Field Demonstration Description


Demonstration Title:  Effects of Tillage on Soil Health and Carbon Sequestration in Vineyard Soil


Name: Indian Springs Ranch, John MacLeod

Address: Glen Ellen, CA

Research Background, Problem, objectives: 

Vineyard floor management in vineyards across Sonoma County typically vary between full (all-row) tillage, alternate-row tillage, and no-till, which is often dependent on the age and vigor of the vine and rootstock. Additionally, site topography, soil depth, microclimate, weed and pest pressure could also play a role in deciding what tillage methods are used.

The objectives of this demonstration are to compare soil health, vine growth, soil carbon sequestration, and cost for the three alternate tillage methods.  Soil health indicators to be monitored include compaction, water infiltration/water holding capacity, total organic carbon, and bulk density.  Vine growth will be monitored by collecting pruning weight and grape yield data (if feasible) during harvest and post-harvest pruning.

In addition to this demonstration project, a second research project is currently underway (funded by a separate grant from the Conservation Innovation Grant Program) and will be gathering information about soil moisture (using soil probes) throughout the season across each treatment plot. The purpose is to document which tillage method retains the most moisture in the ground at different times of the year.

Tillage Systems Being Evaluated:

  1. Full (all-row) Tillage – all tractor rows tilled every year
  2. Alternate Row Tillage – every other tractor row tilled every year
  3. No-Till – all tractor rows remain untilled

Vineyard Description:

Soil map unit(s): Laniger loam

Available water capacity (according to soil survey): Depth to root restrictive layer: 20-40”
Well drained. Low water movement in restrictive layer. Available water to depth of 60” (or   restricted depth) is low. 2.4 “water holding capacity to 20 “ depth and 3.6” to 30” depth.

Slope: 15 – 30%

Surface texture (according to soil survey): loam

Grape variety and clone:   Zinfandel-Wente

Grape rootsock: St. George

Vine spacing: Each vine row is 2 side-by-side rows, with 3’ between rows, 8’ between vines, and a 9’ tractor row.

Vine age: 21 years

Irrigation system: Drip irrigation (.5gph)

                Other (e.g. disease or pest issues): Organic matter content in surface horizon is about 3%.

Soil management (tillage, cover cropping, fertilization, compost/manure/other amendments): Prior to the onset of the CIG experiment, the vineyard block had been managed with alternate row tillage and some yearly applications of mango mulch or green mulch from Grab and Grow. Fertilization is done by yearly fertigation through the drip irrigation system and based on yearly petiole analysis. Calcium is sometimes broadcast on the ground as needed to adjust pH. A vineyard cover crop mix from LeBallister’s is typically seeded each fall in the tilled tractor rows with the non-tilled rows remaining in a native cover mix.

Experimental Design:  The experiment is arranged as a randomized layout with three replications for a total of 9 plots.  Each plot encompasses two tightly spaced, side-by-side vinerows (24 vines) and two tractor rows and is approximately 21ft wide by 100 ft long with 10 ft buffer between the test plots.

Trial Duration:  3 field seasons

Variables measured and recorded

Variable Sampling approach* Timing
Field operations and management issues Vineyard Manager keeps log of activities Whenever vineyard operations are conducted, or when issues are observed
Infiltration (single ring) TBD Winter when soil is at field capacity
Compaction TBD Winter when soil is at field capacity
Soil Moisture Content Data collected via soil probes and dataloggers Throughout the year
Yield (cluster number & weight per vine) Sample 6 vines per plot. Immediately before or during harvest (if feasible)
Soil organic matter and/or soil health assessment suite of measures Soil samples collected from each tractor row within a test plot at 3 depths: 0-10 cm, 10-20 cm, 20-40 cm and analyzed for bulk density, TOC, soil texture Baseline samples collected on 5/1/17 and 5/5/17. Final sample collection slated for 2019.