MICROBIAL ECOLOGY:

Soil, Plant, and Atmospheric Processes

Virginia L. Jin USDA-ARS Agroecosystem Research Management Unit, Lincoln, NE USA

Virginia.Jin@ars.usda.gov

Collaborative Approaches for Understanding and Managing

Air and Water Quality Issues in Livestock Production

13-14 October 2010

• C & N cycling, microbial ecology, greenhouse gas fluxes

• Nevada Desert FACE Facility, Lysimeter CO2 Gradient

RESEARCH PROGRAM SUMMARY

RESEARCH AREAS:

(2) Transport/Fate of Nutrients, Metals, & Emerging Contaminants

• Beneficial reuse of municipal biosolids in central Texas

• Conceptual modeling of transport & fate in ARS watershed

model, the Soil and Water Assessment Tool (SWAT)

(1) Impacts of Global Changes on Agroecosystem Soils

• What are the impacts on soil fertility, plant nutrient use, and

ecosystem productivity?

RESEARCH QUESTIONS:

• How do various global changes affect microbially-mediated

soil processes such as N cycling, C sequestration, and gas

fluxes of N and C?

GLOBAL CHANGE & AGROECOSYSTEMS

IMPACTS:

• Better predict agroecosystem responses to global changes

• Improve management decisions to optimize sustainable

production with soil C storage and minimize GHG emissions

Assess Ecosystem Responses Using Stable Isotopes

δ13C, δ15N (‰) = 1000 x ( Rsample – Rstandard )

Rstandard

R =

Minor isotope (heavy)

Major isotope (light)

13C

12C

15N

14N or

• Naturally occurring (13C ~1.1%, 15N ~0.37%)

• Physical and biochemical fractionations

• Natural abundance of isotopes in ecosystem compartments

• Tracer studies (depleted or enriched tracers 13C, 15N)

GLOBAL CHANGE & AGROECOSYSTEMS

GLOBAL CHANGE & AGROECOSYSTEMS

NDFF: Biochemical Profiling using Phospholipid Fatty Acids

GLOBAL CHANGE & AGROECOSYSTEMS

NDFF: Microbial Functional Composition & Structure

Jin & Evans 2010, Global Change Biology 16: 2334–2344

Principal Component 1 (25%)

-1.0 -0.5 0.0 0.5 1.0

Pri

ncip

al

Co

mp

on

en

t 2 (

18%

)

-1.0

-0.5

0.0

0.5

1.0 Ambient CO2

Elevated CO2

• Persistent changes in functional composition and structure

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Ambient CO2

PL

FA

δ13C

(‰

)

-40.0

-20.0

0.0

20.0

Elevated CO2

-40.0

-20.0

0.0

20.0

General Gram- Gram+

Actinobacteria Protozoa

Fungi

• Microbial use of plant-derived 13C substrates biomarker-specific

Potential change in desert soils as C sinks or sources

GLOBAL CHANGE & AGROECOSYSTEMS

Biofuel Feedstock Systems: Optimizing Production with Provision

• Effects of cropping

system, irrigation,

residue removal, and

tillage on soil C storage

and GHG fluxes

(CO2, CH4, N2O)

• Economic valuation of

ecosystem services

using adaptive manage-

ment practices on soil C

storage, GHG emissions

GLOBAL CHANGE & AGROECOSYSTEMS

CURRENT PROJECTS

(1) SOC dynamics, GHG emissions in rain-fed annual vs

perennial feedstock production systems

• ARDC (Mead, NE) switchgrass/corn study

• Treatments: Crop type (3), N level (4), harvest timing (2),

residue removal rate (2)

(2) SOC dynamics, GHG emissions in irrigated corn

• SCAL (Clay Center, NE); no-till continuous corn

• Treatments: Irrigation level (2), supplemental C (3),

residue removal rate (2), N level (3)

GLOBAL CHANGE & AGROECOSYSTEMS

CURRENT PROJECTS

(3) Economic valuation of ecosystem services and potential

impact of climate changes: Modeling SOC & GHG emissions

• Collaborative research with UNL (Fulginiti, Perrin, Liska)

• Objective: Provide decision-tool for selecting BMPs that

increase C sequestration and adapt cereal crop production

and resource management to predicted climate changes 90°0'0"W

95°0'0"W

95°0'0"W

100°0'0"W

100°0'0"W

105°0'0"W

105°0'0"W

42°0'0"N

42°0'0"N

41°0'0"N

41°0'0"N

40°0'0"N

40°0'0"N

96°0'0"W

96°0'0"W

97°0'0"W

97°0'0"W

98°0'0"W

98°0'0"W

99°0'0"W

99°0'0"W

100°0'0"W

100°0'0"W

101°0'0"W

101°0'0"W

102°0'0"W

102°0'0"W

103°0'0"W

103°0'0"W

104°0'0"W

104°0'0"W

43°0'0"N

43°0'0"N

42°0'0"N

42°0'0"N

41°0'0"N

41°0'0"N

40°0'0"N

40°0'0"N

Annual Moisture Deficit1960-1990

Deficit

Surplus

Source: Bill WaltmanDescription: Mean annual water balances were derived from theNewhall Simulaton Model (Van Wambeke et al., 1992) using1961 to 1990 normals for precipitation and temperature froma population of 125 weather stations (Owenby and Ezell, 1992).The annual water balances represent the cumulative differencesbetween monthly precipitation and potential evapotranspiration. The water balance surface was constructed from a terrainregression applied to the USGS 3 arc-second digital elevationmodels (DEMs; 1:250000) with a final resolution of 200m.

1:5,250,000

Nebraska

Iowa

Colorado

Wyoming

1:6,000,000

Study Area

Verification Area

• Effects of land-applying

agricultural / municipal

biosolids on soil C and

N cycling, water quality

• Modeling nutrient,

trace metal, and EmCon

transport and fate with

the Soil and Water

Assessment Tool

(SWAT)

• Impacts of stochastic

rainfall events

TRANSPORT & FATE IN BENEFICIAL REUSE

TRANSPORT & FATE IN BENEFICIAL REUSE

• Few long-term studies of beneficial reuse in operational settings

• Couple field studies with lab experiments and modeling

• Potential impacts of stochastic climate events on transport

An

nu

al

pre

cip

itati

on

(m

m)

Austin, TX 1856-2007

200

400

600

800

1000

1200

1400

1600

1800

1856 1881 1906 1931 1956 1981 2006

TRANSPORT & FATE IN BENEFICIAL REUSE

HBBMP: Hornsby Bend Biosolids Management Plant

• >1200 acre, zero-discharge facility in southeast Austin, TX

• Revenue from forage production (coastal bermuda), Dillo DirtTM

• Important Bird Area (American Bird Conservancy, Audubon)

• State of Texas’ 2009 top-ranked “Green Project” $31.8 million

TRANSPORT & FATE IN BENEFICIAL REUSE

Channel/Floodplain Processes: Flood routing, Transmission losses,

Evaporation, Sediment routing, Nutrients, Pesticides

Upland Processes: Hydrology, C, N, & P cycling,

Pesticides, Plant growth, Climate change

Non-Cultivated

Lands

Point Sources

Cultivated

Lands

SWAT: Soil and Water Assessment Tool

17

β-E

str

ad

iol

(mg

ha

-1 y

-1)

0.0

2.0

4.0

6.0

8.0

10.0 Coastal bermudagrass

Switchgrass

1980 - 2006 1980 - 2007

TRANSPORT & FATE IN BENEFICIAL REUSE

23%

21%

Leaching from Bergstrom silt loam (0-23 cm), 10 t biosolids ac-1 y-1

Inclusion of 2007 rainfall year resulted in 90% increase

in 17β-estradiol leached annually from surface soils

SWAT: 17β-Estradiol Simulation