406 Clover as a Preparatory Crop for Wheat. 
Assuming the whole field to have produced 3^- tons of clover- 
roots per acre, there will be 99 636 lbs., or in round numbers 
100 lbs., of nitrogen in the clover-roots from 1 acre; or about 
twice as much nitrogen as is present in the average produce of 
an acre of wheat. 
The soil which had been separated from the roots was passed 
through a sieve to deprive it of any stones it might contain. It 
was then partially dried, and the nitrogen in it determined in 
the usual manner by combustion with soda-lime, when it yielded 
•313 per cent, of nitrogen, equal to '38 of ammonia, in one com- 
bustion ; and "373 per cent, of nitrogen, equal to "46 of ammonia, 
in a second determination. 
That the reader may have some idea of the character of this 
soil, it may be stated that it was further submitted to a general 
analysis, according to which it was found to have the following 
composition : — 
General Covxposition of Scil No. I. {^Good Clover). 
Moisture 18-73 
*0r2;aTiic matter 9'72 
Oxides of iron and alumina 13'24 
Carbonate of lime 8'S2 
Magnesia, alkalies, &c 1'72 
Insoluble siliceous matter (chiefly clay) .. .. 47'77 
100-00 
* Containing nitrogen "313 
Equal to ammonia '380 
The second square yard from tlie brow of the soil where the 
clover was bad produced 13 ounces of air-dry and partially 
clean roots, or 1-75 tons per acre. On analysis they were found 
to have the following composition : — 
Clover roots, No. II. {Bad Clover). 
Water 55-732 
*Organic matter 39-408 
Mineral matter (asli) 4-860 
100-000 
* Containing nitrogen '792 
Equal to ammonia .. ,. .. .. •901 
The roots on the spot where the clover was very bad yielded 
only 31 lbs. of nitrogen per acre, or scarcely one-third of the 
quantity which was obtained from the roots where the clover was 
good. 
The soil from the second square yard on analysis was found, 
when freed from stones by sifting, to contain in 100 parts : 
