Experimental Crops at Rotluxmsted. 
lOT 
The evidence afforded by the results in the foregoing Table is 
confessedly quite inadequate to show what are the climatic con- 
ditions favourable or otherwise to the growth of wheat. It is, 
however, quite sufiicient for our present purpose, which is to 
illustrate the comparative independence of the crop on the mere 
amount of rain falling during the period of active vegetation. 
It will suffice to call attention to a few of the more extreme 
examples. 
The four years of largest total fall of rain over the four 
months in question were, 1853, 1855, 1860, and 1867, and tiuee 
of them were also the seasons of smallest average crop, both of 
corn and total pi'oduce, whilst the fourth (1855) was a season 
of generally less than the average produce. On the other hand, 
the three years of highest produce, both corn and total produce, 
Avere 1854, 1863, and 186-1, and all three were seasons of less 
than the average fall of rain during the four months of active 
growth. Lastly, the two seasons of lowest fall of rain during 
April, May, June, and July were 1868 and 1870 ; and both 
gave, with each of the four conditions as to manure, more than 
the average produce of corn over the nineteen years ; and in 
1868, though not in 1870, there was even more than the average 
of total produce also, under each of the three manured con- 
ditions. But although there was in both these years of great 
deficiency of rain during the growing period, more than the 
average produce of corn without manure, there was, in both, 
less than the average amount of both straw and total produce. 
As in the case of the hay crop, so again with the wheat, it is 
seen that, whilst during the earlier years the mineral manure 
and ammonia- salts gave more produce, both corn and total 
produce, than the mineral manure and nitrate of soda, during 
the later years the nitrate has given more, and sometimes con- 
siderably more, of straw especially, than the mineral manure 
and ammonia-salts. The questions arise, how far may this be 
due : to the more rapid and more extended distribution of the 
nitrate of soda, or its products of decomposition, within the soil 
and subsoil ? to the mutual reactions of the manure and the 
soil? to the greater power of retention of moisture acquired by 
the latter, as the result of such reaction ? and to more active root 
development in the spring under these conditions ? 
Unfortunately, no comparative determinations of moisture in the 
soils of these two plots, or of root development, have been made, 
so as to obtain direct evidence in regard to the questions here 
suggested. Due weight should, however, be given to the fact that, 
whilst the ammonia-salts are sown in the autumn, before the seed, 
the nitrate is applied as a top-dressing in March. It is known that 
nitrate of soda, or its nitric acid in combination with some other 
