162 TALKS ON MANURES. 



30 cvvt. (3,JJG0 lbs.) of hay per acre ; the other half was allowed to 

 grow six or seven weeks longer, and was then (October 8th), cut 

 for seed. The yield was a little over 5h bushels of seed per acre. 

 Whether the clover allowed to grow for seed, was on the richer or 

 poorer half of the field, we are not informed. 



" Dr. Voelcker then analyzed the soil. That from the part of the 

 field mown twice for hay, contained per acre : 



J'^rxt six Second six Third six Total, 18. 



iiic/ies. itu'fws. i)icfi/'s. inches <Uep. 



Phosphoric acid 4,950 2,725 8,575 11,250 



Nitrogen 3,3.50 1,875 1,325 6,550 



"The soil /rom the part mown once for Jiuy, and tJitn for seed, 

 contained per acre : 



First six Second six Third six T<Aal,\% 



inches. inches. inches. inches deep. 



Phosphoric acid 3,975 4,150 3,500 11.625 



Nitrogen 4,72.5 3,350 2,225 10,300 



"Dr.Voelcker also ascertained the amount &nd composition of the 

 clover-roots growing in the soil on the two parts of the field. Ou 

 the part 77iown ticice for hiy, the roots contained per acre 24J lbs. 

 of nitrogen. On the part mown once for hn/, and then for seed, 

 the roots contained .5H lbs. of nitrogen per acre." 



" Now," said the Doctor, " these facts are very interesting, but 

 there is no sort of evidence tending to shoir that the clover hfis any- 

 thing to do with increasing or decreasing the qxtantity of nitrogen or 

 phosphoric acid found in the soil.'''' 



" There was more clover-roots per acre, where the clover was 

 allowed to go to seed. But that maj' be because the soil happened 

 to be richer on this part of the field. There was, in the first six 

 inches of the soil, 8,3.50 lbs. of nitrogen per acre, on one-half of the 

 field, and 4,725 lbs. on the other half; and it is not at all surprising 

 that on the latter half there should be a greater growth of clover 

 and clover-roots. To suppose that during the six or seven weeks 

 while the clover was maturing its seed, the clover-plants could 

 accumulate 1,375 lbs. of nitrogen, is absurd." 



"But Dr. Voelcker," said the Deacon, "states, and states truly, 

 that ' more leaves fall on the ground when clover is grown for 

 seed, than when it is mown for hay ; and, consequently, more nitro- 

 gen is left after clover-seed than after hay, which accounts for 

 wheat yielding a better crop after clover-seed than after hay.' " 



" Tills is all true," said the Doctor, " but we can not accept Dr. 

 Voelckcr's analyses as proving it. To account in this way for the 

 1,375 lbs. of nitrogen, we should have to suppose that the clover- 

 plants, in going to seed, shed one hundred tons of dry clover-leaves 



