88 BOARD OF AGRICULTURE. [Jan., 



and right weather. That hundred pounds of Peruvian guano 

 contained about fifteen per cent, of nitrogen, about fifteen per 

 cent, of phosphoric acid, and about three per cent, of potash, 

 to which its fertilizing value was alone due. The soil of an 

 acre of land, taken to the depth of one foot, will weigh about 

 four millions of pounds. Thirtj-three pounds of fertilizer, 

 and four millions of pounds of soil, assuming that the crop 

 got all its nutriment from the first foot of ground, are the 

 two quantities which, put one above the other, the smallest at 

 the top and a line between, make the fraction which the 

 chemist must figure down to if he will find out from an 

 analysis of the soil what elements of fertility that soil is defi- 

 cient in, viz.: ^,0/0^000 or tttIoto- ^^t, in fact, if the 

 chemist in two analyses of the same sample of soil gets re- 

 sults which agree within yxr.iTo ^^® ^^ lucky and his luck does 

 more towards that result than his skill, for usually the tenth 

 of one per cent, is about the limit of accuracy in chemical 

 analysis. It may thus easily happen that the chemist cannot 

 by analysis distinguish between two soils, one of which has 

 had a dressing of one thousand pounds of the best Peruvian 

 guano to the acre and the other nothing. 



There are some cases in which a soil-analysis is really use- 

 ful. A gentleman in Mansfield sent us a sample of soil two 

 years ago. He had been draining a muck swamp, where 

 nothing would grow ; he could not even get buckwheat, and 

 wanted to know what was the matter. We examined that 

 soil and found in it a considerable quantity of copperas, suf- 

 ficient to kill vegetation. We reported that to drain the land 

 and let the air in, and to apply leached ashes and lime, would 

 remedy the trouble. I believe it has been cured, has it not, 

 Mr. Chairman ? 



Chairman. Yes, sir. 



Prof. Johnson. But the cases where analysis fails to be 

 of service have been more numerous. A tobacco grower in 

 the western part of the State had a field that looked to be 

 uniform except a small portion where he could not get any 

 tobacco to come to maturity. The tobacco would start well, 

 grow for a number of weeks, and then suddenly turn brown 



