Alternative Winter Cover

Crops for Virginia

Alternative Winter Cover Crops for Virginia

• Why focus on cover crops? • Which cover crops? • When? • How? • What’s next?

Soil Carbon and Tillage

West and Post, 2002

Soil C and Cover Crops

West and Post, 2002

• 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?

Water

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

Fallow Small Grain Corn Soybean

Volu

me

Leac

hed

(cm

mon

th-1

)

Figure 7 - Volume of water leached per month through soils under different crops from January 2005 to July 2010. Means with the same latter are not significantly different by F-test (P = 0.05).

Nitrate

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

Fallow Small Grain Corn Soybean

NO3-N

(kg

ha-1

mon

th-1

)

Figure 13 - Amount of NO3-N leached per hectare per month through till and no-till systems under different crops from November 2005 to July 2010. Means with the same latter are not significantly different by F-test (P = 0.05).

K. Staver, UMd

K. Staver, UMd

Maryland Research

K. Staver, UMd

What is a “CYCLE”

a course or series of events or operations that recur regularly and usually lead back to the starting point

Which cover crop(s)?

Vaughan, 1994

Which cover crop(s)?

• Scavenge N / Reduce Leaching • Fix N For the Following Crop • Suppress Weeds • Break Pest or Disease Cycles • Cover Soil / Prevent Erosion • Reduce Compaction / Improve Soil Structure • Water Management • Forage

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

Fall / December

0

100

200

300

400

500

600

700

800

Dry

Mat

ter,

lb/a

c

Rye Biomass

2100 lb/ac 1100 lb/ac 3490 lb/ac

390 lb/ac 796 lb/ac 199 lb/ac

March

0

500

1000

1500

2000

2500

3000

3500

4000

Dry

Mat

ter,

lb/a

c

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

Planting Date Affects Fall Growth

0

250

500

750

1000

1250

26-Aug 15-Sep 05-Oct 25-Oct 14-Nov 04-Dec

Biom

ass,

lb/a

c 01-Sep

15-Sep

01-Oct

15-Oct

01-Nov

Mar 22, 2006

Rye+Vetch Early Rye+Vetch Late

Oats Late

2005

Species/Mix Planting

Date Feb. N Rate,

lb ac -1

Rye 4 October 0 Oats 18 October 25 Barley 10-Nov Triticale

50

2005

0

1

2

3

4

5

6

7

Early Mid Late Early Mid Late Early Mid Late Early Mid Late

Barley Barley Barley Oats Oats Oats Rye Rye Rye Triticale Triticale Triticale

Crop and time of planting

Yiel

d, to

n ac

-1

2006

Species/Mix Planting

Date Feb. N Rate,

lb ac -1

Rye 30 Sept 0 Oats 20 October 30 Barley 10-Nov Crimson Clover Vetch Rye+Vetch

Barley Crimson Clover Oats Rye Rye +

Vetch Vetch Control

0 0.5

1 1.5

2 2.5

3 3.5

4 4.5

Early

Mid

Late

Early

Mid

Early

Mid

Late

Early

Mid

Late

Early

Mid

Late

Early

Mid

Late

Late

DM

Yie

ld, t

on a

c-1

2006

Some Rye is better adapted

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1 2 3 4 5 6 7

Rye Cultivar

DM

Yie

ld, t

on/a

c - B

oot S

tage

Nitrogen Uptake

• 2005 • 2006

0

30

60

90

120

150

180

Early Mid Late

N u

ptak

e, lb

/ac

0

30

60

90

120

150

180

Early Mid Late N

upt

ake,

lb/a

c

2005

0 10 20 30 40 50 60 70 80 90

Early Mid Late

Relative Planting Time

N U

ptak

e, lb

ac-1

Uptake potential is reduced with delayed planting!!!

2006 Soil Nitrate

0 10 20 30 40

50 60 70 80 90

NO

3- lb

ac-1

Feb. Early

Feb. Mid

Feb. Late

May Early

May Mid

May Late

Preplant

a b c a a b

Planting Date

Very Early Planting – to Dec 15

0

5

10

15

20

25

30

35

40

45

24-Aug 13-Sep 3-Oct 23-Oct 12-Nov 2-Dec 22-Dec

GDD,

Bas

e 32

F

Date

~2000 GDD

~1500 GDD

~1100 GDD

~700 GDD

~400 GDD

• 143 GDD to germinate • 90 GDD to emerge • 145 GDD/new leaf

Rye Only

0

500

1000

1500

2000

2500

3000

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33

DM B

iom

ass,

kg

ha-1

Shen Valley – early September planting

After Oct 25

Little/no rain after seeding

Planted before Oct 8

Various Crops – 50% Harvested, VASS

y = 0.1762x 2 - 13898x + 3E+08 R 2 = 0.9999

0

500

1000

1500

2000

2500

1-Se

p

8-Se

p

15-S

ep

22-S

ep

29-S

ep

6-O

ct

13-O

ct

20-O

ct

27-O

ct

3-N

ov

10-N

ov

17-N

ov

24-N

ov

1-De

c

8-De

c

15-D

ec

Tota

l Bio

mas

s, lb

/ac

Growth Response to Temperature

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

200 GDD 400 GDD 600 GDD

DM Y

ield

, kg/

ha

Tillage Radish Canola Phacelia Rye Barley Australian Winter Pea Woolypod Vetch Early Cover Hairy Vetch Spring Oats Ryegrass Common Vetch Crimson Clover Sweet Lupin 38

550

2250

Seeding Methods

• We basically looked at everything with an emphasis on aerial and broadcast seeding methods

2009 Plots

Site Seeding Date Previous Crop Conditions

Halifax 21-Oct Corn Tilled

Middlesex 1-Oct Soybean Before leaf drop

Greensville 28-Oct Soybean After leaf drop

Prince George 14-Oct Soybean 30% leaf drop

Essex 2-Oct Corn, 160 bu/ac Stalks bushogged

Northumberland 6-Oct Soybean Before leaf drop

Cover Crop Rate

Rye (assumes 56 lb/bu) 3 bu/ac

Barley (assumes 48 lb/bu) 3 bu/ac

Crimson Clover 20 lb/ac

Vetch 20 lb/ac

Rye+Crimson Clover 2 bu + 10 lb/ac

Rye+Vetch 2 bu + 10 lb/ac

Halifax Seeding Date Previous Crop Conditions

21-Oct Corn Tilled

10/21

10/27

11/18

Halifax, 11/18 Seeding Date Previous Crop Conditions

21-Oct Corn Tilled

Rye, 97.5%

Barley, 90%

Crimson Clover, 44.6%

Vetch, 36%

Rye+Vetch, 94%

Rye+Clover, 97%

Middlesex, Seeding Date Previous Crop Conditions

1-Oct Soybean Before leaf drop

Rye: 20-25% Barley: 90-100% Clover: 50-60% Vetch: 40-50% Rye + Vetch: 35-40% Rye + Clover: 10-20%

11/30

Prince George

Seeding Date Previous Crop Conditions

14-Oct Soybean 30% leaf drop

• Seeded into double-crop soybeans with straw left on field from wheat harvest

• Seeded October 14, 2009 • Soybeans had approximately 30-40% leaf drop • Rainfall occurred on October 15 • Soybeans harvested November 30 • Sandy loam soil types • Pictures 12-1-09 • I would consider this seeding a failure at this

site.

Aerial seeding plots 12-1-09

Essex

Seeding Date Previous Crop Conditions

2-Oct Corn, 160 bu/ac Stalks bush

hogged

Rye Barley Clover Vetch Rye+Clover Rye+Vetch

11/30

Treatments planted on October 2nd. Good soil moisture at the time of planting, but no rain for about 12 days after planting. Rye started germinating very quickly and some of it was up in 7 days or so. Barley was close behind. Took longer for the vetch and clover to germinate.

Rye 42.4%

Barley, 40.1%

Northumberland

Seeding Date Previous Crop Conditions

6-Oct Soybean Before leaf drop

The plot was planted October 6. Weather at that time and since has been unusually warm and wet; if there was ever a fall when seed would sprout without good soil contact, it was this one.

Northumberland, 11/30

Seeding Date Previous Crop Conditions

6-Oct Soybean Before leaf drop

42.4%

60.6%

Initial Observations

• Early establishment and early-season growth are key. – How much growth do we need?

• Crimson clover needs to be seeded earlier – Also Vetch?

• Mixes need to either: 1)include more legume seed or; 2) include less small grain

Aerial/Broadcast Seeding “Success”

• 256 data points • Various species, locations, seeding dates,

seeding rates, etc. • Biomass in December (Fall), C, N, N uptake • Biomass in March (Season/Spring), C, N, N

uptake

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%

Planting date effects on cover crop biomass – December 10

0

50

100

150

200

250

300

350

400

450

500

1 2 3 4 5

DM B

iom

ass,

kg/

ha

Barley

Rye+Hairy Vetch

Rye+Diacon radish

Rye

1 10-Sep 2 24-Sep 3 8-Oct 4 22-Oct 5 5-Nov

ns

ns

ns

ns

ns

Planting date effects on cover crop biomass – Termination (early April)

0

500

1000

1500

2000

2500

1 2 3 4 5

DM B

iom

ass,

kg/

ha

Barley

Rye+Hairy Vetch

Rye+Diacon radish

Rye

1 10-Sep 2 24-Sep 3 8-Oct 4 22-Oct 5 5-Nov

a

a

a

b

a a

a

b a a a

b

ns

ns

Natural Leaf Drop Vs. Chemical Defoliation, Suffolk

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

0

200

400

600

800

1000

1200

1400

1600

1800

DM B

iom

ass,

kg

ha-1

None

Paraquat

LSD = NS

Natural Leaf Drop Vs. Chemical Defoliation, Blacksburg

0

500

1000

1500

2000

2500

3000

None Paraquat

DM B

iom

ass,

kg

ha-1

Rye

LSD = NS

Wheat Stubble Management Effects on Winter Cover Establishment

0

500

1000

1500

2000

2500

Blacksburg Suffolk

Biom

ass Y

ield

, kg

ha-1

Standing Stubble

Baled Stubble

Cultipacker or Vertical tillage

Tilled

LSD = NS

Cover Crop Species for Broadcast Seeding into Soybean Canopy

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

0

500

1000

1500

2000

2500

3000

Blacksburg Suffolk

DM B

iom

ass,

kg

ha-1

Rye+Radish

Rye+Vetch

Spring Oat

Spring Oat+Radish

Barley

Rye

LSD = NS

Common soybean herbicide rotation restrictions