206 On Permanent and Tem-porary Meadoics and Pastures. 
should have to spend on this element alone about 16/. 4*. 'k^d., 
if to this we add the cost of the other necessarj elements, 
viz. — 
d. £ s. d. 
Phosphoric acid .. ..at 4 •355 per lb. 
Lime „ -1.30 
Magnesia „ 3-048 
Potash „ 2-177 
^\itroKen 
. 2 17 \0h 
.036 
. 0 15 4i 
. 4 15 11 
. 16 4 41 
£24 17 0^ 
we should arrive at an excessive cost ; for the value of 10 tons 
of drj hay in the market is not above 32/. 10s. bd., and this 
would only leave 11. 13s. 4irf. to pay for the rent of land, manual 
labour, and carriage to the market, which is clearly insufficient ; 
especially when we take into account that it usually takes 
5 acres, at least, to produce this quantity of hay. 
The problem of the production of hay presents then a double 
contradiction : 
1st. Its production requires assimilable nitrogen in the soil, 
since manures with assimilable nitrogen undoubtedly influence 
it to a large extent. It uses up nitrogen borrowed from the 
soil, and therefore would be expected to exhaust it, whereas the 
analyses of soils previously given unmistakably show that grass- 
growing, so far from exhausting the soil of nitrogen, on the 
contrary greatly enriches it. 
2nd. Practically, grass-lands are let at a higher rent than other 
lands, and supply crops, which, eaten in the sheds, give a 
manure which is used for arable lands, so that not only does 
grass-growing enrich the soil on which the meadow is laid down, 
but it also supplies nitrogen to the root- and grain-crops, 
which contribute to the richness of the farm. 
I have just shown that if it is necessary to make a complete 
restitution to the soil of all the elements removed, then the culti- 
vation of grass-lands would be too expensive. How then can 
the action which assimilable nitrogenous manure has on the 
growth of grass be explained? Like the greater number of 
cultivated plants, meadow-grasses derive from the atmosphere 
the greater part of the nitrogen which is found in their tissues, 
but they only absorb it by means of their leaves, when these are 
sufficiently developed. It must then be at the beginning of the 
season, when vegetation takes a fresh start, that the plants should 
find in the soil and be able to absorb by their roots a small 
quantity of highly assimilable nitrogenous matter, so as to 
enable them to form their first leaves, by means of which they 
will subsequently nourish themselves at the expense of the 
