Spring Cleaning in the Vineyard: How Eliminating Surface Grasses Conserves Water
April 27, 2016
Over the course of about six weeks, the vineyard has gone from looking like:
To looking like:
This transformation takes place as the rainy season ends, and our focus shifts from encouraging a cover crop to hold the topsoil in place to making sure that the vines (rather than the cover crops) get the bulk of the water that is stored in the absorbent limestone-rich soils. Think of each plant that's growing in a given plot of land as like a wick, with its roots delving into the soil for available moisture. If we had overabundant water, we might want to leave some surface weeds to keep levels more reasonable. Instead, in our California climate, eliminating competition from grasses and other surface plants is an essential part of our ability to dry farm. Tilling in the cover crop also allows the insects and microorganisms in the soil to start breaking down the surface biomass accumulated during the winter growth into nutrients that the vines will draw from in the coming months. Finally, the loosening of the soil creates an insulating layer at the surface that helps conserve the water deeper down.
The main tool we use to turn our cover crops under is the spader, shown in action below. The row to the right has been mowed but not turned under, while the spader is chopping up the topsoil with a collection of tooth-like blades that penetrate deep into the topsoil:
The end result, when a whole block has been spaded, is a manicured surface from which weeds rarely re-sprout, like the head-trained Tannat block below:
We're only about 30% done with turning the cover crop under, and the work will continue for another month. The one section that we have finished is Scruffy Hill, and it looks amazing. Two shots follow, beginning with the fully leafed out Grenache block, looking down over the less-advanced Mourvedre vines below:
And a view that shows you a close-up of the soils. Tilling in the surface weeds allows you to see just how calcareous the soils are:
Pretty soon, the whole vineyard will look like this, just in time for summer.