1853. 



NKW ENGLAND FARMER. 



411 



in most cases, yielded so poor a natural herbage 

 as to have been considered unworthy of being en- 

 closed as permanent pasture. 



2. Some grass-lands will retain the good condi- 

 tion they thus slowly acquire for a very long 

 period, and luitkoid manuring— w the same way, 

 and upon nearly the same principle, that some 

 rich corn-lands have yielded successive crops for 

 100 years without manure. The rich grass-lands 

 of England, and especially of Ireland, many of 

 which have been in pasture from time immemori- 

 al, without receiving any known return for all 

 they have yielded, are illustrations of this fact. 



3. But others, if grazed, cropped with sheep, 

 or cut for hay, will gradually deteriorate, unless 

 some proper supply of manure be given to them — 

 which required supply must vary with the nature 

 of the soil, with the kind of stock fed upon it, and 

 with the kind of treatment to which it has been 

 subjected. 



FORM WHICH THE IMPROVEMENT ASSUMES, AND HOW IT 

 IS BROUGHT ABOUT 



In regard to the acknowledged benefit of laying 

 down to grass, then, two points require consider- 

 ation. 



1. What form does it assume — and how is it 

 effected ? 



The improvement takes place by the gradual 

 accumulation of a dark-brown soil rich in vegeta- 

 ble matter, which soil thickens or deepens in 

 proportion to the time during which it is allowed 

 to lie in grass. It is a law of nature, that this 

 accumulation takes place more rapidly in the 

 temperate than in tropical climates, and it would 

 appear as if the consequent darkening of the soil 



the kind of grass and with the kind of soil. When 

 wheat is cut down, the quantity of straw left in 

 the field, in the form of stubble and roots, is some- 

 times greater than the quantity carried off in the 

 sheaf. Upon a grass field two or three tons of hay 

 may be reaped from an acre, and therefore, from 

 half a ton to a ton of dry roots is annually pro- 

 duced and left in the soil. If anything like this 

 weight of roots die every year, in land kept in 

 pasture, we can readily understand how the veg- 

 etable matter in the soil should gradually accu- 

 mulate. In arable land this accumulation is 

 prevented by the constant turning up of the soil, 

 by which the fibrous roots, being exposed to the 

 free access of air and moisture, are made to un- 

 dergo a more rapid decomposition. 



But the roots and leaves of the grasses contain 

 earthy and saline matters also. Dry hay leaves 

 from an eighth to a tenth part of its weight of ash 

 when burned. Along with the dead vegetable 

 matter of the soil, this inorganic matter also ac- 

 cumulates in the form of an exceedingly fine 

 earthy powder ; hence one cause of the universal 

 fineness of the surface-mould of old grass-fields. 

 The earthy portion of this inorganic matter con- 

 sists chiefly of silica, lime, and magnesia, with 

 scarcely a trace of alumina ; so that, even on the 

 stiffest clays, a surface soil may be ultimately 

 formed, in which the quantity of alumina — the 

 substance of clay — is comparatively small. 



There are still other agencies at work, by which 

 the surface of stiff soils is made to undergo a 

 change. As the roots of the grasses penetrate 

 into the clay, they more or less open up a way 

 into it for the rains. Now, the rains in nearly all 

 lands, when they have a passage downwards, have 



were intended, among other purposes, to enable itj a tendency to carry down the clay with them, 

 to absorb more of the sun's warmth, _ and thusj yiigy do so, it has been observed, on sandy and 

 more speedily to bring forward vegetation wher&^peaty soils, and more quickly when these soils are 

 the average temperature is low and the summersjiaid down to grass. Hence the mechanical action 

 comparatively short. _ of the rains — slowly in many localities, yet surely 



If the soil be very light and sandy, the thicken- 1 — has a tendency to lighten the surface soil, by 

 ing of the vegetable matter is sooner arrested ; ifi removing a portion of its clay. They constitute 

 it be moderately heavy land, the improvement' one of those natural agencies by which, as else- 

 continues for a longer period : and some of thej where explained, important differences are ulti- 

 heaviest clays in England are known to bear the niately established, almost everywhere, between 

 richest permanent pastures. ^ , the surface crop-bearing soil and the subsoil on 



The soils formed on the surface of all our rich - - - - 



old pasture lands thus come to possess a remark- 

 able degree of uniformity — both in physical char- 



which it rests. 



But further, the heSts of summer and the frosts 

 of winter aid this slow alteration. In the extremes 



acter and in chemical composition. This uniformity If j^^^,. ^^^ ^f- ^^^^ ^^e soil contracts more than 



^t^^,?" !!ii^nT.T/'l!!° "il'^'^u J^':?i^'„ itlie roots of the grasses do ; and similar, though 



less visible, differences take place during the 

 striking changes of temperature which are expe- 

 rienced in our climate in the different parts of 

 almost every day. When the rain falls, also, on 

 the parched field, or when a thaw comes on in 

 winter, the earth expands, while the roots of the 

 grasses remamed nearly fixed ; hence the soil rises 

 up among the leaves, mixes with the vegetable 

 matter, and tlius assists in the slow accumulation 

 of a rich vegetable mould. 



The reader may have witnessed in winter how, 

 on a field or by a way-side, the earth rises above 

 the stones, and appears inclined to cover them ; 

 he may even have seen, in a deserted and undis- 

 turbed highway, the stones gradually sinking and 

 disappearing altogether, when the repetition of this 

 alternate contraction and expansion of the soil for 

 a succession of winters has increased, in a great 



the lias and Oxford clay, which originally, no 

 doubt, have been left to natural pasture — as many 

 clay lands still are — from the difficulty and ex- 

 pense of submitting them to arable culture. 



2. How do they acquire this new character, 

 and why is it the work of so much time. 



When the young grass throws up its leaves 

 into tlie air, from which it derives so much of its 

 nourishment, it throws down its roots into the 

 soil in quest of food of another kind. The leaves 

 may be mown or cropped by animals, and carried 

 off" the field ; but the roots remain in the soil, and, 

 as they ilie, gradually fill its upper part with veg- 

 etable matter. On an average, the annual pro- 

 duction of roots on old grass-land is equal to 

 one-third or one-fourth of the weight of hay carried 

 off* — though no doubt it varies much, both with 



* See the Author's Z,ec<«rM on Agricultural Ckemistrv 

 and Geology, 2ii edilion. 



