ch. x] Seed-Mixtures 171 



itself, but experience shows that this is most readily accomplished 

 when we work in harmony with the natural conditions by which 

 we are faced. 



The most critical period in the life of a pasture is generally 

 from the second to the fifth year after sowing. One reason for 

 this is that the initial fertility of the soil has become more or less 

 depleted by that time. Another cause is the gradual dying out 

 or even total disappearance of some of the short-lived species 

 sown. Moreover the truly perennial species which remain have 

 to meet with keen competition from the in-coming indigenous 

 species of the neighbourhood 1 . 



It should be remembered that different localities and varying 

 elevations possess distinct climatic conditions, and associated with 

 these conditions are specialised forms of indigenous plants. These 

 plants, e.g. grasses, are those varieties or biologic forms which are 

 most adapted to their special habitat, and have therefore proved 

 most successful in the struggle for existence. Native grasses like 

 Florin, Crested Dog's-tail, Sweet Vernal-grass, and the various 

 forms of Sheep's Fescue, etc. commonly compete very successfully 

 with their commercial counterparts (generally the -product of foreign- 

 grown seeds) and so gradually take possession of the ground from 

 the second year onwards until a certain semi-natural stable con- 

 dition has been reached. It is therefore probably true that when 

 land is sown down to permanent grass the proportions of the 

 species in the original mixture sown and in the resulting turf ten 

 years later are very seldom anything like the same. 



This modification of the turf generally occurs most rapidly on 

 soils of the extreme types (very dry or wet) and at high elevations. 



On all fertile soils at low elevations in this country the in- 

 coming indigenous species will — under good farming conditions — 

 be of the better and more useful kinds. 



Whilst the foregoing facts do not constitute a sufficient reason 

 against the sowing of suitably selected mixtures of seeds, it is 

 obvious that they form the strongest possible argument in favour of 

 the production and propagation of races of our own native grasses. 

 Until this is done it cannot be maintained that we are dealing 

 with the problem of grass production on really scientific lines. 

 1 See Bibliography, No. 28. 



