Decomposition of Sweet Clover as a Green Manure 147 



should be compact and treated seed should be used. The use of treated 

 seed is important also from the standpoint of economy. Treating the 

 seed with acid increases the percentage of germination threefold, and 

 seed so treated does not lose its increased germinating power for at least 

 ten months. Satisfying the lime requirement of the soil was found to 

 increase the yield 50 per cent for the crop grown four months. 



A crop of sweet clover grown for three or four months decays rapidly 

 when used as green manure. It was found that in the limed pots sufficient 

 nitrates had been produced four months after harvest to account for 

 approximately 50 per cent of the nitrogen added in the material turned 

 under. From the standpoint of the amount of available plant food, 

 it is desirable that sweet clover, to be used as a green manure, should be 

 grown for at least four months. 



The measurement of nitrate formation in pot experiments is subject 

 to a large probable error. This fact is a real objection to the method as 

 a quantitative measure of rate of decay. 



259 



