The Food of our Agricultural Crops. 
75 
upon the growth of red clover, the result of which showed that 
under no conditions of manuring could we continue year after 
year to grow this crop upon the same arable soil. A few years 
before this we had sown some red clover upon a piece of ground 
which had been used as a kitchen-garden for several centuries, 
and had, most probably, never before grown red clover. The 
first crops were exceedingly large, and the seed sown in 1854 
did not require to be re-sown until 1860 ; and even now, at the 
end of thirty-six years, although the seed generally requires to be 
re-sown every two or three years, and the crops have become much 
smaller than they were at first, still they are quite as good as 
the ordinary farm crops, and the average yield over the whole 
period we estimate to have been nearly 3 tons of hay per acre 
per annum, and the amount of nitrogen carried off in the hay 
to have been 1631b. per acre per annum. Samples of the soil 
were taken in 1857, and again in 1879 —comprising twenty-one 
years of growth. The loss of nitrogen in the first nine inches 
was estimated at 2,732 lb. per acre ; this was less by one-fourth 
than the quantity removed by the clover during that period. 
Unfortunately, in 1857 we did not take samples of the soil 
below the first nine inches ; we are, therefore, unable to measure 
the loss which has taken place in the soil below this depth. As 
however, the subsoil is very rich in nitrogen, and the roots of 
clover are known to penetrate deeply into it, there can be very 
little doubt that the crop has taken nitrogen from this source, 
or that the soil is the real source of all the nitrogen removed in 
the crops. Notwithstanding the very large removal of nitrogen 
from this soil, it is still richer in this substance than the farm- 
land growing the permanent wheat crop, which has received 14 
tons of farmyard dung per acre every year for the last forty-six 
years. This experiment is highly interesting, as proving that it 
is the want of food of the right sort in our farm soils which pre- 
vents our growing red clover more frequently upon them ; it also 
shows that a vast amount of fertility may accumulate in a soil 
which has been used as a garden for a very long period. 
Upon some old pasture-land mineral manures, but no 
nitrogen, have been applied every year since 1856. Under 
this application the crop of hay removed annually has been con- 
siderably larger than that removed from the unmanured land, 
and the effect of the minerals has been largely to increase the 
leguminous herbage, so that it constitutes about one-fifth of the 
whole crop ; while upon the unmanured land not more than 8 
per cent, is leguminous herbage. At the end of twenty years, 
careful analyses of the soil of both plots were made, and it was 
found that the first nine inches of the plot receiving the mineral 
