562 Report of Experiments with dij^erent Manures 



observed scarcely to have increased at all ; whilst the whole plot 

 was thickly covered with Perennial Red Clover {Tr if olixim -pro- 

 tense peremie) and some other Leguminous plants. Such a result 

 is perfectly consistent with what has been before established re- 

 garding the (so to speak) characteristic adaptation of mineral and 

 nitrogenous manures respectively, to those crops of the respective 

 families which are grown in our rotations. 



Mineral manures alone have then much increased the growth 

 of the Leguminous plants on the meadow land. They enabled 

 the Graminaceous ones, on the other hand, to assimilate but little 

 more of nitrogen or carbon from natural sources, than did the 

 normal supply of available mineral constituents in the unmanured 

 land. Very different was the action of mineral manures upon 

 the growth of the Graminaceous plants of the Meadow, when 

 those manures were associated with a liberal artificial supply of 

 available nitrogen. In the case of experiments both upon Wheat 

 and upon Barley, too, it has been shown that the land experi- 

 mented upon was competent, for a series of years, to yield up 

 annually enough of mineral constituents for a considerably larger 

 crop than could be grown under the influence of the annually 

 available natural supplies of nitrogen alone. The annually 

 available mineral constituents were, however, not sufficient for 

 sucli full crops as the seasons would yield, when there was a 

 liberal artificial supply of available nitrogen. There appear to 

 be obvious reasons why this should be expected to hold good to a 

 greater extent with Meadow Grass than with these Graminaceous 

 corn crops. In land of pretty equal original characters, the 

 amount of mineral matter taken annually from a given area in 

 Grass (mown for hay) is, under the same annual climatic cir- 

 cumstances, much greater than that taken off in the corn and in 

 the straw of the seeding crop. The mechanical operations, and 

 the exposure to the atmosphere, in the case of the arable land, 

 would appear to indicate a greater annual disintegration and 

 liberation of total mineral constituents over a given area, though 

 not perhaps more within the limits of the immediately superficial 

 layers. In the case of Meadow Grass, therefore, the original 

 characters of the soil, and the seasons, being equal, both the 

 annual demand for mineral constituents would be greater, and the 

 total annual yield of them from the soil would be less, than in 

 the case of the cereal crop. 



Consistently with the foregoing considerations, it was found, 

 that although the ammoniacal salts when used alone gave an 

 annual increase of only 11 cwts. of hay, the same amount of 

 ammoniacal salts, when in conjunction with the " mixed mineral 

 manure'' (Plot 10), gave an annual increase of 1 ton 15| cwts. 

 of hay. Tims, the combination of ammoniacal salts and the 



