Your SlideShare is downloading. ×
  • Like
Cfsa sac 2013 cover crops (1)
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.


Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Cfsa sac 2013 cover crops (1)


Molly Hamilton Cover Crops

Molly Hamilton Cover Crops

Published in Technology , Business
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads


Total Views
On SlideShare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. Cover Crop Selection and Management Molly Hamilton Extension Assistant NC State University, Crop Science Department
  • 2. Why use cover crops?
  • 3. Why use cover crops? • Fertility – N-fixing legumes
  • 4. How much N can a legume fix? • Fix N over spring, reaching peak at full flower Cover Crop Subterranean Clover Average N content %N in Maturity biomass 30-80 lb/acre 2 Mid-April Crimson Clover 100-150 lb/acre 2.5 Late April Austrian Winter Pea 100-150 lb/acre 3.5 Early May Hairy Vetch 150-200 lb/acre 4 Early May Berseem Clover 100-140 lb/acre 3 Late May Common Vetch 120-170 lb/acre 3.5 Late May Nitrogen contents of several winter annual legume cover crops in 2009 and 2010 in NC. Ranges are approximate and will vary from year to year. Courtesy of Dr. Julie Grossman, NCSU Soil Science
  • 5. Why use cover crops? • Fertility • Weed suppression – Out compete weeds – Leaf canopy that suppresses germination – Allelopathy
  • 6. Why use cover crops? Weed Suppression • Seed at high rates • Don’t let the cover become a weed. • “Allelopathy is rarely amazing”
  • 7. Why use cover crops? • Fertility • Weed suppression • Improve soil – – – – – – – Water infiltration Relieve compaction Improve soil tilth Increase biology Enhance nutrient cycling Improve soil moisture Improve water holding capacity
  • 8. Why use cover crops? Organic Matter Add organic matter Increase biological activity (& diversity?) May reduce soil-borne disease Pore structure improved Decomposition Aggregation increased Humus formed Nutrients released Improved tilth HEALTHY PLANTS Courtesy of Chris Reberg-Horton
  • 9. Why use cover crops? • • • • Fertility Weed suppression Improve soil Reduce erosion
  • 10. Selecting Cover Crops What are your needs? Timing? Location? Rotation?
  • 11. Selecting Cover Crops Winter annual Non-legumes Wheat Barley Oats Rye Triticale Summer annual Non-legumes Buckwheat Sorghum-Sudangrass Millet Sunflowers Winter annual Legumes Austrian Winter Pea Crimson clover Hairy vetch Berseem clover Subterranean clover Summer annual Legumes Cowpeas Soybeans Sunhemp Velvetbean
  • 12. Small Grains: barley, oats, wheat, triticale • • • • • • Winter annual grasses (cereal grains) Scavenge nutrients Add organic matter Suppress weeds Can be grazed Can be companion planted with legumes
  • 13. Barley, Oats, Wheat, Triticale Management • Plant in fall • Around 100 #/acre for thick cover – (1/4 # per 100 sq ft) • Fertility needs are moderate • To kill: – Mow, scythe, or roll-kill at milk to soft dough stages of kernel formation (spring) – Mow and till (winter or spring) – Till (winter) – Oats may winter kill Oats
  • 14. Rye (Secale cereale) • • • • • • • • • Winter annual grass Nutrient catch crop Large amount of organic matter Very competitive with weeds Good companion crop Can graze Inexpensive Very cold tolerant Earlier maturing than other grass cover crops
  • 15. Rye Management • Plant in fall • Moderate fertility needs • About 100 #/acre (1/4 # per 100 ft2)or 30-50 #/acre if planting with a legume • To kill: – Till (plow/disc) in winter or early spring – Mow, scyth, or roll-kill when full flower or into milk-stage (spring: May)
  • 16. Management Cautions Grain Cover Crops • Needs adequate fertility to produce biomass • Can tie up nitrogen when decomposing • Produce lots of biomass • They are grasses – consider when planning rotations
  • 17. Winter Annual: Brassicas • Mustards, forage turnip, forage radish, rape, canola • Characteristics: large taproot, varied cold hardiness, rosettes in winter turn to large stalked plant in spring • Biofumigant • Sulfur may be needed • Don’t do great in sandy soils • Management: – Seed 1 to 2 months before first frost at 5 to 15 lb/acre (0.03 lb or ½ oz./100 ft2) ½ inch to ¼ inch deep – To kill – mow and disc
  • 18. Winter Annual Legume: Austrian winter pea • Also known as field pea (but not in the South) • High-N fixer (90-150 lb N/acre), lots of biomass, cold hardy, viney growth, • Management: – Drill/plant about ¾ to 1 inch deep (broadcast not recommended) – Plant in fall – 70-90 lb/acre (1/5 # per 100 ft2) – Kill: Just after full-bloom • mow, disc, roll-kill, scythe – Decomposes quickly – Use correct innoculant
  • 19. Winter Annual Legumes: Hairy Vetch • Characteristics: viney growth, high Nfixer, cold tolerant • Management: – Seed at 20-30 lb/A (0.05 lb/100 ft2) – in fall (3/4 inch deep) – Use correct innoculant – To kill: • Mow and disc, roll-kill at early seed “set” stage – Re-seeding/weed issues?
  • 20. Winter Annual Legume: Crimson Clover • Characteristics: Good N fixer, good beneficial insect/pollinator habitat, beautiful • Does not like wet feet • Matures slightly earlier • Management: – Use correct innoculant – 20-25 lb/acre (0.05 lb/100 ft2)planted in fall, ¼ to ½ inch deep – To kill: • Mow and disc • Mow or roll-kill at late bloom/early seed set – Will re-seed
  • 21. Other winter annual legumes (that will work in NC) • • • • Berseem clover Subterranean clover Woolypod vetch Cahaba white vetch
  • 22. Management Cautions for Winter Legumes • Use correct innoculant – Nitragin Co., INTX microbials, Johnny’s Select Seeds, Peaceful Valley Farms, etc. • Most N is in above ground biomass • Max N in plant at full-bloom • N is not readily available to subsequent crop
  • 23. Summer Cover Crops?
  • 24. Summer Annuals: Buckwheat • Characteristics: fast growing, suppresses weeds, good pollinator habitat, effective nutrient scavenger • Succulent plant decomposes quickly • May go to seed = weed problem in next crop • Management: – Frost-sensitive, likes cool weather – Plant ½ inch deep 30-90 lb/acre – 0.1 lb/100 ft2 – Kill by mowing or disking (1 week after flowering) • Can be frost killed (not reliable to prevent re-seeding)
  • 25. Summer Annuals: Sorghum-sudangrass • Cross between grain sorghum (milo) and sudangrass • Characteristics: grows well in hot/dry, large biomass producer, suppresses weeds (allelopathic) • Management: – Plant 1-1 ½ inches deep from late spring-midsummer at 45 lb/acre (0.06 lb/100 ft2) – Can be mowed (or grazed) – Does well planted with viney legumes – To kill • Mow and disc • Frost kill – Will tie up N
  • 26. Summer Annual: Millets • Grasses, companion planted, frost-killed • German (foxtail) (Setaria italica) – 2-5 ft tall, small seeded – Plant mid-May-August at 25-30 lb/acre (0.06 lb/100ft2) – Avoid sandy soils • Pearl or cattail (Pennisetum glaucum) – 4-12 ft tall and performs well in sandy soils – Plant late April-July at 5 to 15 lb/acre (0.02 lb/100ft2 – Harder to kill • Japanese (Enchinochloa frumentacea) – 2-4 ft tall and quick maturing – Plant April to July at 20-25 lb/acre (0.05 lb/100ft2) – Avoid sandy soils
  • 27. German (foxtail) Millet From Iowa State Univeristy From Western Illinois State University Japanese Millet From Texas A&M University
  • 28. Summer Annual: Sunflowers • Characteristics: Tall, weed suppressive, pretty • Management: – Plant in warm soils at 4-5 lb/acre (0.01 lb/100 ft2) ½ - 1 inch deep – Modest fertility needs – Variety selection: cheapest seed or whatever looks pretty – To kill: • Mow, disc • Frost-kill
  • 29. Summer Annual Legume: Cowpeas • Also called black eyed, southern, crowder, and field pea • Characteristics: can produce 90-100 lb N, succulent, decomposes quickly, can be viney, need warm weather • Management: – Plant 40-100 lb/acre (up to ¼ lb/100 ft2) – ‘Ironclay’ or ‘Red Ripper’ recommended – To kill: • Mechanical means not reliable • Frost-killed
  • 30. Summer Annual Legumes: Soybean • Characteristics: 2-4 ft tall, bushy, inexpensive, high N-fixer, forage types available • Management: – Plant 60-100 lb/acre (up to ¼ lb/100 ft2)when soil warms – Plant late-maturing varieties (Group VI or later) – To kill: • Mow and disc • Frost-killed
  • 31. Alternative Summer Annual Legumes • Velvetbean (Mucuna deeringiana) – Viney legume (good in combinations) – does well in sandy/poor soils • Sunhemp (Crotalaria juncea) CEFS, NC State University – Very tall, herbaceous annual that needs good drainage CEFS, NC State University – Recommended to plant after summer crop (like corn) to grow in months up to first frost • Seed for these plants is hard to find and can be expensive
  • 32. Perennial Cover Crops • Paths, between rows (“living mulch”), forage/hay, long-term planning • Options: – Alfalfa: short-lived perennial • • • • Can be mowed or grazed Needs well-drained, near neutral soil Seed in fall Most susceptible to pests – White clover (Trifolium repens): perennial • Seed in late summer/fall • Choose intermediate sizes (i.e. Dutch white) • Can be mowed, grazed, trafficked – Red clover (Trifolium pratense): short-lived perennial • Mammoth red (can be cut once) or medium red (multi-cut) • Seed in fall • Kill mechanically when in bloom or dormant
  • 33. Organic No-till?
  • 34. Organic No-till • Winter annual cover crop is roll-killed • Cash crop planted into rolled cover • Need a lot of biomass (8,000 lb dry matter/A or over 18 lb/100 ft2) – Don’t attempt with poor or spotty stands • Roll at full bloom or just beyond • Roller-crimper, cultipaker, scythe, mower, etc. • Need to get through cover crop mat to plant
  • 35. Kill timing for legume cover crops MATURITY Early Mid SPECIES none Crimson clover Late-April/ Early May Late TIME Mid-April Late-April/ Early May Hairy vetch AU Earlycover Late-May Hairy vetch AU Merit Experimental USDA line Late-May Early June Early June Mid June Hard-to-kill Not winter hardy CULTIVAR none AU Robin Dixie AU Sunrise Tibbee Winter pea Common vetch Berseem Clover Sweet clover Sub clover Blue Lupine Winter hardy Earlycover (unstated) and Whistler (unstated) Bigbee Hubam Denmark Tifblue 78 Courtesy of Chris
  • 36. Kill times for rye (Secale cereal) cover crops MATURITY TIME Early CULTIVAR Late April Wrens Abruzzi Wrens 96 MatonII Mid Early May Aroostook Late Mid to late Rymin May Wheeler
  • 37. Rules of thumb for planting in no-till • Need to get through thick mat of rolled cover • Use straight edged no-till coulters. • Heavy duty downforce springs or a pneumatic downforce system is often needed. • Some planter may need extra weight mounted on the frame. • Cast iron and rolling spider closers are reported to be the best choices. Even with the heaviest of closers, sealing the trench can be difficult at times.
  • 38. How much N am I getting? • Nearly all N comes from above ground biomass • Material must decompose for crop to get N • About 50% of N will be available for next crop (40% if residue left on surface) Cover Crop Subterranean Clover Average N content %N in Maturity biomass 30-80 lb/acre 2 Mid-April Crimson Clover 100-150 lb/acre 2.5 Late April Austrian Winter Pea 100-150 lb/acre 3.5 Early May Hairy Vetch 150-200 lb/acre 4 Early May Berseem Clover 100-140 lb/acre 3 Late May Common Vetch 120-170 lb/acre 3.5 Late May Nitrogen contents of several winter annual legume cover crops in 2009 and 2010 in NC. Ranges are approximate and will vary from year to year.
  • 39. How much N am I getting? 1. Determine biomass produced. – Use a frame of known dimensions, clip plants at ground level, dry plants to crunchy dry – Calculate: • Area sampled: 2x2 = 4 sq.ft. x 2 (samples) = 8 sq.ft. 2 ft 2 ft • • Dried samples weigh 1.2 lbs. 1.2 lbs/8 s.f. X 43,560 s.f./acre = 6,534 lbs dry biomass
  • 40. 2. Use tissue test or estimate %N in cover crop – Multiply dry biomass yield with % of Nitrogen (6453 lbs/acre) x (0.035) = 226 lb of N in biomass 3. Predict how quickly biomass will decompose, releasing nutrients for crop – Multiply legume biomass nitrogen with : • 0.50 if residue will be incorporated • 0.40 if residue is left on surface – (226 lb N) x (0.50) = 113 lb N/acre available to crop Cover Crop Subterranean Clover Average N content %N in Maturity biomas s 30-80 lb/acre 2 Mid-April Crimson Clover 100-150 lb/acre 2.5 Late April Austrian Winter Pea 100-150 lb/acre 3.5 Early May Hairy Vetch 150-200 lb/acre 4 Early May Berseem Clover 100-140 lb/acre 3 Late May Common Vetch 120-170 lb/acre 3.5 Late May
  • 41. Seed Sources • • • • • • • • Local feed and seed Southern States Improved Forages Johnny’s Selected Seed Albert Lea Seedhouse Blue River Organic Hybrids Welter Seed and Honey Co. Innoculant Sources: – Nitragin Co., INTX microbials
  • 42. Further resources • Bowman, G., C. Shirley, and C. Cramer. 1998. Managing Cover Crops Profitably. The Sustainable Agriculture Network Handbook Series, Book 3. Available from Sustainable Agriculture Publications, Hills Building, Room 10, University of Vermont, Burlington, VT05405-0082. ( • SAREP cover crop database: • Hoyt, Wagger, Crozier. 2004. Soilfacts: Winter Annual Cover Crops (AGW-439-58); • Creamer, Baldwin. 1999. Summer Cover Crops; • Growing Small Farms: Cover crops for sustainable production: • NCSU Organic Grain Program: • ATTRA: Overview of cover crops and green manures: • Oregon SU Small Farm cover crop calculator: • NCDA Plant Tissue Analysis (Agronomic Division): • NCSU Small Grains: