Early Experiments on Wheat at HolJcham. 11 



forms of combination, is also volatile, and might be exhaled 

 into the atmosphere and so lost. This is not the case with 

 the mineral constituents of manure. 



Upon the whole a careful study of these experiments 

 proves : 



1. That the soil, even with the most unusual and very 

 exhausting process of carrying off the land the total grain 

 and straw of several successive corn crops, after a root crop 

 which had also been drawn from the land, still contained a 

 larger annual available supply of minerals than the annual 

 natural supplies of other constituents, nitrogen or carbon, 

 were adequate to turn to account. 



2. That the excess of the annual supply of minerals in the 

 soil over that required to appropriate the natural resources 

 of nitrogen is proved, by the effects of ammonia-salts alone, 

 to have been equal to the further growth, during four years, 

 of about 32 bushels of wheat, or an average of about 

 8 bushels per annum. 



3. That beyond the increased annual produce which the 

 supply of minerals in the soil was adequate to provide 

 when nitrogen was not wanting, the average capabi- 

 lities of the climate were competent for the maturing of a 

 still greater produce, if additional minerals as well as the 

 amrnonia-salts were provided; and, in that case, from once 

 and a half to twice as much corn was grown as the natural 

 supplies of nitrogen, even with a most liberal supply of 

 minerals, were sufficient to produce. 



4. That carbonaceous organic matters (such as are contained 

 in rape cake and farmyard manure) are of themselves of little 

 or no effect in increasing the growth of wheat. 



The concluding words of this paper, written more than 

 thirty years ago, are still of interest : There cannot be a 

 doubt of the legitimacy of the inference from these and 

 other experiments that, provided the land receive in a course 

 of years a due share of the home manures derived from 

 feeding of horses and other stock on the farm, the mineral 



