76 CULTURE OF FARM CROPS. 



food sent into our towns can be re-distributed over the area 

 from which they came. Indeed, having regard to the 

 inapplicability of dilute liquid sewage to arable land, except 

 in small quantities and at particular seasons, and at the 

 assumed cost of distribution, it appears probable that the 

 most profitable mode of utilization of sewage will be, to 

 limit the area by applying the greater part, if not the 

 whole, to permanent or other grasses, laid down to take it 

 the year round, trusting mainly to the periodically broken- 

 up rye-grass land, and to the application to arable land of 

 the solid manure resulting from the consumption of the 

 sewaged grass, for obtaining other produce than milk and 

 meat by means of sewage. 



" In the illustrations given above, therefore, it is sought 

 to convey an approximate idea, on the one hand, of the 

 utmost extent, and on the other, of the probable limit of 

 the loss to which our arable soils are subject by the sale of 

 corn and meat, supposing the mineral constituents be not re- 

 turned to the soil whence they came. Confining attention to 

 this object, we necessarily keep out of view the cases in which 

 roots, hay, or straw are largely sold, for, in such, compen- 

 sation is generally made by the return to the land of town 

 manures of some kind. If this be not done the loss of 

 mineral constituents will, of course, be very considerable. 



" In view of the facts above adduced, we think it may 

 safely be concluded, that the modern practices of this 

 country, taken as a whole, do not tend to the injurious ex- 

 haustion of the mineral constituents in anything like the 

 degree that has been assumed by some. Further than this, 

 we think the evidence is more in favour of the supposition 

 that, in a great majority of our soils, they are, by the com- 

 bined aid of progressive liberation, and of restoration from 

 without, becoming, in the course of cultivation, richer rather 

 than poorer in immediately available mineral constituents 

 relatively to immediately available nitrogen. So far as this is 

 attained at the expense of the constituents of the soil itself, 

 there is of course the less to fall back upon within a given 

 depth from the surface. But it surely cannot be denied, 



