Progress 01/01/12 to 12/31/17
Outputs
Target Audience: 1. Two volunteered oral presentations at the 2018 ASA-CSSA-SSSA meeting held in Tampa, FL, atotal ofapproximately of80 attendees. 2. A Ph.D. defense presentation (March 2017) attended by approximately 30 people in the Department of Plant and Soil science, Texas Tech University. 3. A webinar forMissouri EPSCoR Climate Team. Half of the presentation was on this project and approximately 30 attendees on-site and online from the whole Missouri EPSCoR transect community. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Chenhui Li had been working on this project and earned their Ph.D. degrees inMay 2017. Dr. Li has started her post-doctoral training at University of Missouri since June 2017. How have the results been disseminated to communities of interest? Presentations at international scientific conferences, classroom examples, and in dialogue with NRCS staff with Dr. Moore-Kucera's current role in NRCS-Soil Health Division. Additionally, two peer-reviewed manuscripts and a second Ph.D. dissertation have been published. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Numerous ecological benefits have been achieved as a result of the Conservation Reserve Program (CRP) program including soil erosion control, improvements in water quality, increased wildlife habitat, and carbon (C) sequestration. When contracts expire, some CRP grassland (permanent soil cover and plant inputs) may be converted to cropland that is disturbed by tillage and exposed for part of the year. This land management shift may negatively impact many of the ecosystem benefits established under CRP restoration. Texas, and specifically the Southern High Plains region (SHP), leads the nation in acres enrolled in the CRP program and acres of expiration from CRP. Soil microorganisms are involved in the majority of soil functions, such as nutrient provisioning and cycling, pest and pathogen protection, symbiotic and compensatory associations with plants, as well as the formation of stable aggregates to reduce soil erosion and build soil organic matter. Therefore, soil microbial community (SMC) composition and diversity are often coupled to the assessment of soil processes (C storage and nutrient cycling) and provide early indications of ecosystem response to disturbances and recovery. The overall objectives were to determine if the increasing years under CRP influenced soil health and soil microbial community composition (obj1) and to evaluate changes during the first four years when CRP is converted to cropland (obj2). Soil samples have been collected from 32 fields, and >35 soil analyses conducted that include soil physical, chemical, and biological properties. Objective 1: Determine SMC structure shifts, biogeochemical processes and soil C dynamics using a CRP chronosequence of 26 fields from 0 (cotton-based cropland) to 28 years.? Relative to cropland, CRP grasslands with year-round plant cover provided supplementary plant organic residues into the soil and reduced soil diurnal temperature range, which supported greater microbial biomass and assisted C sequestration. The obj1 results demonstrated the CRP benefits in the accrual of soil organic carbon (SOC) and the potential biogeochemical improvement (nutrient cycling), which were also coupled with the changes in the soil microbial community composition. The SMC shifted in a direction of decrease of bacteria abundance and increase of fungi abundance particularly AMF with the increasing CRP restoration years. The arbuscular mycorrhizal fungal (AMF) likely played a crucial role in soil C sequestration. AMF are well-known to provide numeric soil functions such as assisting plant in absorbing water and nutrients, increasing C sequestration, alleviating salinity, improving soil structure, sequestering potential toxic elements in soil, and biocontrol of plant pathogen. The SOC increased at a rate of 69.8 and 132.9 kg C ha-1 y-1 at depths of 0-10 cm and 0-30 cm, respectively. Scaling these results to the 0.92 million ha of CRP lands in the SHP resulted in an average C sequestration potential of 64.1 and 122 Gg C y-1 and would take approximately 74 and 77 y to reach the rangeland levels at depths of 0-10 cm and 0- 30 cm, respectively. These results also highlight the need for more extended restoration periods and enhanced management efforts such as the proper integration of livestock into CRP lands to facilitate SOC accrual rates and associated ecosystem benefits, especially in the SHP region with extreme weather (e.g., frequent drought) and fragile, sandy soils. Objective 2: Assess short-term dynamics of the SMC structure, biogeochemical processes and soil carbon dynamics as CRP is converted to a row crop during the first four years.? We assessed the impacts of CRP to cropland conversion on soil health by comparing soil health indicators in three pairs of CRP and its adjacent cropland (C-CRP) from 2012-2015, which both have or had been under CRP for 25 yr by 2012. The soil health indicators included a suite of soil microbial properties (community size, diversity, and metabolic activities), as well as the basic soil physical and biochemical properties. The precipitation increased with the years after conversion (2011: 133mm, 2012: 261mm, 2013: 351mm, 2014: 488mm, and 2015: 692mm), which influenced the impacts of the conversion on soil health. The results showed that the conversion practices from CRP back to cropland has some potential adverse impacts on soil health after one year of the conversion, which was mainly reflected by the decreased soil health condition in 2013 and the less recovery when the environmental condition improved in 2014 and 2015 compared to the reference CRP sites. Within 1-2nd years after conversion in 2012, the research area was under extreme drought condition. The conversion practices including chopped the soil surface and buried the organic residues from CRP to the soil slightly buffered the drought, showed by the trend of increase in SOC storage, particular organic matter, soil microbial biomass, and enzyme activity potentials (C, N, P, and S) in 2012. From 2013-2014 (2-3rd years after conversion), the drought stress was gradually alleviated. Soil health in CRP field showed a recovery with the increased precipitation, especially in 2014. However, C-CRP did not respond to the enhanced environment as substantially as it did in CRP. Soil health indicators of C-CRP either kept declining or improved less than CRP did in 2013 and 2014. From 2012 to 2014, the SMC has a shifting trend from fungal-dominated to bacterial-dominated. In 2015 when received more rainfall than the average level, the SMC was statistically different between two systems, with CRP had the highest total biomass and dominated by fungal groups, especially AMF. With a significant amount of rainfall in 2015, SOC was statistically higher in CRP than C-CRP at the surface soil. Additionally, aaccumulated CO2flux in C-CRP was greater than CRP in 2013 (2.9 vs. 2.7 Mg CO2-C ha-1as of September), which was likely because the drought limited biomass growth in both systems but the incorporation of organic residues during the conversion relieved the drought stress in C-CRP slightly. However, in 2014 and 2015, accumulated CO2flux was lower in C-CRP than CRP, in addition the difference of accumulated CO2 flux between two systems increased (CRP - C-CRP: -0.2, 0.5, and 2.1 Mg CO2-C ha-1 from 2013 to 2015), which was likely due to depletion of the organic residues from previous CRP in C-CRP. We also measured soil microbial biomass carbon (MBC) in every November from 2012 to 2015 to calculate metabolic quotient (qCO2=CO2/MBC). TheqCO2increased in 2013 and 2014 in C-CRP but did not change in CRP, which was another indicator that C-CRP depleted the organic residues from previous CRP without much assimilation. These results suggested that if the CRP is converted to cropland, then conservation management practices are necessary to keep the soil healthy, such as minimum tillage and cover cropping.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Li, C., Fultz, L.M., Moore-Kucera J., Acosta-Martinez V., Horita, J., Strauss R., Calderon, F., Zak, J., & Weindorf, D. (2017). Soil carbon sequestration potential in semi-arid grasslands in the Conservation Reserve Program. Geoderma, 279,80-90
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Li, C., Fultz, L.M., Moore-Kucera, J., Acosta-Mart�nez, V., Kakarla, M. and Weindorf, D.C., 2018. Soil microbial community restoration in Conservation Reserve Program semi-arid grasslands.�Soil Biology and Biochemistry,�118, pp.166-177.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Li, C., Moore-Kucera, J., Acosta-Mart�nez, Fultz, L.M. 2017. Changes in Soil Microbial Community under a 28-Year Conservation Reserve Program in the Semi-Arid Grasslands. Poster presentation. ASA, CSA, SSSA Annual Meeting, Tampa, FL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Li, C., Moore-Kucera, J., Acosta-Mart�nez, Fultz, L.M. 2017. Soil Enzyme Activities as Indicators of Soil Health in Long-Term CRP and CRP Converted to Cropland. Oral presentation ASA, CSA, SSSA Annual Meeting, Tampa, FL.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2017
Citation:
Li, C., 2017. Carbon Sequestration and Soil Health in Conservation Reserve Program Grasslands in the Southern High Plains. Texas Tech University. Lubbock, TX.
|
Progress 01/01/15 to 12/31/15
Outputs
Target Audience: two volunteered oral presentationsat the 2015 Soil Ecological Society Meetings held inColorado Springs, CO (June 11), total ofapproximately75 attendees; an invited oral presentationat the 2015 ASA-CSSA-SSSAmeetings held in Minneapolis, MN, approximately100 attendees; two volunteered oral presentationsat the 2015 ASA-CSSA-SSSA meetings held in Minneapolis, MN,approximately100 attendees total; an oral presentationas required from the granting agency for annual updates but represents a diverse group of scientists, held in October inWashingtion DC, approximately50 attendees; aninvitedoral presentationat the Southern Pasture and Forage Crop Improvement Conference in Apalachicola, FL, approximately100 attendees; aninvitedoral presentationat the Louisiana Forage and Grassland Council, approximately30 attendees; aninvitedoral presentationat theAmerican Forage and Grassland Council, approximately50 attendees; a Ph.D. defensepresentation (October 2015)attended by approximately 30 people in department of plant and soil science, Texas Tech University. About120 students enrolled in four undergraduate/graduate level soil sciences courses at either Texas Tech University (PI Moore-Kucera) or Louisianna State University (Dr. Lisa Fultz; former post-doc on our project) were exposed to concepts of soil conservation, microbial diversity, and ecological functioning using results and a discuss based on our CRP project. We regularly interact with the 7 county NRCS agents, 3 private landowners, 1 land manager for the Muleshoe National Refuge, and multiple faculty within the Natural Resources Management and BiologyDepartment sat Texas Tech University who assist us in gaining access to fields and historical land use information. Two Ph.D. students and multiple (3) undergraduate assistants were trained in various aspects of both field and laboratory analyses related to this project. This training included experiential learning opportunities for three undergraduates (plant and soil science and natural resources management majors) who visited CRP and cropland sites, learned about the conservation program and study goals and had hands-on experience with sampling efforts. Changes/Problems:Dr. Jennifer Moore-Kucera resigned from TTU and is now employed by USDA-NRCS. She serves as the West Regional Soil Health Team Leader and is stationed in Portland, OR. We have filled out the necessary paperwork through our granting service. What opportunities for training and professional development has the project provided?Two Ph.D. students, and multiple (3) undergraduate assistants were trained in various aspects of both field and laboratory analyses related to this project. This training included experiential learning opportunities for three undergraduates (plant and soil science and natural resources management majors) who visited CRP and cropland sites, learned about the conservation program and study goals and had hands-on experience with sampling efforts. Students in advanced microbial ecology coursework at Texas Tech University (Dr. Moore-Kucera's class) and at Louisiana State University (Dr. Fultz's class) received training in molecular and enzymatic assessments and were led in multiple discussions on the role of CRP in microbial diversity and functionality. How have the results been disseminated to communities of interest?National/International Scientific Meetings:More than530individualswere exposed to our research from both conceptual and analytical perspectives over 2015.These individuals included soil scientists, soil microbial ecologists, crop and grassland scientists, climate scientists, university students,and NRCS agents who attended the following invited and volunteered presentations: two volunteered oral presentationsat the 2015 Soil Ecological Society Meetings held inColorado Springs, CO (June 11), total ofapproximately75 attendees; an invited oral presentationat the 2015 ASA-CSSA-SSSAmeetings held in Minneapolis, MN, approximately100 attendees; two volunteered oral presentationsat the 2015 ASA-CSSA-SSSA meetings held in Minneapolis, MN,approximately100 attendees total; an oral presentationas required from the granting agency for annual updates but represents a diverse group of scientists, held in October inWashingtion DC, approximately50 attendees; an invitedoral presentation at the Southern Pasture and Forage Crop Improvement Conference in Apalachicola, FL, approximately 100 attendees; aninvitedoral presentationat the Louisiana Forage and Grassland Council, approximately30 attendees; aninvitedoral presentationat theAmerican Forage and Grassland Council, approximately50 attendees; Classroom instruction: Soil samples fromthis project were utilized in lab sections of soil microbial ecology class taught by Dr. Moore-Kucera and Mamatha Kakarla (Ph.D. student). To understand and appreciatehow diverse soil samples were, students were assigned with a project that included soil samples from various sources such as croplands, grasslands,garden, compost pit, backyard, playa, and water from variuos sources. Soils from croplands and grasslands from CRP sites were given to the students. The class included 24 students that comprise both undergraduate and graduate students.Similarly, Dr. Fultz included results from this project in multiple lectures, classroom discussionsand laboratory activities in her microbial ecology and nutrient cycling in soils and soil conservation courses. Across all courses, approximately 64 students were provided instruction and training related to the project's goals and methods. Formal departmental seminars/local workshops: Mamatha Kakarla defended doctoral dissertation and gave an open oral presentation of key findings from her dissertation research. Approximately 30 people attended oral defense which included faculty and students of various departments from college of Agricultural sciences and natural resources and members from USDA-ARS. What do you plan to do during the next reporting period to accomplish the goals?We have completed our final sampling in November/December 2015. The majority of sample analyses have been completed and the team is working hard to complete all analyses. We are working on an array of publications with lead authors by the two Ph.D. students (one completed her Ph.D. this past year and the second is expected to defend Dec 2016). Additionally, abstracts will be submitted for at least one national scientific meeting (e.g., SSSA or ESA).
Impacts
What was accomplished under these goals?
Objective 1: Determine the shifts in soil microbial community (SMC) structure, biogeochemical processes and soil carbon dynamics using a CRP chronosequence of 26 fields from 0 (cotton-based cropland) to 26 years a. Carbon dynamics summary: Conservation Reserve Program (CRP) lands on the Southern High Plains (SHP) of Texas potentially play a critical role in regional C sequestration, offering substantial offsets to atmospheric CO2. Recognizing the influence of small changes in soil texture on the rate and threshold of soils to store C, soil C measurements were normalized by the % clay+silt content. Soil organic C (SOC) increased at a rate of0.0085 Mg C ha-1y-1per unit of soil clay +silt (%) at 0-30cm. Preliminary scaling at the regional level revealed that depending on soil texture, 0.92 million ha of CRP lands in SHP of Texas hold an average C sequestration potential of210,849 Mg C y-1at 0-30cm. With CRP restoration of these highly erodible lands to grasslandsperennial ground coverincreased which resulted inreduced diurnal soil temperatureand helped retain soil moisture. The improved soil environment supported increased microbial biomass and specifically increased arbuscular mycorrhizal fungal (AMF)biomarkers (using fatty acid profiles). These symbiotic associations between fungi and plant roots are known to reallocate C belowground and increase SOC. Although not directly investigated, we found an increase in the amount of POM-C coming from C4 plants (e.g., grasses) increasing relative abundance of AMF, and thus, AMF play a major role in C sequestration in grassland ecosystems. Our results suggest that the CRP program not only contributes to reduced erosion with ground cover protecting the soil, but also contributes to a significant sink of atmospheric CO2; this is despite the relatively low overall SOC levels of these semi-arid soils. Recognizing that CRP levels are still lower than the native rangeland sites and are projected to take 36 years to reach similar levels, we hypothesize that the incorporation of sustainable livestock management should be considered and hold the potential for greater improvements in soil health and overall ecosystem sustainability. b. Microbial summary: Soil bacterial community composition and structure in cropland were distinct from CRP and rangeland with highest diversity in grasslands (CRP and rangelands). Bacterial communities within the young CRP fields (< 17 years) were not statistically different from those communities in the old CRP (17-28 years) or rangeland fields. Shifts in bacterial composition were related to nutrient fluxes and disturbance levels. For example, croplands were dominated byNitrospirae, andGemmatimonodetes,that are known to respond to N fertilizers, andBacteriodetesand certain members ofProteobacteriathat respond rapidly to nutrient fluxes (copiotrophic taxa) following harvest and turnover of crop residues. CRP and rangelands were dominated byAcidobacteria, Verrucomicrobia, Rubrobacteria, andFirmicutes,which are associated with low nutrient conditions (oligotrophic taxa), andPlanctomycetes,which are sensitive to disturbances. Soil fungal diversity was higher in rangeland compared to CRP fields (young and old) and cropland. Fungal OTU richness increased by 40% in CRP compared to cropland. The increased fungal diversity in grasslands (CRP fields and rangelands) was likely due to increased C substrate availability from roots in grasslands as opposed to monoculture croplands. Increased fungal diversity is correlated with SOC indicating potential role of fungi in C sequestration. In contrast to bacterial communities, fungal community composition was impacted by time under CRP restoration. However, the most striking differences were between cropland and CRP/rangeland. Conversion of cropland to CRP resulted in a shift from fungal communities dominated by general decomposers (Sordariomycetes, Tremellomycetes) in cropland to those involved in decomposition of complex C compounds, promotion of soil stability, and phosphorus solubilization in CRP (Dothideomycetes, Agaricomycetes, Eurotiomycetes, Pezizomycetes, Leotiomycetes, and Glomeromycetes). Furthermore, croplands were characterized by members of fungal genera that are potentially pathogenic (Fusarium, Acremonium, Lecytophora, and Ilyonectaria). Objective 2: Assess short-term dynamics of the SMC structure, biogeochemical processes and soil carbon dynamics as CRP is converted to a row crop during the first four years. a. Carbon dynamicssummary: We utilized a suite of dynamic C properties (DCPs) to evaluate the soil health status of soils in transition from CRP back to intensive annual cotton crop production. The DCPs include microbial biomass C (MBC), POM-C, and the ratio of enzyme activity to MBC (specific metabolic activity; SMA). SMA is often interpreted as a microbial stress indicator because more energy is being expended relative to the building of biomass. However, it is sensitive to rapid influx of C inputs and high values are not always associated with stress but rather a reflection of C resources. A hypothetic framework to interpret these indicators as measures of soil health was developed. Within the first 2 years of conversion, SMA was high but POM-C and MBC were also high suggesting that soil health indicators were enhanced during the initial conversion and incorporation of above and belowground grass residues. However in the next two sampling years (3-4 years following conversion), MBC and POM-C declined by 52% and 41%, respectively and SMA increased between 14 and 47% depending on the enzyme activity used. These results indicate rapidly declining soil health status and increased microbial metabolic stress which is hypothesized to be followed by rapid decline in SOC, soil stability and overall ecological sustainability. Furthermore, microbial community composition using fatty acid methyl ester (FAME) profiling indicated a shift to lower relative abundance of fungi and an increase in additional physiological stress indicators using specific FAME ratios (e.g., saturated/monounsaturated FAMEs). b. Microbial summary: Bacterial diversity increased in converted CRP in response to the incorporation and redistribution of organic material providing a rapid influx of C and other energy resources. The composition of the bacterial community shifted from dominance of members known for being heat resistant, drought tolerant and having a high C affinity in CRP fields to taxa that reflected the composition of the long-term cropland sites in objective 1. For example, both the long-term cropland from the restoration study (>50 years in crop production) and converted CRP cropland (<5 years under crop production) had relatively higher abundances of taxaBacteroidetes,β-proteobacteria,Gemmatimonadetes,Firmicutes, andγ-proteobacteria,Sordariomycetes, andTremellomycetescompared to CRP fields (>20 years in CRP management) in their respective studies. Soil fungal communities shifted from mycorrhizal and dark septate fungi dominated communities in CRP to general decomposers and putative pathogenic genera in converted CRP.Sordariomycetes,Tremellomycetes,Pezizomycetes, andChytridiomycetesincreased following conversion at the expense ofEurotiomycetes,Agaricomycetes,Leotiomycetes, andGlomeromycetes that are of ecological importance for stability and nutrient acquisition (P and micronutrients) in low input grasslands.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Li, C., Moore-Kucera, J., Fultz, L.M., Kakarla, M., Acosta-Martinez V., Zak C.J., Weindorf D., and Horita J. What Happens to Soil Ecological Properties When Conservation Reserve Program Land Is Disturbed? ASA-CSSA-SSSA International Meeting (Nov 15-18), Minneapolis, MN.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Li, C., Moore-Kucera, J., Fultz, L.M., Kakarla, M., Acosta-Martinez V., Zak C.J., Weindorf D., and Horita J. The Impacts of Inherent Soil Properties, Environmental Conditions, and Restoration Time on Ecological Benefits during CRP Restoration. ASA-CSSA-SSSA International Meeting (Nov 15-18), Minneapolis, MN.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Moore-Kucera, J., Kakarla, M., Fultz, L.M., Li, C., Acosta-Martinez V., Zak C.J., Kottapalli K.R., and Wright R. Soil bacterial and fungal community responses across a Conservation Reserve Program chronosequence in Texas high plains region. ASA-CSSA-SSSA International Meeting (Nov 15-18), Minneapolis, MN.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Li, C., Moore-Kucera, J., Kakarla, M., Fultz, L.M., Acosta-Martinez V., and Zak C.J. Evaluating soil restoration under conservation reserve program using microbial indicators. Soil Ecology Meeting (June 8-12), Colorado Springs, CO.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Moore-Kucera, J., Kakarla, M., Fultz, L.M., Li, C., Acosta-Martinez V., and Zak C.J. Phylogenetic changes in soil bacterial communities as CRP land is converted back to cropland. Soil Ecology Meeting (June 8-12), Colorado Springs, CO.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2015
Citation:
Kakarla, M. Soil Microbial Community Composition and Diversity during Conservation Reserve Program (CRP) Restoration and CRP Conversion to Cropland (Ph.D.). Texas Tech University.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Moore-Kucera, J. Connecting Soil Microbial Communities to Soil Functioning and Soil Health. ASA-CSSA-SSSA International Meeting (Nov 15-18), Minneapolis, MN.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Fultz, L. Soil Management for Soil Quality: Linking Microbial Communities and Ecosystem Functions. Southern Pasture and Forage Crop Improvement Conference (April 1), Apalachicola, FL.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Fultz, L. Pasture Soil Management for Soil Quality: Linking Microbial Communities and Ecosystem Functions. American Forage and Grassland Council Meeting (Jan 10), Baton Rouge, LA.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Fultz, L. Linking Soil Microbial Ecology and Ecosystem Functions to Systems Management. Louisiana Forage and Grasslands Meeting (Dec 4). Alexandria, LA.
|
Progress 01/01/14 to 12/31/14
Outputs
Target Audience: More than 630 individuals were exposed to our research from both conceptual and analytical perspectives over 2014. These individuals included soil scientists, soil microbial ecologists, crop and grassland scientists, climate scientists, students, and NRCS agents who attended the following invited and volunteered presentations: 1) an invited oral presentation at the 69th Soil Water Conservation Society International Annual Conference held in Lombard, IL (July 2014), approximately 75 attendees; 2) two volunteered oral presentations at the 2014 Ecological Society of America Annual Meetings held in Sacramento, CA (August 12), total of 120 attendees; 3) an invited oral presentation at the 2014 ASA-CSSA-SSSA meetings held in Long Beach, CA, approximately 50 attendees; 4) an invited oral presentation at the Texas Tech University Climate Science Center seminar series (November 2014), approximately 40 attendees; 5) an oral presentation as required from the granting agency for annual updates but represents a diverse group of scientists, held in October in Washingtion DC, approximately 50 attendees; and 6) a volunteered poster presentation at the 6th annual Argonne Soil Metagenomics Meeting (October 2014), held in St. Charles, IL, approximately 200 attendees. About 90 students enrolled in four undergraduate/graduate level soil sciences courses at either Texas Tech University (PI Moore-Kucera) or Louisianna State University (Dr. Lisa Fultz; former post-doc on our project) were exposed to concepts of soil conservation, microbial diversity, and ecological functioning using results and a discuss based on our CRP project. We regularly interact with the 7 county NRCS agents, 3 private landowners, 1 land manager for the Muleshoe National Refuge, and multiple faculty within the Natural Resources Management Department at Texas Tech University who assist us in gaining access to fields and historical land use information. Two Ph.D. students, one post-doctoral scientist (now employed as an Assistant Professor at Louisianna State University, and multiple (6) undergraduate assistants were trained in various aspects of both field and laboratory analyses related to this project. This training included experiential learning opportunities for five undergraduates (plant and soil science, geology, and natural resources management majors) who visited CRP and cropland sites, learned about the conservation program and study goals and had hands-on experience with sampling efforts. An additional 4 undergraduate students were provided laboratory instruction on study objectives and gained hands-on experience with soil sample processing. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Dr. Moore-Kucera mentored one post-doctoral research associate, two Ph.D. candidates, and 4 undergraduate research associates during the 2014 reporting year. The post-doctoral research associate, Dr. Lisa Fultz was assigned to lead and train one of the Ph.D. candidates, Ms. Chenhui Li in soil chemical analyses including light-fraction particulate organic carbon fractionation and subsequent analysis for total C, total N, and C isotopic analyses. Ms. Li now works independently on all aspects of these techniques and data interpretation. Dr. Fultz recently (2014) accepted an assistant professorship at Louisiana State University. She continues to play an active role in manuscript development and has been asked to serve as an additional Ph.D. committee member for Ms. Li. Dr. Moore-Kucera works closely with weekly meetings with both Ph.D. candidates to discuss all aspects of the project including but not limited to: sample collection, methods of analysis, and data processing, interpretation and manuscript preparation. Currently, two manuscripts are in preparation for submission by summer 2015. Four undergraduate research assistants have been trained in various aspects of proper soil collection, the concept of the CRP, and various field (CO2) and laboratory analyses for soil physical, chemical, and biological properties. Ms. Mamatha Kakarla (Ph.D. candidate) attended the 6th Annual Argonne Soil Metagenomics Conference where she presented and interacted with the scientific community involved in soil metagenomic research. Dr. Moore-Kucera and Ms. Kakarla have worked diligently to self-teach themselves (led by Ms. Kakarla) modifications of the super computer facilities at TTU and the QIIME pipeline for bacterial analysis and RDP pipeline for fungal analysis. Additionally, Ms. Kakarla learned how to develop networks and shared and unique OTUs for our data sets in cytoscape and R software packages, respectively. Both Ph.D. students attended and presented research results at the Annual Ecological Society of America conference held in Sacramento, CA in August 2014. How have the results been disseminated to communities of interest? National/International Scientific Meetings: Four oral presentations (two invited) and one poster presentation were presented at: the SWCS society meeting (invited oral), the ASA-CSSA-SSSA International meeting (invited oral), the Ecological Society Meeting (two oral presentations) and the 6th Annual Argonne Soil Metagenomics Conference (poster). Classroom instruction: Dr. Moore-Kucera presented data and conceptual information regarding soil conservation and microbial diversity in an undergraduate/graduate level 'Environmental Soil Science' course (spring 2014), an undergraduate introductory soil science course (Fall 2014). Additionally, Dr. Fultz included some of the data as part of a soil conservation class (spring 2014). Formal departmental seminars/local workshops: Dr. Moore-Kucera and Dr. Fultz shared results and preliminary interpretation of data at four total seminars/workshops in 2014. Regular project meetings: planning and follow-up meetings were conducted with all local PI's and lab members to discuss progress of analyses, data management, and manuscript preparation. Additionally, weekly meetings take place for the PI Moore-Kucera and both PhD students and post-doc to discuss results, status of project, statistical analyses, and development of presentations for national meetings. What do you plan to do during the next reporting period to accomplish the goals? Our final soil sampling effort for objective 2 will take place in November/December 2015 in the converted and long-term CRP fields. To date all analyses have been completed. We currently have two manuscripts in preparation for submission (target submission date April 30, 2015). One Ph.D. student is the lead for one manuscript each. Ms. Kakarla successfully completed her preliminary/qualifying exams and will defend her dissertation work in summer or early fall semester 2015. She is in the process of drafting an additional 2-3 manuscripts as part of her dissertation work which are expected to be submitted for publication by summer 2015. Dr. Moore-Kucera has been invited to present at a special symposium at the SSSA meeting held in Minneapolis, MN in November 2015. The title of the symposium is, "Connecting Phytobiomes with Soil and Plant Health" and the tentative title of her presentation is, "Connecting Soil Microbial Communities to Soil Functioning and Soil Health." She will present research results from this project to highlight these relationships. Dr. Moore-Kucera is also the lead organizer of another special syposium of the SSSA, soil biology and biochemistry division, "Role of Soil Microbial Community Structure and Function in Restoration of Ecosystems," where her team's research will be highlighted along with other leading research in teh field of restoration and microbial ecology by invited and volunteered speakers. Dr. Fultz will assist with the organization of this symposium and will be one of the highlighted speakers.
Impacts
What was accomplished under these goals?
The Conservation Reserve Program (CRP) has reduced soil erosion and increased biodiversity and carbon (C) storage. The Texas High Plains (THP) has >2.2 million ac. enrolled in CRP. When contracts expire, some CRP grassland (permanent soil cover and plant inputs) may be converted to cropland (Crop) that is disturbed by tillage and exposed for part of the year. This land management shift may negatively impact many of the ecosystem benefits established under CRP restoration. Soil microbial community (SMC) composition and diversity often are coupled to the assessment of soil processes (C storage and nutrient cycling) and provide early indications of ecosystem response to disturbances and recovery. Our overall goals were to determine if age of CRP influenced soil quality (obj1) and evaluate changes during the first 4 years when CRP is converted to Crop (obj2). 287 soil samples have been collected from 32 fields and >35 soil analyses conducted that include soil physical, chemical, and biological variables. Based on our results, 28 years under CRP restoration has not been long enough to reach secondary ecological benefits (e.g., C sequestration; ecosystem resilience to resist abiotic stresses such as drought). Conversion of CRP fields initially increased some soil quality parameters but any benefit may be short-lived. Shifts in SMC composition occurred and the redistribution of C to lower depths is hypothesized to be rapidly decomposed resulting in soils that are more depleted in SOM and have lower microbial diversity than occurred when these fields were enrolled in CRP. These soil changes may result in irreversible ecological consequences and lead to highly degraded lands of short-lived productivity. Objective 1: Determine SMC structure shifts, biogeochemical processes and soil C dynamics using a CRP chronosequence of 26 fields from 0 (cotton-based cropland) to 28 years. Sampling for obj 1 was completed in 2014. The objectives of the first manuscript are to: (1) determine the impacts of CRP age on soil organic carbon (SOC) and N pools; and (2) estimate rates of SOC accumulation or loss with increasing years of CRP enrollment. The second manuscript is microbial focused and aims to determine how years of CRP restoration affects microbial composition. In 2012 and 2014, 52 samples were collected each year from 7 dryland annual cropping systems (0 y restored), 16 CRP fields (6-28 y restored) and 3 native rangelands (NAR; permanent grasslands). More than 35 soil quality analyses were conducted, including sequencing data that required use of high powered, 'super-computing' facilities on campus. Our intensive analyses of key soil quality properties will provide multiple layers of evidence to evaluate how years of CRP restoration affects important soil quality parameters. SOM and SOC were similar between Crop and CRP, but were 32% and 58% lower than NAR, respectively. Two more sensitive pools of SOM, particulate organic matter (both years) and microbial biomass C (MBC; 2012 only) increased with years under CRP at 0-10cm.In 2014, MBC responded to increased moisture but was lower in CRP than NAR. Isotopic data provided evidence that maximum C accrual occurred around 14 years under CRP. If further C accrual is possible, at least 45 more years are needed to reach similar levels measured in NAR. 8/9 enzyme activities (EAs) linked with nutrient cycling and CO2 flux increased with years under CRP (0-10cm). All CRP EAs, however, were lower than those in NAR. The metabolic quotient (CO2 flux per unit MBC (stress indicator) was not sensitive to years under CRP but in 2012, it was lower (greater stress) in Crop than CRP. SMC composition did not differ with years under CRP but bacterial diversity increased from Crop to CRP to NAR. Crop had higher abundance of Nitrospirae and Gemmatimondadetes (important in cycling N and respond to N fertilizers) than CRP and NAR. Bacteriodetes and some members of Proteobacteria that tend to respond rapidly to nutrient fluxes were higher in Crop compared to CRP or NAR; which likely occurred following harvest with incorporation of plant residues and root biomass turnover. In contrast, Planctomycetes, which tend to be sensitive to disturbance, and Verrucomicrobia, Acidobacteria, and Firmicutes, which tend to associate with low nutrient conditions, were higher in CRP than Crop. Bacterial diversity and richness were higher in 2012 (extreme drought) than in 2014. Drought may have reduced the competition that allowed normally low abundant taxa to survive. In 2014, rewetting of dry soil (and rapid release of nutrients) may have favored certain taxa and/or stimulated microfaunal grazers that decreased overall diversity. For example, higher Proteobacteria abundance were found in the wetter 2014 samples compared to the drier 2012 conditions and are known to respond to high nutrient contents. In contrast, Acidobacteria, Firmicutes and Actinobacteria were more prevalent during 2012 and are typically associated with droughty, hot soils, intense UV radiation, and low nutrient conditions. Accrual rates of SOC and microbial biodiversity has not been significantly changed over 28 y under CRP. Secondary ecological benefits (e.g., C sequestration, ecosystem resilience), may not be achieved within the program's timeframe (10-15 y contracts). The SMC was sensitive to management (CRP vs. Crop vs. NAR) and abiotic stresses (e.g., drought) and are directly tied to the response trajectory of restoration programs. Objective 2: Assess short-term dynamics of the SMC structure, biogeochemical processes and soil carbon dynamics as CRP is converted to a row crop during the first four years. In 2014 (3rd sampling year), soil samples were collected from 3 long-term (>20 y) CRP fields and 3 fields recently (within 1-2 y in 2012) converted from CRP (>20 y) to dryland crop production (Crop). Each field had 3 subplots, which were splitted into 3 soil depths (0-10, 10-30, and 30-50cm). Thus, 54 samples were collected in 2014 for a running total of 183 samples. 35 soil analyses were conducted as described in obj 1 above. Additionally, monthly soil CO2 fluxes are collected from each field. This intensive analyses will provide multiple layers of evidence to evaluate how conversion from 20+ y CRP to Crop affects soil quality and functionality. Within 3 y following conversion of CRP to Crop, SMC composition shifted toward lower relative abundance of arbuscular mycorrhizal fungi (AMF) and higher relative abundance Gram positive bacteria. In 2012, MBC was greater in Crop than CRP but by 2013, CRP had greater MBC than Crop. EAs at 0-10cm were also greater in CRP than Crop. These findings persisted in 2014 and suggests that the initial stimulation of the microbial biomass with recent conversion of grassland to cropland is relatively short-lived and organic matter rapidly depleted in these sandy, inherently low SOC soils. Crop fields at 10-30cm, however, had similar MBC, SOC and EAs to CRP. Bacterial diversity was not affected in 2012, but in 2013, diversity was higher in CRP than Crop at 0-10cm and diversity was lower in CRP than Crop at 10-30cm, supporting the data that showed a redistribution of SOC and SOM in the lower depth. 2013 and 2014 sequencing data currently are being processed to determine trends over time. Within 3 y after converting CRP to Crop, there was an initial 2012 release of labile organic C, stimulating microbial activity, biomass, and nutrient turnover, but followed by a rapid depletion (2013 & 2014). SMC composition was negatively affected with a reduction in AMF, an important taxonomic group known to play key roles in plant H2O and P uptake. At the surface, numerous EAs involved in nutrient cycling were reduced and the redistribution of SOC, MBC and EAs at 10-30cm are expected to rapidly decline. Data collected in 2014 (3rd y) and 2015 (pending) will aid in testing this hypothesis.
Publications
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
Moore-Kucera, J., Acosta-Martinez, V., Fultz, L., Kakarla, M., Li, C., 2014. Influence of Conservation Reserve Program Age and Conversion to Cropland on Soil Quality, Microbial Diversity and Metabolic Capacity: Implications for Our Decisions about Soil Conservation. http://www.slideshare.net/SWCSevents/moore-kucera-solutions-to-new-challenges and (abstract) http://www.swcs.org/documents/filelibrary/14ac/2014_Final_Program__LIVE_LINKS_D760B16D60022.pdf 69th Soil Water Conservation Society International Annual Conference (July 27-30), Lombard, IL.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
Li, C., Moore-Kucera, J., Fultz, L., Kakarla, M., Acosta-Martinez, V., Zak, J.C., 2014. CRP to cropland conversion: Short-term impacts on soil quality in the Southern High Plains. The 99th Ecological Society of America Annual Meeting (August 12), Sacramento, CA. http://eco.confex.com/eco/2014/webprogram/Paper48939.html.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
Kakarla, M., Moore-Kucera, J., Fultz, L., Li, C., Acosta-Martinez, V., Zak, J.C., 2014. Microbial community response to increased years of grassland restoration under the Conservation Reserve Program in semiarid sandy soils. The 99th Ecological Society of America Annual Meeting (August 12), Sacramento, CA. http://eco.confex.com/eco/2014/webprogram/Paper47874.html.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
Acosta-Martinez, V., Moore-Kucera, J., Fultz, L., Kakarla, M., Li, C., 2014. Influence of Conservation Reserve Program Age and Conversion to Cropland on Soil Quality, Microbial Diversity and Metabolic Capacity: Implications for Our Decisions about Soil Conservation. ASA, CSSA, & SSSA International Annual Meeting (November 4), Long Beach, CA. https://scisoc.confex.com/scisoc/2014am/webprogram/Paper85049.html.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
Kakarla, M., Moore-Kucera, J., Fultz, L.M., Li, C., Acosta-Martinez, V., Zak, J.C., Rao, K. 2014. Soil bacterial composition dynamics across a Conservation Reserve Program (CRP) chronosequence in the Texas High Plains region using Illumina MiSeq paired-end sequencing. 6th Annual Argonne Soil Metagenomics Meeting (October 1-3, 2014), St. Charles, IL.
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2013
Citation:
Bugge, A. 2013. Shifts in Plant Community Composition Across A Conservation Reserve Program Chronosequence and Associated Soil Chemical Properties of Amarillo Loamy Sand in the Texas High Plains. Master's thesis, Texas Tech University. Retrieved from: http://portal.nifa.usda.gov/reeport/progress_reports/126373-soil-microbial-communities-key-indicators-of/products (accessed 3/29/2015)
|
Progress 01/01/13 to 12/31/13
Outputs
Target Audience: Targeted audiences included soil scientists, soil microbial ecologists, crop and grassland scientists who attended our two poster and one oral presentations at the 2013 ASA-CSSA-SSSA meetings held in Tampa, FL. There were approximately 35-40 attendees at the oral presentation and posters were available for review during the entire 3-day meeting (total attendees were approximately 4000). Active interaction with the authors occurred during a 2hr time slot during which, at least 20-30 people viewed and engaged discussions with the authors. Highlights from this project were presented to faculty and students of the Plant & Soil Science Department at TTU during a 1-hr seminar. Approximately 25 people were in attendance. Highlights from this project were presented to faculty and students of the School of Plant, Environmental and Soil Science at Louisiana State University. Attendees = 20. An oral presentation at the project directors meeting held in Baltimore, MD was given in summer 2013. This presentation reached about 40 scientists actively engaged in the Renewable Energy, natural Resources program. Interactions with NRCS agents (one from each of the 7 counties we work in) and producers continued throughout the year to provide informal (oral) updates regarding the status of this project, sampling schedules, etc. Additionally,three native rangeland sites were added which involved developing relationships with individuals at the Muleshoe National Wildlife Refuge, a producer owned and operated ranch in Leveland, TX, and faculty within the Natural Resources Management Department at Texas Tech University who manage the rangeland. 47 students in an introductory soil science class were exposed to the CRP program and key findings from our work during multiple lectures and laboratory assignments during the fall 2013 semester. Two Ph.D. students, one post-doctoral scientist, and multiple (6) undergraduate assistants were trained in various aspects of both field and laboratory analyses related to this project. This training included experiential learning opportunities for five undergraduates (plant and soil science, geology, and natural resources management majors) who visited CRP and cropland sites, learned about the conservation program and study goals and had hands-on experience with sampling efforts. An additional 4 undergraduate students were provided laboratory instruction on study objectives and gained hands-on experience with soil sample processing. Changes/Problems: Dr. David Weindorf was hired by the TTU Department of Plant and Soil Science to replace Dr. Wayne Hudnall. Dr. Weindorf will fulfill the role of soil pedologist previously identified. Two fields were eliminated from the CRP chronosequence as they did not meet the previously identified requirements. Three native rangeland fields were identified and samples to serve as models for undisturbed grasslands in this region. One of the the CRP/converted CRP fields was eliminted from the Obj 2 fields. This field was an irrigated cotton field while the remaining three fields are managed as dryland crop fields. Chenhui Li was brought on as a Ph.D. student for the project. Due to alterations necessary for the fractionation method (see year 1 report), FAME analyses on fractions was not possible. However, our new sequencing approach (Illumina MiSeq) will result in far greater coverage of microbial diversity analyses than previous attained with pysequencing methods. THis greater coverage will provide more detailed information regarding microbial community structure in CRP and cropland sites. What opportunities for training and professional development has the project provided? Dr. Moore-Kucera arranged for PhD candidate, Mamatha Kakarla to actively interact with and participate in molecular characterization of soil bacterial and fungal communities at Research & Testing Laboratory in Lubbock, TX. Ms. Kakarla also has been learning how to process these data sets using QIIME and mutlivariate statistical analysis in "R." Aug-Dec 2013: A second PhD candidate, Chenhui Li, began working on the project. Ms. Li has been trained by Dr. Lisa Fultz on proper isolation of light-fraction POM and isotopic analysis. Ms. Li is also being trained in the use of R for statistical evaluations and C and soil erosion models relevant to CRP management. Andre Bugge (M.S. student) successfully completed his M.S. program. The title of his thesis was: Shifts in Plant Community COmposition across a Conservation Reserve Program Chronosequence and Associated Soil CHemical Properties of Amarillo Loamy Sand in the Texas High Plains. Scott Darby (M.S. student) under the supervision of Dr. Robert Cox (TTU faculty) conducted a detailed vegetation survey of eight of the CRP chronosequence fields and one of the native rangeland fields. Expected graduation date is May 2014. Two undergraduate assistants (Jesus Blanco and Betsy Perafan) were trained in laboratory methods to assist with soil carbonate analysis, soil organic matter, and particle size analysis. How have the results been disseminated to communities of interest? a) Two poster presentations and one oral presentation were presented at the ASA-CSSA-SSSA Internation meeting in November 2013. b) Preliminary data was used for demonstration purposes in the PSS 2432 (Principles and Practices of Soil Science) course in the Fall of 2013. c) Planning and follow-up meetings were conducted with all local PI's and lab members to dicuss progress of analyses, data assimiulation, and planning for sampling scheduled for 2014. d) Weekly meetings take place for the PI Moore-Kucera and both PhD students and post-doc to discuss results, status of project, statistical analyses, and development of presentations for national meetings. What do you plan to do during the next reporting period to accomplish the goals? A second soil sampling event is scheduled to occur in 2014 for the CRP chronosequence and native rangeland fields. DNA samples extracted from Obj 2 soil samples collected in 2012 and 2013 have been submitted for sequencing using the Illumina MiSeq (submitted 2/18/2014). Both Ph.D. students are planning on presenting research results at the Ecological Society of America conference in Sacramento, CA (summer 2014). Dr. Moore-Kucera and Dr. Acosta-Martinez have beeninvited to share research results at a jointsymposium on “Sustainable Transitions to Land Use Change from Expiring CRP Contracts”. Dr. Moore-Kucera will present at the SWCSMeeting (SWCS) held in Lombard, IL (July 27-30, 2014). Dr. Acosta-Martinez will present at the SSSA meetings, held in Long Beach, CA (Nov 2-5, 2014). It is a joint SWCS-SSSA symposium
Impacts
What was accomplished under these goals?
The conservation reserve program (CRP) has reduced soil erosion and increased biodiversity and carbon (C) storage. The Texas High Plains (THP) region has >2.2 million ac. enrolled in CRP. After these contracts expire, some land may be converted back to cropland. In the THP, conversion of grasslands that had year-round cover to cropland that is disturbed by tillage and exposed for part of the year may have a negative impact on many of the ecosystem benefits established during CRP restoration. Assessments of soil microbial community composition and diversity are often coupled to the assessment of soil processes (C storage and nutrient cycling) to better address the ecosystem response to disturbances and recovery. Our overall goal was to measure these sensitive soil quality indicators to determine if age of CRP influenced soil quality (objective 1) and what happens in the first few years when CRP land is converted to cropland (objective 2). Obj 1: soil samples from 16 CRP lands (range in age from 6-26 yrs) and 7 non-irrigated croplands were compared to samples collected from 3 native rangelands (NR). Preliminary results suggest that the CRP lands have not reached soil C levels of the NR and require decades longer to reach these levels. Also CRP lands had lower ecological stress indicators than cropped fields and stress decreased with increasing CRP age. CRP age also positively influenced nutrient cycling and key soil organisms such as AMF that are important for soil stability and water and nutrient uptake. Obj 2: indicators of ecological stress were lower in converted fields than CRP. However, CRP had higher AMF biomass during the 1st yr. In the 2nd sampling yr, one of the stress ratios was lower in CRP fields. These findings indicate that the initial measures of improved soil quality in the converted fields may be only short lived. Obj 1: Determine the shifts in soil microbial community (SMC) structure, biogeochemical processes and soilC dynamics using a CRP chronosequence of 26 fields from 0 (cotton-based cropland) to 26 yrs. Analyses completed: Soil samples from 7 crop, 16 CRP, 3 NR were categorized into 8 groups based on years under restoration: 0, 6, 12, 14, 21, 23, 26 and NR (age unknown). Microbial biomass (MBC) and composition were evaluated using fatty acid methyl ester (FAME) profiles and deep-sequencing of the 16S rRNA and 18S rRNA genes for bacterial and fungal community composition, respectively. Data analyses included distance-based redundancy analysis (dbRDA), indicator species analysis (ISA) and phylogenetic diversity according to the Shannon diversity index and species richness. SOC dynamics and biogeochemical functions: Particulate organic matter (POM) was isolated and POM-C and whole-SOC content and δ13C were measured to determine relative fraction of C from C4 grasses. Metabolic quotient (qCO2), macro- and micro-nutrients and 8 enzyme activities involved in C, N, P, and S cycling were measured to determine biogeochemical functionality. Metabolic quotient (qCO2) was calculated as the ratio of CO2-flux to MBC. Summary statistics: Microbial richness and diversity of bacteria or fungi were not affected significantly by time under CRP. Bacterial community composition was affected significantly by CRP yrs (p<0.03) and distinct groups were identified by dbRDA with unique genera identified by ISA for all age groups except NR (p<0.05). Fungal community composition (genus level) was not affected by years under restoration (p<0.28), however, ISA identified specific taxa according to age (p<0.05). Between 0 and 26 yrs of restoration, the relative abundance of Ascomycetes increased 25% and the relative abundance of Glomeromycetes and Basidiomycetes decreased 78 and 24%, respectively. Whole-SOC was not significantly affected by CRP age, however POM-C and MBC:SOC ratio increased with years restored (0.63 to 1.38 Mg ha-1 and 0.02 to 0.05, respectively) indicating an increase in more labile C pools. Within the POM fraction, SOC at 0-yrs was primarily from C3 sources (cotton) compared to relict C4 grasses. After 13-yrs in CRP, the proportion of POM-C from C4 grasses increased to 85% and plateaued. For every additional year under CRP, POM-C increased 0.03 Mg ha-1. Assuming a linear trajectory, an additional 50+ yrs are needed to reach POM-C levels measured in NR. The qCO2 decreased with years restored (from 3.6 to 1.4 µg CO2-C mg-1 Cmic h-1). The geometric mean of eight enzyme assays (EAs) increased linearly with CRP age. In general, total FAME concentration and MBC increased linearly with CRP age. At 15 yrs, GM- bacteria, AMF, and saprophytic fungal biomass markers were greatest. These 15-yr maximums paralleled maximum levels of C influx from transformation of C4 grasses. Only biomarkers for AMF (FAME and Glomeromycota based on sequencing) were taxa positively correlated with nutrient cycling (P and S enzyme activities) and the formation of POM-C (important for aggregate formation and aggregate stability). Change in knowledge: We expected the oldest CRP lands to have the highest soil quality levels. However, 15 yrs CRP lands had the highest levels of many soil quality indicators. We are exploring the relationships between aboveground and belowground biodiversity to explain this finding. Also a second sampling is planned in 2014 (severe drought during 2010-2012 may have curtailed the effect of restoration time). Change in conditions: Soil quality was improved in CRP compared to cropland but levels were not as high as those measured in NR. Key microbial groups (e.g., AMF and Glomeromycota) were identified as important taxa responsible for increased C storage, nutrient cycling, and potential soil stability. Obj 2: Assess short-term dynamics of the SMC structure, biogeochemical processes and soil carbon dynamics as CRP is converted to a row crop during the first four yrs. Soil samples from 3 SHP locations with 2 management treatments (CRP grasslands and CRP fields that were converted to non-irrigated croplands within 1-2 yrs at the time of sampling were sampled) in Nov 2012 and Dec 2013. All CRP fields were at least 23yrs old. Three replicates of each treatment with 3 sub-samples were collected at 3 depths (0-10cm, 10-30cm, 30-50cm). Methods used included the soil management assessment framework to calculate a soil quality index (SQI), 7 soil EAs, MBC, and FAME profiling. Whole and POM-C content, isotopic analyses, and deep-sequencing data processing are pending. Summary statistics: Metabolic quotient (qCO2) was not affected by conversion to cropland in 2012. However, in 2013, CRP fields had lower qCO2 and thusmore efficient microbial metabolism and lower 'stress'. In 2012, conversion did not significantly affect enzyme activities (EAs)andMBC, and the ratios of each EA:MBC. However, there was a consistent pattern of higherEA, MBC and lower ratios for converted cropland than CRP.Mean MBC and SOM was also higher in cropland (125mg kg-1 and 21 mg ha-1, respectively) than CRP (89mg MBC kg-1 and 18 mg SOM ha-1). Cropland also had lower EA:MBC (indicator of enhanced microbial metabolic efficiency). Converted croplands had relatively lower AMF abundance and higher relative abundance of GM+ bacteria than CRP. Change in knowledge: We expected lower soil quality indicators in converted CRP fields due to the higher disturbance (termination of perennial cover and tillage operations). However, converted fields typically had enhanced soil quality variables and metabolic functioning. These trends could be an artifact of increased degradation of organic residues via termination of grasses and tillage, which would initially stimulate microbial activities and reduce nutrient acquisition stress. However, samples were collected following 2 yrs of extreme drought, which may have preserved SOM. A return to normal precipitation levels may facilitate rapid decomposition, loss of SOM, and reduced microbial biomass and enzyme activities.
Publications
|
Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Activities May-Dec 2012: Mamatha Kakarla (Ph.D. candidate) and Dr. Lisa Fultz (post-doctoral scientist) were identified and began working on this project. July 2012: Soil samples were collected from 18 CRP fields (6-26 yrs under CRP) and 7 cotton-based fields in 7 counties in West Texas (Cotton fields represent age "0" in the chronosequence) for obj. 1. Nov 2012: Soil samples from four paired CRP and recently converted CRP to cotton fields were collected for obj. 2. Jul - Dec 2012. Analyses completed include: a)Soil nutrient analysis, pH, and organic matter (obj. 1&2). b)Bulk density (field) and microbial biomass C and N and fatty acid methyl ester profiles for community composition. c) Soil CO2 at each field site was measured for metabolic quotient calculations at each site (obj. 1&2). d)Soil CO2 is measured approximately every 30 days beginning in Nov and is ongoing (obj 2). e)Analyses in progress for both objectives: 1.DNA has been extracted and is being quality checked before high throughput sequencing. 2.7 enzyme assays, isotopic C analysis on whole and fractionated soil, FTIR analyses, and density fractionation (particulate organic matter has been isolated). Events a)Dr. Lisa Fultz collaborated with Dr. Juske Horita (Co-PI) and developed a method to identify presence and removal of soil carbonates and determine 13C/12C ratios on whole and fractionated samples. b)4 undergraduate research assistants (Andrew Alleman, Brittany Irle, Franchely Cornejo, and Sarah Dyess) have been hired and trained in various aspects of field and laboratory methods. c)An additional MS student, Andre Bugge (externally funded), conducted plant community composition surveys on the 18 CRP sites from obj. 1. Two undergraduates assisted with this analysis (Brittany Irle and Sarah Dyess). Products a)We established a collaborative relationship with Dr. Susan Crow (University of Hawaii), who has expertise in density fractionation methods. A technique was identified and modified to meet the unique properties of our soil samples (i.e., low clay and organic matter content). b)Collaborations were made with NRCS agents in each county and/or landowners to acquire permission to access land, explain our objectives, obtain site histories, and share our results. c)A public website is under development for expected launch in Spring 2013. Dissemination a)Project objectives and a subset of soil samples were disseminated to PSS 2432 (Principles and Practices of Soil Science) undergraduate students in Fall 2012. Students worked with these soil samples and soil maps as part of a group project. At the end of the semester, students presented results from their samples and map locations and discussed the pros and cons of a conservation program in W. Texas. b)Multiple planning and follow-up meetings with all PIs and lab members have occurred for site selection, project updates, laboratory protocol finalizations, and to establish team leaders for various project objectives. PIs who are not local were called in and/or updated via emails, phone conversations, and detailed meeting notes. PARTICIPANTS: Project Director and Co-Project Director: Jennifer Moore-Kucera, Plant & Soil Sciences (PSS), Texas Tech University (TTU), Lubbock, TX and Veronica Acosta-Martinez, USDA-ARS, Lubbock, TX. Other project investigators: Francisco Calderon, USDA-ARS, Akron, CO; Juske Horita, Geosciences, Texas Tech University, Lubbock, TX; John Zak, Biological Sciences, Texas Tech University, Lubbock, TX. Ph.D. Graduate student: Mamatha Kakarla, Ph.D. at PSS, TTU. Post-doctoral associate: Lisa Fultz at TTU. Undergraduate research assistants (all within PSS): Andrew Alleman, Brittany Irle, Franchely Cornejo, and Sarah Dyess. Partner organizations include the USDA-ARS in Lubbock, TX and Akron, Co. Collaborations and contacts: USDA-NRCS agents: Jason Eckert, Lamb Co.; Kayla Schulte in Bailey Co.; Lynnette Payne in Hockley Co.; Landon Kerby in Cochran, Co., Kerry Weinheimer in Lynn, Co.; Kegan Crouch in Terry Co.; Seth Sowden, Bailey Co. farmer; Austin Keesee, farmer in Terry Co.; Tanner Heffington, farmer in Lamb & Hockley, Co. Dr. Susan Crow from the University of Hawaii for consultation regarding soil fractionation technique and interpretation; Rao Kottapalli at the Center for Biotechnology and Genomics (for bioinformatics and Illumina MiSeq training of Mamatha Kakarla. Training or professional development: Post-doctoral associate, Lisa Fultz received training in Juske Horita's lab to learn about isotopic analyses of soil samples. Together they identified and tested a soil carbonate fumigation technique to remove this C source from samples. Undergraduate assistants Brittany Irle and Sarah Dyess received training on field plant identification and contributed to Andre Bugge's MS research; Brittany Irle and Sarah Dyess were also trained in how to measure soil carbonates and particle-size analysis. Ph.D. student, Mamatha Kakarla received training on DNA extraction, FAME profiling, and PCR for soil samples in the labs of Acosta-Martinez and Moore-Kucera; Radiation safety training and hazardous materials transport training for radioactive materials completed by Jennifer Moore-Kucera, Jon Cotton (USDA-ARS research technician at Lubbock, TX), Scot Weeks and Kevin Evenson (undergraduate research technicians at USDA-ARS, Lubbock, TX) to operate, handle and transport neutron density gauge used for soil bulk density measurements in objective 1. TARGET AUDIENCES: Targeted audiences are local, regional, national and international, and include farmers and producers who have or are considering enrolling land in the CRP program, as well as NRCS and extension agents working with these landowners. Additionally, we are targeted soil scientists and microbial ecologists to share results related to soil microbial diversity and functionality across our CRP chronosequence and in four case studies of land recently converted from CRP to dryland annual crops. We have successfully made contacts and collaborative relationships with six NRCS agents across 7 counties in W. Texas as well as four private landowners. We are in the process of developing a public website to reach a broader area than our research group and local stakeholders. Finally, a semester-long group project in an introductory soil science course utilized as subset of soil samples and site information to use a teaching tool to explain the CRP program, its benefits and limitations from soil, water, wildlife and cultural perspectives. This class was instructed by Jennifer Moore-Kucera and a teaching assistant, Travis Conley and had approximately 40 participants. PROJECT MODIFICATIONS: Deviations: In personnel: Dr. Colin Bell, the original post-doc at the USDA-ARS, accepted a new position at Colorado State University in summer 2011. Due to financial cuts at the federal level, his position was terminated. A new post-doc, Lisa Fultz has been identified. Dr. Wayne Hudnall, soil pedologist and Co-PI, passed away in summer 2012. The Department of Plant & Soil Science at TTU is actively advertising and interviewing to fill the position for a soil pedologist. In approach: For obj. 1: soil samples were not collected in July 2011 by the ARS scientists due to unforeseen severe financial cuts and loss of the post-doctoral associate position. Thus, the first set of soil samples were collected in July 2012. The number of CRP lands increased from 13 to 18 (same CRP age range) but the number of croplands was decreased to 7. After consultation with a local statistician, we chose to group the CRP fields into five age groups and not assess on a paired comparison basis. Age Group 1 (0 yrs; 7 cropped fields; 1 for each county); Group 2 (6-11 yrs; 4 reps); Group 3 (13-15 yrs; 5 reps); Group 4 (20-23 yrs; 4 reps); Group 5 (25-26 yrs; 4 reps). For obj 2: given the extreme drought of 2011-2012, fields originally identified to be converted were kept in grass. Four new CRP fields that were converted to cropland within 2 years (and a paired CRP field of similar age) were identified. However, these fields were not all in Amarillo soils but some were under a similar soil series, Arvana or Patricia (differs mainly in location of carbonates in the soil profile). To account for these differences, carbonate content will be measured on all samples and removed if necessary. In methods: A new high throughput sequencing method using an Illumina MiSeq sequencer for soil microbial diversity may replace the pyrosequencing technique. Illumina results in more reads for much less money and is available to us via the Center for Biotechnology and Genomics at TTU. Dr. Kottapalli has agreed to train Mamatha Kakarla, serve on her committee, and is currently instructing Mamatha in a bioinformatics course. A small trial run will take place in March 2013 to determine if this method will be adopted. Also, a density fractionation will be used to fractionate soils because the originally proposed size fractionation technique was less ideal for the coarse-textured soils. Dr. Susan Crow, soil scientist at the University of Hawaii, has expertise in this method and has agreed to oversee our protocols and assist with data interpretation. We have added plant basal and foliar area coverage and diversity measurements in CRP fields for obj 1 with an additional M.S. student supported on external funds. This information will not only result in an additional MS thesis document but also help in the interpretation of our microbial and soil C dynamics across the chronosequence.
Impacts
Knowledge a)Highest soil organic matter content was measured in the CRP age group 3 (13-15 yrs under CRP) and not in the oldest (26 yrs) age group (5)as hypothesized. However, microbial biomass C was highest in the oldest CRP fields. b)A new molecular technique, sequencing with an Illumina MiSeq instrument, has recently been reported in the literature to successfully characterize soil microbial diversity. This instrument is available at TTU, Center for Biotechnology & Genomics and will be used to assess bacterial and fungal diversity in our samples. It is far more cost effective than pyrosequencing (about $4000 for 100 samples compared to $10,000 for 100 samples with pyrosequencing) and if successful with our trial run scheduled for Mar 2013, will enable us to assess all depths collected and not only the first depth as originally proposed. Actions a)Dr. Moore-Kucera acquired a neutron density gauge which was used to determine soil bulk density for obj. 1 sites. The depth limit of the gauge is only 30cm and thus, bulk density in fields for obj. 2 was measured by the core method as originally proposed. b)External funding for an additional M.S. student has allowed for vegetation community assessments in all CRP fields to help with soil C and microbial shifts over the chronosequence. c)Soil fractionation technique was modified to isolate density instead of size-fractions for enhanced soil spatial analyses.
Publications
- Media Interviews: Moore-Kucera, J. Fall 2012. CRP Focus; Texas Tech soil research team receives $480,000 USDA-NIFA grant. Interviewed and written by Norman Martin and posted on TTU College of Agricultural Sciences and Natural Resources News Center. http://www.depts.ttu.edu/agriculturalsciences/news/p=1005
|
|