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The application of large quantities of bulky organic 
manure, such as cattle manure, would almost cer- 
tainly be of value on some soils, which, owing to- 
their previous history and cultivation over a period 
of many years prior to the cultivation of rubber, 
are lacking in organic matter and nitrogen; but,, 
unfortunately, such manure is available only to a 
small extent in Malaya. Good results, however, are- 
said to have been produced by applying nitrates 
during the wintering season and field experiments 
on these lines are required in Malaya. 
Liming. The soils of Malaya are, as a whole, 
acid — some strongly so — but there is 
no evidence that acidity, as such, is injurious to 
rubber, although the resultant inferior soil texture 
may be. For this reason, improvement of mechanical 
condition by the addition of quantities of lime, small 
in comparison with the “ lime requirement ” (i.e. the 
amount required to neutralise the acid present) is 
frequently found to be beneficial. It would often be 
decidedly dangerous to apply the full amount of 
lime indicated by routine analysis. 
Conservation The prevention of soil wash on undu- 
of Soil. lating and hilly land is to-day one of 
the most insistent problems confront- 
ing rubber growers. Wherever possible on such land 
cover crops should be established; and, in addition or 
as an alternative, if the slopes are at all steep, silt 
pits, terraces or bunds should be constructed. 
Silt pits are trenches, usually about 2 fe^t deep 
and 2 feet 6 inches wide and 6 to 8 feet long, so- 
situated that all but the heaviest storm water with 
the suspended washed soil is caught and absorbed. 
The capacity of the silt pits should be sufficient to 
