Thus it will be seen, according to the above analysis of Sprengel, that of the total of grain, less than 11/2 per cent., and of straw, rather more than 31/2 per cent. is earthy or inorganic matter; while all the remainder is composed of the organic materials, carbon, oxygen, hydrogen, and nitrogen, of which carbon alone constitutes about one half. All these constituents are absolutely essential to the perfection of the crop. In the natural condition of a fertile soil when first reclaimed, these materials are usually found in sufficient abundance to produce wheat. Such was the condition of nearly all the land in New England, and the eastern portion of our own state; but a few years of careless, unscientific cropping, has exhausted one or more of those constituents which may have existed in an available form; and much of it, after a very few of the first years of its cultivation, has been of little or no value for wheat, under the system of tillage there adopted. It has been asserted by Dr. Dana, that in a soil purely granitic (and much of the land in that region partakes of this character), there is potash enough for successive crops of wheat for 3,000 years, and lime enough to last more than twice that period. But the result is the same for the growing vegetation, whether the materials do not exist at all, or are locked up beyond the reach of it. It is absolutely certain, if wheat will not grow with care and industry, and all the usual appliances of good husbandry, where it once nourished successfully, there is one or more ingredients wanted, in such a condition, that the plants can appropriate them to their own nourishment. And first of the inorganic matters. The proportion of straw will vary from 2 to 31/2 times the weight of the grain. Suppose the quantity taken off the land be estimated at 21/2 times the weight of the grain. In a series of crops averaging 20 bushels of wheat per acre, for 30 years, we shall have as the result 36,000 lbs. of grain, and 90,000 lbs. of straw carried off the soil, charged with all the materials above enumerated, and probably sufficient to reduce the land to a very small capacity for production.