AMERICAN INSTITUTE. 187 



lost by the air more than one half of its value, hut he thought, as most 

 farmers did and do now, that the essences of his manure filtered into 

 the soil. 



" Professor Mapes, in answer to the question, how sandy a soil must be to 

 make it improper to back furrow and ridge it, answered that any land 

 which was sandy enough to be " blowy" ought not to be ridged ; the flatter 

 that lay the better. A New Jersev farmer mucked a sandy field in the 

 winter, raised a green crop, turned it in and rolled the field ; after that he 

 was troubled no more with the drifting, though before half the fence would 

 sometimes be buried. But when he came to put in corn on the field, he 

 would hill it. The hills were very high, and of course through the winter 

 it was left very much in the condition that it would have been in if ridged. 

 The frost and sun alternating powdered the whole surface, and next spring 

 it was as blowy as ever again. Now, any soil so sandy as that should be 

 left flat. Another rule was a good one : any land that is improved by 

 plowing in wet weather ought not to be ridged in the fall. Clayey soils 

 are badly damaged by wet plowing, sandy ones improved. 



The regular text of the day was the " Winter treatment of Manures." 

 Prof. Mapes said that the value of barn yard manure was not dependent so 

 much on the constituents of the manure as on the condition of those con- 

 stituents. One pound of potash in that manure was worth more to the 

 land than 100 pounds of potash taken from a feldspar rock, though the 

 chemist could detect no difference in the two articles. The organic con- 

 stituents of a cord of barn yard manure, when it has been burned, may be 

 put in your hat, but that little is worth a ton of chemically the san)e mate- 

 rials that have been through none of its organic changes. Take a dose of 

 sulphate of magnesia directly from the rock, and if it dont kill it will ter- 

 ribly gripe you. But let the chemist take it and subject it to frequent 

 crystalizations, and then a very much smaller dose M'ill act as a gentle 

 cathartic, and prove an invaluable medicine. But neither analysis nor the 

 microscope exhibits any difference between the two articles. No chemist 

 living can tell the difference between carbonate of lime taken from a piece 

 of Westchester limestone and taken from a chalk cliff of England ; yet 

 1,000 bushels of the former spread on an acre of land makes it barren for 

 years, while the chalky fields of England are fertile. The latter is formed 

 of the debris of animals, the other is not, and hence the difference. Hence 

 it is evident that it is not enough that you have certain substances in cer- 

 tain quantities in your manure to make it valuable; its value is enhanced 

 with every new manipulation it receives. Chemistry is always at work in 

 the manure heap, winter and summer. There is no winter in it except 

 on the surface. In the open dished barn yard, see how every little pool 

 gives out its carburetted hydrogen gas, how the bubbles of gas are con- 

 stantly rising, and the strong currents of air sweep them away, wasting 

 them. Every bent straw is a syphon to give new points of surface and 

 facilitate the evaporation. No one looking intelligently at it can doubt 

 the waste. The heap should have but one surface, should be sheltered 



