16 
The Effect of Climate and Weather on the Soil 
fallowed throughout the summer contained nitrate equivale 
to no less than 690 lb. nitrate of soda per acre m the top 18 in. 
The winter 1911-12 was very wet, and 19'9 in. of rain fell 
in the five months September 13th— February loth. By 
latter date only 186 lb. nitrate was left, the rest, equivalent 
to 504 lb. of nitrate of soda, being lost. One heard a goo 
many complaints at the time of the badness of the season, but 
it may be doubted whether many realised exactly how serious 
the loss was. Even land in much poorer condition suffered 
greatly; a poor plot started out in September, 1911, with mti ate 
equivalent to 306 lb. nitrate of soda per acre and ended up m 
February, 1912, with only 168 lb., a loss of 138 lb. This 
on a loam. On clays the loss is less because there is less 
accumulation of nitrate during the summer and less percolation 
during winter; a stiff clay at Ridgemont began m ep em er 
with 234 lb. and ended in February with 180 lb., a loss of 
only 54 lb. The harm done to a clay soil by a wet winter 
is the iniury to its texture rather than to its nitrate content 
On sands also the loss of nitrate is less than from loams ; a sand 
at Milbrook started with 102 lb. in September and ended up 
with only 54 lb. in February, a loss of 4 8 lb. In a dry 
winter much less loss goes on. These relationships are shown 
in Fig. 4. 
The Effect on the Crop. 
All these actions show up in the crop yields. Of couise, 
other disturbing factors may come in to mask them in a 
particular season, and the character of the season has a great 
direct effect on the crop, but taking the yields over a series ot 
years the effects due to the soil are very plainly visible. 1 he 
damage done by a wet winter is sharply brought out in two 
sets of the Rothamsted plots. 
Two plots on the Broadbalk wheatfield receive the same 
rather liberal dressing of artificial manures including sulphate 
of ammonia, superphosphate, sulphate of potash, &c., the only 
difference between them being that in one case (plot 7) the 
ammonium salts are applied in spring, while in the other 
(plot 15) they are applied in the autumn shortly after sowing. 
In years of low winter rainfall there is on an average 
practically no difference in yield, the ammonium salts, and the 
nitrates formed from them, remaining in the soil till the plant 
has had time to take all it wants. But in years of high winter 
rainfall the autumn dressings give considerably poorer results 
than the spring dressings ; the nitrate formed does not remain 
in the soil but washes out so that the plant does not get all it 
wants. The results are : — 
