464 EVENING DISCOURSES 



weeks, and grazing, by milch cows and other stock, as soon as the grass 

 attains a height of 4-5 inches, leaving ' followers ' (dry cows and cows in 

 calf) to clear up the remains. When the cows come off the pasture, it is 

 harrowed to spread the dung, and then treated again with sulphate of 

 ammonia. This ' new system ' was started on the farm of Mr. Brunton 

 at Marton, near Middlesbrough, and has been successfully worked there 

 for ten years ; under it, the number of cows carried by an acre of grassland 

 during the summer has been doubled. 



Although the ' new system ' never became general, the experimental 

 work done with it left a valuable aftermath, notably the extension of the 

 grazing season in the spring and in the autumn. By suitable management 

 of grazing, and applying a moderate dressing of nitrogen in February or 

 March, sufficient growth can as a rule be obtained to feed cattle on pasture 

 two or three weeks earlier than usual, thus saving the farmer the cost of 

 feeding concentrates during that period. 



Until about ten years ago our farmers never contemplated the use of 

 nitrogenous fertilisers on pastures : they would kill the clovers, and es- 

 pecially wild white clover, which is the chief permanent nitrogen-fixing 

 legume in a pasture. Mr. Brunton, however, found that the ' new system ' 

 did not involve the destruction of clovers. 



About eight years ago Sir Frederick Keeble and Lt.-Col. W. R. Peel 

 decided to start experiments upon the eifect of fertilisers and of manage- 

 ment on the composition of a pasture, and this work was placed under 

 the direction of Mr. Martin Jones, who had been working with Prof. R. G. 

 Stapledon at Aberystwyth. 



Mr. Martin Jones demonstrated that the bad effects of nitrogenous 

 fertilisers were due to insufficient grazing, and grazing at the wrong time, 

 which allowed the coarser grasses to grow long and choke the finer grasses 

 and clovers. 



I think I can best illustrate the result of Martin Jones' work by reference 

 to Fig. s, on which are shown the times of the year at which some grasses 

 grow leaf. A pasture is made up of many grasses, but the consideration of 

 these few grasses will, I hope, be enough to make the principle clear. 



Nardus only grows leaf in July, and rapidly becomes fibrous and un- 

 palatable. It is therefore considered a weed. 



Bent is better. It grows leaf for a period of three months. 



Indigenous Perennial Rye Grass grows leaf during six months of the 

 year if — 



(i) it has already a well-established and developed root system ; 

 (ii) the supply of water in the soil is sufficient for growth ; 

 (iii) the necessary nitrogen and minerals are present in the soil in a 

 suitable form. 



If the pasture is grazed in early April when perennial rye grass has only 

 made little growth, and cocksfoot has made no growth at all, then the 

 perennial rye grass receives a check, for stock will eat its young palatable 

 shoots to ground level since there is no other green growth available. If, 

 after grazing, the field is rested, cocksfoot, which is now starting to grow, 

 has no perennial rye grass to compete with and no grazing animals to check 

 its growth : it passes through its critical period under favourable conditions. 

 It becomes strong, and successfully competes with the perennial rye grass 

 which is now endeavouring to make its second growth. If, on the other 

 hand, the field is rested in April when perennial rye grass is starting to 

 grow, and grazed a fortnight later when cocksfoot starts, the cocksfoot will 



