Successful Farming – August 2019

What is the

biggest obstacle

to soil health?

Attitude is everything.

The automaker Henry Ford is

attributed with this quote: “If

you think you can do a thing

or think you can’t do a thing,

you’re right.”

“It has been my experience

that several growers ignore

significant problems because

they do not want to make the

changes needed to address

them,” says Lee Briese, a

Centrol crop consultant based

in Edgely, North Dakota. “Not

having the right equipment

• or having poorly maintained
  equipment – is a recipe for
  disaster,” he says.

18

Why is carbon
so important?
Carbon is “the building
block of life,” accord-
ing to NRCS literature.
Adopting soil health
practices reduces car-
bon dioxide emissions
and sequesters it into
the soil.
How? Photosynthesis
removes carbon dioxide
from the atmosphere
and converts it to
organic carbon, reports
the National Sustainable
Agriculture Information
Service.
Practices that retain soil
carbon can sequester
harmful greenhouse
gases that influence
climate change. Indigo
Ag’s goal in launching
its Terraton Initiative in
June is to remove 1 tril-
lion tons of atmospheric
carbon dioxide.
As part of the plan,
Indigo Ag plans to pay
participating farmers
$15 to $20 per ton of
carbon they sequester
using tools like no-till
and cover crops. (This
translates into $30 to $60
per acre, depending on
factors like soil type and
climate, according to
Indigo Ag officials.)
David Perry, CEO of
Indigo Ag, says only
a small percentage of
growers now farm in
ways that increase soil
carbon.
So why aren’t more
using practices like
no-till? “Changing to
something else is a risk,”
Perry says.

How do I maximize

soil carbon?

Understanding the

carbon-to-nitrogen (C:N)

ratio is key. It’s simply the

mass of carbon to the mass of

nitrogen in the soil. NRCS

says soil microorganisms

work best with a 24:1 C:N

ratio, with 16 parts of carbon

used for energy and eight

parts for maintenance.

Imagine the soil as an

engine, with carbon as the

fuel and nitrogen as the ig-

niter, Ray Ward with Ward

Laboratories explains.

“The more nitrogen you

have, the faster you eat up

the carbon,” he says. “Too

much nitrogen creates more

soil bacteria at the expense of

fungi. Soil fungi is what

creates the glues that keep

soil aggregates together.”

According to the accom-

panying NRCS chart, wheat

straw has a higher C:N ratio.

That means soil microbes

will have to find additional

nitrogen in order to consume

the wheat straw.

This has to come from

excessive N in the soil. This

could temporarily create an

N deficit (immobilization)

if insufficient N is in the

soil. This could continue

until some microbes die and

release N contained in their

bodies (mineralization). 

Have you ever wondered

why soybean stover doesn’t

last long on the soil surface?

That’s because it has

a low C:N ratio of 20:1,

according to Purdue

University data. However,

following that soybean

stover with a high-carbon

crop like wheat (80:1) or

corn (57:1) helps balance

the C:N ratio over a two-

year growing season.

Planting cover crops,

however, helps balance the

C:N ratio more quickly and

helps to fuel soil microor-

ganism population.

That’s one reason cover

crop blends are so popular.

Adopters can mix multiple

species to tweak the C:N

ratio and accomplish a

multitude of goals – whether

improving soil health, pro-

viding grazing, or keeping

cover on the field.

Material C:N Ratio

Rye straw 82:1

Wheat straw 80:1

Oat straw 70:1

Corn stover 57:1

Rye cover crop (anthesis) 37:1

Pea straw 29:1

Rye cover crop (vegetative) 26:1

Mature alfalfa hay 25:1

Ideal microbial diet 24:1

Rotted barnyard manure 20:1

Legume hay 17:1

Beef manure 17:1

Young alfalfa hay 13:1

Hairy vetch cover crop 11:1

Soil microbes 8:1

Source: NRCS

52 Successful Farming at Agriculture.com |August 2019