66o 



^THE TROPICAL AGRICULTURIST. 



[March 2, 18S5. 



portion of it reprinted in the Indian Tea Gazette, to 

 that our readers can judge for themselves as to the 

 correctness of our representation of the statements 

 made and the value of those statements regarding 

 the recuperative effects of Albizzia stipnlata. The 

 gentleman who set the ball rolling was Mr. J. Buck- 

 ingham of Amgoorie, who in October 18S4 wrote as 

 follows : — 



The "Sau" (Albizzia Stipulate) is fully described in 

 Gamble's Manual on Indian Timbers, page 160. It is com- 

 mon in most parts of Assam, and may be generally found on 

 land lying rather low. Some years ago a gentleman in Upper 

 Assam first drew the attention of tea planters to this tree 

 (see Tea Cyclopaedia, IPS), very properly calling it a tea 

 fertilizing tree ; but it is only within the last few years 

 that experiments have been made to prove that the " Sau" 

 tree possesses peculiar properties in bringiug round ex- 

 hausted soils thereby causing lea bushes to flush vigorously, 

 in fact, imparting a vitality which we are now begin- 

 ning to find old tea sadly deficient in. 



I am not in a position to state the reason of the " Sau" 

 exercising such an influence on tea, and 1 believe a 

 thorough chemical analysis of the soil can be the only 

 means of ascertaining the cause. 



Anarea of three acres planted with "Sau " about 10 

 years ago has yielded for the last four years more than 

 double as much tea as any other part of the garden. 



I think we may put aside shade as the cause of this 

 hi. (ease in yield ; in fact, the generality of planters con- 

 demn shade It teuds to make the bush throw out long 

 stalky shoots, racing with each other to reach the light, 

 and the Hushes from such trees are necessarily meagre 

 and woody. 



Such, however, is not the case under " Sau." The tea 

 bushes under this tree, which easts a light, shade, are 

 broad in proportion to their height, have an even growth 

 over the whole surface, and yield flushes equal to the 

 finest tea I have seen in the open, where the condition of 

 the soil and age of bush are both in its favour. I do not 

 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 f he character of the soil, and unless we 

 restore some of those essential parts, we are yearly, 

 I may say weekly, abstracting, the tea planter in a few 

 more years will find himself surrounded by tea which the 

 very best cultivation and the most scientific pruning can 

 never bring round. 



The mere fact that blight has during the last few years 

 been more prevalent than formerly, strengthens the argu- 

 ment that soil is deteriorating, and there is the strongest 

 proof to show that tea under the " Sau " is particularly free 

 from blight when the surrounding trees are suffering. 



Professor Johnson, in his Elements of Agricultural 

 Chemistry, says, the improvement of land therefore by the 

 pla: ling 'of trees depends in part upon the quintity of 

 organic food which the trees can extract from the air, and 

 afterwards drop in the form of leaves upon the soil, and 

 in part upon the kind and quantity of inorganic matter 

 which the roots can bring up from beneath, and in like 

 manlier strew upon the surface, The action therefore of a 

 tree is two-fold ; 



i-! - It causes vegetable matter to accumulate on the 

 surface. 



2nd. — It brings up from bpnwtli certain substances which 

 are of vital importance to the growth of plants, but in which 

 the upper soil may have been deficient. The same author 

 also proves that laud can be improved ten-fold by planting 

 trees. 



In some trees certain mineral salts are supposed to exude 

 from the root-cells into the water of the soil, these silts 

 acting in some instances, we all know, as a poison. From 

 the same cause may not some mineral salts prove beneficial 

 to the tea bush ? 



My object in collecting the following circumstantial proofs 

 of the erne-icy of the "Sau" principally, and of a few 

 other trees, partially in restoring exhausted soils, is to en 1 

 t'.n attention Of the tea planting (.'immunity ■ 

 this important fact, and to urge the necessity of a careful i 



chemical investigation of the matter on the spet. My 

 thanks are especially due to the gentlemen who have come 

 forward so liberally with their opinions in this matter. 

 There are the important facts stated by Mr. Bucking- 

 ham, that a plot of tea land planted with sau trees ten 

 years ago has lor four years bock yielded twice as 

 much tea as all the rest of the garden, while th» bushes 

 which gave the double yield of leaf were particularly 

 free from blight. With reference to the quotation from 

 Johnston, we may say it is beyond doub; one of the 

 functions of forest trees to pump up water from the 

 lower subsoil strata, and with the water, it may be 

 taken as granted, some of the fertilizing ingredients in 

 the subsoil are also brought to the surface. Why some 

 trees should be specially beneficial in this and other 

 respects does not seem to be known. But. such is the 

 fact, opposed to the other fact that certain trees are 

 not only not beneficial but inimical to cultured plants. 

 Next comes 



Mr. Newington, who writes regarding the " Sau " tree : — 



I was out at one of the out-gardens this morning and 

 tock particular notice of tea growing under the "Sau" 

 trees. I feel confident that it is beneficial to the tea plant, 

 and will increase the yield. In the first place, it is a cultiv- 

 ator, as the lateral roots grow so near the surface, which 

 seems to open the soil and make it porous ; then again I 

 notice this tree does not thoroughly open its leaves until 

 about 8 a. m,, just when the sun is getting hot. When the 

 leaves are quito open it gives a slight shade, while at the 

 same time it does not exclude the sun ; this is beneficial 

 to the tea plant. Also this slight shade prevents the 

 ground getting dried and baked by the heat of the sun. 

 As far as the fact of the leaves acting as manure is con- 

 cerned, this is very slight, as the foliige is comparatively 

 light. I quite believe iu the tree. For the last three days 

 I have been planting out my "Sau" nurseries anong the 

 tea 50 X 50. 



Now as regards the lateral roots of the tree being 

 surface feeders, that might be rather an objection if 

 the roots fed ou the same substances as tea requires 

 and did not, on the contrary, add to the soil, fert- 

 ilizing matter drawn up by the larger roots from the 

 subsoil. The mere mechanical opening up of the soil 

 is, of course, beneficial, but this alone would not 

 account for the good done by the sau tree. Next 



Mr. Eaban writes : — Regarding the "Koroi" or "Sail" 

 tree, from what 1 saw at Amgoorie, I was quite convinced 

 that it benefited the tea growing under it, so much so 

 that I have this year planted out 1U0 acres of it myself. 

 I fiud it difficult to account for the beneficial effects it 

 produces on the tea plant but it is possible that Acacia 

 trees take up nourishment from the soil not required by 

 the tea plant, give sufficient, not too much shade, keep 

 down jungle, and, sending their roots down much lower 

 than the tea plant, drain the subsoil and enable the latter 

 to send roots down lower than it otherwise could. I do 

 not say this is a sufficient or satisfactory explanation, but 

 it .is the only way I can account for the beneficial effects 

 produced. 



Then, Dr Simons writes i — 



I will endeavour to give you all the information I can 

 collect about the "Sau" (Acacia Stipnlata). It is a tree 

 worth cultivating among tea more than any other I am 

 acquainted with, for in the way the branches spread, it 

 dees not keep the sun entirely off the plants, but moder- 

 ates the strong heat of the sun's rays, through which 

 evaporation from the leaves is lessened and the flushes 

 come in quicker and larger than on those growing ex- 

 posed in the open. The "Sau" grows to a very large size 

 and quickly. Dr. Roxburgh in his " Flora Indica " states 

 that one tree planted by himself had a trunk iah inches 

 iu circumference, 4 feet above the ground, when only 7 

 years old. Another tree in the Botanical Gardens 20 years 

 old measured 13 feet in circumference. I do not know 

 whether you took notice of the " Sau " tree which was 

 growiug iu Borsillah Factory, not 100 yards south of the 

 Iron Tea bouse ; I once measured the trunk and as far as 

 1 eau recollect, 3 feet above the base it was 14 feet in 

 circumference, and the branches spread over at least one 

 twentieths! ■"' •" There were no vacancies among th 



