Soil Microbial Communities: Key Indicators of Soil Carbon Transformations When Conservation Reserve Program Land is Converted to Cropland

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)

Soil Fungal Community More Sensitive to Restoration Time Than Soil Bacterial Community

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

Thank You!