Decomposition of Sweet Clover as a Green Manure 135 



It is seen in table i that little dry matter was produced in the first 

 two months of growth and that no differences due to liming are discernible. 

 During the third month the growth increased fourfold on the unlimed 

 pots and an even greater growth resulted in the soil to which lime had 

 been added. The dry matter produced during the first three months 

 was doubled during the fourth, and here again the effect of lime was 

 manifest. The results indicate that in order to obtain the largest yield 

 the lime requirement of the soil should be satisfied;, the yields for the 

 two kinds of lime do not differ sufficiently, however, to permit any 

 suggestion as to which is the better form to apply. 



The results for nitrogen content show that sweet clover compares 

 favorably in this respect with other legimies. The percentages do not 

 vary widely, but the figures indicate that the nitrogen content per gram 

 of dry weight reaches a maximum before the end of the four-months 

 growth. The figures showing the amount of nitrogen produced follow 

 those for dry matter rather closely. 



The percentage of fiber appears to be somewhat greater at the end 

 of the second period of growth than at either of the other times of 

 examination. This seems rather surprising, but probably may be explained 

 on the basis of the cultural observations made. It was observed that 

 during the second period the greatest increase in height and thickness 

 of stems occurred, while the final period was characterized by a develop- 

 ment of foliage. Thus in the last period a proportionally smaller amount 

 of woody tissue was formed and the percentage of crude fiber dropped. 

 A comparison of reported analyses of sweet clover for fiber shows a wide 

 variation in the results obtained, depending on the locality, the time 

 of cutting, and other factors. In general, analyses show a crude fiber 

 content of from 30 to 35 per cent at blooming time the second season. 

 From the standpoint of rate of decay, the crop should be of much more 

 value at the end of the first season, when the fiber content is from 10 

 to 15 per cent less. 



\ Figuring the results obtained in the pot experiments to the acre basis, 

 it is found that at the end of the four-months growth the yield from the 

 pots limed with ground limestone corresponds to about two tons per 

 acre. The nitrogen produced corresponds to 115 pounds per acre, an 

 amount to supply which would require ten tons of stable manure. It 

 is realized that this computation is of limited value, in that considerable 

 error may enter into the calculation. Further, it is realized that results 

 under field conditions might vary considerably from those obtained in 

 pot experiments. However, the figures are useful for the interpreta 

 tion of the results given in the tables, and they indicate what sweet clover 

 would do in the same soil in the field under optimum conditions. 



247 



