9. A Very Gravelly Sandy Clay Loam
Soil is an essential part of a vineyard's identity. I recently was very lucky to host three soil scientists from the Natural Resources Conservation Service (NRCS) which is part of the USDA. The knowledge and expertise they shared was very encouraging and helpful. They dug two observation holes, one in the vineyard site that will be planted next spring and one a few hundred feet higher on the slope which may be planted in the future. They described the different layers of soil in each location. Some key take-aways were: the soil is volcanic in origin and ranges from 30% clay and 50% sand near the surface to 50% clay and 30% sand at a depth of 40 inches. There are a lot of rock fragments throughout. The soil is deeper than 40 inches but because we were digging by hand we were not able to investigate the deeper layers. In the future I plan to dig some deep pits with a backhoe in order to get a good look at the deeper soils. The NRCS guys have already agreed to come back and help me out again whenever we can dig the deeper pits.
This is good news for grapes! The abundance of rock fragments and sand content will mean that the soil drains well and the clay content will mean that the soil will be able to store some water which means that both rain and irrigation water will stick around in the soil and be available to the roots longer.
Another service provided by the guys from the NRCS was cataloguing all the plant species present at the site. Over 40 plant species were identified in a small area around where we were digging indicating that the ecosystem was balanced and healthy. A big part of Alta Marfa is going to be doing as much as possible to minimize the disturbance of this natural balance and using the strength and resilience of the native plants to the benefit of the vineyard as cover crops and ground cover.
A big thank you to Lynn, David and Will from the NRCS in Marfa! I look forward to working with them again in the future.
Click the link below to read the Soil Analysis