AMERICAN INSTITUTE. 169 



THE PHYSICAL PROPERTIES OF SOILS AS AFFECTING 



FERTILITY. 



By Sa?m(cl W. Johnso?i, Professor of Analytical and Agricultural 

 Chemistry in Yale College, and Chemist to the State Agricultural 

 Society of Coiinecticut. Presented to the American Institute, Ocf. 23, 

 1858, by Prof. Johnson. 



From tliis valuable essay we extract enough to show that is one which 

 should be in the library of every farmer in America. 



1st. The fertility of soil depends upon no cause or class of causes. It 

 involes the whole range of the Physical Sciences — geology, chemistry, 

 botany, physiology, meteorology, mechanics, hydrodynamics, heat, light, 

 and electricity, are all intimately related to it ; it is not strange, therefore, 

 that all the labors to illustrate such a topic should have only recently met 

 with any degree of success. 



The learned professor begins with the mechanical structure of soils. A 

 few lichens, only, grow on a solid rock. Crush that rock to a coarse pow- 

 der, and a more abundant vegetation is maintained by it. If it is reduced 

 to a very fine dust, and duly watered, cereals will grow, and perfect their 

 grain. There are sandy soils in the Eastern States, which, without manure, 

 yield only the most meagre crops of rye, or buckv/heat ; and there are 

 sandy soils in Obio, which, withoiit maimre, yield on an average, eighty 

 bushels of Indian corn per acre, and have yielded this for twenty to fifty 

 years in unhrolien succession — the inorganic ingredients being, by chemi- 

 cal analysis, the same. There is at present known no dijfferencc, except 

 the different fineness of the particles ; the first being, in great part, of 

 coarse grains, while the Ohio soil is an exceedingly y???e powder. 



2d. The power of soil to absorb, or condense, gases or vapors. The 

 best observations we possess are forty years old. They were made by 

 Schubler, a teacher in Fellenberg's school at Hofwyl, Switzerland. The 

 solid bodies condense gases. Schubler gives the absorption of water and 

 of oxygen daily, for thirty days, by moist soil, viz: 



Oxygen. Moisture. 



Quartz sand, 1.1000 0.1000 



Gypsum, 1.7 i 



Lime sand, 4 3 



Plough land, 10 . 5 23 



Clay soil (60 per cent clay), 6 28 



Slaty marl, 7 33 



Loam, 7 85 



Fine carbonate of lime, 7 35 



Heavy clay soil (80 per cent clay), 9 41 



Garden mould (7 per cent humus), , 11.5 52 



Pure clay, 10 49 



Carbonate of magnesia (fine powder), 11 82 



Humus, 13 120 



