I I STING GRAPE VARIETIES IN THE VINIFERA REGIONS. 9 
SONOMA EXPERIMENT VINEYARD. 
The Sonoma Experiment Vineyard was established in the spring of 
1904, on the property of the Gundlach-Bundschu Wine Company, 
about 2 miles south of Sonoma, Sonoma Co., Cal., about 110 feet 
above sea level. (See PL IV, fig. 2.) The soil is of rather poor 
quality, and to a depth of 8 or 10 inches is a gray loam more easily 
tilled than its texture indicates. The subsoil to 6 feet or more in 
depth is clay, changing at 4 feet, with an increase of sand, from a 
light-brown to a yellowish brown color. The soil is found near where 
weathered shales from the surrounding hills have been partially 
broken down and transported into the valleys, where they decom- 
pose. The soil usually occupies small, undulating ridges, or eleva- 
tions, and is surrounded by the dark-brown, alluvial clay loam of the 
valley floor. The surface drainage is good, and no injurious quan- 
tity of alkali exists. This soil occupies extensive areas in the Sonoma 
Valley and in the adjacent bay regions and produces superior white 
wines of the Riesling, Chasselas, and Traminer types. 
STOCKTON EXPERIMENT VINEYARD. 
The Stockton Experiment Vineyard was established in the spring 
of 1907, on the property of the San Joaquin Valley Realty Company, 
a little over a mile southeast of Stockton, about 15 feet above sea 
level, on Stockton clay-loam adobe. (See PL IV, fig. 3.) This type, 
locally known as black adobe, was laid down in a swamp or tidal marsh 
in quiet water, the decomposing vegetation giving it a black color. It 
is a clay loam in texture, adhesive and sticky when wet and very hard 
when dry, cracking into large, cubical blocks full of small, cubical 
fractures. Sufficient rain slacks the clods readily. Cultivated when 
neither too wet nor too dry, the soil is friable and pulverizes well. 
The subsoil is a light-yellow silt loam, usually separated from the 
surface soil at a depth of 2J feet by a thin stratum, about one-half 
inch thick, of rather soft marly or calcareous hardpan, which is not 
always continuous and is often broken or disintegrated. Roots and 
water readily penetrate the subsoil, often passing through the hard- 
pan. The depth to the water table varies from 3 \ to 6 feet for wet 
seasons and from 6 to 10 feet for dry seasons. This variation is 
influenced by a thin, marly hardpan which appears to hold the water 
down under pressure. It is somewhat difficult to establish vineyards 
on these soils, but when established they are very productive and last- 
ing. Grapes for diverse purposes are grown on them. One of the 
largest sweet-wine establishments in the world is located near Stock- 
ton, and heavy shipments of table grapes grown on these soils are 
made. Soils of this type have been mapped in California as follows: 
Stockton, 53,312; Hanford, 5,470; and Fresno, 5,664 acres. It cov- 
ers many thousand acres between the Marysville Buttes and about 
North Durham in the Sacramento Valley. 
