The Supplement to the Tropical Agriculturist 



e.g., the deep roots of wheat as compared with 

 the shallow roots of barley. Let us examine 

 what - 01 per cent potash really means. The ap- 

 parent density of average soils is a little over 1, 

 and taking the weight of a cubic foot of water 

 at 62 - 5 lb., the weight of soil, calculated to a 

 depth of 1 foot, gives roughly, 3,000,000 lb. per 

 acre. Now -01 of this is equal to 300 lb. per acre, 

 and even this is a considerable amount, or as 

 much as would be contained in fully 5 cwt. of 

 muriate of potash. Yet experiments have 

 proved over and over again that the addition 

 of, say, 1 to 2 cwt. of soluble potash manures 

 to these soils, together with nitrogenous and 

 phosphatic manures, has given not only an in- 

 crease, but a profitable increase, over the un- 

 manured and incompletely-manured plots. To 

 sum up the matter in characteristic American 

 terseness, much of the natural potash in soils is 

 "just about as soluble as window-glass," and 

 so to secure a vigorous start for the young 

 seedlings there must be present in the soil 

 readily available supplies of all the essential 



Elant foods, including potash. Planters are 

 eginning to recognise this from actual experi- 

 ence, with the result that complete, well- 

 balanced manures, containing nitrogen, phos- 

 phate, and potash, are being more and more 

 used every year. 



Recent confirmation of this is given in the 

 experiments conducted by Mr. ft. von Nord- 

 heim, on tea plantations in Java. These 

 experiments were introduced in 1907, and the 

 plots, four in number, were carefully chosen 

 to ensure that they were all on the same level, 

 and that the soil by previous results, was prac- 

 tically uniform. The area in each case was, 

 approximately, one bouw, 6qual to If acres, 

 though the main point governing the area of 

 each plot was the number of bushes, which was 

 6',0G0. The scheme of manuring of the four 

 plots was as follows : 



1. Unmanured (0) ; 2. 2 kg. crotolaria leaves, 

 as green manuring per bush (nitrogen); 3. 

 green manuring as in 2, with 20 grams 40 per 

 cent superphosphate (nitrogen and phosphate); 

 4, manuring as in 3, with 30 grams 50 per cent 

 muriate of potash (nitrogen, phosphate, and 

 potash). 



The crotolaria leaves, which, on analysis, 

 showed I per cent nitrogeu, and from one- fifth to 

 one-tenth percent of phosphate and potash to- 

 gether, were chopped up, aud well mulched into 

 the soil, whilst the artificial manures were dis- 

 tributed evenly around each bush, in a circle 

 about 1$ feet from the stem. The cultivation 

 received by each plot was the same, and the 

 results from December, 1907, to November, 

 1909, was as follows : 



Green Manur- 

 Unnianured. ing only. 

 1st 2nd 1st 2nd 

 quality quality quality quality 

 lb. lb. lb. lb 



From December, l"07, to 

 Novembr, 1S09, Green 



Leaves .. 1,544 6,148 1,604 6,279 



Dry tea for two years' 



harvest ... 1,789 l.f33 



Increase over unmanured — 4i 



Value of increasd at 9d 



per lb, - 33s. 



Green Manur- 

 ing with Phos- 

 phate. 

 1st 2nd 



Green manur- 

 ing with Phos- 

 phate & Potash. 

 1st 2nd 



lb. 



lb. 



6?16 



1671 



6810 



1972 



lb. lb. 



From December, 1907, to 

 November, 1909, iGreen 

 Leaves 1513 

 Dry tea for two years' 



harvest 1797 

 Increase over un- 

 manured 8' 183 

 Value of increase at 9d 

 per lb. 6s 137s 3d 

 In order to make sure that such a favour- 

 able result to the application of a complete, 

 well-balanced manure was no chance result, 

 another set of experiments on younger tea was 

 commenced in April, 1909, with the only 

 difference that the number of bushes was 3,000, 

 and the area accordingly of each plot was J 

 bouw, or seven-eighths of an acre. In this ex- 

 periment, also, the artificial manures were 

 not distributed in a circle round the bushes, 

 but were distributed over the crotalaria 

 leaves, and mulched into the soil on the upper 

 side of each bush. The manures, which need 

 not be quoted, were just half the quantities 

 used in the former experiment, and the re- 

 sults from April, 1909, to December, 191<">, 

 were as follows : — 



Green mania • 

 Unmanured. ing only. 



1st 2nd 1st 2nd 



From April, 1909, to De- 

 cember, 191", Green 

 Leaves 



Dry tea for 20 month's 

 harvest 



Dry tea for one years' 

 harvest 



Increase over un- 

 manured 



Value of increase at 9d 

 per lb, 



lb. 



lb. 



lb. 



lb. 



750 5618 

 1449 



869 



Green manur- 

 ing with Phos- 

 phate. 

 1st 2nd 



766 6039 



930 



61 



15s 9d 

 Green Manur- 

 ing with Phos- 

 phate & Potash, 

 1st 2nd 



From April, 1909, to De- 

 cember, 1910, Green 

 Leaves 



Dry tea for 20 months' 

 harvest 



Dry tea for one year's 

 harvest. 



lb. 



lb. 



lb. 



lb. 



5:38 



1424 



789 6536 

 1663 



998 



854 

 Decrease of 

 Increase over un- 

 manured 15 129 

 Value of increase at 9d 

 per lb. Loss : 96s 9d 

 Commenting on these results, Mr. Nordheim 

 states that as these experiments were carefully 

 conducted under the supervision of European 

 planters, one may safely conclude that the 

 two essential plant foods in this plantation are 

 nitrogen and potash, for from both experiments 

 the addition of superphosphate diminished 

 rather than increased the yields. One has 

 abundant proof, however, of the advantage of 



