270 On the Growth of Mangolds, Cahhages, &g. 
crop is by no means merely carbonaceous ; all vegetable matter contains 
nitrogen ; and in an autumn green crop there is carried away such and such 
a number of pounds of nitrogen per acre — as well as a not insignificant 
weight of mineral plant food. ... Is not, then, the following root crop 
robbed by the autumn catch-crop, which is surely appropiiating the good 
things in advance ? No, for in autumn tlie root crop is not sown, nor will 
it be sown for many months. It is not there to get for itself the good things 
then in the soil ; but the catch-crop is there, aud gets them. But would not 
the good things of the soil remain there intact but for the catch-crop, and be 
in due season appropriated by the main crop ? No, for the chief of the good 
things is nitric acid, in combination with lime, in which form it is one of the 
most soluble materials that exist, so that it is readily washed down into the 
subsoil and into the drains by the rains of winter ; a portion only of the 
autumn store being left till the following summer for the use of the roots. . . . 
The idea that autumn cropping impoverishes the land is based upon a mis- 
conception of the chemical economy of the soil, and so far from temporarily 
exhausting or lessening its fertility by catch-cropping, we rather retard the 
exhaustion of that fertility, and so in effect increase it." 
What is there then to prevent farmers, even in those districts 
where root growing is most highly appreciated, from filling up 
that long interval of autumn, winter, and spring by growing 
crops which, wliether fed on the land or converted into silage, 
abstract very little fertility, and indeed add greatly to the 
manurial resources of the farm when additional produce is con- 
sumed ? In Norfolk, obtaining good crops of swede turnips is 
considered to lie at the very foundation of successful farming. 
The Norfolk man will not do the slightest thing to imperil the 
chances of a crop so valuable, because he will tell you he mainly 
depends on his swedes for the fattening of cattle in winter. In 
all probability he would secure this object just as effectually by 
taking a crop of rye or early vetches or mixed winter oats and 
vetches in the long interval from the autumn of one year to the 
early spring of the next ; but so long as he is under the appre- 
hension that such would not be the case it is in vain to argue 
with him. Too often he does not get what he desires, with all 
the waiting and tiresome costly processes that have to be at- 
tended to in the long interval, and then his loss is great indeed. 
He forgets that the catch crop he might almost always make 
certain of obtaining would most likely be of equal value to the 
average of such swede crops as he is in the habit of growing. 
And this is to be gained well-nigh cost free, inasmuch as the 
sam^e rent, outgoings, and the major part of the tillage expendi- 
ture have to be borne whether one crop be taken or two. 
Probably Norfolk farmers, and many others who fallow for 
swedes and turnips, do not require immense quantities of arable 
green crops for sheep-feeding on the land during the spring and 
early summer : consequently in the past they have not cared to 
grow them. But now that we have the ensilage system, there 
