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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
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