Progress 04/01/18 to 12/31/23
Outputs
Target Audience: Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for two PhD students was provided by this project. Both students have graduated, and the majority of their work has now been published. One of the recently graduated PhD students is assisting with the preparation of the shotgun metagenomic data manuscript. How have the results been disseminated to communities of interest?Results from this project have been presented at local, state, national, and international meetings by graduate students and PIs. These include the International Microbial Ecology Society meeting (ISME) in August 2022, and multiple annual meetings of the Soil Science Society of America (SSSA). State presentations include the UF/IFAS Soil, Water, and Ecosystem Sciences Research Forum. Presentations have also been made at extension seminars, such as the Florida Polk County Citrus Squeezer, that are attended primarily by citrus growers in the state. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
What was accomplished under these goals? Over the course of this project, we accomplished all our goals and therefore made significant discoveries in our understanding and characterization of agroecosystem biocrusts. Our project has provided the first detailed assessment of the composition and function of agroecosystem biocrusts, as well as their potential to contribute to crop growth. The project supported the research of two PhD students and several research assistants. We have published six papers based on research from this project and have one currently in review. There are an additional two manuscripts in preparation, which will bring the total publication number for this project to nine. In addition, an extension article about agroecosystem biocrusts has been published in the University of Florida IFAS Electronic Data Information Source (EDIS). Due to COVID-19, which occurred during the early stages of the project, the Florida members of the project were unable to travel to Oregon to collect samples in person. However, the member of the project located in Oregon was able to collect samples and ship them to Florida for analysis. SO1: Determine the N cycling potential of agroecosystem BSCs. Biocrusts identified in citrus, grape, and apple agroecosystems actively fix N, and rates of N fixation in these agroecosystem biocrusts were similar to those measured in previous studies of natural ecosystem biocrusts. While the biocrusts in citrus and grape agroecosystems fixed N all year, there were seasonal patterns of N fixation rates that were influenced by management practices for each crop. For example, biocrusts in vineyards had high N-fixation rates during the summer than winter when there was greater soil moisture from rainfall. However, biocrusts in citrus, which had a more consistent soil moisture year-round due to irrigation (see SO3), had fewer changes in N-fixation rates during the year. These results were published in Frontiers in Microbiology. Biocrusts in agroecosystems also impact nitrogen cycling and microbial communities in the soil below biocrusts. This impact also varied by season, with greater N cycling potential and soil moisture in soil under citrus biocrusts during the dry winter. As the winter is the nutrient-demanding period of fruit set for citrus, the increased N cycling in soils under biocrusts indicates biocrusts could potentially provide additional N for citrus trees (see SO4). These results were published in Soil Biology and Biochemistry. SO2: Characterize the competition and function of BSC microbial communities The bacterial community composition of citrus, grape, and apple agroecosystem biocrusts was significantly different than the composition of adjacent bare soil, confirming the presence of biocrusts in these agroecosystems. The diazotroph composition of these agroecosystem biocrusts were dominated by N-fixing cyanobacteria from the Nostocales order, similar to the composition of natural ecosystem cyanobacterial biocrusts. However, agroecosystem biocrusts had overall lower abundance of other cyanobacteria compared to natural ecosystem biocrusts and were dominated by proteobacteria. The differences in N-fixation activity due to management differences (lower irrigation and fertilizer in the vineyard compared to citrus) identified in SO1 were supported by differences in the bacterial and diazotrophic community composition of vineyard and citrus biocrusts. Differences in soil type and climate differentiated the apple orchard biocrust microbial community composition from those in citrus orchards and the vineyard. The manuscript with these results is currently in review for publication in FEMS Microbiology Ecology. To further examine how these agroecosystem biocrust organisms might transfer nutrients through the soil to crops, we performed shotgun metagenomic sequencing on a subset of biocrust samples from the citrus site. This work will be the first metagenomic analysis of agroecosystem biocrusts and will allow us to assess the links between the microbes within the biocrusts and the soil below the biocrusts and nutrient availability. The sequencing and preliminary analysis for this study has been completed, and a manuscript of these results is currently being prepared for submission. SO3: Assess the factors driving BSC growth and function in agroecosystems. Nitrogen fixation rates of grape and citrus agroecosystems were impacted by changes in soil moisture and fertilization that reflect different management practices for these crops. For example, vineyards are not irrigated extensively during the dry winter season like citrus orchards, and thus N-fixation rates of biocrusts in the vineyards were significantly greater in the summer (during the rainy season) than in the winter. In contrast, citrus biocrust N fixation was relatively consistent throughout the year, as was soil moisture. Fertilization types and rates also impacted N-fixation rates. For example, N fixation rates in citrus decreased after a dry fertilizer application, but rates recovered and then remained consistent throughout the rest of the year. These results were published in Frontiers in Microbiology. Further examination of the impact of N and phosphorous fertilizers on biocrust N fixation, growth, and microbial community composition were conducted in greenhouse manipulation trials. The fertilizer applications had little impact on the diazotroph community composition but did reduce the biocrust N fixation rates. However, within two weeks of fertilizer applications, N fixation rates returned to levels similar to the unfertilized controls. Results of this study are being prepared for submission to a peer-reviewed journal. SO4: Examine the influence of BSCs on crop growth. In a greenhouse experiment, the growth of citrus seedlings was slightly impacted by the presence of surrounding biocrusts. However, plantd15N was significantly lower in citrus seedlings grown with biocrusts than the control, indicating that biocrusts could potentially serve as N sources for seedlings. These results were published in Agrosystems, Geosciences, and the Environment. A more detailed study of the transfer of N from biocrusts to a crop was conducted in a citrus orchard using biocrusts labeled with stable isotope 15N. The labeled biocrust N was found in the soil below the biocrust and in the citrus roots adjacent to the biocrust one day after the labeled biocrusts were transplanted into the orchard. Labeled N was present in leaves after three days. The labeled N increased in the fibrous roots of the citrus during a root flush period, and then decreased prior to a leaf flush and fruit harvest. At fruit harvest, approximately 23.8% of the total biocrust 15N was in the fruit tissue. Overall, the results of this study indicated that agroecosystem biocrusts can contribute N necessary for tree growth. These results were published in Nutrient Cycling in Agroecosystems.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2024
Citation:
Nevins C, Strauss SL, Inglett P (2024) Uptake of biocrust nitrogen by tree crops in a sandy soil agroecosystem. Nutrient Cycling in Agroecosystems doi: 10.1007/s10705-023-10334-5
- Type:
Journal Articles
Status:
Under Review
Year Published:
2024
Citation:
Sorochkina K, Martens-Habeena W, Reardon C, Inglett P, Strauss SL (2023) Nitrogen-fixing bacterial communities differ between perennial agroecosystem crops. FEMS Microbiology Ecology
- Type:
Other
Status:
Published
Year Published:
2023
Citation:
Nevins C, Sorochkina K, Inglett P, Strauss SL (2023) An introduction to biological soil crusts in Florida perennial agroecosystems https://edis.ifas.ufl.edu/22719
|
Progress 04/01/22 to 03/31/23
Outputs
Target Audience:Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:COVID-19 related delays from supply chain shortages and travel/work restrictions delayed our final collection and assessment of shotgun metagenomic sequence data. This led to us requesting a 9 monthNCE to complete this work and finish submitting manuscripts for publication. What opportunities for training and professional development has the project provided?Training and mentorship for two PhD graduate students was provided by this project. One of the recently graduated PhD students is currently assisting in the analysis of the shotgun metagenomic data. How have the results been disseminated to communities of interest?Results from this project were presented by the PI at the International Microbial Ecology Society meeting in August of 2022. Results were also presented by a graduate student at the 2022 Soil Science Society of America annual meeting in November. An overview of the project was presented by the PI at the UF/IFAS Soil, Water, and Ecosystem Sciences Research Forum in February 2023. An Extension document about biocrusts in agroecosystems has been prepared for publication by the UF/IFAS EDIS (Electronic Data Information Source) of UF/IFAS Extension. What do you plan to do during the next reporting period to accomplish the goals?At least four additional manuscripts will be submitted for publication, including the results of the shotgun metagenomic sequencing. Presentations of results will be made at regional and national scientific conferences, including the annual meetings of the Ecological Society of America and the Soil Science Society of America. Presentations will also be made to perennial crop growers regarding biocrusts in agroecosystems.?
Impacts
What was accomplished under these goals?
We are in the final stages of examining the influence of biological soil crusts (BSCs; biocrusts) on soil carbon (C) and nitrogen (N) cycling in perennial agroecosystems. BSCs have been examined in Florida citrus and grape agroecosystems and an Oregon apple orchard. Two PhD students, one supported by the grant, and another awarded a University of Florida fellowship, worked to address the project goals. Both PhD students have now graduated and are in the final stages of publishing their findings. Three publications of results from this project were published in the past year, bringing the current total publication count for this project to five. There are at least three more manuscripts that will be submitted by the end of 2022. However, due toCOVID-19 related delays from supply chain shortages and travel/work restrictions that delayed our final assessment of shotgun metagenomic sequence data, we requested a NCE. SO1: Determine the N cycling potential of agroecosystem BSCs Biocrusts in citrus, grape, and apple agroecosystems were actively fixing N during the year. Results from the citrus and grape biocrust N-fixation studies have been published inFrontiers in Microbiology. These N fixation rates were similar to those measured in natural arid and mesic biocrusts. To determine how biocrusts might influence the soil underneath, and therefore N cycling within the agroecosystem, a year-long study was completed to examine the interaction between seasonal environmental changes and biocrusts on soil carbon and nitrogen cycling below the biocrusts in a citrus orchard. Indeed, the impact of biocrusts on soil N cycling and the microbiome (see SO2) did vary by season, with greater N cycling potential and soil moisture during the dry season. These increases corresponded with the nutrient-demanding fruit set period for citrus, indicating biocrusts could play a role in providing additional nitrogen for citrus trees. These results were published inSoil Biology and Biochemistry. SO2: Characterize the competition and function of BSC microbial communities To examine the seasonal changes in the composition of biocrusts in different agroecosystems, samples were collected from biocrusts in citrus, grape, and apple agroecosystems when N-fixation measurements were made (see SO1). DNA from these samples was extracted and sent for amplicon sequencing of the bacterial 16S rRNA gene and the nifH gene used by N-fixing bacteria. Overall, biocrusts had significantly different bacterial community composition based on their agroecosystem, but the dominant phyla were similar for all biocrusts examined. Nostacales were the primary diazotrophs for all sampled biocrusts, though there were differences in diazotroph composition between agroecosystems. The manuscript with these results is currently being prepared for submission in 2023. We are currently finalizing a study to examine how these agroecosystem biocrust organisms might be transferring nutrients through the soil to the crops. We recently performed shotgun metagenomic sequencing on a subset of biocrust samples, and once the analysis is complete, this work will be the first metagenomic analysis of agroecosystem biocrusts and enable us to assess the links between biocrust bacteria, fungi, and soil nutrient availability. Although COVID delayed this data, we expect the sequencing to be completed by the end of January and result in over 200 GB of data. The no-cost extension will provide time for analysis, preparation, and manuscript submission. SO3: Assess the factors driving BSC growth and function in agroecosystems. Soil moisture and fertilization appear to impact N fixation rates of biocrusts in grape and citrus agroecosystems, with soil moisture impacting biocrust N-fixation in grape biocrusts more than in those located in citrus agroecosystems. Fertilization types and rates also appear to impact N-fixation, as citrus N-fixation rates decreased after dry fertilizer application but were otherwise consistent. Greater N-fixation rates also tended to occur in biocrusts with higher concentrations of available phosphorous. These results were part of the manuscript published in 2022 inFrontiers in Microbiology. Greenhouse trials were conducted in 2021 to assess the influence of fertilization (N and phosphorous) on biocrust N-fixation, growth, and microbial community composition. Bacterial DNA was extracted from soil collected from these trials and sent for amplicon sequencing of the nifH gene to assess changes in the composition of the N-fixing bacteria with fertilization. Overall, N and phosphorous fertilizer applications did not impact the diazotroph community composition, but they did reduce the biocrust N-fixation rates. However, N-fixation rates returned to levels similar to the unfertilizer controls within two weeks of fertilizer application. Results of this study are currently being prepared for submission in 2023. SO4: Examine the influence of BSCs on crop growth. An initial greenhouse project examining the interaction between citrus seedling growth, soil nutrient concentrations, soil microbial communities, and biocrust presence was completed in 2020 and was published inAgroecosystems, Geosciences & Environmentin 2022. A field experiment using stable isotope 15N to determine if biocrust N is transferred to the soil profile and citrus concluded in Spring 2021, and the manuscript is currently being prepared for submission in 2023.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Nevins C, Strauss SL, Inglett PW (2022) Agroecosystem biological soil crusts impact seedling growth and nitrogen content in a greenhouse environment. Agroecosystems, Geosciences & Environment, e20295; doi: 10.1002/agg2.20295
|
Progress 04/01/21 to 03/31/22
Outputs
Target Audience:Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:COVID restrictions in the last year delayed the collection of some samples and recipt of necessary supplies. This led to the request for a no-cost extension in order to complete the proposed objectives. What opportunities for training and professional development has the project provided?Training and mentorship for two PhD graduate students is being provided by this project. How have the results been disseminated to communities of interest?Preliminary data was presented by both graduate students at the 2022 Annual Soil Science Society of America conference in November. Preliminary data have also been presented at state-wide citrus grower meetings. What do you plan to do during the next reporting period to accomplish the goals?At least three additional manuscripts will be submitted for publication, and at least two additional manuscripts will be drafted. The diurnal measurements of biocrust N fixation will occur during 2022. Analysis of the greenhouse trials examining the interaction between fertilizers and biocrust N-fixation activity will be completed, and preparations will begin on the manuscripts. Presentations of results will be made at regional and national scientific conferences, including the annual meetings of the Ecological Society of America and the Soil Science Society of America.?
Impacts
What was accomplished under these goals?
We continued to assess the influence of biological soil crusts (BSCs) on the soil carbon (C) and nitrogen (N) cycling in tree crop agroecosystems. BSCs are being examined in Florida citrus and grape agroecosystems and an apple orchard in Oregon. Two PhD students, one supported by the grant and another awarded a University of Florida fellowship, are working to address the project goals. Three publications of results from this project have been published. At least three more manuscripts will be submitted during 2022. However, due to COVID restrictions, progress on some objectives has been slightly delayed, resulting in our request for a no-cost extension. SO1: Determine the N cycling potential of agroecosystem BSCs Citrus and grape biocrusts were actively fixing N throughout the year in a study completed and submitted for publication to Frontiers in Microbiology, and rates were similar to those found in natural arid and mesic biocrusts. Soil moisture appeared to have a greater influence on N-fixation rates in the grape biocrusts compared to citrus biocrusts, possibly due differences in irrigation between the two crops. Fertilization types and rates also appear to impact N-fixation, as citrus N-fixation rates decreased after dry fertilizer application but were otherwise consistent. Greater N-fixation rates also tended to occur in biocrusts with higher concentrations of available P. Measurements of N-fixation in biocrusts from apple orchards in Oregon were also completed in 2020 and are part of a manuscript examining the microbial community composition of different agroecosystem biocrusts (see SO2). Building on initial findings that biocrusts in Florida citrus agroecosystems significantly impact soil C and N and moisture underneath the crusts, down to a 15 cm depth at one time point, a year-long study was completed to examine the interaction between seasonal environmental changes and biocrusts on soil carbon and nitrogen cycling below the biocrusts in a citrus orchard. Indeed, the impact of biocrusts on soil nitrogen cycling and the microbiome (see SO2) did vary by season, with greater N cycling potential and soil moisture during the dry season. These increases corresponded with the nutrient-demanding fruit set period for citrus, indicating biocrusts could play a role in providing additional nitrogen for citrus trees. These results were recently published inSoil Biology and Biochemistry. SO2: Characterize the competition and function of BSC microbial communities Following the initial results of the composition of the microbial communities in soils under citrus biocrusts published in 2021 inPlant and Soil, we took a closer look at the relationship between season and the composition of microbial communities under the biocrusts. The seasonal impacts on soil N cycling potential found in SO1 under biocrusts were driven by changes in the soil microbial community composition. In particular, microbial biomass N and potential ammonia oxidation were higher during the fall, and there was a greater abundance of copiotrophic bacteria and fungi capable of nitrification. The results were also recently published inSoil Biology and Biochemistry. To examine the seasonal changes in the composition of biocrusts in different agroecosystems, samples were collected from biocrusts in citrus, grape, and apple agroecosystems when N-fixation measurements were made (see SO1). DNA from these samples was extracted and sent for amplicon sequencing of the bacterial 16S rRNA gene and the nifH gene used by N-fixing bacteria. Data is still be analyzed, but initial results indicate significantly different biocrust bacterial composition for each agroecosystem as well as seasonal shifts in N-fixing organisms that correspond to changes in N fixation activity. SO3: Assess the factors driving BSC growth and function in agroecosystems. The seasonal field measurements of N-fixation (see SO1) found that moisture and fertilizer did influence N-fixation rates in citrus and grape agroecosystem biocrusts. Greenhouse trials were conducted in 2021 to assess the influence of fertilization (N and phosphorous) on biocrust N-fixation, growth, and microbial community composition. Bacterial DNA is currently being extracted from soil collected from these trials and will be sent for amplicon sequencing of the nifH gene to assess changes in the composition of the N-fixing bacteria with fertilization. An additional growth chamber experiment to assess the contributions of phototrophic vs heterotrophic N-fixing organisms to biocrust N fixation are currently planned for 2022. These experiments will allow for more accurate estimates of the N-fixing potential of agroecosystem biocrusts, as previous measurements of N fixation were only conducted during daylight. SO4: Examine the influence of BSCs on crop growth. An initial greenhouse project examining the interaction between citrus seedling growth, soil nutrient concentrations, soil microbial communities, and biocrust presence was completed in 2020, and the manuscript will be submitted for publication in Spring 2022. A field experiment using stable isotope 15N to determine if biocrust N is transferred to the soil profile and citrus concluded in Spring 2021, and the manuscript is currently being prepared for submission in 2022.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Nevins C, Inglett P, Strauss SL (2022) Seasonality drives microbiome composition and nitrogen cycling in soil below biocrusts. Soil Biology and Biochemistry; doi: 10.1016/j.soilbio.2022.108551
- Type:
Journal Articles
Status:
Submitted
Year Published:
2022
Citation:
Sorochkina K, Strauss SL, Inglett P (2022) Contrasting seasonal patterns and factors regulating biocrust N2-fixation in two Florida agroecosystems. Frontiers in Microbiology
|
Progress 04/01/20 to 03/31/21
Outputs
Target Audience:Researchers, producers, extension agents, citrus growers, and field specialists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for two PhD graduate students is being provided by this project. How have the results been disseminated to communities of interest?Preliminary data was presented by one graduate student at the 2020 Ecological Society of America annual meeting in August (held virtually) and the other graduate student presented at the 2020 Annual Soil Science Society of America conference in November (held virtually). The project plan and preliminary data have also been presented at state-wide citrus grower meetings. What do you plan to do during the next reporting period to accomplish the goals?At least three manuscripts will be submitted for publication, and at least two additional manuscripts will be drafted. Both the field trial using 15N to trace biocrust N into citrus and the greenhouse project to assess the interaction between fertilizers and biocrust N-fixation activity will be completed, and preparations will begin on the manuscripts. Presentations of results will be made at regional and national scientific conferences, including the annual meetings of the Ecological Society of America the Soil Science Society of America.
Impacts
What was accomplished under these goals?
During the third year of the project, we continued to assess the influence of biological soil crusts (BSCs) on the soil carbon (C) and nitrogen (N) cycling in tree crop agroecosystems. BSCs are being examined in Florida citrus and grape agroecosystems and an apple orchard in Oregon. Two PhD students, one supported by the grant and another awarded a University of Florida fellowship, are working to address the project goals. The first publication of results from this project was published in the Journal of Plant Nutrition and Soil Science in 2020, and the second manuscript is currently in review for Plant and Soil. At least three more manuscripts will be submitted during 2021. SO1: Determine the N cycling potential of agroecosystem BSCs A study examining seasonal changes in biocrust N-fixation rates in citrus and grape agroecosystems was completed in May 2020. Both citrus and grape biocrusts were actively fixing N throughout the year, and rates were similar to those found in natural arid and mesic biocrusts. Soil moisture appeared to have a greater influence on N-fixation rates in the grape biocrusts compared to citrus biocrusts, possibly due differences in irrigation between the two crops. Fertilization types and rates also appear to impact N-fixation, as citrus N-fixation rates decreased after dry fertilizer application but were otherwise consistent. Greater N-fixation rates also tended to occur in biocrusts with higher concentrations of available P. Greenhouse experiments in SO3 will help address the interaction between N-fixation and fertilization. A manuscript reporting these results will be submitted in Spring 2021. Measurements of N-fixation in biocrusts from apple orchards in Oregon were also completed in 2020 and will be part of a manuscript examining the microbial community composition of different agroecosystem biocrusts (see SO2). Biocrusts in Florida citrus agroecosystems significantly impact soil C and N and moisture underneath the crusts, down to a 15 cm depth. More specifically, nitrate and inorganic N were enriched below the biocrusts. At one location, the soil below biocrusts also had 44% more microbial biomass C. Stable isotope(δ15N) N was also lower underneath biocrusts than soil without biocrusts at one location, indicating that the biocrust was likely fixing atmospheric N, and therefore a source of N for the soil underneath the biocrust. This information is part of a manuscript published in 2020 in the Journal of Plant Nutrition and Soil Science. In Fall 2020, an assessment was completed to determine if there is a seasonal component to these contributions of the biocrusts to the soil profile.The results of this study will be submitted for publication in Spring 2021. SO2: Characterize the competition and function of BSC microbial communities Biocrusts had significantly different bacterial and fungal community composition compared to soil without biocrust in Florida citrus agroecosystems. As with the soil nutrient concentrations, biocrusts significantly influenced the soil microbial community composition under biocrusts, with differences in the bacterial and fungal community composition occurring down to a depth of 15 cm compared to soil without biocrusts. These below biocrust soils also had increased relative abundances of Nitrospira and other taxa involved in N cycling. This information is part of a manuscript currently in review for Plant and Soil. Samples have been collected from biocrusts in citrus, grape, and apple agroecosystems when N-fixation measurements were made (see SO1). DNA from these samples have been extracted and will be sent for amplicon sequencing in Spring 2021 to determine the bacterial and diazotroph community compositions. SO3: Assess the factors driving BSC growth and function in agroecosystems. The seasonal field measurements of N-fixation (see SO1) found that moisture and fertilizer did influence N-fixation rates in citrus and grape agroecosystem biocrusts. Preparations are underway to begin a greenhouse project in Spring 2021 to assess the influence of fertilization (nitrogen and phosphorous) on biocrust N-fixation, growth, and microbial community composition. SO4: Examine the influence of BSCs on crop growth. An initial greenhouse project examining the interaction between citrus seedling growth, soil nutrient concentrations, soil microbial communities, and biocrust presence was completed in 2020, and the manuscript will be submitted for publication in Spring 2021. A field experiment using stable isotope 15N to determine if biocrust N is transferred to the soil profile and citrus began in Fall 2020 and will conclude in Spring 2021.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2020
Citation:
Nevins C, Strauss SL, Inglett P (2020) Biological soil crusts effect nitrogen cycling in Florida citrus agroecosystems. Journal of Plant Nutrition and Soil Science, doi: 10.1002/jpln.20200000218
- Type:
Journal Articles
Status:
Under Review
Year Published:
2020
Citation:
Nevins C, Inglett P, Strauss SL (2020) Biological soil crusts vertically structure the subsurface microbiome in a sandy agroecosystem. Plant and Soil
|
Progress 04/01/19 to 03/31/20
Outputs
Target Audience:Researchers, other graduate students, and citrus growers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for two PhD graduate students is being provided by this project. One graduate student attended the Root Phenotyping Workshop held by the International Plant Phenotyping Network and another graduate student attended a virtual workshop on Cydrasil, hosted by Arizona State University, to learn about utilizing a new database for cyanobacterial 16S rRNA sequences. How have the results been disseminated to communities of interest?Preliminary data was presented by one graduate student at the 2019 Annual Soil Science Society of America conference in November and by two graduate students at the Board of Agriculture and Natural Resources of the National Academics of Science, Engineering, and Medicine 75thAnniversary event at UF/IFAS, Gainesville, FL in January 2020. The project plan and preliminary data have also been presented at state-wide citrus grower meetings. What do you plan to do during the next reporting period to accomplish the goals?Plans are underway to begin two greenhouse trials to assess the interaction of moisture and fertilizer on biocrust N-fixation activity, and to use 15N to assess how N fixed by biocrusts is distributed through the soil profile and to a crop. Biocrusts were identified in a Washington orchard and efforts will continue to identify them in orchards in Oregon. Plans are underway to collect and assess N-fixation and microbial composition in the Western orchard biocrusts. Presentations of results will be made at regional and national scientific conferences, including the annual meetings of the Ecological Society of America the Soil Science Society of America.
Impacts
What was accomplished under these goals?
During the second year of the project, we continued to assess the influence of biological soil crusts (BSCs) on the soil carbon (C) and nitrogen (N) cycling in Florida agroecosystems. BSCs are being examined in Florida citrus and grape agroecosystems, and several apple orchard locations in the Pacific Northwest have been identified. Two PhD students, one supported by the grant and another awarded a University of Florida fellowship, are working to address the project goals. The first publication of results from this project was recently submitted to Scientific Reports, and a second manuscript will be submitted to Frontiers in Microbiology this spring. SO1: Determine the N cycling potential of agroecosystem BSCs Field measurements of biocrust N-fixation have been performed in citrus and grape agroecosystem biocrusts during the summer, fall, and winter seasons. During each season, and in both agroecosystems, biocrust N-fixation rates were significantly greater than soil without biocrusts, and had significantly greater microbial C and N. Biocrusts in the grape agroecosystem had higher N-fixation rates than the citrus system during the summer, but this may be related to lower fertilization rates for this crop during the summer. Greenhouse experiments in SO3 will help address the interaction between N-fixation and fertilization. Greater N-fixation rates also tended to occur in biocrusts with higher concentrations of available P. Final analysis of this data is being performed and prepared for publication. BSCs in Florida citrus agroecosystems significantly impact soil C and N and moisture underneath the crusts, down to a 15 cm depth. More specifically, nitrate and inorganic N were enriched below the biocrusts. At one location, the soil below biocrusts also had 44% more microbial biomass C. Stable isotope(δ15N) N was also lower underneath biocrusts than soil without biocrusts at one location, indicating that the biocrust was likely fixing atmospheric N, and therefore a source of N for the soil underneath the biocrust. This information is part of a manuscript currently in review for Scientific Reports. Assessment of the soil C, N, and moisture at different depths below biocrusts are continuing at one agroecosystem in an effort to determine if there is a seasonal component to these contributions of the biocrusts to the soil profile. SO2: Characterize the competition and function of BSC microbial communities Biocrusts had significantly different bacterial and fungal community composition compared to soil without biocrust in Florida citrus agroecosystems. As with the soil nutrient concentrations, biocrusts significantly influenced the soil microbial community composition under biocrusts, with differences in the bacterial and fungal community composition occurring down to a depth of 15 cm compared to soil without biocrusts. These below biocrust soils also had increased relative abundances of Nitrospira and other taxa involved in N cycling. This information is part of a manuscript currently in preparation for submission later this spring. Samples have been collected from biocrusts in citrus and grape agroecosystems when N-fixation measurements were made (see SO1). DNA from these samples will be extracted and used to assess bacterial community composition, the composition of the N-fixing bacterial composition. SO3: Assess the factors driving BSC growth and function in agroecosystems. Preliminary tests found no significant difference in N-fixation rates between low and high light levels for citrus agroecosystem biocrusts. However, preliminary data from field measurements suggests that moisture plays a role in N-fixation activity. Preparations are underway to begin a greenhouse project to assess the influence of moisture and fertilization on biocrust growth and activity later this spring. SO4: Examine the influence of BSCs on crop growth. An initial greenhouse project examining the interaction between citrus seedling growth, soil nutrient concentrations, soil microbial communities, and biocrust presence recently concluded. Data has been collected and final analysis is being performed in preparation for publication. Another greenhouse project using stable isotope 15N to determine if the N fixed by biocrusts is transferred to plants and the soil profile will begin later this spring.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2020
Citation:
Nevins, CJ, Strauss SL, Inglett PW. 2020. Biocrust presence enhances moisture and nutrients in the rooting zone of sandy soil agroecosystems. Scientific Reports. submitted Jan. 2020
|
Progress 04/01/18 to 03/31/19
Outputs
Target Audience:Researchers, graduate students, and citrus growers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and mentorship for two PhD graduate students is being provided by this project. How have the results been disseminated to communities of interest?Preliminary data and project plans have been presented at scientific conferences and state-wide grower meetings. What do you plan to do during the next reporting period to accomplish the goals?Plans are underway to collect samples in no-till wheat fields and vineyards in Oregon and Washington in May 2019. Measurements on these samples will further address Objectives 1 and 2. Greenhouse experiments using 15N to assess whether N fixed by organisms in BSCs is available and used for plant growth will begin this summer. Presentations of results will be made at regional and national scientific conferences this year, including the Annual Soil Science Society of America conference in November.
Impacts
What was accomplished under these goals?
In the first year of this project, we have determined that soils with biological soil crusts (BSCs) in Florida citrus groves have significantly greater soil carbon (C) and nitrogen (N) concentrations as well as soil moisture compared to soils without BSCs. This difference extends to 15 cm below the BSC, indicating potential influence of BSCs on soil nutrient availability for citrus trees. As these BSCs occur naturally in citrus groves and other agroecosystems, they have the potential to serve as a sustainable method for increasing soil moisture and N, allowing growers to reduce irrigation and fertilizer inputs. Two PhD students, one supported by the grant and another awarded a University of Florida fellowship, joined UF in August 2018 and are working to address these research goals, and others, for their dissertations. Both students have drafted their research proposals and made initial measurements on Florida citrus grove BSCs. Plans are in place to collect samples from Pacific Northwest BSCs in late spring 2019. These samples will be used to continue to address Objectives 1 and 2. SO1: Determine the N cycling potential of agroecosystem BSCs Preliminary measurements of N-fixation rates were made at citrus BSCs located across Florida. These rates were compared with adjacent samples that did not appear to have BSCs, and no N-fixation was detected in the non-BSC samples. The rates measured are similar to those reported for other mesic BSC sites. An assessment on the influence of BSCs on soil C and N concentrations underneath BSCs has been completed and results are being analyzed and prepared for publication. Soil cores were collected at three Florida citrus groves from both BSCs and soils without visible BSCs. The cores were divided into three layers: the BSC (0-1 cm), 1-5 cm, and 5-15 cm. Soil N (nitrate, ammonia, microbial biomass N, total N, andδ15N) and C (total C, microbial biomass C), and moisture measurements were made. Six cores were collected at each location. Data from these measurements determinedthat the presence of BSCs in Florida citrus groves significantly increasedthe soil moisture, C and N underneath the BSC, but only to the 5 cm depth. SO2: Characterize the competition and function of BSC microbial communities Samples collected for the assessment of BSC influence on soil carbon and N concentrations underneath BSCs were also examined for differences in soil bacterial and fungal community composition through high-throughput amplicon sequencing. This data has been collected, and final analysis is also being performed and prepared for publication. Initial assessment found significant differences in the bacterial and fungal communities at different depths under near BSCs, and between BSCs and soils without BSCs. SO3: Assess the factors driving BSC growth and function in agroecosystems Preliminary tests were performed to examine light levels on N-fixation rates for citrus BSCs and found no significant difference in N-fixation rates under low (40 umol m2s-1) and high (1030 umol m2s-1) light levels for samples from two citrus groves. Preparations are underway to examine in greater detail the influence of light levels, moisture, and fertilization on BSC activity. SO4: Examine the influence of BSCs on crop growth. Preparations are underway to begin greenhouse 15N-label studies this summer to examine the fate of N fixed by BSCs.
Publications
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