82 
INVESTIGATIONS ON KOTHAMSTED SOILS. 
You may be reminded that a large quantity of chlorin is supplied 
to many of these soils in the form of ammonium ehlorid, for, in every 
case in which ammonium salts are used they consist half of ammo- 
nium sulphate and half of ammonium ehlorid. Of the chemically 
manured plats, plat 5 alone receives, intentionally, no chlorin, but a 
small quantity is introduced as impurities in the other commercial 
saline matters used as mineral dressings. Thus we notice that there 
is more chlorin in the upper depths of plat 5 than in the correspond- 
ing depths of plat 3 ox plat 4, which receive nothing but the chlorin 
which annually finds its wajMnto the land in rain. In the dunged 
plats, down to the third depth, we find on the average about twice as 
much chlorin as in the unmanured plats. 
The plats manured with ammonium salts are, as we should expect, 
richer in chlorin than the plats not so manured, though the quantity 
found in the surface soils is, as a rule, smaller than we might expect, 
owing, no doubt, to washing down from the surface soils into the 
lower depths during the rains between harvest and the time of col- 
lecting the soil samples. 
The quantity of chlorin contained in the lower depths of the plats, 
the sampling of which has been carried down deeply, especially of 
plat 5 — which receives no chlorids except as impurities in its mineral 
manures — is far higher than would have been expected. The total 
quantity of chlorin contained, from the surface to the tenth depth 
(90 inches), is nearly 153 pounds per acre, or 15.29 pounds per acre,: 
on the average, for each depth of 9 inches. On the whole, too, tliiaj 
quantity is fairly uniformly distributed. 
Now, the average quantity of chlorin which falls annually in the 
rainfall at Rothamsted, as calculated on observations for twenty-two 
harvest years, 1877-78 to 1898-99, was 14.75 pounds. Observations 
made on the waters running through the soil drain gauges during the 
same time have shown that the chlorin in the drainage from the gauge 
containing 20 inches of soil has averaged 14.20 pounds per annum; 
thai in the water from the gauge containing 40 inches of soil, 15.28 
pounds; and thai in the water from the gauge containing GO inches of 
soil. L3. 90 pounds, the average of the three being 14. 4G pounds per 
annum — thai is to say, the average annual quantity of chlorin con-, 
bained in the water flowing from the soil drain gauges is almost 
i act ly equal to the average annual quantity coming down in rain. 
Yei we see thai the soil of plat 5 in theBroadbalk wheat field retains, 
en t Ik- average, within each depth of 9 inches down as far as 90 inches 
a quantity of chlorin equivalent to that which falls upon its surface 
each year in the form of l ain. In other words, down to a depth of 90 
inches the soil, though continually subjected to the washing influence 
of the pain, contains a quantity of chlorids equivalent to that which 
rails upon it during ten years, neglecting the very few pounds annu- 
ally supplied to ii as impurities in the manures. 
