472 
Afjricultural Chemistrij. 
would not give an increase of wheat by the use of ammonia-salts 
alone, and that would, after one or two years, be strikingly bene- 
fited by the application of mineral manures, it would be such a 
one as has been last described. Let us see what are really the 
facts of the case. 
By the use of ammonia-salts alone, an average total increase 
was obtained of corn and straw, per acre, at Woburn of 1G40 lbs., 
at Holkham of 1442 lbs., and at Rothamsted of 1714 lbs. And 
when to the ammonia-salts a liberal supply of minerals was added, 
the total increase became at Woburn 1757 lbs., at Holkham 
2357 lbs., and at Rothamsted 3035 lbs. 
As the seasons in which tliese results were obtained were not 
the same in all the three cases, no precise quantitative com- 
parisons can be made. But it is a curious fact, that the soil at 
Holkham, which is described as having at any rate a good sub- 
soil, was more benefited by the addition of a full supply of 
mineral constituents, than that at Woburn. And again, the soil 
at Rothamsted, assumed by Baron Liebig to be so exceedingly 
rich in minerals, gave a greater increase by the combination of 
minerals with a large supply of nitrogen, than was obtained in 
either of the other cases. 
It is established, then, by direct experiment, that the " recipe " 
to which we come, is not applicable only to our " own lands, and 
to them only, in so far as experimented on." And also, that if 
we extend our conclusions to " other land of different quality," 
they are not necessarily '•' entirely erroneous." 
Let us now again refer to Table IV., and contrast the effects 
of characteristic constituents, or combinations of manure, upon 
some of the most important of our agricultural crops ; which 
stand in relation to each other, in very different positions in our 
rotations. 
We may first premise, that owing to the gi'eat liability to 
disease in the leguminous crops, especially when grown conti- 
nuously, the final produce in their cases, was frequently much 
less than it promised to be in the earlier stages of growth. The 
results relating to beans, are in all cases the averages of several 
seasons ; and those in regard to clover, apply to the years 1849, 
1851, and 1852, wheat being the crop in the intermediate year; 
and, as will readily be understood, the produce in the two last 
years, was both meagre and irregular as compared with that on 
the same plots in 1849, in which season the crop was very large. 
For the sake of comparison with the other crops, the clover is 
given as before stated in about tlie same state of dryness as the 
beans and grain ; that is to say, the figures in the Table represent 
the dry substance, plus one-sixth of its weight of water. 
It will be observed, that with a manure of potass alone, the 
