Soil Microbial Communities: Key Indicators of Soil Carbon Transformations When Conservation Reserve Program Land is Converted to Cropland
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This document summarizes a study on changes in soil microbial communities under different land management practices. The study compared soil bacterial and fungal communities in land under the Conservation Reserve Program (CRP) for varying lengths of time, as well as land converted from CRP back to cropland. Key findings include: 1) Soil microbial communities differed between long-term cropland and CRP/rangeland, but time under CRP restoration did not significantly impact bacterial composition. 2) Conversion of CRP land to cropland increased soil bacterial diversity in the short-term but bacterial communities resembled long-term cropland within 5 years. 3) Soil fungal communities were
Soil Microbial Communities: Key Indicators of Soil Carbon Transformations When Conservation Reserve Program Land is Converted to Cropland
- 1. 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 Science Depart of Biological Sciences Dept of Geosciences Award #: 2012-67019-30183
- 2. nual row crops 7 fields Rangeland 3 fields CRP 16 fields Objective 1: ective 1: Evaluate soil microbial and quality nges with increasing time under CRP restoration >50Early: 6-15 yrs restored Late: 20-26 yrs restored yrs estored 26 fields sampled across 7 Texas High Plains Counties Sampled in 2012 (5.7% H2O) and 2014 (14% H2O) Target soil series: Amarillo fine sandy loam Soil: Amarillo fine sandy loam pH: 7.6 (0-30cm)
- 3. Soil Restoration following Disturbance Ecosystem Disturbance Original Ecosystem Long-term ow crops Early CRP Late CRP Rangeland
- 4. reased restoration time increased nutrient ling potential and decreased metabolic stress Metabolic quotientzymatic activity MBC/CO2 with positive correlation:
- 5. Time Under Restoration Not Significant Driver of Soil Bacterial Composition Cropped fields: Proteobacteria, Firmicutes, Bacteroidetes, Nitrospirae, and CRP & Rangeland: Rubrobacteria, Acidobacteria, Verrucomicrobia, Chlorobi, Fibrobacters and Planctomycetes
- 6. Verrucomicrobia and Planctomycetes: Key taxa involved in soil organic matter? anctomycetes, Verrucomicrobia, and Rubrobacteria y = 4.1x - 0.57 R = 0.744** 0 5 10 15 20 25 30 35 0.0 2.0 4.0 6.0 8.0 Soilorganicmatter(gkgsoil) Verrucomicrobia (%)
- 7. 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)
- 8. Soil Fungal Community More Sensitive to Restoration Time Than Soil Bacterial Community
- 9. j 1 Conclusions urrent 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
- 10. Objective 2: What happens to the soil ecosystem when CRP land is converted? Ecological Benefits: Reduced soil erosion Improved water, air, soil quality ?
- 11. 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 counties Sampling: Fall 2012, 2013, 2014 23-25 yrs enrolled 22-25 yrs enrolled (converted 2010 or 2012) Soil texture: Fine sandy loam pH: 7.6 (0-30cm) SOM: 1.4% plit-plot RCB:
- 12. 10-30cm: Converted fields had greater bacterial cies richness and diversity measures in P and converted CRP fields Phylogenetic diversity indexSpecies Richness Phylogeneticdiversityindex p<0.0001p<0.0001 Converted CRP CRP Converted CRP CRP 10-30cm 10-30cm 10-30cm 10-30cm
- 13. nverted CRP fields associated with a istribution of SOM Initial SOM incorporation provides flux of resources to bacteria promotes bacterial diversity Converted CRP CRP 10-30cm 10-30cm Soil organic C
- 14. nversion of CRP back to crop systems altered terial communities in both depths p<0.001 0-10cm 0-10cm 10-30cm 10-30cm Converted CRP CRP Bacterial communities
- 15. nversion of CRP back to crop systems altered terial communities in both depths 0-10cm 0-10cm 10-30cm 10-30cm Converted CRP CRP CRP 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%)
- 16. reduction in Verrucomicrobia or Planctomycetes ay be early indications of SOM decline? Planctomycetes, and Verrucomicrobia were positively y = 4.1x - 0.57 R = 0.744** 0 5 10 15 20 25 30 35 0.0 2.0 4.0 6.0 8.0 Soilorganicmatter(gkgsoil) Verrucomicrobia (%)
- 17. j 2 Conclusions onversion 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
- 18. Thank You!