486 Transactions. 



of subsoil. Now, not only are there found in widely separated districts — 

 e.g., the Wairarapa and Canterbury Plains- — soils of similar geological origin 

 but of diverse agricultural properties owing to differences in climate, but 

 the same thing is found even in areas of narrow limits. Thus within 

 a few miles of Lincoln there are three different types of soil : (1) The 

 heavy clay loam on sandy-clay subsoil of Lincoln ; (2) the silty loam on 

 fine sandy subsoil of Tai Tapu ; (3) the light gravelly soil on gravel beds 

 of Burnham. 



All these soils are, of course, derived from the same "kind of material 

 (petrologically), and two at least are of similar mode of formation ; they 

 experience in general the same climatic conditions ; and they are of about 

 the same chemical composition. But because of wide differences in their 

 textures and in the nature of their subsoils the methods of farming them 

 are entirely different. 



The writer does not deny, however, that sometimes a geological forma- 

 tion does give rise to a peculiar soil type — as, e.g., the Lower Greensand in 

 England. In the North Island the rhyolites and pumice of the central 

 volcanic plateau seems to be of such a type ; while in Otago the mica 

 schists probably produce a type of soil unique physically because of the 

 presence in amount of flat plates of mica. 



In a classification of the soils of New Zealand, therefore, it is urged 

 that the great divisions must be decided on by climatic considerations — as, 

 indeed, nature has already indicated in the distribution of her own vegeta- 

 tion—while soil texture must be looked to as the main guide in further 

 subdivision. Geological formations that give rise to soils of peculiar type 

 must, however, be recognized, and this may be done in either of two ways : 

 (1) by throwing such areas outside the general scheme of classification, 

 or (2) by subdividing according to geological structure the primary divi- 

 sions (see " Soil districts," below) based on climatic differences. 



At this stage it will be well to take into consideration some suggestions 

 made by Mr. H. T. Ferrar at the meeting of the Canterbury Philosophical 

 Institute at which the first part of this paper was read. He pointed out 

 that, as the detailed work of soil-surveying is first directed towards a 

 classification of the cultivated land, a preliminary division of the country 

 on soil-utilization lines is useful. He suggested that there should first 

 be marked out: (1) Unproductive areas — e.g., the mountainous region 

 of south-west Otago ; (2) areas capable of being made productive — e.g., 

 North Island forests ; (3) areas that cannot be other than pasture — 

 e.g., tussock mountain-slopes ; (4) areas available for cultivation. To the 

 last two classes of land attention would naturally first be paid ; the third 

 class is capable of being made to carry more stock when the most appro- 

 priate grasses have been experimentally determined ; while the fourth class 

 includes land the productiveness of which can be raised by the discovery 

 of the most suitable systems of cropping and manuring. 



Definition of Terms used in the Proposed Scheme of Classification. 



Soil districts : The great divisions based on climatic factors we propose 

 to caH " soil districts." The United States Bureau of Soils uses the term 

 " soil province " in this sense, but in our country this term would obviously 

 lead to confusion with the political divisions of that name. 



Subdistricts : If geological formations occur within a soil district that 

 give rise to soils of peculiar type the district is to be subdivided accordingly. 



