61 
Assuming these figures to be approximately correct, it would appear at 
first glance somewhat of a puzzle to determine how the tree manages to 
thrive and take up 8 much nourishment each year from a soil seemingly 
so devoid of fertility as that along the sea at San Ramon. However, 
when we consider the total amount of soil available to each tree, the 
problem becomes a simple one. The root mass of a coconut draws nutri- 
ment from a depth of at least 2 meters below the surface of the ground 
and outward on all sides for from 34 to 63 meters distance from its base. 
It thus comes in contact with an exceedingly large mass of material and 
it makes use of all the available nourishment therein. 
In 1 hectare, or 10,000 square meters, of land there is available to the 
coconut trees planted thereon a total of at least 20,000 cubic meters of soil, 
or, if we allow a specific gravity of about two, 40,000,000 kilos, 
From the table of analyses of San Ramon soils, we find that the soils 
near the sea average about as follows: ; 
Per cent. 
oe ir ee 0.07 
i) re ea 50 
Phosphoric: eid si..:.sstscsccc--osis1sseassosectesdetesttn a 07 
In 40,000,000 kilos we have— 
Kilos. 
Ei ie. 28,000 
RII nove aco cet ese ecdashonwtniah sic detsssentcateiacacee SAS Mg 200,000 
Phomphorio acid 2.2. ..c.ccossccccec.0cscs00s8:-ss1esouie a 28,000 
From the amount taken from the soil in each year, even though no 
fresh addition were made, we can calculate the number of years required 
completely to exhaust this soil of its plant food as follows: 
Years. 
INTE ea srs cere iactgc cece ev recs sn cc tninistose.shoss ve ee. 307 
Potash .......:......c0tsea tei knee 1,478 
Phosphoric acid .... ogee oh oid. ae ec: 677 
These figures are naturally only an approximation, but they show that 
even in a comparatively poor ground there exists more than an abundance 
of nourishment for the coconut tree, provided the soil itself is sufficiently 
porous and well watered.* 
It seems very probable that in San Ramon at least, if not in most plan- 
tations along the seacoast, the nutritive material comes not from the soil 
in which the trees are actually growing but from an inexhaustible supply 
of water, laden with plant food, which is constantly seeping down from 
the higher ground toward the ocean. This underground water supply 
would account for the flourishing condition of trees in a sandy soil near 
the sea, even in times of drought, when individuals farther inland in 
higher, less permeable ground would be dying from want of water. 
“See the paper by E. B. Copeland on the transpiration of the coconut and the 
amount of water taken up by an individual tree. 
