280 TALKS ON MANURES. 



ance, which they retained for some time. This result was not an- 

 ticipated, though it is well known that superphosphate of lime has 

 the effect of stimulating the germination of turnip-seed, and tho 

 early growth of the plants to an astonishing degree; yet, as it has 

 no such effect on wheat, it appeared probable that it would not 

 produce this effect on Indian corn, which, in chemical composition, 

 is very similar to wheat. The result shows how uncertain are all 

 speculations in regard to the manurial requirements of plants. 

 This immediate effect of superphosphate of lime on corn was so 

 marked, that the men (who were, at the time of planting, somewhat 

 inclined to be skeptical, in regard to the value of such small doses 

 of manure), declared that * superphosphate beats all creation for 

 corn.' The difference in favor of superphosphate, at the time of 

 hoeing, was very perceptible, even at some distance. 



" Although every precaution was taken that was deemed ne- 

 cessary, to prevent the manures from mixing in the hill, or from 

 injuring the seed, yet, it was found, that those plots dressed with 

 ashes and guano, or with ashes and sulphate of ammonia, were in- 

 jured to some extent. Shortly after the corn was planted, heavy 

 rain set in, and washed the sulphate of ammonia and guano, down 

 into the ashes, and mutual decomposition took place, with more 

 or less loss of ammonia. In addition to this loss of ammonia, these 

 manures came up to the surface of the ground in the form of an 

 excrescence, so hard that the plants could with difficulty penetrate 

 through it. 



"It will be seen, by examining the table, that although the su- 

 perphosphate of lime had a good effect during the eaily stages of 

 the growth of the plants, yet the increase of ears of corn in the end 

 did not come up to these early indications. On plot 5, with 300 Ibs. 

 of superphosphate of lime per acre, the yield is precisely the same 

 as on plot 2, with 100 Ibs. of plaster {sulphate of limc\ per acre. 

 Now, superphosphate of lime is composed necessarily of soluble 

 phosphate of lime and plaster, or sulphate of lime, formed from a 

 combination of the sulphuric acid, employed in the manufacture of 

 superphosphate, with the lime of the bones. In the 300 Ibs. of 

 superphosphate of lime, sown on plot 5, there would be about 100 

 Ibs. of plaster; and as the effect of this dressing is no greater than 

 was obtained from the 100 Ibs. of plaster, sown on plot 2, it fol- 

 lows, that the good effect of the superphosphate of lime was due 

 to the plaster that it contained. 



" Again, on plot 4, with 150 Ibs. of sulphate of ammonia por 

 acre, we have 90 bushels of ears of sound corn, and 15 bushels of 

 ears of soft corn, ('nubbins,') per acre ; or a total increase over the 



