Page 57 - Grapevine SeptOct 2021

Around The Vineyard

tial of this agricultural practice? During the 2020
Oregon Wine Symposium, held virtually from
February 16 to 19, 2020, two panels delved into
the nuances of what defines high quality soil and
the role cover crops play in generating organic soil,
focusing particularly on how to best utilize cover
crops in the vineyard setting.

At the first panel, “Soils and Cover Crops: Back
to Basics,” James Cassidy, Senior Instructor in
Soil Science & Sustainable/Organic Agriculture
at Oregon State University, opened with a short
presentation on Soil 101. He described soil as “rot-
ted” rock and decomposed organic matter. Next,
he broke down soil into soil solids (mineral 45%,
organic 5%) and pore space (air 20-30%, water
20-30%). Carbon from the atmosphere and energy
from the sun transform these materials into soil
courtesy of the billions of organisms present in a
single pinch of soil.

“Internalize the idea that soil is habitat for every-
thing that is alive on this planet,” Cassidy said.

During irrigation, rain or another precipitation
event, gravity pulls the water into the soil’s mac-
ropores. As water flows through these macropo-
res, it sticks in the micropores inside the soil and
eventually fills with water. Then the soil drains, and
there’s air in the soil.

“When the soil is draining, it’s actually breathing,”
Cassidy said.

The rate at which water moves into the soil is
impacted by various factors, including soil type
(texture structure, aggregate stability, hydrodynam-
ic characteristics), topography and morphology of
slopes, flow supply (rain intensity, irrigation flow),
and the initial condition of the soil’s humidity.

Currently, on Earth, a hectare of productive
soil is lost every six seconds. While farmers can’t
change their land’s soil type or topography, they
can manage for stable aggregates, a wide pore size
distribution structure and minimized compaction.
Well aggregated, stable soil pulls in water. This
means the water goes deeper into the soil instead
of producing runoff, which carries away the small

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