Parent Material
Limestone is a known parent material in southwestern and northeastern parts of the Sonoita AVA.1 Igneous rock, quartzite, schist, granite and gneiss, as well as igneous and metamorphic rock also occur in northeastern areas.
Parent material is the type of bedrock from which soil forms. As a component of vineyard soils, it influences water infiltration, storage, and drainage, erodibility, pH, nutrient availability, and heat absorption, which affect root, canopy, and fruit growth.
Jeremy Weiss
Major Rock Types
Conglomerate and sandstone are the most abundant rock types in the northwestern, north-central, central, and southeastern parts of the Sonoita AVA.2 Gravel, sand, sandstone, siltstone, rhyolite, and felsic metavolcanic rock occurs in many northeastern and west-central areas.
Major rock types are the most common solid, loose, and unstratified rocks, defined by composition, texture, and origin. As a component of vineyard soils, they influence water infiltration, storage, and drainage, erodibility, pH, nutrient availability, and heat absorption, which affect root, canopy, and fruit growth.
Jeremy Weiss
Depth to Bedrock
Known depths to bedrock are 12 to 24 inches in the western, northeastern, and southeastern parts of the Sonoita AVA.1 Areas with depths less than 12 inches also occur in the northeastern and southeastern parts.
Depth to bedrock represents the distance from the soil surface to the top of a restrictive layer, such as bedrock and other dense layers. As a component of vineyard soils, such restrictive layers can impede water drainage and restrict root depth.
Jeremy Weiss
Texture
Loam is known to occur in areas throughout the Sonoita AVA.1 Sandy loam and silt loam are common along perennial, intermittent, and ephemeral surface water features like Ciénega Creek and Babocomari River. Areas of fine sandy loam exist along the eastern boundary of the AVA, as do areas of sandy clay along the southern boundary.
Texture represents the relative proportions of mineral grains in soil based on their size. As a component of vineyard soils, it influences water infiltration, storage, and drainage, erodibility, pH, nutrient availability, and heat absorption, which affect root, canopy, and fruit growth.
Jeremy Weiss
Drainage Class
Almost all of the Sonoita AVA has well-drained soils.1 Areas of somewhat excessively, moderately well, and somewhat poorly drained soils additionally exist in the east-central and southeastern parts.
Drainage class refers to the rate at which water drains from soil, how frequently water occurs in soil, and at which soil layers water is found. As characteristics of vineyard soils, these conditions influence soil moisture and nutrient and oxygen availability, which affect root, canopy, and fruit growth.
Jeremy Weiss
Available Water Storage
Many areas in the Sonoita AVA have available water storage in the top approximately 40 inches of soil greater than three inches.1 Available water storage values greater than five inches are common along perennial, intermittent, and ephemeral surface water features like Ciénega Creek and Babocomari River. Areas with values less than two inches occur in the northeastern, southeastern, southwestern, and northwestern parts of the AVA.
Available water storage represents the amount of water soil can store, in this case in the top approximately 40 inches (1 meter), for plants. As a characteristic of vineyard soils, it influences how much rain, melted snow, and irrigation can be absorbed as well as irrigation frequency.
Jeremy Weiss
pH
Soil pH is between 8 and 9 for many areas in the central and north-central parts of the Sonoita AVA.1 Areas with pH between 7 and 8 co-occur in these parts of the AVA along perennial, intermittent, and ephemeral surface water features like Ciénega Creek and Babocomari River, as well as along the east-central and southwestern AVA boundaries. Isolated areas with pH between 6 and 7 appear in the central part of the AVA, in addition to more widespread areas in northeastern, southeastern, and northwestern parts.
Soil pH reflects the relative acidity (values less than 7) or alkalinity (values greater than 7) of soil. As a component of vineyard soils, it influences nutrient availability, which affects root, canopy, and fruit growth.
Jeremy Weiss
1 Gridded Soil Survey Geographic (gSSURGO) Database for Arizona, United States Department of Agriculture, Natural Resources Conservation Service, July 2020 Release. Not all areas have complete or available data.
2 US Geological Survey Mineral Resources, Arizona geologic map data