and Magazine of the Ceylon A gricultural Society, 



185 



PROGRAMME OF EXPERIMENTAL 

 WORK. 



At Heeleaka for the Season 1908. 



Calcutta, 2nd July, 3908. 



In the Report on the Heeleaka Experimental 

 Station for the years 1905 to 1907 a general 

 account has been given of the various manu- 

 rial and other experiments carried out there 

 during the past three seasons. The present 

 report is intended to give some idea of the 

 further work which it is hoped to carry on 

 in the present and following years : — 



Manukial Experiments. — It has been 

 pointed out in previous reports that the econo- 

 mic value of such manures as Superphosphate 

 and Sulphate of Potash depends largely upon 

 their residual effect, and that their compara- 

 tively high price must be counterbalanced by a 

 corresponding maintenance of the increased 

 yield which they produce. With a view to 

 elucidating this point, a system of manurial 

 rotation has been instituted, based upon the 

 assumption that the amounts of Phosphates 

 and Potash originally applied to the plots 

 Nos. 4, 5, 6, 7, should be sufficient to meet 

 the requirements of the bushes for at least 

 three years, whilst Nitrogen, as Nitrate of 

 Soda, will be supplied annually. These four 

 plots originally received dressings of Phos- 

 phatic and Potash manures in the form of 

 Superphosphate (Nos. 4 and 6—3 cwt. per 

 acre), and Basic Slag (Nos. 5 and 7 — 5 owe. 

 per acre) whilst all four plots received 2 cwt. 

 Sulphate of Potash. Nitrate of Soda was 

 applied at the rate of 2! cwt. per acre to Nos, 6 

 and 7, and the greatly increased yield of these 

 two plots was obviously due to its action in com- 

 bination with the phosphoric acid and potash, 

 its absence in Plots Nos. 4 and 5 producing 

 a corresponding diminution of yield as com- 

 pared with the former. These applications were 

 repeated in the second year, but no manure was 

 applied in tbe third ; and it is now proposed to 

 make use of these four plots as the starting 

 point of a manurial rotation, in which the origi- 

 nal dressings will be depended upon to supply 

 phosphates and potash for the next two years, 

 the more rapidly exhausted Nitrogen being ap- 

 plied annually. In previous publications stress 

 has been laid upon the 



value of a proper propoktjon between the 



various ingredients 

 of a manurial mixture, and especially the 

 amount of Nitrogen, any excess of which may bo 

 regarded as injurious. In a mixture of Super- 

 phosphate, Sulphate of Potash, and Nitrate of 

 Soda, the two former may be considered as 

 coming into action as plant foods with compara- 

 tive slowness, whilst the Nitrogen in the latter 

 is already available, so that in a manure of the 

 above composition the effective ratio of Nitrogen 

 to Phosphates and Potash varies as the season 

 advances, being high at the commencement but 

 rapidly becoming less by reason of the great 

 solubility of the nitrates in rain water, and the 

 inability of the soil to retain them as it does 

 phosphoric acid and potash. Thus in supplying 

 nitrogenous manures we have two points to 



24 



consider: first, the liability to lose nitrogen in 

 drainage water, and secondly, the difficulty 

 of maintaining the proper proportion be- 

 tween the supply of this element and 

 that of the phosphoric acid and potash ; 

 the importance of preserving this propor- 

 tion throughout the year is especially great 

 in connection with a leaf crop, the uniform 

 quality of which has to be maintained, so far as 

 is possible, for some six consecutive months. 

 The adoption of the annual small dose of oil- 

 cake in preference to the triennial large one is 

 an admission and recognition of this state of 

 affairs, and it is now proposed to take further 

 steps in the same direction by extending the 

 principle of the small dose, and applying it not 

 only to differentiate annual from triennial ap- 

 plications, but to modifying the method of 

 manurial treatment throughout the season. The 

 method depends upon the assumption that the 

 greater success of the annual small doso of 

 manure is principally due to the fact that the 

 roots of the tea bush are only able to take up a 

 limited amount of nitrate in solution during 

 any given period of time, and that any excess 

 present in the soil is lost by removal in drainage 

 water. In order to avoid each loss it would then 

 seem necessary to supply the nitrogenous manure 

 in small doses at frequent intervals, and this 

 method is now being adopted in the various ex- 

 perimental plots receiving nitrogen, whether 

 in the form of Oilcake, Animal Meal, Nitrate of 

 Soda, Sulphate of Ammonia, or Nitrate of 

 Potash. The following table shews the arrange- 

 ment of the plots and the amounts of the 

 manures applied : — 



Table No. 1 



Number of 



Plot No. Manure Rate per acre, doses. 



9 f Ammonium) cwt. 



\ Sulphate / 2 2 



2a do 1 1 



3 Nitrate of Soda* 2?, 2 



3ra do lj l 



i do If 3 



5 do 1| 3 



6 do 1£ 3 



7 do 14 3 



In the above series Nos. 4 and 6 originally 

 received dressings hi Superphosphate (3 cwt. 

 per acre) ; Nos. 5 and 7 being manured with 

 Basic Slag (5 cwt. per acre) : all four plots 

 received sulphate of Potash (2 cwt. per acre) : 

 the object of the experiment being to determine 

 the residual effect of these minerals in conjunc- 

 tion with repeated doses of Nitrate of Soda. 



In order to complete this experiment four 

 plots have been arranged as follows, making 

 use of the Nos. 3 and' 4 of the Pruning Plots 

 which are no longer required for experi- 

 mental pruning ; on these plots the relative 

 merits of the divided and of the single dose 

 it is hoped will be ascertained : — 



Plot No. Manure. Pel- Acre. 



3 Oilcake 6 mds. 



3a do 6 „ 



i Animal Meal 3 ,, 



4a do 3 „ 



Number of 

 Applications. 

 3 of 2 mds, 

 1 „ 6 „ 

 3 ,, 1 ,, 

 1 3 „ 



This method of application will be further 

 tested on Plot No. 20 Manurial Series where 

 the annual application of Nitrate of Potash on 

 both halves of the plot will be subdiv ided, the 

 one receiving its dressing in two doses, the other 



