Spring 2023 - 20

FEATURE
nitrogen is added can be a question that also relates to the
C:N ratio.
Young, green, plant material is more likely to be 10 or less.
The C:N ratio goes up as the plants mature. In a mixed-species
cover crop, the C:N
ratio will vary widely.
A legume is best
at fixing nitrogen,
but a legume is
usually combined
with a cereal grain.
Mature wheat straw
could have a C:N
ratio of 50:1 but will
break down and tie
up nitrogen faster
when tilled and
incorporated than
when left on the
surface.
"
" It's not only
C:N ratio and
nitrogen content;
it's also how fast
the plant material
will break down, "
Hoskins said. " It's
really difficult to
accurately predict
Manure can be a good, organic material, but the C:N ratio
will depend on how much bedding was used. The more
bedding, the slower the nitrogen release.
In cool, wet years, there's
slow mineralization and then
higher rates of denitrification
and leaching, as opposed to
warm, dry years when there's
fast mineralization and the
nitrogen doesn't move.
"
- Bruce Hoskins, assistant scientist, University of Maine's
School of Food and Agriculture
the nitrogen benefit of a cover crop. "
Organic fertilizer and cover crop calculators from Oregon
State University are tools often quoted in the industry to
help with these decisions. They are available at extension.
oregonstate.edu/organic-fertilizer-cover-crop-calculators.
Compost works well if you need organic matter, but a lot of
the nitrogen has become less available during composting.
" We don't recommend it as a fertilizer - especially not a
nitrogen fertilizer, " Hoskins said.
The U.S. Department of Agriculture's National Organic
Program (NOP) guidelines
specify hold-out times when
uncomposted manure has been
applied. You can't harvest
for 90 days after planting for
aboveground crops and 120 days
after planting for root crops.
A good nitrogen plan for
organic vegetables could be
to start by estimating the
nitrogen contributions from
organic matter breakdown, then
estimating how much nitrogen is
coming from cover crops.
The next step would be to look
at a product like pelleted poultry
manure applied at planting to
provide some long-term release,
and then hold some fast release
material in reserve for side dressing.
" Most growers estimate how
much nitrogen will be available,
watch the crop, and then side
dress accordingly, " Hoskins said.
A pre-side dress nitrogen test can
help make side dress decisions, even though the sample has to be
sent to a lab and there's at least a one-week lag time. There are
field testing meters for nitrate, but they can be quite expensive.
A pre-side dress nitrogen test should be taken about three
weeks into the crop cycle, between Memorial Day and
Independence Day in the Northeast and earlier in southern states.
" It will accurately determine how much nitrogen has been
mineralized to that point in the year, and then you can make
adjustments if needed, " Hoskins said.
20 SPRING 2023
http://www.oregonstate.edu/organic-fertilizer-cover-crop-calculators

Spring 2023

Table of Contents for the Digital Edition of Spring 2023

Table of Contents
Editor's Letter
Feature: High-altitude Pears
Cover Story: In-depth Data
Feature: Berry Boom
Special Section: The Survey Shows ...
Feature: Nitrogen Needs
Feature: Setting Ground Rules
Company Spotlight
Industry News: Connection Coordinator
Ad Index & Events
Spring 2023 - 1
Spring 2023 - 2
Spring 2023 - Table of Contents
Spring 2023 - Editor's Letter
Spring 2023 - 5
Spring 2023 - Feature: High-altitude Pears
Spring 2023 - 7
Spring 2023 - Cover Story: In-depth Data
Spring 2023 - 9
Spring 2023 - 10
Spring 2023 - 11
Spring 2023 - Feature: Berry Boom
Spring 2023 - 13
Spring 2023 - 14
Spring 2023 - 15
Spring 2023 - Special Section: The Survey Shows ...
Spring 2023 - 17
Spring 2023 - Feature: Nitrogen Needs
Spring 2023 - 19
Spring 2023 - 20
Spring 2023 - 21
Spring 2023 - Feature: Setting Ground Rules
Spring 2023 - 23
Spring 2023 - Company Spotlight
Spring 2023 - 25
Spring 2023 - Industry News: Connection Coordinator
Spring 2023 - Ad Index & Events
Spring 2023 - 28
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/spring-2023
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/winter-2023
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/fall-2022
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/summer-2022
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/march-april-2022
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/january-february-2022
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/november-december-2021
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/september-october-2021
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/july-august-2021
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/may-june-2021
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/march-april-2021
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/fall-2020
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/summer-2020
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/spring-2020
https://www.nxtbook.com/greatamericanmediaservices/Organic-Grower/winter-2020
https://www.nxtbookmedia.com