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Soil Microbial Communities: Key Indicators of Soil Carbon Transformations When Conservation Reserve...
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Transcript of Soil Microbial Communities: Key Indicators of Soil Carbon Transformations When Conservation Reserve...
Phylogenetic Changes in Soil Bacterial and Fungal Communities in Land under CRP and during Conversion to Cropland
PI: Jennifer Moore-Kucera, Co-PIs: Veronica Acosta-Martinez
John Zak, Juske Horita, Franciso Calderon, David Weindorf
Ph.D. students: Mamatha Kakarla, Chenhui Li, Former post-doc: Lisa Fultz
Depart of Plant & Soil ScienceDepart of Biological Sciences
Dept of GeosciencesAward #:
2012-67019-30183
nual row crops7 fields
Rangeland3 fields
CRP16 fields
Objective 1:ective 1: Evaluate soil microbial and quality nges with increasing time under CRP restoration
>50Early: 6-15 yrs restoredLate: 20-26 yrs restored
yrsestored
26 fields sampled across 7 Texas High Plains CountiesSampled in 2012 (5.7% H2O) and 2014 (14% H2O)
Target soil series: Amarillo fine sandy loamSoil: Amarillo fine sandy loam
pH: 7.6 (0-30cm)SOM: 1.4%
Soil Restoration following Disturbance
EcosystemDisturbance
OriginalEcosystem
Long-term row crops
Early CRP
Late CRP
Rangeland
reased restoration time increased nutrient ling potential and decreased metabolic stress
Metabolic quotientzymatic activityMBC/CO2
with positive correlation:
Time Under Restoration Not Significant Driver of Soil Bacterial Composition
Cropped fields:Proteobacteria,Firmicutes, Bacteroidetes,Nitrospirae, and Gemmatimonadetes
CRP & Rangeland:Rubrobacteria, Acidobacteria, Verrucomicrobia, Chlorobi, Fibrobactersand Planctomycetes
Verrucomicrobia and Planctomycetes:Key taxa involved in soil organic matter?
anctomycetes, Verrucomicrobia, and Rubrobacteriai i l l d i h SOM & i i i
y = 4.1x - 0.57R = 0.744**
0
5
10
15
20
25
30
35
0.0 2.0 4.0 6.0 8.0
Soil
orga
nic
mat
ter (
g kg
soil)
Verrucomicrobia (%)
Microbial Network Analysis: Rare Microbiome Differentiate Management
Common OTUs bring nodes or samples together No
Distinct OTUs repel nodes
Long-term croplands
Early CRP(6-14y)
Late CRP (21-26y)
Abundant Microbiome(counts are 1700 or more):
Rare Microbiome(counts are 5-10)
j 1 Conclusionsurrent conservation contracts may not be long nough to realize optimal ecosystem functions
oil bacterial communities were not affected by estoration time but were distinct from croplands.
Rare” bacterial biome may provide more insight
oil fungi were more sensitive to time under estoration than bacteria
acterial taxa were identified that may play key oles in SOM sequestration and nutrient cycling.
Objective 2: What happens to the soil ecosystem when CRP land is converted?
Ecological Benefits:Reduced soil erosionImproved water, air, soil qualityEnhanced wildlife
?
Converted CRPCRP
aluate short-term changes in soil quality and crobial dynamics after CRP conversion
Main plot: System (CRP vs. Converted)Split: 3 depths (0-10, 10-30, 30-50cm)
Block: 3 countiesSampling: Fall 2012, 2013, 2014
23-25 yrs enrolled 22-25 yrs enrolled(converted 2010 or 2012)
Soil texture: Fine sandy loampH: 7.6 (0-30cm)
SOM: 1.4%
plit-plot RCB:
10-30cm: Converted fields had greater bacterial diversity and species richness compared to CRP
cies richness and diversity measures in P and converted CRP fields
Phylogenetic diversity indexSpecies Richness
Phyl
ogen
etic
div
ersi
ty in
dex
p<0.0001p<0.0001
ConvertedCRP CRP Converted
CRP CRP
10-3
0 cm
10-3
0 cm
10-3
0 cm
10-3
0 cm
nverted CRP fields associated with a istribution of SOM
Initial SOM incorporation provides flux of resources to bacteria promotes bacterial diversity
ConvertedCRP CRP
10-3
0 cm
10-3
0 cm
Soil organic C
nversion of CRP back to crop systems altered terial communities in both depths
p<0.001
0-10cm
0-10cm10-30cm
10-30cmConverted
CRP
CRP
Bacterial communities changed rapidly following
nversion of CRP back to crop systems altered terial communities in both depths
0-10cm
0-10cm10-30cm
10-30cmConverted
CRP
CRPCRP Greater:Verrucomicrobia(18%)Cyanobacteria (58-80%)Rubrobacteria(40%)Acidobacteria
Converted Greater:γ-proteobacteria(49-62%)β-proteobacteria(74-97%)Gemmatimonadetes(104-138%)Firmicutes(20-36%)
reduction in Verrucomicrobia or Planctomycetesay be early indications of SOM decline?
Planctomycetes, and Verrucomicrobia were positively l d i h SOM d i i i
y = 4.1x - 0.57R = 0.744**
0
5
10
15
20
25
30
35
0.0 2.0 4.0 6.0 8.0
Soil
orga
nic
mat
ter (
g kg
soil)
Verrucomicrobia (%)
j 2 Conclusionsonversion of CRP to cropland resulted in
ncreased SOM into lower soil depths and ncreased bacterial diversity but this is ypothesized to be a short-term effect
Within 1-5 yrs of conversion, bacterial ommunities resembled long-term cropped fields
Low resiliency
onverted CRP were associated with reductions in cologically significant taxa involved in OM
l C t ti d t i t li