388 
Both the nature of the soil and the requirement of the crop has 
to be considered in applying fertilizers. 
Nitrogen is essential to the production of a good leaf growth. 
Phosphates are essential to seed production. Potash is necessary in 
the production of woody growth and in the elaboration of carbo- 
hydrates (sugar, starch, etc.,) and since it is believed that the caoutchouc 
substance is built up from carbohydrate material, the application of 
Potash should be beneficial. Lime is the essential constituent of the 
wood, but is of more value indirectly in rendering available other 
dormant plant foods in the soil. 
In the Federated Malay States, the soils are usually rich in 
Nitrogen, although this constituent may not be in a readily available 
form — owing to the sourness of many of the soils when first broug t 
V into cultivation from virgin jungle, this being especially so in the 
lowlying coast districts. 
Lime, Potash and Phosphate are generally very deficient. In spite 
of the richness of the soil of many rubber estates, there are marked 
exceptions where the soil may be described as very poor and where 
the growth of the trees is very slow. 
4 
Method of Application. 
Fertilizers should not merely be spread on the surface of the soil, 
which on most estates is hard, as with a heavy rainfall they would 
be rapidly washed into the drains. On all estates where the trees are 
two years old or more, it will be found more economical and effective 
to broadcast the manures and lightly fork over, the surface soil. 
Artificial fertilizers are best applied after mixing with fine earth to 
ensure better distribution. 
Fertilizers applicable to Certain Soils. 
Another important point in connection with the application of 
manures is that certain manures must not be used on certain soils, 
thus, Superphosphates as a source of Phosphoric acid and Ammonium 
Sulphate as a source of Nitrogen should not be used on peaty soils 
as they increase the acidity of such soils. Superphosphates should 
not be used on day soils, and Sodium or Potassium nitrate should not 
be used on clay soils as it deflocculates the clay, and renders it more 
heavy. 
Organic nitrogenous manures, as a source of nitrogen, Potash 
fertilizers and lime are specially suitable on light sandy soi s. 
The application of lime to improve the physical texture and Bacis 
slag as a source of phosphates is especially applicable to clay soils 
which usually contain potash in excess. 
