977 



of eacl) ^). Tlie timber may be chiefly considered as hear! wood, so 

 that the auiomit mentioned above must yield 20.743470 kg., con- 

 taining 5.()94082 kg. of phosphoric acid. To |)revent overeslimation 

 the (irewoüd was taken for sapwood. A weighl of 4855.447740 kg. 

 furnished 35.930313 kg. of ash containing 11.486921 kg. of phosphoric 

 acid. Tlie total amount of P'O* of which the ground of the djati- 

 forests were deprived in (he years 1902 — 1915 is 17.181003 kg. or 

 a yearly average of 1.2272 J 2 kg. on > surface of 713474 H.A. ') 

 or 1.72 kg. per H.A. 



As known, Teclona thrives on any soil, even a poor one. In tlie 

 island of .lava by far most of its forests lie on limemarls, which 

 ai-e reckoned to belong to |)liosphoric acid poor soils. It has to 

 surmou)it the difficulty of procuring the required amounts of P'O' 

 by means of its roots. In ils youth this is achieved by a strong 

 taproot. H. J. Kekbert established that the root of a 31 month- 

 old tree had already reached the height of 140 cm. ') 



When the ti-ee has reached the polewood stage the taproot dies 

 down, while the lateral roots develop into a strong root-system, 

 enabling the tree to draw the available foodstuffs from the soil in 

 an effectual way. 



According lo S. H. Kookdkks and Th. Valeton djatitrees ± 25 m. 

 high, had lost the taproot, on the other hand numerous lateral roots, 

 of 3 m. length at the most, branched out considerably, to 3 m. 

 round about the slem *). 



As yet it has not appeared that the gi-ounds in Java covered 

 with djati, have been explored from (inie immemorial. Sometimes*) 

 the ground is said to be "tired" of djati, but nobody has as yet 

 ti'ied to ascertain whether want of phosphoric acid is the cause of it. 



We wish lo emphasize the circumstance that the above mentioned 

 1227112 kg. of phosphoric acid, withdrawn every year from the 

 grofinds, is not really a loss, bul only a displacement ofP''0\ Onl}- 

 such a (piantity of phosphoric acid as is comprised in the leakwood 

 exported, may be called a real loss. 



') J. S. Gamble A Manual of Indian Timbers. New Ed. London lOOïJ. p. 532. 



-) Verslag van den Dienst van hel Boschwezen in iNederlandsch-lndië over het 

 jaar 191 ó. Batavia 1916, p. 1. il mailers lillle Ihat formerly the surface was 

 thousands of hectares smaller. 



^) Worleldiepte van de djati. Bosclibouwkundig Tijdschr. Teclona 1. Noordwijk- 

 Weltevreden 1908—9. p. 340. 



^) Bijdrage N". 7 lot de kennis der boomsoorten op Java. Mededeelingen uit 

 's Lands Planlenluin N". XLII Batavia 1900, p. 166. 



'") A. E. J. Bruinsma, Opmerkingen van een oudgediende. Bosclibouwkundig 

 Tijdschr. Teclona 3. Noordwijk — Weltevreden 1911, p. 5. 



