43 2 THE FERTILITY OF SOILS IN THE TROPICS 



In the close neighbourhood of the experimental field 

 the head-teacher of the State School on Buderim Moun- 

 tain carried out some manuring experiments with 

 bananas, besides growing a large number of different 

 varieties. The soil was a virgin soil of good quality, 

 and the results of his experiments show that on a virgin 

 soil the application of our standard (KPN), twice a year, 

 gave the most profitable harvest. The incomplete fer- 

 tilizer, without potash, did but barely pay for the applica- 

 tion of the fertilizer, as compared with the unmanured 

 plot, showing the importance of potash to the banana 

 plants. The results of his experiments were as follows : 



Application of nil (PN) (KPN) 2(KPN) 



manure 

 Cost of manure nil 9 8s. 6d. 12 6s. 6d. 23 45. od. 



per acre 

 Value of crop 28 us. gd 39 35. od. 67 2s. 3d. 5$ 155. 2d. 



per acre 



Of particular interest to the agriculturist will be the 

 question, how such heavy manurial dressings affect the 

 physical and chemical properties of the soil. New 

 samples of soil were taken after the experiments had 

 been in progress for four years. One sample was 

 obtained from the unmanured row 15, another was taken 

 from the heavily manured row 12, a few feet from the 

 stool, at places where the fertilizer was actually applied. 

 Another sample was taken between the unmanured rows 

 15 and 16, and lastly a sample was taken between the 

 heavily manured rows 19 and 20, where lime was applied, 

 'but outside the zone of artificial fertilizer. The last 

 sample shows clearly that the manure does not spread its 

 effect to any distance and that the plants evidently utilize 

 it as soon as it is applied. In row 12 only do we find 

 a distinct increase in the amounts of available plant food 

 (see Table III). 



The physical conditions of the soil were improved by 

 cultivation and manuring, and the soil is now in excellent 

 condition, enable of producing good crops, as the plants 

 are enabled to utilize the fertilizers easily. 



The owners of the experimental fields are quite con- 

 vinced of the profits derived from the application of our 



