TURNING IN OF GREEN CROPS. 269 



salts and geine are removed. This process simply restores 

 them. 



1. The green crop being buried deeply in the ground, 

 soon begins to ferment and decay ; a large quantity of or- 

 ganic food is thus added to the soil. But humus or geine is 

 not the only substance required by plants. They must have 

 alkalies. 



2. These are supplied in part by the influence of the at- 

 mosphere, the ordinary process of disintegration. But this 

 is trifling compared with 



3. The galvanic effect of the living plant. The agency of 

 growing plants has hitherto been overlooked in this connec- 

 tion. As the roots form a galvanic battery with the soil, they 

 become the most powerful decomposing agents. Now we 

 know that the poorest soils (the pine-barrens) contain a large 

 quantity of alkalies, potash, lime, etc. locked up in the rocks. 

 These are drawn into the organs of plants, where, as soon as 

 covered with earth, they exist in a fit state to nourish future 

 crops. If, then, we can make a plant grow at all upon such 

 soils, we can render them fertile by turning in green crops, 

 and thus furnishing the requisite amount of geine, alkalies 

 and salts. If the soil is too barren to produce plants, a small 

 coating of ashes will give a start to the green crop, and then 

 the soil may soon be rendered fertile. 



In case of clayey soils, the turning in of green crops not 

 only restores what is exhausted by tillage, but renders the 

 texture much better fitted for the roots of plants, and the soil 

 itself a better retainer of heat. 



In case of dry, gravelly soils, the additional vegetable mat- 

 ter gives the power of absorbing moisture and equalizing the 

 heat ; hence, it protects the plant from the extremes of dry 

 and wet seasons. 



The importance of this mode of improvement is not fully 

 felt by our farmers. By sowing a few pounds of clover-seed 

 with his grain-crops, the farmer may be constantly augment- 

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