Alternative Winter Cover Crops and Systems for Virginia

• Cover crops offer the best opportunity to “intensify” our current row crop rotations

• Increase soil organic matter • Retain and cycle nutrients• Retain water• Manage pests?

Species Demonstrations• Early Cover Hairy Vetch • Common Vetch • Wooly pod vetch (Lana)• Crimson Clover • Austrian Winter Peas

• Sweet Lupins • Tillage Radish • Phacelia

• Rye • Barley • Ryegrass • Spring oats

• Barley+Crimson+tillage radish • Rye+Vetch+Pea+tillage radish • Rye+ryegrass+tillage radish • Spring oats+canola • Spring oat+tillage radish • Spring oat + barley • Barley+Crimson+Woolly Pod

Vetch+Peas +tillage radish+canola

• Ryegrass+Crimson+Woolly Pod Vetch+Peas +tillage radish+canola

WINTER SPRINGDM BIOMASS

N UPTAKE

DM BIOMASS

N UPTAKE

---------LB/AC---------

---------LB/AC---------

Rye+Ryegrass+Tillage radish 1660 57 3277 76Barley 1543 55 2705 57Ryegrass+Crimson+Woolly Pod Vetch+Peas +Tillage radish+Canola 1426 49 2556 68Rye+Vetch+Pea+Tillage radish 1343 41 2705 62Barley+Crimson+Tillage radish 1327 44 2513 58Tillage Radish 1285 43 211 3Barley+Crimson+Woolly Pod Vetch+Peas+Tillage radish+Canola 1264 39 1848 40Rye 1251 36 2376 59Spring oats+Tillage radish 1239 40 1289 22Phacelia 1092 38 506 12Spring oats+Canola 1054 33 2173 46Spring oats 1052 33 1112 17Ryegrass 954 30 1556 32Wooly pod vetch (Lana) 728 24 1610 50Crimson Clover 685 16 1385 38Indian Head Lentils 655 21 107 4Common Vetch 576 17 525 17Austrian Winter Peas 566 17 565 25Spring Oat + Barley 500 11 2087 30Sweet Lupins 491 14 730 14Persian Clover 442 12 202 4Early Cover Hairy Vetch 318 11 1374 40Yellow Sweet Blossom Clover 244 5 525 11Arrowhead Clover 180 4 265 6Subterranean Clover 168 2 191 5

Rye Biomass

2100 lb/ac1100 lb/ac 3490 lb/ac

390 lb/ac 796 lb/ac199 lb/ac

Summary

• Fall growth– Rye, barley, and mixtures with them– Radish, phacelia, and spring oats

• Spring growth– Rye, barley, and mixtures with them– Vetch and clover (depending on termination)

Summary

• Canola deserves a look• Mixtures were surprisingly good

Mar 22, 2006Rye+Vetch Early Rye+Vetch Late

Oats Late

Growth Response to Temperature

200 GDD 400 GDD 600 GDD0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Tillage RadishCanolaPhaceliaRyeBarleyAustralian Winter PeaWoolypod VetchEarly Cover Hairy VetchSpring OatsRyegrassCommon VetchCrimson CloverSweet Lupin

DM Y

ield

, kg/

ha

38

550

2250

Species X Date Interseeded into Soybean, 2012-13. Average of 4 locations

Rye Barley Rye+hairy vetch Rye+tillage radish

0

100

200

300

400

500

600

700

800

900

1000

10-Sep24-Sep8-Oct22-Oct5-Nov

DM B

iom

ass,

kg h

a-1

Aerial/Broadcast Seeding “Success”

Aerial/Broadcast Seeding “Success”All types Rye only Legumes

Dry Matter, lb/ac in December

------% of samples------

<200 lb/ac 40% 9% 75%<800 lb/ac 46% 29% 92%>800 lb/ac 54% 61% 8%

Rye Only

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 330

500

1000

1500

2000

2500

3000

DM B

iom

ass,

kg h

a-1

Shen Valley – early September planting

After Oct 25

Little/no rain after seeding

Planted before Oct 8

Natural Leaf Drop Vs. Chemical Defoliation, Suffolk

(Dual + Prowl PRE fb Roundup + FirstRate POST to Soybean)

Rye+R

adish

Rye+V

etch

Sprin

g Oat

Sprin

g Oat+

Radish

Barley Rye

0

200

400

600

800

1000

1200

1400

1600

1800

NoneParaquat

DM B

iom

ass,

kg h

a-1

LSD = NS

Natural Leaf Drop Vs. Chemical Defoliation, Blacksburg

None Paraquat0

500

1000

1500

2000

2500

3000

Rye

DM B

iom

ass,

kg h

a-1

LSD = NS

Wheat Stubble Management Effects on Winter Cover Establishment

Blacksburg Suffolk0

500

1000

1500

2000

2500

Standing Stubble

Baled Stubble

Cultipacker or Vertical tillage

Tilled

Biom

ass Y

ield

, kg

ha-1

LSD = NS

Cover Crop Species for Broadcast Seeding into Soybean Canopy

(Dual + Prowl PRE fb Roundup + FirstRate POST to Soybean in Suffolk)

Blacksburg Suffolk0

500

1000

1500

2000

2500

3000

Rye+Radish

Rye+Vetch

Spring Oat

Spring Oat+Radish

Barley

Rye

DM B

iom

ass,

kg h

a-1

LSD = NS

Leaching and EFI

• EFI = Precip * soil AWHC

0 1 2 3 4 5 6 7 80

102030405060708090

100

Exchange Frequence Index

Est.

N lo

ss o

verw

inte

r, 0-

60 c

m

Exchange Frequency Index

<1.5 0.5-1.5 1.5-2.5 >2.5

Rel. Risk Low Moderate High Very High

% of years in leaching risk category

Loamy Sand 0.7 41.1 37.6 20.6

Sandy Loam 7.1 59.6 31.9 1.4

Silt Loam 12.1 69.5 18.4 0