268 IMPROVEMENT OF THE SOIL. 



and turned in, either before the seed ripens (in which case two 

 crops may be turned in the same season), or after the crop is 

 nearly ripe. In the first case, before the ripening of the 

 seed, the plant derives most of its substance from the atmos- 

 phere ; but when the seeds are maturing, it draws directly 

 upon the matters in the soil. Some experiments have been 

 made to decide which course is best, and they incline to the 

 dry crop. If but one crop is to be added to the soil, this 

 would be the best process, because it adds a greater amount 

 of salts and humus ; but two green crops are better than one 

 dry crop. Buckwheat and oats answer well for this purpose. 

 2. But the better course is to save the crop by sowing clover 

 with other grain, and the next spring turn it in ; and, having 

 rolled it down, plant directly upon the furrows with potatoes 

 and corn. The surface, then, should be tilled with the cul- 

 tivator or hoe, so as not to disturb the sod. Some recom- 

 mend, in this case, to spread a light covering of compost- 

 manure, lest the soil should be too much exhausted by the 

 crop. 



Now it is found that the quantity of vegetable matters 

 added to the soil by this process, will exceed 12 tons to the 

 acre. Elias Phinney, Esq. of Lexington, has actually weighed 

 the vegetable matter in a cubic foot o^ green sod, from which 

 he made an estimate that one acre contained more than 13 

 tons ! 



The best thne for turning in green crops, or breaking up 

 green-sward (unless the soil is a stiff clay), is the spring and 

 early part of summer; because the sod will become rotted 

 before winter, and will not afford, as it otherwise might, a 

 shelter for worms, during that season, ready to injure the 

 succeeding crop. 



Theory. The theory of this process is exceedingly simple. 

 It is evident that what is taken from the soil must be returned 

 to it, or the land will be impoverished. We have seen that 



