Fall 2020 - 34

SOIL HEALTH
tillage which is a main method of weed control and you need
to compensate for that somehow, " Brainard said.
The rye cover crop poses challenges - mainly the crop
interface. Thick cover crop residue can delay planting and
reduce crop stand establishment and yield.
Less nitrogen availability is an issue in the short-term
because the large amounts of mulch sometimes result in
high rates of nitrogen immobilization. The rye cover crop
may also be an alternate host for pests such as nematodes
in sweet corn.
The strip tillage system has shown the benefit of reduced
soil splash during rain or irrigation which has reduced fruit
staining and disease.
ORGANIC SYSTEMS' CONCERNS
The strive for soil quality is especially important for
organic producers, said Doug Collins, Washington State
University (WSU) Extension specialist. Collins also spoke
on soil health at the Great Lakes EXPO. Collins has
worked extensively with organic growers in the Pacific
Northwest.
" Tillage is important, especially in organic systems, " Collins
said. Washington's northern location means a shorter growing
season and the west part of the state has the rains rolling in
from the Pacific. Reduced tillage in that environment means
significantly cooler soils. " Anything we do to reduce soil
temperature will be problematic, " Collins said.
Terminating cover crops is a big concern for organic
growers and WSU is evaluating a number of systems for
improved termination.
One project is evaluating the use of flail mowing.
Crimping is an effective way for organic growers to
terminate rye, but must be done at a specific growth stage.
" With flail mowing, can we broaden that termination
window? " Collins asked. Initial results have been
promising.
Many organic producers trying to limit tillage utilize
rotational, reduced tillage. This is a system of minimal
tillage in the spring followed by crimping or flail mowing
to terminate the cover crop. The vegetable crop is then
planted with a reduced amount of tillage. This is followed
by conventional tillage late in the season to get ready for
the fall seeded cover crop.
" With flail mowing or roller crimping to terminate in the
spring, organic growers will have some weeds by fall and
need tillage to control them, " Collins said. " How do we
decrease the soil disturbance in this system and not need
full tillage in the fall? Getting good weed control is part of
that answer. "
" There's been a new understanding of soil organic
matter, " Collins said. " We know the location of the
soil organic matter and we know it's stable while in the
aggregates. The question is, 'how do we manage weeds and
still have a healthy soil?' "
34 FALL 2020
Fall 2020

Table of Contents for the Digital Edition of Fall 2020
