THE FERTILITY OF SOILS IN THE TROPICS 415 



to texture or drainage have been noticed, they have been 

 directly referable to the phosphate content. 



Comparing soil 5, for instance, with another from the 

 same estate, of which the mechanical analysis is practically 

 the same, which contains as much nitrogen and more 

 potash, and yet gives only 300 Ib. per acre in place of 

 the former's 450 Ib., from equally old trees, it is seen 

 that the " available " phosphate present in the worse- 

 yielding soil is only half that in the other (0*0017 to 

 0*0033 P er cent.). A field poorer still from the same 

 place contained only 0*0012 per cent. " available." 



Still it is not possible to lay down any rule as to the 

 minimum quantity essential for a satisfactory yield as 

 this must depend on the texture. In two soils the 

 amounts of available plant food required to produce an 

 equal effect may be assumed to be inversely proportional 

 to the extent of root development attained by the trees 

 in those soils, other conditions being equal. 



Lime. The hill soils normally contained from 0*02 to 

 0*10 per cent, of lime, the clay soils from 0*15 to 0*30 per 

 cent. In rare cases only, usually coast soils, is up to 

 i per cent, found. 



Small though these quantities seem, they yet appear 

 to be sufficient, except in the case of acidic peaty lands. 



It is by no means proved that liming is necessary on 

 the lighter lands; in fact, on No. i it has been found 

 to produce very little effect on the yield of the tree. On 

 the clays, however, it is of benefit in improving the 

 texture, and liming is the only measure capable of pro- 

 ducing amelioration that has as yet been tried. 



COCONUT SOILS. 



Although native-owned coconuts are to be found in 

 every part of the country, on all classes of soil, those 

 owned by European companies are, with a few excep- 

 tions, to be found on the more or less peaty lands lying 

 along, the west coast. When well drained, this soil 

 proves itself admirably adapted to the cultivation; some- 

 times the trees begin to fruit as early as 4 or 4^ years, 

 and by their eighth or ninth year are yielding yearly 

 sixty to eighty nuts per tree. 



