SOILS. 13 



&quot;We see by this how small a proportion of the ash element is taken from the soil by a 

 single crop of the above mentioned quantity. 



There is a wise provision in nature which prevents some soils from being worn out or 

 permanently exhausted, as they otherwise might be, could all their fertilizing elements be 

 extracted by man at will, which is in the slow and gradual solution of their stored -up treas 

 ures of mineral wealth, and the chemical changes wrought in time through the agency of 

 air and water. 



It is a fact well-known to any farmer that when soils have become poor or infertile from 

 too extensive cropping without sufficient fertilizers of the proper kind to restore in a measure 

 the elements extracted by the production of the crops, often a rest of a few years, without 

 aid from any kind of applied fertilizers, will in a measure restore the fertility. This is caused 

 by the -decay of the insoluble part of the soil, which thus assumes a new chemical combination 

 and becomes soluble, these being chemical changes brought about through the agencies of the 

 atmosphere and water. 



Prof. Wm. H. Brewer, also of the Connecticut Agricultural Experiment Station, says 

 in relation to this subject: 



u If the original rock which furnishes the sand and gravel of a soil, contains all the min 

 eral elements of fertility, such a soil may be impoverished by too hard cropping, but it cannot 

 be exhausted, or, as you- would say, worn out. The annual weathering, by making soluble 

 what was before insoluble, is a process of continually restoring fertility to a greater or less 

 degree. We are told of certain soils in Greece which have been cropped for thousands of 

 years, and are still reasonably fertile, because of such changes. 



A soil having this character in a less marked degree may be temporarily impoverished; 

 we say then, that it is in a low condition, or &quot; run down,&quot; and yet it recuperates rapidly with 

 rest, and with proper tillage or pasturage. 



On the other hand, there are some soils that have great fertility for a time, and when they 

 run down remain very poor indeed. What fertilizing material the soil had that was mostly 

 in an available condition for plant-food, is used up by a few crops, and then barrenness fol 

 lows. I have heard of some remarkable cases of this in the Western States, where the soils 

 seemed wonderfully fertile at first, produced a few large crops, then utterly failed, and are 

 now abandoned. These first few large crops took up the plant-food which had been prepar 

 ing for centuries. It was like a long investment suddenly becoming available in ready cash, 

 which is as suddenly spent, poverty following in its track. 



Some years ago I began a microscopic examination of different sands in connection with 

 certain geological studies. Sands from the sea-shore in many parts of the world, from the 

 shores of lakes fresh and salt, the wash of rivers, from placer mines, from mountains and 

 valleys, the drifting sands of the Pacific slope, and from the deserts of the great basin, and 

 finally the sands washed out from various soils, arable and otherwise. It is curious to see 

 how some of those from soils have been modified by the influences here spoken of often 

 there is a partial cementing again, by which each larger particle is coated with smaller grains 

 adhering to it; in others the splits and cracks by frost, and more interesting still, the way 

 some show that they have been partly dissolved. Only this week I was examin 

 ing some from a sandbank deposited in Central New York, near Cayuga lake, so long ago 

 that a ravine four hundred feet deep has been worn in the rock since that sand was depos 

 ited. When deposited it was evidently all worn and rounded by the water which left it 

 where we now find it. Now each quartz grain is all roughened by little pits sunk into it by 

 being partly dissolved in the long ages it has lain there. In another, from the old silt left 

 near Niagara Falls before the gorge was made in its present shape, the solution of some 

 ingredients has partially re-cemented others. 



The matter of oxidation is a curious one. Wooden posts last very differently in differ- 



