Effects of Cover Crop Management on Corn

Production

Brian JonesAgronomy Extension Agent

245-5750brjones8@vt.edu

http://www.valleycrops.cses.vt.edu

Benefits of Cover Crops - Review Cut fertilizer costs

“Fix” atmospheric N (legumes) Scavenge / redistribute nutrients (grasses,

some legumes) How much??

Big question Depends on: time of killing, season, etc. More later…

Benefits of Cover Crops - Review Suppress weeds / other pests

Smother early emerging annuals Competition for water, light and nutrients Root exudates or compounds provide natural

chemical and nematode control (sometimes) Encourage beneficial insects

Benefits of Cover Crops - Review Improve yields

Increased infiltration (less runoff) Decrease compaction Improve soil structure Increase organic matter Improve nutrient cycling

Benefits of Cover Crops - Review Prevent erosion

Dense roots hold soil in place Prevents the “splash” effect Cover over the winter months

Benefits of Cover Crops - Review Conserve soil moisture

Residue increases infiltration Surface and root zone

Reduce evaporation from bare soil Must avoid killing too late

Problem with mechanical control systems

Challenges of Cover Crops Main Challenge:

Fitting them into your system Have to have the feed…

Nutrient cycling How much N? May be variable and will need to

test (PSNT) N tie up with high C:N cover crops

Rye killed late May not see N until following year

Challenges of Cover Crops Cropping challenges

Allelopathy may affect cash crop Stand / emergence issues Planting equipment adjustments Mechanically killing for some Good environment for harmful insects Cost of production

Challenges of Cover Crops Need to understand these questions with

our systems and conditions No perfect cover

Depends on rotation, needs, etc. Need local research…

Objectives1. Quantify the effects of cover crop species

on soil fertility and nutrient cycling2. Determine how cover crop kill date

affects cover crop biomass, corn yield and nutrient cycling

– Part of a larger study looking at low-input cover crop management

– Funded by the Shenandoah RC&D Council

Methods Project established in 2006 in Rockingham County Planted seven different cover crop treatments in fall of

2006 Three replications of each

Each treatment was killed at three different timings Residue rolled flat

Cover crop biomass, soil samples, and cover samples were taken prior to each rolling

Corn was planted no-till after each rolling 0 lbs N applied to corn

Whole plot was harvested with chopper and yield determined

Methods

40’

10’

RYE (120 lb) RYE (90 lb) + HAIRY VETCH (25 lb)BARLEY (120 lb) RYE (60 lb) + HV (10 lb) + CC (10 lb)CRIMSON CLOVER (20 lb) RYE (90 lb) + FORAGE RADISH (15 lb)HAIRY VETCH (20 lb) NO COVER

Methods Timing of killing was based on small grain

development: May 10 (boot stage) June 1 (soft dough) June 11 (hard dough)

Only talk about data from May 10 and June 1 treatment today Latest that most of us will be planting corn

Results: Cover Crop DM and Yield

Cover Crop Dry Matter at Two Kill Dates

0.00

10.00

20.00

30.00

40.00

50.00

60.00

Rye

Crimso

n Clo

ver

Vetch

Rye/V

etch

Rye/V

etch/C

lover

Rye/R

adish

Check

Cover Crop Species

Dry

Mat

ter

(%)

10-May

1-Jun

Results: Cover Crop DM and Yield

Cover Crop Yield at Two Kill Dates

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Rye

Crimso

n Clo

ver

Vetch

Rye/V

etch

Rye/V

etch/C

lover

Rye/R

adish

Check

Cover Crop Species

Yie

ld (

ton

ac-

1)

10-May

1-Jun

a

a

Daicon Radish

Not a traditional radish Being marketed as biological compaction relief Some evidence of increased microbiological

activity as a cover crop

QUESTIONS?

Total N from Cover CropPlant Nitrogen at Two Kill Dates

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

Rye

Crimso

n Clo

ver

Vetch

Rye/V

etch

Rye/V

etch/C

lover

Rye/R

adish

Check

Cover Crop Species

Pla

nt

Nit

rog

en (

lb a

c-1)

10-May

1-Juna a

aa

a

a

Available N From Cover Total N is not all available for mineralization

and crop uptake Loss factors include:

Volatilization (loss to atmosphere) Immobilization (tied up by bacteria) Leaching (loss to groundwater)

Available N From Cover Volatilization losses

Depend largely on whether or not cover was incorporated

Without incorporating cover crop in our climate figure approximately 50% loss due to volatilization

Species10-May 1-Jun

Rye 43.7 47.9Crimson Clover 85.3 * 119.7 *Hairy Vetch 63.1 145.8 *Rye/Vetch 107.5 * 88.7Rey/Vetch/Clover 86.3 * 124.8 *Rye/Radish 68.1 62.9None 23.6 44.3

Potentially Available N (lb/ac)

Available N From Cover Immobilization losses

Depend largely on the carbon to nitrogen ratio (C:N) of the cover crop species

Low C:N (<25) bacteria quickly break down vegetation making N available immediately

High C:N (>25) N will become available, but may not be until the following growing season

Also, bacteria will tie up soil N in order to digest high carbon residue

Often see this with the yellowing of corn in early spring with high residue

Cover Crop C:N at Two Kill Dates

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

Rye

Crimso

n Clov

er

Vetch

Rye/V

etch

Rye/V

etch

/Clo

ver

Rye/R

adish

Check

Cover Crop Species

C:N

Available N From Cover

Net Loss of PANfrom immobilization

Net gain of PANfrom mineralization

Available N From Cover

SpeciesPotentially

Available N (lb/ac) C:NAvailable N (lb/ac)

10-MayRye 43.7 31.76 ?Crimson Clover 85.3 14.55 85.3Hairy Vetch 63.1 11.68 63.1Rye/Vetch 107.5 18.27 107.5Rey/Vetch/Clover 86.3 23.81 ?Rye/Radish 68.1 43.85 ?None 23.6 28.89 ?

1-JunRye 47.9 45.71 ?Crimson Clover 119.7 20.45 119.7Hairy Vetch 145.8 13.07 145.8Rye/Vetch 88.7 39.71 ?Rey/Vetch/Clover 124.8 37.89 ?Rye/Radish 62.9 75.34 ?None 44.3 36.69 ?

Available Soil N Sampled the NO3-N and NH3-N fraction at

the time of kill and corn planting to see how much was potentially available These are highly mobile Most of crop uptake

Available Soil NAvailable Soil N at Two Kill Dates

0.005.00

10.0015.0020.0025.0030.0035.0040.0045.0050.00

Rye

Crimso

n Clo

ver

Vetch

Rye/V

etch

Rye/V

etch/C

lover

Rye/R

adish

Check

Cover Crop Species

Ava

ilab

le N

(lb

s ac

-1)

10-May

1-Jun

Available Soil N

Species

Available N (lb/ac) from

Residue

Available Soil N (lb/ac)

Total PAN (lb/ac)

10-MayRye ? 32.5 ?Crimson Clover 85.3 23.3 108.6Hairy Vetch 63.1 23.9 87.1Rye/Vetch 107.5 45.4 152.9Rey/Vetch/Clover ? 43.9 ?Rye/Radish ? 40.0 ?None ? 16.3 ?

1-JunRye ? 19.9 ?Crimson Clover 119.7 30.5 150.2Hairy Vetch 145.8 45.5 191.3Rye/Vetch ? 39.0 ?Rey/Vetch/Clover ? 15.3 ?Rye/Radish ? 29.5 ?None ? 19.7 ?

QUESTIONS?

Crop Response So how much N was actually available to the

corn crop from our cover crop treatments? Best observed by looking at the plant itself

Ear leaf samples show the % N in the plant at silking and provide a good “in-season” analysis of N uptake

Crop Response – Ear Leaf N

Corn Ear Leaf N from First Kill Date

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Rye

Crimso

n Clo

ver

Vetch

Rye/V

etch

Rye/V

etch/C

lover

Rye/R

adish

Check

Cover Crop Species

% N

in

Ear

Lea

f

a a a

Crop Response – Silage Yield

Corn Silage Yield at Two Kill Dates

0.002.004.006.008.00

10.0012.0014.0016.00

Rye

Crimso

n Clov

er

Vetch

Rye/V

etch

Rye/V

etch

/Clov

er

Rye/R

adish

Check

Cover Crop Species

Co

rn S

ilag

e Y

ield

(to

n a

c-1

)

10-May

1-Jun

a a a a

QUESTIONS?

Economics Bottom line Seed and establishment not cheap

Cover Crop Variety

Wheat VNS4 19.00$ bu 2 bu/ac 15.86$ ac 53.86$ ac 35.00$ ac 20.00$ ac (18.86)$ ac (33.86)$ ac

Rye Graze Master 16.00$ bu 2 bu/ac 15.86$ ac 47.86$ ac 40.00$ ac 25.00$ ac (7.86)$ ac (22.86)$ ac

Wheeler 17.75$ bu 2 bu/ac 15.86$ ac 51.36$ ac 40.00$ ac 25.00$ ac (11.36)$ ac (26.36)$ ac

Huron 18.50$ bu 2 bu/ac 15.86$ ac 52.86$ ac 35.00$ ac 20.00$ ac (17.86)$ ac (32.86)$ ac

Abruzzi 16.25$ bu 2 bu/ac 15.86$ ac 48.36$ ac 40.00$ ac 25.00$ ac (8.36)$ ac (23.36)$ ac

Barley Nomini 10.88$ bu 2 bu/ac 15.86$ ac 37.62$ ac 35.00$ ac 20.00$ ac (2.62)$ ac (17.62)$ ac

Thoroughbred 11.25$ bu 2 bu/ac 15.86$ ac 38.36$ ac 35.00$ ac 20.00$ ac (3.36)$ ac (18.36)$ ac

Triticale VNS 24.25$ bu 2 bu/ac 15.86$ ac 64.36$ ac 35.00$ ac 20.00$ ac (29.36)$ ac (44.36)$ ac

Crimson VNS 2.11$ lb 20 lb/ac 15.86$ ac 58.06$ ac 25.00$ ac 25.00$ ac (33.06)$ ac (33.06)$ ac

Vetch Common 1.04$ lb 20 lb/ac 15.86$ ac 36.66$ ac 25.00$ ac 25.00$ ac (11.66)$ ac (11.66)$ ac

Notes1. Average price taken from a seed dealer survey on August 132. Seeding rates based on requirements in the 2009 BMP manual3. Seeding cost based on the 2007 VCE farm custom rate survey4. VNS = variety not stated.

After Oct 5

Producer Costs for Cover Crop Establishment

Establishment Costs

Before Oct 5 After Oct 5

Cost ShareAverage

Price1

Seeding

Rate2

Seeding

Cost3

Before Oct 5

Economics – Yield Advantage

Cover Crop1 Variety2Seeding

Rate

Seed

Cost3Establishment

Cost4Corn Silage Yield

@ 35 DM

Value of Corn

Silage5Return over

Establishment Costslb ac-1 tons ac-1

Rye Wheeler 120 35.50$ 51.36$ 8.98 269.52$ 218.16$ Crimson Clover VNS 20 42.20$ 58.06$ 13.79 * 413.82$ 355.76$

Hairy Vetch VNS 20 20.80$ 36.66$ 13.79 * 413.82$ 377.16$ Rye/Vetch Wheeler/VNS 90/25 52.63$ 68.49$ 10.62 318.53$ 250.04$

Rye/Vetch/Clover Wheeler/VNS/VNS 60/10/10 49.25$ 65.11$ 14.52 * 435.60$ 370.49$ Rye/Radish Wheeler/VNS 90/15 67.13$ 82.99$ 12.98 * 389.32$ 306.33$ No Cover 0 -$ -$ 5.99 179.69$ 179.69$

------------------$ ac-1---------------- ------------------$ ac-1----------------

Economics – N Advantage

Cover Crop1 Variety2

Total PAN Available from

Residue3

Adjusted PAN Available from

Residue4

PAN from Soil

NO3 and Soil NH3

Estimated PAN for Corn

Silage Crop5Value of N Returned

(@ 0.90 N)$ ac-1

Rye Wheeler 87.48 0.00 32.45 * 32.45 29.21$ Crimson Clover VNS 170.55 * 85.27 23.31 * 108.58 97.72$

Hairy Vetch VNS 126.22 63.11 23.94 * 87.05 78.35$ Rye/Vetch Wheeler/VNS 215.06 * 107.53 45.36 * 152.89 137.60$

Rye/Vetch/Clover Wheeler/VNS/VNS 172.53 * 86.26 43.88 * 130.15 117.13$ Rye/Radish Wheeler/VNS 136.14 0.00 39.96 * 39.96 35.97$ No Cover 0.00 0.00 16.29 16.29 14.66$

--------------------------------------------------------lb ac-1 -----------------------------------------------

Economics – $ Advantage

Cover Crop1 Variety2

Corn Silage Value after Establishment

CostsValue of N Returned

(@ 0.90 N)

Total Short-Term Dollar

Value3

Rye Wheeler 218.16$ 29.21$ 247.37$ Crimson Clover VNS 355.76$ 97.72$ 453.48$

Hairy Vetch VNS 377.16$ 78.35$ 455.51$ Rye/Vetch Wheeler/VNS 250.04$ 137.60$ 387.64$

Rye/Vetch/Clover Wheeler/VNS/VNS 370.49$ 117.13$ 487.62$ Rye/Radish Wheeler/VNS 306.33$ 35.97$ 342.29$ No Cover 179.69$ 14.66$ 194.34$

----------------------------------------$ ac-1---------------------------------------

THANK YOU!

QUESTIONS?