Post on 18-Aug-2015
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
Conservation
District
Chanda L. Cooper, Richland SWCDColumbia, South Carolina
Education Coordinatorcooperc@rcgov.us
Project TeamTechnical Director:
Dr. “Buz” Kloot
Project Management
Arnold School of Public Health
Marlboro Soil and Water
Conservation District
Conservation Innovation GrantSC-NRCS
Context
1. “You can’t build organic matter in Southeastern soils.”
2. Fertility recommendations based on conventional systems
Soil Test Debate in 1982
CIG Project Objectives: 1
Demonstrate and document the benefits of multi-species cover crops across a range of SC soils
CIG Project Objectives: 2
Demonstrate the use of the Haney-Brinton CO2 Burst Test and crop biomass samples to measure organic nitrogen
CIG Project Objectives: 3
Measure the impact of cover crops and reduced commercial fertilizer applications on crop yields and net operating costs
Project Field Locations
Dillon (3) Marlboro (1) Richland (1) 8-15 acre fields 58.9 acres (total)
Soil Characterization
Soil series, control points
Norfolk
Lynchburg
Soil Characterization
Topsoil color and structure Soil compaction
Maximum root depth Bulk density Penetrometer measurements
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
Winter Cover CropsJanuary 6, 2014
Soil Testing to Measure Nitrogen Benefit
Biological Soil Testing, aka…
Soil Respiration Test
CO2 Burst Test Solvita (“soil
life”) Haney-Brinton
Test
Haney-Brinton CO2 Burst Test
Biomass Sampling
Y1: 500-9,500 lb/acre dry biomassY2: 850-8,400 lb/acre dry biomass
Commercial Nitrogen Reductions Based on Haney-Brinton Results
Norfolk
Lynchburg
Half of FieldStandard
Commercial Nitrogen
Application(as per standard
inorganic N recommendations)
Half of FieldReduced Commercial Nitrogen Application
(standard N recommendation minus plant available nitrogen
from cover crop, as indicated by CO2 Burst
Test)
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)
Corn Crop2014
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 pollinator benefits; IPM; etc.
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
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
subsoilingOrangeburg loamy sand
(70-85% sand) after three years
of cover crops.
Granules ~5mm
diameter.
pH
Additional Benefits
Jason Carter has over $100/ac less in the CIG field in N and K fertilizer, herbicides and fungicides.
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
Outreach:Media
YouTube
District Newsletters
South Carolina Wildlife Magazine
Newspape
rs
BlogsSocial Media
Join us on Facebook:
Carolina Cover Crop
Connectionhttps://www.facebook.com/groups/carolinacovercropconnection/
Join us on Facebook:
Carolina Cover Crop
Connectionhttps://www.facebook.com/groups/carolinacovercropconnection/
"Science is way behind the leading farmers
[when it comes to cover crops]“ –Dr. Ray Weil
Farmer-Led Research
Clio meeting New experiments
“Use check strips: they save us hundreds of thousands of dollars.” –Ray
Archuleta
Soil Health Movement
Practice (Farmers)
Science (Researchers
)
Outreach
(Communicators)
“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 soil.” –Ron Nichols
Questions ?
Join us on Facebook:
Carolina Cover Crop
Connection
"The most powerful thing you can do for
the soil is plant a seed."
-Ray Archuleta