4/8/2019

1

Building Soils with Cover Crops

Rongzhong Ye

Depart. of Plant & Environmental Sciences

Pee Dee Research & Education Center

Clemson University

04/03/2019

Soil Health Research

Ma

na

ge

me

nt,

la

nd

use,

clim

ate

Soil

Health

Soil

chemical

processe

s

Soil

biological

processe

s

Soil

physical

processe

s

Goal: Better understand the ecology of soil and hence to improve

management of agroecosystems and their sustainability

Environmental Outcomes:

1. Water quality

2. Carbon sequestration

3. GHG emissions

Agronomic Outcomes:

1. Resource use efficiency

2. Crop resilience

3. Quality and quantity of

production

4/8/2019

2

Many SC soils are highly degraded

• Long-term cultivation and intensive tillage

• Hot and humid climate favor microbial

decomposition

• Extensive clay mineral weathering and

clay eluviation

• Degraded soil structure

• Low soil organic matter

• Poor water and nutrient holding capacity

• Meager soil fertility USDA-NRCS

Purposes of cover cropping

• Reduce soil erosion • Increase soil organic matter • Improve biodiversity • Enhance nutrient availability • Promote biological nitrogen fixation • Reducing resources inputs • Suppress weeds and disease • Manage soil moisture and temperature • Minimize soil compaction

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3

Cover crops are different

e.g. growth, root structures, nutrient requirements

How the functional trait diversity of cover

crops affects designed outcomes?

Cereal Rye Winter Pea Crimson Clover Cotton

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4

Field and laboratory analyses

Agronomic Assessment

Texture Bulk density Soil structure pH Labile C Water content Available N and P N leaching potential Electrical conductivity Microbial biomass N mineralization potential Enzymatic activities Respiration Residue decomposition

Soil Health Attributes

Biological

Chemical

Physical

Cover crop production Cotton growth Lint yield Lint quality

Difference in carbon and nutrient credits

0.01.02.03.04.05.06.0

Rye

Crim

son

Pe

a

RC

RP

CP

RC

P

Bio

mas

s (t

on

e h

a-1)

010203040506070

Rye

Crim

son

Pe

a

RC

RP

CP

RC

P

Bio

mas

s N

(kg

ha-1

)

02468

1012

Rye

Crim

son

Pe

a

RC

RP

CP

RC

P

Bio

mas

s P

(kg

ha-1

)

0

20

40

60

80

Rye

Crim

son

Pe

a

RC

RP

CP

RC

P

Bio

mas

s K

(kg

ha-1

)

Biomass

N

P

K

4/8/2019

5

0

50

100

150

200

250

20-May 9-Jun 29-Jun 19-Jul 8-Aug 28-Aug 17-Sep 7-Oct

Bio

mas

s (g

)

Rye

Crimson

Pea

RC

RP

CP

RCP

Control

Affect cotton plant growth

Hurricane Florence

0

100

200

300

400

500

600

700

800

900

1000

Rye Crimson Pea RC RP CP RCP Control

Lin

t Y

ield

(kg h

a-1)

Cotton lint yield

a

b

ab ab

ab ab ab ab

Stepwise Regression Analysis

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6

0 20 40 60 80 100

Rye

Crimson

Pea

RC

RP

CP

RCP

0 20 40 60 80 100

RyeCrimson

PeaRCRPCP

RCPControl

0 20 40 60 80 100

Rye

Crimson

Pea

RC

RP

CP

RCP

0 20 40 60 80 100

Rye

Crimson

PeaRC

RP

CP

RCP

Control

2. N provision capacity

3. N Leaching potential

4. Soil N availability 1. C sequestration potential

Trade-offs

0 20 40 60 80 100

RyeCrimson

PeaRCRPCP

RCPControl

5. Yield

• Mixtures not necessary better

• Management goal matters

Synchronization of nutrient releases and crop

uptakes

Cover crop mineralization

Time

10-Apr 30-May 19-Jul 7-Sep 27-Oct

Rat

e o

f m

iner

ali

zati

on a

nd

upta

ke

of

P

10-Apr 30-May 19-Jul 7-Sep 27-Oct

Rat

e o

f m

iner

ali

azti

on a

nd

upta

ek o

f K

K release

P release

P uptake

K uptake

Termination timing?

4/8/2019

7

Demonstrating the influence of cover crop

termination time on nutrient provision and yield

of cash crops (2018-2021)

Contact: Email: rongzho@clemson.edu

Phone: (843)519-0494

0

20

40

60

Micro Macro

% Clay

Control

0.0

0.2

0.4

0.6

0.8

Clay Control

mm

0

200

400

600

800

1000

Clay Control

kg

C h

a-1

0

50

100

150

CB NAG LAP PHO BG XYL

mg

g-1

h-1

Clay Control

a b c d