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be said to be the case where sau is employed. The tea bushes under that tree have been 

 reported by those who believe in it to yield a considerably higher amount in a given area 

 than in any other part of the garden, under similar conditions of soil and age of bush. It 

 has been observed that tea grown under sau enjoys a considerable immunity from blights 

 and pests while the surrounding trees are suffering badly. 



" The action of the sau was attributed by some to the beneficial shade which it casts 

 over the plants ; others considered that it was the manure furnished by the dead leaves ; a 

 few thought that the advantage of interplanting the trees was the fact that the roots went 

 to a greater depth that the tea roots, and drained the superabundant moisture from the 

 surface soil while, on the other hand, they brought up from the subsoil food material for 

 the tea plants. Mr. Buckingham remarks : I do nat wish to contend that sau is capable 

 of improving tea plants where the soil contains elements which in some instances nature has 

 abundantly supplied for the support of the bush, but I do assert that the vitality of the 

 tea bush is limited, probably in a great measure depending on the character of the soil, and 

 unless we restore some of these essential parts we are yearly, I may say weekly, abstracting, 

 the tea planter in a few more years may be surrounded by tea which the very best cultiva- 

 tion and the most scientific pruning can never bring round. 



"The immediate benefit which Albizzia confers upon the soil and the tea plants where 

 it grows is not due to some chemical ingredient imparted to the soil, as was once supposed, 

 but to the presence of tubercles which are attached to the toots. The discovery * of these 

 tubercular bodies on the roots of the sau tree was made by Dr. Watt during his tour 

 in Assam in 1895." 



It will thus be seen that the sau tree (Albizzia, sttpulata) was 

 the first tree which was supposed to have fertilising properties. 

 Others have been since used with nearly as much, if not with equal, 

 success. But all of them have belonged to the same family of legumin- 

 osae, and all have had nodules on the roots which fix the nitrogen 

 of the air. Such are the medeloa (Dalbergia Assamica\ the koroi 

 (Albizzia odorattssima), and still other species of Albizzia have been 

 used, as well as Erythtina indua. 



The advantages claimed for these trees are as follows : 

 i. They give a slight shade to the tea which is itself an 

 advantage, The value of shade, however, has been very much 

 doubted, but probably this is only another instance of general 

 conclusions drawn from particular districts being quite fallacious 

 in others. In the lower part of the Brahmaputra valley, except 

 where mosquito blight is abundant, slight shade will, I think, be 

 found of distinct advantage. This will probably be especially the 

 case in Nowgong. And it will be of advantage here because it 

 will to a certain extent prevent evaporation from the soil by the 

 exceedingly hot sun in a district rather deficient in rainfall. On 



* I believe the nodules or tubercles on the roots of the sau tree were observed long ago by 

 Mr. Bamber, but he did not publish his observations. 



