14 
soil culture particularly as a means of breaking up heavy sub-soils. 
Experiments were conducted at Kuala Lumpur Government Planta- 
tion with dynamite where good results were obtained as regards 
girth increase of young rubber. The greatest objection would 
appear to be that of cost. 
Manuring. 
The question of artificial fertilizers as applied to rubber is a 
rather delicate one and requires to be carefully considered. As long 
as good yields can be obtained by cultivation it is probably a mistake 
to resort to manuring. At Castleton Estate, Telok Anson, an 
extensive series of manuring tests are being conducted on good class 
land and the results obtained so far would not appear to justify their 
application, and many estates with rich soils would, in all probability, 
behave in a similar way. There are, however, many cases where it 
would appear that manuring is to be recommended and the man 
with Jong practical experience can generally discover those areas. 
A test was conducted in the Kuala Lumpur Gardens with young 
rubber growing on poor l&terite soils with the following results : 
In the first year, the trees in the manured plots, in every case, showed 
a good excess in girth measurements over the trees in the 
unmanured plots. In the second year, there was no manure applied, 
and the average girth increases for this period were about equal to 
that of the control plots, which goes to prove that the manures had 
good effect for one year only. At the commencement of the third 
year, a second application of similar manures was applied, and the 
results for this year were also satisfactory but the excess was not as 
large as that of the first year. In the fourth year, no fertilizers 
were applied, and it was found that the manured plots had not given 
as large an average girth increase as the control plots. In this 
particular soil, the manures appear to have had a stimulating effect, 
as regards growth, after each application, for about oue year but 
afterwards there seemed to be a slight reaction. Over the four 
years, however, the total girth increases of the manured plots in 
every case considerably exceed that of the controls. At the close of 
the four years tapping was commenced and it was found that the 
control plots gave the poorest yields of rubber while the highest 
yields were obtained from those manured plots which gave the 
largest girth increases. This is the result for the first nine months of 
tapping and it will be interesting to see how long the high yields are 
obtained. In the ninth month of tapping the manured plots continue 
to. give the proportionate excess of rubber over the unmanured plots, 
and there se.ems no evidence at present of a declining superiority ; 
rather the contrary. I have not the slightest doubt that the 
fertilizers in this soil were beneficial, for we would appear to have 
recovered the costs of application in the first nine months of 
tapping. It should be remembered that increase of girth means a 
corresponding increase in length of tapping cut. 
