M.— AGRICULTURE 253 



sods become in effect, and to a greater or lesser extent, pot-bound, with 

 the result that the plant covering is incapable of reacting in full measure 

 to the inherent fertility of the soil, while to plough, aerate and lime 

 (where necessary) is to give life to favourable biochemical changes and 

 further to enhance the productivity of the soil. The best grassland 

 holds within itself an immense store of arable potentiality, while the soil 

 rejuvenated by ploughing and aeration, even after yielding several white 

 straw or other crops, can be put back to ever better and better grass. 

 That is the experience of every competent ley-farmer, and ley-farming 

 is creeping into ever better and better permanent grassland. 



To plough up an old sod full of white clover, and one that has carried 

 an abundance of stock, and therefore which has been well impregnated 

 with stock nitrogen, and to harrow lime into such upturned sod, is to 

 make and spread a compost at one operation. This, in short, is to mix 

 with the soil three essential ingredients, vegetable and animal residues, 

 and lime, and under conditions most conducive to favourable biochemical 

 activity. It is the arable or crop-producing attributes of sod that 

 I maintain constitute the strongest case for ley-farming, for without the 

 intervention of cropping the full fertility value of superb sods can never 

 be cashed.® 



At the other extreme — the poorest soils — there is nothing to match 

 the continued ploughing down of sod, accompanied by adequate liming 

 and phosphating, to build up fertility. In my own experiences of land 

 improvement gained on what must be some of the poorest soils in Britain, 

 as well as on soils of great inherent virtue, I have been astonished at the 

 progressive improvement in sward and carrying capacity attained when 

 three or four four-year leys have been ploughed down in succession 

 (each sown on the upturned sod of its predecessor) without the interven- 

 tion of a removed nurse crop or of a hay crop. The sequence here is 

 all grass, all grazing and stock nitrogen the whole way, the plough being 

 called in only to assist in compost-making and to ensure adequate ad- 

 mixture of lime, phosphates, organic residues and soil, and to prepare the 

 way for the sowing of the sequential leys. By the adoption of this pro- 

 cedure over a sufficient run of years it is possible to bring land of a most 

 unpromising character into a condition capable of maintaining a rotation 

 balanced between leys and white straw and other crops. 



There is nothing new in the idea of sowing down immediately on the 

 upturned sod, just as there is nothing new in the idea of ploughing up 

 grassland as a means of improving it. Marshall as long ago as 1789 

 remarked, ' Old pasture lands overrun with ant-hills and coarser grasses 

 are not easily reclaimed without the powerful assistance of the plough.' 

 The idea of the all-grass rotation perhaps, however, has an air of novelty 

 about it ; wild white clover as a commercial commodity is comparatively 

 novel ; cheap phosphatic manures are comparatively novel ; the tractor 

 and modern implements are a recent novelty, and more recent are the 



* It is true that it is sometimes difficult to utilise the richest sod to the best 

 arable advantage because of wireworm and the lodging of cereal crops. Much 

 remains, however, to be achieved in the direction of the breeding of short stiff- 

 strawed cereal varieties, while in so far as cereals are concerned wireworm is not 

 so destructive after properly managed leys as after permanent grass. 



