19, 4 keinking and Groff: Siamese Seedless Pummelo 403 
fore any definite statement can be made in regard to the effect of 
salt on the quality of fruit produced, careful control experiments 
will have to be conducted. Enough evidence has been collected, 
however, to indicate that the salt water does have some relation 
to the quality of the fruit. 
SOIL 
In general, the surface soil in the delta region is heavy, clayey, 
and of an entirely alluvial formation. The subsoil is a heavy, 
gray, brick clay, which is rather impervious to water. The 
topsoil in the orchards at Ban Mai is a dark gray to grayish 
brown (dark brown when wet), clay to clay loam soil. Some grit 
and sand are present. The subsoil for the same region is a very 
sticky, light slate brown clay. The canal mud, which is com- 
monly used as a fertilizer, as it is composed of the decomposition 
products of organic material and the deposit of fine clay that has 
fallen into the canal, is light brown, with a slaty tint, clay to 
sandy clay, with some grit. The topsoil, collected in the re- 
gion of Bang Bakok near Bangkok, which is noted for its 
production of the commercial Kao Phuang variety of pummelo, 
is not quite so clayey as the Ban Mai soil, being a light brown 
clay to sandy clay grit. The canal mud from the same region 
is a dark gray to light brown, heavy, clay soil. Samples of the 
topsoil, subsoil, and canal mud used for fertilization were col- 
lected for physical analysis from the Ban Mai and Bang Bakok . 
regions. Samples 1 to 8 are from a Nakorn Chaisri orchard; 
and samples 4 and 5 are from a Bang Bakok orchard. The 
standard United States Bureau of Soils centrifuge method was 
used, and the results are given in Table 11. 
TABLE 11.—Physical analyses of soils in pummelo orchards at Ban Mai 
and at Bang Bakok, Siam.* 
Sample. Clay. Silt. Sand. Location. 
Per cent. | Per cent. |Per cent. 
Dig ee ee ee a 3.7 21.4 4.9 | Topsoil, Ban Mai. 
EE EEE spa 78.8 18.4 2.8 | Subsoil, Ban Mai. 
,_ Ne ro regt RS are GREE WEN UE oe 55.2 33.6 11.2 | Canal mud, Ban Mai. 
TREE aie VEG ethane aia Lec ex eect SENN es 56. 98 31.1 11.92 | Topsoil, Bang Bakok. 
_ EE aE See eal POE Be Nay ae aR EG 64.5 33.6 1.9 | Canal mud, Bang Bakok. 
® Determinations by Miss H. Kenward, of the department of chemistry, College of 
Agriculture, Los Bafios. 
The results of the physical analyses show that all of the soils 
are extremely clayey, containing over 50 per cent of clay. The 
