122 BIOLOGICAL PROBLEMS 



It will now be my business to enquire how a 

 temporary ley is to be made to achieve its five 

 essential functions, and why in practice it so seldom 

 does. 



To deal firstly with what is perhaps the most im- 

 portant duty of our temporary ley, namely, to build 

 up fertility. This turns upon having a turf full of 

 clover to plough down at the end stage of the ley, 

 and this depends upon proper manurial treatment and 

 stocking, and upon sowing the right clovers in the 

 first instance. The degree of persistence of the clovers 

 under varying conditions is therefore at once seen to 

 be a matter of prime importance to agriculturists, but 

 as far as 1 know it has not been made the subject of 

 detailed research. The clovers are most variable in 

 this respect. Of the Red Clovers it may, in general, 

 be said that those of the late-flowering type, that is to 

 say, those with rather a deep-going tap-root, and that 

 flower only once in a season, persist longer than those 

 of the broad-leaved type, and there is little doubt that, 

 for use in Britain, Red Clover seed harvested in Britain 

 gives plants of more prolonged duration than seed 

 from oversea sources seed from Brittany is generally 

 considered to give more durable plants than other 

 foreign seed. Small-scale trials I have myself con- 

 ducted in Wales have tended to confirm this view, and 

 incline me to go even further, for I found that on poor 

 fields in Mid Wales at comparatively high elevations 

 the Red Clovers which persisted best were those (in- 

 trinsically poor samples so far as germination was 

 concerned) which had been harvested on thin soils 

 at high elevations and under adverse weather condi- 

 tions in Montgomeryshire or on the Cotswolds, whilst 

 Chilian Clover (the most attractive-looking seed on 

 the market) almost invariably died out after the first 

 year. Alsike Clover, moreover, in cold and wet 



