly of great 

 benefit, though it is apparently for wheat especially that there 

 appears to be some uncertainty as to the relative merits of legu- 

 minous and non-leguminous crops. 



The Economic Value of Green Manures. — In conclusion, it 

 must be pointed out that we are not in possession of precise data 

 concerning the economic value of green manures. The fact that 

 they find extended application in many places abroad and in 

 special districts of this country is good evidence that their use in 

 many circumstances is economically sound,' but in considering 

 them as an alternative to animal manures we are brought up 

 against the vexed question of whether the keeping" of animals 

 merely as manure-makers is an economic proposition. There is 

 no doubt that on light lands, the standard system of feeding 

 green crops to sheep folded on the land will hold its own against 

 green manuring in many districts, but after all, there is a limit 

 to the number of sheep any farmer can keep, and many specialist 

 growers would prefer to do without them ; moreover, some of 

 the poor light lands like those of Suffolk are not suitable to sheep. 



On heavy lands it is often not practicable to fold sheep on the 

 arable fields, and on such lands, if green manuring is not adopted, 

 all the animal manure which is required beyond that given by the 

 stock normally kept for fatting or dairy purposes, must be pro- 

 vided by extra cattle kept primarily for the manure they provide, 

 or must be bought in. By going in for green manures, the 

 farmer could wholly or partly dispense with these extra cattle, 

 could reduce his area under roots and forage crops, and use a 

 greater proportion of his land every year for growing marketable 

 crops. Although in some circumstances a green manure 

 crop itself may encroach somewhat on the time the land is avail- 

 able for growing a marketable crop, it must be remembered that 

 this may be more than made up for by the increased crops ob- 

 tained, and by the fact that in growing a green manure on the 

 land to which it is to be applied, all charges for carting and 

 spreading dung are avoided. With prevailing prices of feeding 

 stuffs and of labour the cost of producing and applying animal 

 manure to the land is undoubtedly very many times that of the 

 same amount of organic matter and nitrogen applied as green 

 manure. 



