CHAP. i. CATCH-CROPPING. 999 



ploughed in for manure. Thus treated they lighten the soil by adding 

 to it a large bulk of readily decaying organic matter, the nitrogen and 

 minerals in which form a supply of quickly available plant food for the 

 succeeding roots. Leguminous crops, such as vetches, are particulai'ly 

 suitable for such catch-cropping, on account of their now well-recog- 

 nised power of assimilating atmospheric nitrogen through their root- 

 nodules, and so enriching the soil. 



" Catch -cropping " of this sort is often objected to on the ground 

 that it prevents the thorough cleaning of the land from weeds, for 

 which purpose autumn and winter fallowing are so useful. On the 

 other hand experience teaches that a good heavy crop of thickly-sown 

 green stuff' often " smothers " weeds, bringing about as effective a de- 

 struction as occurs in the ordinary mechanical cleaning of land. Where 

 land, however, is foul from twitch or couch-grass, the ordinary fallow- 

 ing system is perhaps more safely adhered to. 



The twitch and other weeds that are removed from land in ordinary 

 cleaning by tillage operations may be utilised by burning them into 

 " vegetable ashes " in heaps, and afterwards spreading them. In this 

 way their nitrogen is lost, and only their mineral constituents are 

 utilised, but it is preferable to ploughing in, if the vitality of the 

 creeping stems of twitch is not entirely destroyed. Trimmings of 

 hedges and other vegetable refuse may be burnt in the same way and 

 the ashes similarly utilised. More importance was attached formerly 

 to the value of vegetable ashes than is now the case, seeing that the 

 potash and phosphoric acid that they contain is less intrinsically 

 valuable, on account of the cheap and plentiful supplies of these 

 substances obtainable in artificial forms. Nevertheless their utilisa- 

 tion should not be neglected. 



When carted off the land in too wet or too succulent a condition for 

 burning, the weeds should be made into a heap and allowed to remain 

 until the inner part has decayed ; the outsides should then be worked 

 inward by turning the heap, when a good compost manure will result. 

 If there is any danger of the seeds of annual weeds lying dormant, it 

 is advisable to apply the decayed mass to grass-land, upon which it will 

 be found to exercise useful effect. 



MANURING BY MEANS OF STOCK. The most old-fashioned form of 

 manuring, and the one that forms the backbone of our farming system, 

 is manuring by means of stock, either by feeding animals on the soil, 

 or by carting on to the land the manure that they make in the farm- 

 yard. For many generations we had no other manure, and the home 

 consumption of everything but grain diminished as far as possible the 

 annual loss of soil food, which there was no means of replacing. Now- 

 a-days it is hopeless, however, for the farmer to content himself, even 

 if he consumes all his green stuffs, hay and straw, with the low average 

 produce that such a system of farming would yield him. The raw 

 material in the way of plant food that he buys with the rent is insuffi- 

 cient to manufacture the crops and the meat that he must turn over 

 year by year in order to live ; and he has recourse to raw material 

 purchased in the market, as well as that paid for at the rent audit. 



