This document summarizes a project that demonstrated the benefits of multi-species cover crops for improving soil health and reducing fertilizer needs in South Carolina. The project tested soils from several fields for plant-available nitrogen from cover crops using a soil respiration test. In fields that received reduced commercial nitrogen based on test results, crop yields were maintained while reducing costs. Soil organic matter increased by 0.2-0.6% annually with cover cropping. Outreach events were held to communicate the soil health benefits to farmers.

1. Using Soil Respiration Tests to
Measure Plant Available Nitrogen in
Cover Cropped Soils:
Demonstrations, Research, & Outreach in South
Carolina
Arnold School of Public Health
Marlboro
Soil and
Water
Conservatio
n District
Chanda L. Cooper, Richland SWCD
Columbia, South Carolina
Education Coordinator
cooperc@rcgov.us

2. Project Team
Technical
Director: Dr. “Buz”
Kloot

3. Project Management
Arnold School of Public Health
Marlboro Soil
and Water
Conservation
District
Conservation Innovation Grant
SC-NRCS

4. Context
1. “You can’t build organic
matter in Southeastern
soils.”
2. Fertility recommendations
based on conventional
systems
Soil Test Debate in 1982

5. CIG Project Objectives: 1
Demonstrate and document
the benefits of multi-species
cover crops across a range of
SC soils

6. CIG Project Objectives: 2
 Demonstrate the use of the Haney-Brinton
CO2 Burst Test and crop biomass samples
to measure organic nitrogen

7. CIG Project Objectives: 3
 Measure the impact of cover crops and
reduced commercial fertilizer applications
on crop yields and net operating costs

8. Project Field Locations
 Dillon (3)
 Marlboro (1)
 Richland (1)
 8-15 acre fields
 58.9 acres (total)

9. Soil Characterization
 Soil series, control points
Norfolk
Lynchburg

10. Soil Characterization
 Topsoil color and structure
 Soil compaction
 Maximum root depth
 Bulk density
 Penetrometer measurements

11. Multi-Species Cover Crops
 Grass (1+)
 Rye, oats, barley
 Legume (2+)
 Crimson clover, Austrian
winter pea, hairy vetch
 Brassica (1+)
 Daikon/tillage radish,
purple top turnip, forage
rape
 October 31-March 15

12. Winter Cover Crops
January 6, 2014

13. Soil Testing to Measure Nitrogen
Benefit

14. Biological Soil Testing, aka…
 Soil Respiration
Test
 CO2 Burst Test
 Solvita (“soil life”)
 Haney-Brinton
Test

15. Haney-Brinton CO2
Burst Test

16. Biomass Sampling
Y1: 500-9,500 lb/acre dry biomass
Y2: 850-8,400 lb/acre dry biomass

17. Commercial Nitrogen Reductions
Based on Haney-Brinton Results
Norfolk
Lynchburg
Half of Field
Standard Commercial
Nitrogen Application
(as per standard
inorganic N
recommendations)
Half of Field
Reduced Commercial
Nitrogen Application
(standard N
recommendation minus
plant available nitrogen
from cover crop, as
indicated by CO2 Burst
Test)

18. Treatments
Ϯ winter peas – 3% N
*Plus a check strip –
0 N
Field
Est Nmin
(lb/ac) Based
on Soil CO2-C
Est N in
Cover Crop
(lb/ac)
Crop
Standard N
Application
(lb/ac)
Low N
Application
(lb/ac)
Carl ~40 ~170 Corn 120 65 (-55)
Jason ~40 ~190 Soybeans N/A N/A
Alan ~25 ~ 10 Corn 120 95 (-25)
John ~25 ~240Ϯ Milo 90 40 (-50)
Sonny ~25 ~270Ϯ Cotton 90 55* (-35)

19. Corn Crop
2014

20. Expected
Results
 Reduced commercial
nitrogen will not
reduce crop yield
while reducing
operating costs
 Soil health will
improve
 Additional benefits:
 Increased soil water-
holding capacity;
reduced runoff;
temperature
regulation; wildlife and

21. Yield Results
Std N Low N Notes
Field 1 - Corn (bu/ac) 33 32 Poor rainfall
Field 2 - Soybeans N/A N/A No Std N/Low N difference
Field 3 - Corn (bu/ac) 183 126
Field 4 - Cotton
(lb/ac)
1014 1143 Check strip (0 N) – 928 lb/ac!
Field 5 - Milo (bu/ac) 110 134

22. Soil Health Changes
 OM increases 0.2%-0.6% per year
 Soil pH steady (5.9-6.1)
 P, K steady without additions
 Reduced compaction; less
subsoiling
Orangeburg
loamy sand
(70-85% sand)
after three
years of cover
crops.
Granules
~5mm
diameter.

23. p
H

24. Additional Benefits
 Jason Carter has over $100/ac less in the CIG
field in N and K fertilizer, herbicides and
fungicides.

25. Outreach: Field Days &
Workshops“If you don't believe soil health works,
Imma take you out onto my fields so
you can see for yourself!“
–Carl Coleman, Dillon
County

26. Outreach
:
Media
YouTube
South Carolina Wildlife Magazine
Blogs
Social Media

27. Join us on Facebook:
Carolina Cover
Crop Connection
https://www.facebook.com/group
s/carolinacovercropconnection/

28. Join us on Facebook:
Carolina Cover
Crop Connection
https://www.facebook.com/group
s/carolinacovercropconnection/
"Science is way behind the
leading farmers [when it
comes to cover crops]“ –Dr.

29. Farmer-Led Research
 Clio meeting
 New experiments
“Use check strips:
they save us
hundreds of
thousands of

30. Soil Health Movement
Practice
(Farmers)
Science
(Researchers)
Outreach
(Communicato
rs)
“During the past
half century we’ve
had an army of
soil scientists
telling us what our
soils are. In just a
few short years
America’s soil
health farmers
have shown us
what our soils can
be. They’ve
demonstrated the
hope in healthy

31. Questions ?
Join us on Facebook:
Carolina Cover
Crop Connection
"The most powerful
thing you can do for
the soil is plant a
seed."