59 



soil the best results being only obtained when more than 35 per 

 cent, of the non-sandy portions of the soil consist of organic 

 matter, and 0'8 per cent, of nitrogen. Provided this is present, tea 

 can be cultivated with success in presence of a minimum quantity* 

 of other constituents, notably Phosphoric Acid and Potash, but to 

 obtain high quality tea these latter materials must exist in the 

 soil in larger amount, and other things being equal, the larger 

 the quantity of phosphoric acid (in presence of sufficient nitrogen) 

 the better will be the tea. Potash runs parallel with phosphoric 

 acid, but is probably present in ample quantity in Assam soils. 

 In short, much nitrogen with little phosphoric acid will produce 

 rank growth with medium tea only much nitrogen with much 

 phosphoric acid will give luxuriant growth and high quality tea little 

 nitrogen with much phosphoric acid will give high quality tea, but 

 comparatively littl eof it and if there is a deficiency in both, tea can 

 never be profitable. Other constituents beside the three named may 

 possibly have an intimate connection with the quality of the tea. 

 Lime probably has little or none and is in any case present in ample 

 quantity everywhere. Iron available Iron may have some influ- 

 ence and apparently decreases in old soils, but this requires further 

 investigation, and Iron, at any rate, does not apparently need to be 

 applied as manure. Manganese whatever its value, which needs to 

 be proved yet by thorough experiment on a garden is, I believe, 

 generally present in abundance in an available form in Assam. The 

 deficiencies, and the increasing deficiencies, of the soils of many of 

 the tea gardens in the Brahmaputra Valley render manuring a 

 necessity in the future, To the methods by which the necessary 

 replacement of the materials indicated above as affecting the yield 

 and quality of tea, the next chapter will be devoted, 



* One might tabulate these results and say that in general terms if on analysis a soil 

 presents 



1. Less than 35 per cent of Organic Matter i on the non-sandy portion of the soil it 



2. Less than o % 8 per cent, of Nitrogen > needs these constituents as manure. 



3. Less than 0-25 per cent, of Phosphoric Acid, calculated in the same way, it needs 

 phosphates, and if high quality tea is to be produced o - 4 per cent, should bp present. 



4. Potash in amount less than 3-0 per cent, of the Oxide of Iron and Alumina, taken 

 together, it needs Potash manures. 



