TESTING GRAPE VARIETIES IN THE VHSTIFEEA 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 PI. 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 Trammer types. 



STOCKTON EXPERIMENT VINEYARD. 



The Stockton Experiment Vinej^ard 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 PI. 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. 



