240 SELECTIONS FROM ADDRESSES. 



ployed could always be selected from among others, by the su- 

 perior luxuriance, and the peculiar dark green of the leaves and 

 stalks. That this was owing to nitrogen, was proved by the 

 appearance of the same distinctive characters where nitrates 

 had been applied. Every farmer who allows the dark-colored 

 drainings from his barnyards to run over his grass, has seen the 

 same dark green color and great luxuriance. Very careful ex- 

 periments have lately been concluded in England, having, for 

 their object, the decision of this question. The result arrived 

 at seems, in the main, to be, that ammoniacal manures have, in 

 most cases, a marked effect; they do not always increase the 

 yield of grain, but always the growth of straw. Why is it, 

 that the small quantity of ammonia, added in the shape of gu- 

 ano, or very rich barnyard manure, produces such an effect, 

 when there are already thousands of pounds in the soil ? Clearly, 

 this large quantity must either be in some form inaccessible to 

 plants, (and it would be difficult to conceive of any such form,) 

 or it is not in most cases present. 



When the proportion of lime, or any other inorganic manure, 

 is sufficient in a soil, the addition of more is of no service ; this 

 we know by repeated experience; might not the same thing be 

 expected of ammonia? In this way, the objection that ammo- 

 nia is frequently of no use, should be answered. It is quite 

 true, that, where it would fail to produce a crop, bones, perhaps, 

 might succeed perfectly ; but this only proves, that phosphate of 

 lime, or bone earth, was the particular substance which that 

 soil wanted. If a soil were entirely deficient in lime, the addi- 

 tion of every other manure under the sun, so long as they did 

 not contain lime, would not secure a good crop of any plant, 

 requiring that mineral ingredient. On the other hand, if there 

 were already lime enough, tons of it in addition would not com- 

 pensate for the absence of potash. 



So, also, there are soils where an abundance of ammonia is 

 already present ; on these, further additions do no good, and 

 even in many cases do harm, by causing an exceedingly rank 

 and luxuriant growth of stalks, so that the grain docs not come 

 to maturity, or is injured by lodging ; the inorganic matter, not 

 having kept pace with the organic, the stem is weak. Such is 



