Promoting Adoption of Cover Crops in Southeastern Farming Systems

Final report for LS18-294

Project Type: Research and Education
Funds awarded in 2018: $48,000.00
Projected End Date: 03/31/2020
Grant Recipient: NC Foundation for Soil and Water Conservation
Region: Southern
State: North Carolina
Principal Investigator:
Michelle Lovejoy
NC Foundation for Soil and Water Conservation
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Project Information

Abstract:

Multi-species cover crops provide numerous conservation benefits, but documenting the successes and failures is important as an educational process. Cover crops can be planted in a timely manner, allowed to accumulate biomass and nitrogen, and be terminated without tillage to maximize soil health benefits. Soil health is defined as the continued capacity of soil to function as a living ecosystem. Soil functions with the use of cover crops is improve by: minimizing soil disturbance, increasing plant and animal diversity above-ground to enhance soil biodiversity, keeping a living root growing year-round, and keeping residue cover on the surface as long as possible. Cover crop systems improve soil microbial activity, increase nutrient cycling, mitigate against drought and pests, and increase profits over time. We want to be able to document these changes in this participatory network framework. Once producers understand these principles, the obstacles of putting them into practice is overcome.

The project is an ongoing effort with the first demonstration plot started in 2013 and more demonstration plots added each year. The Southern SARE Education Grant funds will be used to maintain six demonstration plots in winter 2018 and support field days and outreach efforts in 2019 / 2020 in the Coastal Plain region counties of Brunswick and Duplin, the Piedmont region counties of Alamance and Davidson, and the Blue Ridge region counties of Ashe and Henderson. All other county’s demonstration plots were funded from grants through Cotton Inc and the NC Agriculture Development and Farmland Preservation Trust Fund.

Project Objectives:
  1. Engage North Carolina producers in soil health benefits of multi-species cover crops.
  2. Quantify short-term changes in soil chemical, physical, and biological properties as a result of using multi-species cover crops in various no-till and reduced till production systems across the three physiographic regions of North Carolina.
  3. Refine best management practices for multi-species cover crops in production systems common to North Carolina and neighboring states in the region.
  4. Promote soil health improvement from use of multi-species cover crops in North Carolina and the Southeast to increase agricultural sustainability.

Research

Materials and methods:

Conservation Districts Partnering with Producers: Conservation Districts establish a county level technical support team to help with project management. Technical support team members included Conservation District staff, NRCS field staff, county level Cooperative Extension, NC Department of Agriculture and Consumer Services’ regional agronomists and soil scientists, as well as producers with a history of utilizing cover crops. The technical support team selected a producer to establish demonstration plots. The following were guidelines for producer selection.

  • EQIP-eligible producers currently using conservation tillage practices that would be interested in the next level of soil health management.
  • Preference for producers that would be willing to continue beyond the timeline of funding availability.

 

Demonstration Plot Requirements: Conservation Districts select a field that is easily accessible for field days and has a minimal range of soil types. Demonstration plots in the Coastal Plain and Piedmont are required to be a minimum of 10 acres. Mountain demonstrations are allowed a smaller size of 2 to 5-acre plots. The reason for the acreage difference is that in many mountain counties the best farmland is on the floodplain of creeks in a narrow valley, and therefore many fields might not be as large as 10 acres. Fields are required to accommodate the establishment of 4 test strips with a minimum width of 40 feet, allowing for comparison of test and control strips side-by-side. In the control strips, producers could plant either a single-species cover crop (to compare with more typical conservation practice) or no cover crop (to compare most typical conventional practice and address soil erosion concerns).

 

Cover Crop Requirements: Each Conservation District and producer are allowed to select their own seed mixes, based on the producer’s management goals and to highlight mixes that would work well in their county. Each seed mix is required to include 4 species at a minimum, including 2 legumes. Producers are allowed to broadcast or no-till drill the seed mix. If broadcasting, it is recommended to consider 25% more seed than if no-till drilling. All producers have access to a no-till drill through Conservation Districts. Chosen establishment methods are based on preference and cash crop harvesting needs. For termination, producers are permitted to roll down the cover crop and/or apply a chemical treatment. Termination method chosen is influenced by equipment available to the producer, as not many producers had access to a roller-crimper. The following planting and termination dates are target dates:

  • Coastal Plain & Piedmont September 30 to establish by broadcast
  • Mountain September 15 to establish by broadcast
  • Coastal Plain & Piedmont October 31 to establish by no-till
  • Mountain October 15 to establish by no-till
  • Coastal Plain & Piedmont April 15 termination
  • Mountain May 1 termination

 

Lab Analysis: Project Partners will document nutrient cycling benefits by evaluating results of soil tests for realistic yield expectations and various forms of soil organic matter, including soil microbial activity with the Solvita Soil CO2 Burst test (http://solvita.com/soil). Nutrient availability to plants will be documented with nutrient uptake of cover and cash crops. Surface-soil samples will be collected from crop production fields in winter/spring by compositing 8 cores (4-cm diam) to represent depths of 0-6, 6-12, and 12-20 cm following collection of surface residue mass from 0.04 m2 areas at each of the coring locations.  Soil will be split into two fractions following initial screening and mixing through 8 mm openings: (1) dried at 50 °C, sieved to pass a 4.75-mm screen to determine chemical and physical properties and (2) kept moist at 4 °C, sieved to pass a 2-mm screen to determine soil microbial communities.  The following properties will be determined from this sampling scheme:

North Carolina Department of Agriculture and Consumer Services Agronomic Services Division 

  • Humic matter (g / 100 cc)
  • Density (g / cc)
  • Cation exchange capacity (meq / 100 cc)
  • Base saturation (meq / 100 cc)
  • pH
  • Phosphorus (mg / dm3)
  • Potassium (mg / dm3)
  • Calcium (mg / dm3)
  • Magnesium (mg / dm3)
  • Sulfur (mg / dm3)
  • Manganese (mg / dm3)
  • Zince (mg / dm3)
  • Copper (mg / dm3)
  • Sodium (mg / dm3)

Soil Ecology and Management Laboratory at NC State

  • Total soil C and N (g / kg); dry combustion with Leco TruMac following ball milling
  • Particulate organic C and N (g / kg); dry combustion with Leco TruMac following ball milling of oven-dried sand fraction of soil obtained from dispersion of soil in Na4P2O7 solution
  • Soil microbial biomass C (mg / kg); chloroform fumigation-incubation
  • Mineralizable C and N (mg / kg / 24 days); aerobic incubation at 50% water-filled pore space and 77 °F
  • Flush of CO2 following rewetting of dried soil (mg / kg / 3 days); aerobic incubation at 50% water-filled pore space and 77 °F
  • Residual soil nitrate and total inorganic N (mg / kg); colorimetric determination with Bran-Luebbe segmented flow analyzer following KCl extraction

 

Research results and discussion:

Research Team: Soil and plant samples were collected as part of this conservation project by Alan Franzluebbers, USDA Research Ecologist at the Soil Ecology and Management Lab on the campus of North Carolina State University in Raleigh NC.  Technical support for soil and plant analyses in the laboratory was provided by: Erin Silva, USDA Biological Science Technician; Ellen Leonard, NC State Research Technician; and Katie Pritchett, NC State Graduate Student. Several NC State student workers over the lifetime of the project, including Allison Denton, Hannah Frank, Honovi Locklear, Ashton Mizelle, and Ashley Turner.

 

Demonstration Plots: Working with and through Michelle Lovejoy, NC Foundation for Soil and Water Conservation, contact with local Soil and Water Conservation District (SWCD) staff in several counties was initiated to gain access to field demonstration plots on farmer fields from 2015 to 2019.  Demonstration plots followed guidelines distributed to SWCD staff that were designed to have at least two replicate strips of multi-species cover crops compared with either no cover crop or single-species cover crop on working cropland.  A total of 35 fields were sampled for cover crop biomass production in springtime (April-May) prior to planting a summer cash crop.  A total of 31 fields were sampled for soil conditions in the same time period after maturation of the cover crop.  Repeated demonstrations occurred for several of the participants to gain insight into potential multiple-year benefits of practices on soil health condition. NOTE: Demonstrations of fall 2018 cover corp plantings were supported by SARE funding and are noted by an asterisk (*) .

 

Soil Type Strip Design Cash Crop Types Cover Crop Management Cover Crop Mixture
COASTAL PLAIN REGION
Beaufort County
Rains fine sandy loam with 0-2% slope (fine-loamy, siliceous, semiactive, thermic Typic Paleaquults) 6 alternating strips of multi-species + no cover

2017 Corn

2018 Soybean

2019 Corn

2017 Establishment: Broadcast with minimum-till 10.20 

2018 Termination: chemical treatment 4.25

Winter cover crop mixture consisted of 40 lb/acre abruzzi rye + 15 lb/acre Austrian winter pea + 5 lb/acre crimson clover + 2 lb/acre tillage radish
Brunswick County*

Lynchburg fine sandy loam with 0-2% slope (fine-loamy, siliceous, semiactive, thermic Aeric Paleaquults)

Farm has long history of no-till, firest time using cover crops

22 alternating strips of multi-species + no cover

2017 Corn

2018 Soybean

2017 Establishment: no-till drilled 4.10

2018 Termination: chemical treatment + rolled down 5.4

56 lb/acre rye + 19 lb/acre Austrian winter pea + 6 lb/acre crimson clover + 3 lb/acre radish
Camden County 
Bojac loamy sand with 0-3% slope (coarse-loamy, mixed, semiactive, thermic Typic Hapludults) 16 strips

2017 Cotton

2018 Soybean

2019 Cotton

2018 Establishment: no-till drilled 10.15

2019 Termination: chemical treatment 4.1

2017: 19 lb/acre oat + 16 lb/acre Austrian winter pea + 13 lb/acre crimson clover + 9 lb/acre balansa clover + 3 lb/acre select radish

2018: 60 lb/acre wheat + 6 lb/acre crimson clover + 9 lb/acre daikon radish + 25 lb/acre Austrian winter pea

Duplin County*
Johns fine sandy loam with 0-2% slope (fine-loamy over sandy or sandy-skeletal, siliceous, semiactive, thermic Aquic Hapludults) 4 strips

2017 Corn

2018 Corn

2019 Corn

2017 Establishment: no-till drilled 10.18

2018 Termination: chemical treatment 4.13

98 lb/acre rye + 3 lb/acre barkant forage turnip + 4 lb/acre purple top turnip + 3 lb/acre wooly pod vetch + 9 lb/acre crimson clover
Edgecombe County
Cape Fear loam (fine, mixed, semiactive, thermic Typic Umbraquults), Roanoke loam (fine, mixed, semiactive, thermic Typic Endoaquults), and Portsmouth fine sandy loam (fine-loamy over sandy or sandy-skeletal, mixed, semiactive, thermic Typic Umbraquults) 4 strips

2015 Soybean

2016 Soybean

2015 Establishment: Aerial broadcast 10.20

2016 Termination: chemical treatment

1 lb/acre purple-top turnip + 4.5 lb/acre winter pea + 1 lb/acre hairy vetch + 1 lb/acre tillage radish + 10 lb/acre triticale +  4 lb/acre crimson clover + 5 lb/acre black oat + 20 lb/acre abruzzi rye
Nash County: demonstrations established by 2 farmers at 3 locations in 4 years, with repeat location in final 2 years

2015-2016: Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudults)

3 strips single species

6 strips multi-species

2015 Soybean

2016 Soybean

2015 Establishment: broadcast in 4 strips October 20; no-till drilled in 8 strips On December 8 & January 8

2016 Termination: chemically + disked

Single-species: rye

Multi-species: 45 lb/acre rye + 8.5 lb/acre crimson clover + 6.5 lb/acre tillage radish + 15 lb/acre Austrian winter pea + 1 lb/acre woolypod vetch  

2016-17: Norfolk, Georgeville, and Faceville soils with 2-8% slope (fine-loamy, kaolinitic, thermic Typic Kandiudults) 18 strips

2016 Field Beans

2017 vegetables

2016 Establishment: no-till drilled late Oct

2017 Termination: disked on 4.13

40 lb/acre rye + 10 lb/acre crimson clover + 2 lb/acre daikon radish
2017/2018 & 2018/19: Faceville loamy sand with 1-6% slope (fine, kaolinitic, thermic Typic Kandiudults) 4 strips both growing seasons

2017 Sorghum

2018 Soybean

2017 Establishment: no-till drilled 10.31

2018 Termination: chemically

2018 Establishment: no-till drilled 10.25

2019 Termination: rolled down

Single Species: oat

Multi-Species:  18 lb/acre triticale + 12 lb/acre Florida 501 oat + 2.4 lb/acre trophy rape + 18 lb/acre cereal rye + 10 lb/acre Dixie crimson clover

PIEDMONT REGION
Alamance County*
Cullen clay loam with 2-6% slope that was moderately eroded (very-fine, kaolinitic, thermic Typic Hapludults) 4 strips

2017 soybean

2018 corn silage

2019: corn + sorghum

2016 Establishment: no-till 10.17

2017 Termination: chemically

2017 Establishment: no-till 12.14

2018 Termination: chemically 6.15

2018 Establishment: no-till 10.22

2019 Termination: rolled down

2016 Single Species: barley

2016 Multi-Species: 31 lb/acre rye + 7 lb/acre crimson clover + 7 lb/acre hairy vetch + 2 lb/acre tillage radish

2018 Single Species: triticale Rep 1 & cereal rye Rep 2

2018 Multi-Species Rep 1: 31 lb/acre cereal rye + 7 lb/acre crimson clover + 7 lb/acre hairy vetch

2018 Multi-Species Rep 2: 31 lb/acre triticale replaced rye in the mix in Rep 2

2019 Single Species: triticale

2019 Multi-Species: 12 lb/acre crimson clover + 13 lb/acre Austrian winter pea, 35 lb/acre Cosaque winter oat + 40 lb/acre cereal rye

Davidson County*
Enon fine sandy loam with 2-8% slope (fine, mixed, active, thermic Ultic Hapludalfs) 4 strips; in different portions of large field over 2 years

2016 Corn

2017 Soybean

2016 Establishment: no-till 10.25

2017 Termination: chemically 4.20

2017 Establishment: no-tilled 10.18

2018 Termination: chemically

2016 & 2017 Single Species: rye

2016 Multi-Species: 30 lb/acre cereal rye + 15 lb/acre triticale + 10 lb/acre oat + 10 lb/acre crimson clover + 10 lb/acre hairy vetch + 2 lb/acre daikon radish

2017 Multi-Species: 6 lb/acre hairy vetch + 6 lb/acre crimson clover + 25 lb/acre triticale + 22 lb/acre black oat + 2 lb/acre rape

 

Rowan County
Enon fine sandy loam with 2-8% slope (fine, mixed, active, thermic Ultic Hapludalfs) 4 strips 2016, 2017, 2018 vegetables

2016 & 2017 Establishment: no-till 10.25

2017 & 2018 Termination: chemically 4.15

Single Species: crimson clover

Multi-Species: 5 lb/acre crimson clover + 4 lb/acre hairy vetch + 5 lb/acre Austrian winter pea + 41 lb/acre barley + 0.5 lb/acre rape

2017 mix rates increased for 2 species – 15 lb/acre Austrian winter pea and 1 lb/acre rape

Stanly County
Badin channery silt loam with 2-8% slope (fine, mixed, semiactive, thermic Typic Hapludults)

4 strips

2015 Corn

2016, 2017, 2018, 2019 Cotton

2015 Establishment: no-till 10.15

2016 Termination: chemically 5.2

2016 Establishment: no-till late Oct

2017 Termination: chemically 4.20

2017 Establishment: no-till 10.30

2018 Termination: chemically 4.15

2018 Establishment: no-till 10.30

2019 Termination: chemically

2015: 10 lb/acre crimson clover + 2 lb/acre radish + 15 lb/acre triticale + 15 lb/acre ryegrass

2016 & 2017: 5 lb/acre crimson clover + 50 lb/acre triticale + 10 lb/acre ryegrass + 15 lb/acre Austrian winter pea

2018: 15 lb/acre winter pea + 8 lb/acre crimson clover + 15 lb/acre ryegrass + 50 lb/acre triticale

 

Wake County
Rawlings-Rion complex with 6-10% slope (fine-loamy, mixed, subactive / semiactive, thermic Typic Hapludults) and Wedowee-Saw complex with 2-6% slope (fine, kaolinitic, thermic Typic Kanhapludults) 6 strips

2016 Soybean

2017 Soybean

2018 Soybean

2016 & 2017 Establishment: broadcast 10.15

2017 Termination: chemically 4.17

2018 Termination: chemically 4.21

2016 & 2017: 24 lb/acre ryegrass + 18 lb/acre brooks oat + 6 lb/acre crimson clover + 12 lb/acre Austrian winter pea
BLUE RIDGE REGION
Ashe County*

sloping hillside previously in Christmas trees

Clifton loam with 8-15% slope (fine, mixed, semiactive, mesic Typic Hapludults) and Evard loam with 15-25% slope (fine-loamy, parasesquic, mesic Typic Hapludults). 

8 strips

2016 & 2017 Corn silage

 

2016 Establishment: no-till 10.6

2017 Termination: chemically

2017 Establishment: 9.27

2018 Termination: chemically 5.1

2016: 8 lb/acre hairy vetch + 8 lb/acre berseem clover + 25 lb/acre rye + 25 lb/acre triticale

2017: 12 lb/acre Austrian winter pea + 10 lb/acre foragemaker 50 oat + 10 lb/acre triticale + 6 lb/acre hairy vetch + 5 lb/acre crimson clover + 4 lb/acre daikon radish + 1 lb/acre barkant turnip

Henderson County*

river bottom field

Toxaway silt loam (fine-loamy, mixed, superactive, nonacid, mesic Cumulic Humaquepts), Comus (Colvard) fine sandy loam (coarse-loamy, mixed, active, nonacid, mesic Typic Udifluvents), and Suncook (Biltmore) loamy sand (mixed, mesic Typic Udipsamments). 

4 strips 2016, 2017, 2018 Snap bean

2016 Establishment: no-till 10.6

2017 Termination: chemically 5.31

2017 Establishment: no-till 10.6

2018 Termination: chemically late June

2016: 17 lb/acre crimson clover + 100 lb/acre Austrian winter pea + 7 lb/acre rackmaster trophy radish + 100 lb/acre rymin winter rye

2017: 12 lb/acre crimson clover + 13 lb/acre Austrian winter pea + 2 lb/acre rackmaster trophy radish + 50 lb/acre barley

 

Data Collection & Analysis Methods: Cover crop biomass production was estimated by harvesting two 2.8 ft2 areas from six sampling points in multi-species cover crop portions of field and the same in the comparative no cover crop or single-species cover crop portions of the field.  Biomass was cut about an inch from the ground and placed into cloth bags to be dried, weighed, and analyzed for C and N contents. Dry matter of cover crop mass is reported in Table 1 for each of the demonstration trials from 2015/16 through 2018/19.  In many of those trials that had multi-species cover crops compared with no cover crop, a large statistical difference occurred.  Therefore, one aspect of the demonstration project was fulfilled, i.e. to demonstrate that multi-species cover crops were effective in accumulating biomass. However, demonstrations were also revealing in that not all cover crop plantings led to the same biomass production.  Planting date and weather conditions can play a major role in how well seeds germinate in the fall, how well seedlings develop and persist into the winter, and how well biomass accumulates and which species contribute to biomass production in the spring.  The experiences of participating farmers and SWCD staff will be equally valuable in assessing success, as do these quantitative estimates of plant production.

 

Biomass Accumulation Results: Although we don’t have firm estimates of how much biomass should be produced to be effective, we can say that some conservationists prefer to limit accumulation to a moderate amount of ~3000 lb/acre and others feel there should be no limit and that more is better.  The data collected in this project yielded a fairly wide range of biomass production, from as little as 400 lb/acre to as much as 9000 lb/acre. On average, these demonstrations showed that 3014 lb/acre of cover crop biomass was achieved.  Most conservationists would consider this successful in covering soil and providing sufficient organic resources to feed soil over the cold, wet winter in North Carolina.

Looking more closely at the data, 33% of the multi-species cover crop demonstrations produced <1154 lb/acre of biomass, 33% of the demonstrations produced 1154 to 3384 lb/acre, and 33% of the demonstrations produced >3384 lb/acre.  The lower one-third of demonstrations could likely be considered deficient in biomass production.  This statement is made, because on average that was about the level of biomass production across all demonstrations without a cover crop, i.e. from growth of overwintering weeds.  One has to ask what might have limited biomass production.  Was it weather conditions?  Could it have been late planting?  Were persistent weed control chemical present?  Did seed lay dormant for a long period and only germinate in the spring?  Was seed viable?  Many conditions could lead to poor performance and growers that want to improve cover crop biomass production will try again and make adjustments.

The middle one-third of demonstrations that had 1154 to 3384 lb/acre of biomass production could reasonably be considered successful and this biomass level could contribute to reasonable soil erosion control, good carbon food-sourcing for soil organisms, and potential to biologically sequester nutrients for effective nutrient cycling to the succeeding summer cash crop. Those demonstrations that had the greatest biomass accumulation often had the highest soil fertility conditions, as will be shown in a later section.  Many times growers had previous years of experience and this can be a valuable asset for good production.  However, not always was cover crop experience a factor in getting good production as evidenced in a few first-time successes by some growers.  Getting good quality seed to plant, putting the seed into the ground for rapid germination at a relatively early planting date in the fall, and having good luck with winter and spring weather conditions are important factors.  Nitrogen availability in soil can be a key limiting factor if cover crops do not have a significant legume component.  However, any cereal cover crop in a multi-species mixture still needs nitrogen in soil for sufficient growth, because legume nitrogen fixation only satisfies the needs of the legume plant and only following decomposition will significant nitrogen be released for other plants to thrive on this biologically fixed nitrogen.

 

TABLE 1. Biomass Dry Matter of Cover Crop Treatments

    Biomass (lb/acre)
COUNTY YEAR NONE   SSCC   MSCC
Coastal Plain
Beaufort 2018 171   <<<   622
  2019 0   <<<   819
Brunswick* 2018 469   <<<   2751
  2019 1000   <<<   5402
Camden 2018 312   =   1143
  2019 63   <<   1507
Duplin* 2018 662   <   2564
  2019 654   <<   3388
Edgecombe 2016   892   1543
Halifax E 2016 292   <<   591
Halifax W 2016     928
Nash 1 2016 1128 = 1509 = 1138
Nash 2 2016 265 << 1141 = 1108
Nash 3 2016 530 = 457 = 637
Nash 2017 584   <<   1179
Nash 2018   661 = 976
Nash 2019   3302 = 3377
Pitt 2016 650   <   1132
Piedmont
Alamance* 2017   9554 = 9137
  2018   5071 = 3591
  2019   8704 = 8201
Davidson* 2017   1691 = 1543
  2018   3788 < 4390
Rowan 2017   1319 = 1612
  2018 1739   <<<   6383
Stanly 2016 1739   <<<   6383
  2017 1647   <<   2207
  2018 3138   <<   4010
  2019 1966   <<<   7932
Wake 2017 268   <<<   804
  2018 260   <   416
Blue Ridge
Ashe* 2017 476   <<<   4762
  2018 850   <<<   3746
Henderson* 2017 2500   <<<   9167
  2018 151   <   2351
AVERAGES across fields 1138 << 2852 = 3014

None (no cover); SSCC (single-species cover crop); and MSCC (multi-species cover crop) at each location. To indicate significance between means < represents p ≤ 0.05; << represents p ≤ 0.01, and <<< represents p ≤ 0.05; = is not significant.

 

Biomass Nitrogen Results: This question was answered by the results in Table 2.  We analyzed harvested plant material and analyzed nitrogen concentration with a combination of dry combustion and near-infrared spectroscopy.  On average, there was 50 lb/acre of nitrogen stored in multi-species cover crop biomass, which was not significantly different than the 37 lb/acre of nitrogen stored in single-species cover crops, but was greater than the 19 lb/acre of nitrogen stored in overwintering weed biomass without a cover crop planting.  One-third of demonstrations had multi-species cover crop biomass nitrogen accumulation <19 lb/acre, one-third of demonstrations had 19 to 54 lb/acre of nitrogen accumulation, and one-third of demonstrations had >54 lb/ace of nitrogen accumulation.  If nitrogen accumulation in cover crop is desired, then sufficient biomass has to be accumulated and legume species should be a plentiful component of the mixture.  Many of the most effective demonstrations with large accumulation of nitrogen used Austrian winter pea, crimson clover, and hairy vetch in the mixture.  Crimson clover was the single-species cover crop in the Rowan County demonstration in both years and it also accumulated a reasonable amount of biomass nitrogen.

 

Table 2. Biomass N Content of Cover Crop Treatments

    Nitrogen (lb/acre)
County Year None   SSCC   MSCC
Coastal Plain
Beaufort 2018 2   <<<   9
  2019 0   =   19
Brunswick* 2018 8   <<<   46
  2019 18   <<<   146
Camden 2018 5   =   32
  2019 1   <<   31
Duplin* 2018 14   <   45
  2019 11   <   39
Edgecombe 2016   14 = 20
Halifax E 2016 5   <<   11
Halifax W 2016     16
Nash 1 2016 16 = 20 = 17
Nash 2 2016 7 < 13 = 17
Nash 3 2016 6 = 7 = 9
Nash 2017 10     17
Nash 2018   8 < 16
Nash 2019   44 < 57
Pitt 2016 8   <   14
Piedmont
Alamance* 2017   140 = 148
  2018   93 = 79
  2019   88 = 93
Davidson* 2017   24 = 23
  2018   32 <<< 104
Rowan 2017   34 = 30
  2018   53 = 39
Stanly 2016 16   <<   99
  2017 26   <<   48
  2018 64   <<   89
  2019 35   <<   1005
Wake 2017 6   <   10
  2018 5   <   9
Blue Ridge
Ashe* 2017 9   <<<   74
  2018 19   <<<   64
Henderson* 2017 46   <<<   97
  2018 4   <   37
AVERAGES across fields 19 < 37 = 50

None (no cover); SSCC (single-species cover crop); and MSCC (multi-species cover crop) at each location. To indicate significance between means < represents p ≤ 0.05; << represents p ≤ 0.01, and <<< represents p ≤ 0.05; = is not significant.

 

The ratio of carbon:nitrogen can be an important characteristic of cover crops to determine how fast it will decompose during the subsequent summer.  Ratio of <30 is often desired to avoid potential immobilization of nitrogen to the succeeding cover crop.  However, this issue is much less important in no-tillage cropping systems that keep residues at the soil surface.  Traditionally, cover crops were incorporated into the soil with tillage and high carbon:nitrogen ratio in this production system can indeed immobilize significant quantities of nitrogen during the early stages of decomposition.  As with all organic amendments, early immobilization is often followed by net nitrogen mineralization later in decomposition.  The question then becomes when this transition occurs – will it be one month, several months, or several years?  Again, the issue of nitrogen immobilization is less critical in surface-placed residues in long-term, no-tillage management systems.

Table 3 shows the carbon:nitrogen ratio that occurred in these demonstrations.  One-third of demonstrations had carbon:nitogen ratio of <23, one-third of demonstrations had carbon:nitrogen ratio of 23 to 30, and one-third of demonstrations had carbon:nitrogen ratio of >30.  Carbon:nitrogen ratio of multi-species cover crops were on average very comparable to that of overwintering weeds, but with starkly different amount of total biomass and total nitrogen accumulation.  The positive effect of legume components of multi-species cover crops was evident in the lower carbon:nitogen ratio compared with single-species cover crops.

 

Table 3. Biomass Carbon:Nitrogen (C:N) Ratio of Cover Crop Treatments

    Biomass C:N ratio
County Year None   SSCC   MSCC
Coastal Plain
Beaufort 2018 32   =   31
  2019     19
Brunswick* 2018 26   =   28
  2019 25   >>>   16
Camden 2018 28   >   18
  2019 23   =   22
Duplin* 2018 20   =   25
  2019 24   <   40
Edgecombe 2016   27 = 30
Halifax E 2016 23   =   21
Halifax W 2016     26
Nash 1 2016 33 = 36 = 29
Nash 2 2016 22 < 44 = 30
Nash 3 2016 32 = 24 = 27
Nash 2017 25   <<   31
Nash 2018   32 = 29
Nash 2019   34 > 26
Pitt 2016 34   =   35
Piedmont
Alamance* 2017   30 = 27
  2018   24 = 20
  2019   44 = 42
Davidson* 2017   31 = 31
  2018   55 >>> 19
Rowan 2017   15 <<< 22
  2018   13 << 18
Stanly 2016 32   =   30
  2017 28   >>>   21
  2018 22   =   20
  2019 23   <<   34
Wake 2017 21   <   35
  2018 24   =   20
Blue Ridge
Ashe* 2017 22   <   29
  2018 18   <<   26
Henderson* 2017 24   <<   45
  2018 15   <<   27
AVERAGES across fields 25 << 34 > 27

None (no cover); SSCC (single-species cover crop); and MSCC (multi-species cover crop) at each location. To indicate significance between means < represents p ≤ 0.05; << represents p ≤ 0.01, and <<< represents p ≤ 0.05; = is not significant.

 

Measurable Impacts to Soil Properties:

A diversity of soil physical, chemical, and biological properties was measured in each multi-species cover crop demonstration.  The full list of properties is in Table 4.  This report focused on five properties of key interest in soil health evaluation – total organic carbon, soil-test biological activity, net nitrogen mineralization, soil-test phosphorus, and soil-test potassium.  We also only report here the values for 0 to 2 inch soil depth, although we also measured values at 2 to 6 inch depth.  A peer-reviewed manuscript is being prepared that will contain more of the soil properties and soil depths.

Total organic carbon represents soil organic matter.  Soil organic matter is dominantly comprised of carbon, i.e. 58%.  Multiplying the total organic carbon values by 1.72 would yield soil organic matter.  For example, a value of 2.0% total organic carbon would be equivalent to 3.4% organic matter.  Soil-test biological activity is considered the most active portion of organic matter and is determined from the flush of carbon dioxide (CO2) during the first three days following rewetting of dried soil.  Net nitrogen mineralization is the quantity of nitrogen mineralized during a 24-day incubation of soil at standard temperature (77 °F) and water (50% water-filled pore space).  Soil-test phosphorus and potassium are from Mehlich-III extraction of soil as routine evaluation of fertility.  Therefore, these five properties represent the important fertility elements of carbon, nitrogen, phosphorus, and potassium, as well as a direct estimation of soil biological activity that drives nutrient cycling.

 

Table 4. Soil Properties: Measured from samples collected from six areas within each test strip of each cover crop demonstration field.  Samples were collected at 0 to 2 inch depth and 2 to 6 inch depth.  Soil cores were 1 9/16 inch in diameter and a total of eight cores spaced three feet apart were composited to make a sample of an area.  A typical field demonstration had a total of 48 samples analyzed each year.  Soil physical and biological properties (and inorganic nitrogen species) were analyzed by the Soil Ecology and Management Lab and soil chemical properties (and sieved density) were analyzed by the Soil Testing Laboratory of the NC Department of Agriculture and Consumer Services.

Physical Property Chemical Property Biological Property
Bulk density Acidity Basal soil respiration
Clay content Base saturation Biological activity
Sand content Calcium Carbon mineralization
Sieved density Cation exchange capacity Microbial biomass carbon
  Copper Nitrogen mineralization
  Humic matter Particulate organic carbon
  Magnesium Particulate organic nitrogen
  Manganese Total organic carbon
  pH Total soil nitrogen
  Phosphorus  
  Potassium  
  Sulfur  
  Zinc  

 

COASTAL PLAIN REGION
Beaufort 2017/18   2018/19                        
  TOC % STBA (ppm) 0-3 d NMIN (ppm) 0-24 d STP (ppm) STK (ppm)   TOC % STBA (ppm) 0-3 d NMIN (ppm) 0-24 d STP (ppm) STK (ppm)   TOC % STBA (ppm) 0-3 d NMIN (ppm) 0-24 d STP (ppm) STK (ppm)   TOC % STBA (ppm) 0-3 d NMIN (ppm) 0-24 d STP (ppm) STK (ppm)
No Cover Crop 1.14 124 32 91 87   1.34 160 37 137 55                        
P-value  * = = =   = * = = *                        
Multi-Species 1.21 144 31 94 81   1.35 179 31 148 43                        
Brunswick* 2017/18   2018/19                        
No Cover Crop 2.23 199 57 146 131   2.37 276 47 172 237                        
P-value  *** ** = = **   ** ** = = ***                        
Multi-Species 2.47 294 63 132 102   2.70 415 73 159 93                        
Camden 2017/18   2018/19                        
No Cover Crop 1.8 180 56 281 151   1.38 182 21 257 92                        
P-value = * = = =   ** = = =                        
Multi-Species CC 1.81 199 51 288 142   1.68 259 36 252 95                        
Duplin* 2017/18
  2018/19                        
No Cover Crop 2.04 185 56 606 203   2.23 185 61 643 107                        
P-value = = = = **   = = = = *                        
Multi-Species 2.23 185 61 643 107   2.14 216 50 652 84                        
Edgecombe 2015/16                            
No Cover Crop 2.03 218 62 83 221                                    
P-value = = = = =                                    
Multi-Species 1.93 231 79 74 193                                    
Nash 2015/16   2016/17   2017/18   2018/19
No Cover Crop 1.31 106 36 161 87   0.47 107 15 169 121   1.22 184 36 46 111   1.96 450 77 30 88
Single-Species; P-Value 0.93 90 25 96 98   = = = = =   * ***   = = * =
Multi-Species 0.90 80 24 115 77   0.45 97 14 153 119   1.44 204 45 30 149   2.03 462 95 20 95
PIEDMONT REGION
Alamance* 2016/17   2017/18   2018/19            
No Cover 3.26 483 125 133 426   4.41 625 110 120 544   5.55 706 136 111 316            
P-value = = = =   = = = = =   = = = = =            
Multi-Species 3.23 519 133 121 354   4.16 595 122 125 564   5.70 708 120 125 331            
Davidson* 2016/17   2017/18                        
Single-Species 1.91 369 68 68 188   2.47 328 97 71 195                        
P-value ** = =   = * = = *                        
Multi-Species 2.13 428 89 67 189   2.36 383 107 64 119                        
Rowan 2016/17   2017/18                        
Single-Species 1.36 248 62 25 65   1.68 294 54 28 85                        
P-value * = = =   = = * = =                        
Multi-Species 1.47 313 61 29 75   1.63 270 28 33 95                        
Stanly 2015/16   2016/17   2017/2018   2018/2019
No Cover 3.74 340 103 582 514   3.56 507 164 411 355   4.51 592 194 540 431   4.72 673 145 504 438
P-value = ** * =   = = = = *   * = = = **   = = = * =
Multi-Species 3.93 394 150 557 617   3.91 590 184 430 276   5.04 626 221 477 360   4.80 696 152 461 404
Wake 2016/17   2017/18        
No Cover 0.73 112 30 27 129   0.75 129 35 33 102                        
P-value = = = =   * = = =                        
Multi-Species 0.79 129 28 32 112   0.85 150 38 25 96                        
BLUE RIDGE REGION
Ashe* 2016/17   2017/18                        
No Cover 3.7 456 152 165 131   3.7 367 123 185 125                        
P-value = = = **   = = = = **                        
Multi-Species 3.7 437 138 197 81   3.8 358 118 143 71                        
Henderson 2017/18   2018/19                        
No Cover 3.38 187 47 85 132   3.21 156 52 90 195                        
P-value * = = = =   = = = = =                        
Multi-Species 3.24 231 59 91 131   3.23 170 59 95 199                        

 

Conclusions: Biomass production with multi-species cover crops spanned the range from relatively poor production in one-third of sites (<1154 lb/acre) to good production in one-third of sites (1154 to 3384 lb/acre) to excellent production in one-third of sites (>3384 lb/acre).  Nitrogen accumulation in the cover crop biomass was equally well distributed and reached excellent levels in one-third of sites at >54 lb/acre.  Since demonstrations were relatively short-term in nature, we didn’t anticipate seeing many soil differences, but there were some of notable significance.  At six sites, consistent cover cropping effects across years at the same location were not observed at all.  However, there were four sites that consistently had greater soil-test biological activity under multi-species cover cropping than with no cover crop.  There were also two sites that had consistently lower soil-test K under multi-species cover cropping than without cover crops, as well as one site with consistently lower soil-test P under multi-species cover cropping than with single-species cover crop.  These short-term multi-species cover cropping effects suggest that soil biological activity is enhanced and nutrient dynamics can be altered.  Soil-test P and K are simply indices of availability, not mass balances.  Further experimentation is warranted to better understand the unique soil biological changes that may be occurring with these cover crop mixtures.

Participation Summary
6 Farmers participating in research

Educational & Outreach Activities

12 Consultations
8 Curricula, factsheets or educational tools
1 Journal articles
5 On-farm demonstrations
10 Published press articles, newsletters
5 Workshop field days

Participation Summary

70 Farmers
70 Ag professionals participated
Education/outreach description:

Producer Outreach Workshops consisted of an educational meeting with field tours. Workshops were advertised through traditional mailings as well as email distributions, newsletters, project and county websites, Facebook and twitter.  External partners such as the Farm Credits, Southern Cover Crop Council and NC Farm Bureau Federation advertised the events to their members as well. Some Districts were able to offer continuing education credits for pesticide and animal waste licenses. Speakers included soil health experts from a variety of agencies within the conservation partnership, NACD Soil Health Champions, and the producers and hosted the on-farm demonstrations. SARE was given funding credit in the advertisements, printed materials and from the podium.

A journal article is under review with the Soil and Water Conservation Society, with Dr. Franzluebbers as lead author. Michelle Lovejoy, Foundation Executive Director, highlighted the soil health initiative at the North Carolina Association of Soil and Water Conservation Districts annual meetings yearly and once at the Georgia Association of Soil and Water Conservation Districts annual meeting. The SARE Cover Crop Economics Technical Bulletin was distributed to all North Carolina Soil and Water Conservation Districts.

Producer Outreach Workshop attendees included North Carolina, South Carolina, and Virginia producers, USDA Farm Service Agency and Natural Resources Conservation Service staff, NC Cooperative Extension staff, Soil and Water Conservation District staff from surrounding counties, NC Department of Agriculture and Consumer Services Division of Soil and Water Conservation and Agronomics Division staff, fertilizer dealers, seed dealers, and others. A total of 481 people were given the opportunity to received continuing education related to soil health, cover crops, seed mixes, planting types, and groundwater management during the SARE grant.  Overall, evaluations continue to show a high approval rating with producers indicating that they could apply the information to their current operations. Since the initiative began in 2013, over 1,454 educational opportunities have been provided to our agriculture and conservation community. The table provides a summary of the workshops held during the SARE grant. NOTE: ADFP = NC Agriculture Development and Farmland Preservation grant; Cotton = Cotton Inc. grant.

REGION COUNTY DATE ATTENDEES FUNDER
Coastal Plain Beaufort 3.19.18 9 ADPF
12.12.18 25 SARE
Brunswick 2.1.18 39 ADFP
3.13.19 26 SARE
Camden 4.4.18 9 ADFP
12.14.18 13 SARE
Duplin 3.15.18 36 ADFP
3.15.19 47 SARE
Nash 11.19.18 21 Cotton
Piedmont Alamance 12.6.18 25 SARE
Davidson 4.10.18 47 ADFP
1.22.2020 31 SARE
Rowan 10.26.19 26 ADFP
Wake 2.15.18 22 ADFP
Blue Ridge Henderson 5.2.18 12 ADFP
4.4.19 17 SARE

Learning Outcomes

145 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

10 Farmers changed or adopted a practice
4 Grants received that built upon this project
3 New working collaborations
Project outcomes:

Initiative Enhancements

The initiative started in 2013 with Cotton Incorporated interested in finding solutions to hardpan and NRCS wanting to test multi-species cover crops in the southeast. Cotton Incorporated has awarded 7 grants to date towards these efforts. The Foundation was awarded a USDA NRCS 2014 Conservation Innovation Grant entitled “Managing Multi-Species Cover Crops in Southeastern USA” contract number 69-3A75-14-233.  The additional funding allowed the Foundation to partner with Dr. Michael Wagger and Dr. Steve Broome, with NC State University’s Department of Soil Science and Dr. Alan Franzluebbers with USDA Agriculture Research Services to scientifically document the soil health benefits being realized in the demonstration plots.

The Foundation secured funds to expand the initiative in 2016 and 2017 to mountain and piedmont counties with a focus on different crop rotation systems. Funding for the expansion was provided by the NC Agriculture Development and Farmland Preservation Trust Fund managed by the NC Department of Agriculture and Consumer Services.

The Foundation secured a Southern SARE On-Farm Research grant that funded installation of soil moisture units in the cash crops to test out heat stressors in cover crop strips versus no cover crop strips. These efforts expanded the partnership to include Dr. Chris Reberg-Horton with NC State University’s Department of Crop Science. A second Southern SARE Education grant was awarded to the Foundation in 2018, allowing the project to continue in six counties in addition to the Cotton Incorporated sites.

The cover crop project is part of a larger soil health initiative that includes the Mobile Soils Classrooms. Since the 2018 SARE grant was awarded, the Foundation received its first EPA Environmental Education grant that will fund demonstrations in 2019 and 2020, 5 school outdoor learning center gardens, and the 5th Mobile Soils Classroom. Conservation partners are also in discussions regarding creating a “Soils Trails” online tool that would invite the public to explore various educational resources related to soils and soil health.

The current project results include producer-focused literature sharing lessons learned distributed to all District and conservation partners. A technical report is also available on the Foundation’s website, including data as of Spring 2019. The Foundation’s Soil Health Initiative is playing a critical role in communicating the importance of protecting and improving the soils, a vital national resource. Project reports will be provided at http://ncsoilwater.org/programs/soil-health-initiative-multi-species-cover-crops/.

 

Initiative Expansion – Heavy Rye Cover Crops

In 2018, a technical support group determined it would be beneficial to also promote Heavy Rye Cover Crops. Other southeastern states are seeing good results with yield increases. The Foundation partnered with the NC Cotton Producers Association, the NC Soybean Producers Association, and Wrangler to establish four sites in Halifax, Hoke, Northampton, and Stanly counties. Research was overseen by Drs. Vann, Collins, and Cahoon. The efforts were highlighted at the 2019 NC Joint Commodities Conference in addition to Field Days. Researchers produced an Extension publication entitled Managing Cereal Rye for Benefits in Cotton and Soybeans which can be found at https://content.ces.ncsu.edu/managing-cereal-rye-for-benefits-in-cotton-and-soybeans

 

Total Project Impacts

Since the initiative began, over 1,500 people have been directly impacted (workshop attendees and District Boards) and up to 150 acres were planted with multi-species cover crops annually. The Foundation is a founding member of the Southern Cover Crop Council and continues to promote soil health practices through the Conservation Districts across the southeast. Conservation partners continue to note what a value these on-farm demonstrations are and that they are observing a greater willingness for their producers to use cover crops. After hurricanes Matthew, Michael, and Florence, many producers and conservation partners noted the value of cover crops to those that were impacted from the flood waters, they could get equipment back into their fields much sooner than their neighbors. Since this initiative started, North Carolina’s acreage in cover crops has increased, according to SARE’s survey. The Foundation cannot draw a direct correlation to the ideas that sprout in enriched minds at Field Days to actual changes in management, but causalities seem to point to this effort playing a role in the overall expanded use of cover crops.

 

The Soil Health Horizon’s Future – Carbon Farm Planning, Natural Infrastructure, and Addressing Climate Change

A ground-swelling is occurring nationally related to how the traditional agriculture community thinks about and engages with climate change. North Carolina joined the US Climate Alliance in 2018 and since that time much work has been done across all sectors to consider how to proactively address issues that impact climate change, from flood mitigation to carbon sequestration.

The Foundation is rolling out a Carbon Farm Planning Initiative, thanks to a 2019 SARE grant, a 2019 NC Agriculture Development and Farmland Preservation Grant, and a 2020 USDA NRCS Conservation Collaboration Grant. This process will follow the on-farm demonstration model established in the soil health initiative, train up to 40 conservation partners based on the process used by the California Conservation Districts and Carbon Cycle Institute, partner with Sustainable Forestry and Land Retention Program at the Roanoke Center, Virginia Tech and the Virginia Conservation Districts, and NC State University’s Amazing Grazing Program.

A second process focusing on how to use traditional conservation practices of no-till and cover crops in addition to larger natural infrastructure to mitigate the impacts of flooding is also underway through the NC Policy Collaboratory grant, NC Sea Grant is the lead investigator. Project partners continue to seek resources to expand the FloodWise concept beyond the initial pilot county. More to be posted online in 2020 at www.ncsoilwater.org.

The Foundation and our conservation partners are headed down a path of exploring conservation practices through the lenses of flood mitigation and carbon sequestration. As a partnership, we are much better prepared to take this journey because of all of the lessons learned in the multi-species cover crop initiative.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.