Progress 11/01/06 to 10/31/11
Outputs
OUTPUTS: This research examined environmental factors that influence the species composition and functions of microbial communities in soil. The project focused in particular on the ecology of plant growth promoting bacteria (PGPR) in the rhizosphere, soil factors influencing the populations and activity of phosphorus solubilizing bacteria, methods for measuring biologically assimilable carbon in soils, a metagenomic analysis of oil contaminated soils, and the effects of biochar on microbial communities and population densities of PGPR. International cooperative research included studies on the microbial community structures in deep sediments of desert soils, development of DNA microarrays for characterizing microbial communities in soils, and carbon modeling in Chinese rice paddy soils. Related outputs from these research activities has included the training of four Ph.D. students, two visiting scientists from China, two visiting scientists from Chile, a visiting scientist from Mexico, and a Ph.D. student from Brazil all of whom worked for periods ranging from 2 months up to one year in my laboratory. The research output for this project year has been disseminated in nine technical journal articles, oral presentations at workshops in China and Brazil, and in a workshop on soil salinity deliverd to avocado growers at the California Avocado Commission. Outputs related to teaching include dissemination of knowledge via courses taught in Soil Ecology and Soil Conditions and Plant Growth. PARTICIPANTS: J.P. Baquiran Ph.D. student (awarded Ph.D. December 2010) Richard Belcher Ph.D. candidate (fifth year) Lauren Hale Ph.D. candidate (third year) Lindsey Saum Ph.D. candidate (third year) Sun Ran (Ph.D. candidate, visiting student from Northwest A and F University Yangling, Shaanxi, China) Xiayu Wang (Visiting scientist, Northeast Normal University, Changchun,Jilin Province, China) Macario Bacillio (Visiting scientist, CIBNOR, Baja Mexico) Oscar Martinez (visiting Ph.D. candidate, Universidad de la Fronterra, Temucco, Chile Milko Jorquera (visiting professor, Universidad de la Fronterra, Temuco, Chile Gisele Nunes Lopes (visiting Ph.D. student, University of Sao Paulo, ESALQ campus, Piracicaba, S.P. Brazil Partner organizations: California Avocado Commission TARGET AUDIENCES: This target audience for this project included both the academic research community (students and soil scientists) and farmers. Soil quality is dependent on biological processes and there is considerable interest in how to best manage soils to improve the soil biological functions, whether for cleanup of contaminated soils, or for improving agricultural yields. A unifying approach in this research was the application of artificial neural network models to link soil chemical, physical, and biological properties and enable predictions of the rates of specific biological processes, or effects on plant growth and yields. During the project year, advanced lectures on ANN modeling were delivered at the Universidad de la Fronterra in Temucco Chile, the University of Sao Paulo in Brazil, and to scientists at the Chinese Academy of Sciences at Beijing Agricultural University, and in Xinjiang Province, West China. Applications of ANN models were presented to avocado growers in S. California at several workshops aimed at salinity management of soils in which we are examining the effects of soil chemical, physical, and biological properties on avocado fruit yields. In 2011, an invited talk was delivered at the national meetings of the Soil Science Society of America on use of neural network models for examining the impact of environmental variables on microbial community structures in agricultural soils. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project has led to new fundamental knowledge on the relationships between soil chemical, physical, and biological properties that shape microbial community structure and function in soil media. The main impacts of this research were advancement of our understanding of how environmental factors influence soil microbiology, and the development of new methods to analyze these relationships. The project also led to the development of human resources through the training of graduate students, and visiting scientists. Fundamental knowledge generated from this research include methods for the design and analysis of DNA microarrays for use in characterizing microbial communities in different soils, basic knowledge on the ecology of plant growth promoting rhizobacteria in different soils, the influence of biochar soil amendments on microbial communities, the use of artificial neural networks for modeling the effects of soil chemical and physical variables on soil microbial communities and plant salinity tolerance. This research also advances our knowledge of how chemical contamination of soils by petroleum hydrocarbons results in selection of specific microbial communities, and the types of genes that are carried by microbial communities in oil contaminated soils.
Publications
- Martinez, O., M.A. Jorquera, D.E. Crowley, M.L. Mora. 2011. Influence of nitrogen fertilisation on pasture culturable rhizobacteria occurrence and the role of environmental factors on their potential PGPR activities. Biology and Fertility of Soils. 47: 875-885.
- Chapman, R., H.L. Hayden, T. Webster, D.E. Crowley, P.M. Mele. 2010. Development of a microarray approach for measurement of microbial functional genes associated with soil health in Australian agroecosystems. Pedobiologia. 55:41-49.
- Ma, J., A.M. Ibekwe, X. Yi, H. Wang, A. Ymazaki, D.E. Crowley, and C-H Yang. 2011. Persistence of Escherichia coli O157:H7 and it mutants in soils. PLoS One 6:1-9.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: This research is examining environmental factors that influence the species composition and functions of microbial communities in soil. Outputs this year reflect dissemination of knowledge generated by laboratory research activity and cooperative international research. Research conducted at UCR has focused primarily on the ecology of plant growth promoting bacteria (PGPR) in the rhizosphere, soil factors influencing the populations and activity of phosphorus solubilizing bacteria, methods for measuring biologically assimilable carbon in soils, a metagenomic analysis of oil contaminated soils, and the effects of biochar on microbial communities and population densities of PGPR. International cooperative research has included studies on the microbial community structures in deep sediments of desert soils, development of DNA microarrays for characterizing microbial communities in soils, and carbon modeling in Chinese rice paddy soils. Related outputs from these research activities has included the training of four Ph.D. students, two visiting scientists from China, two visiting scientists from Chile, a visiting scientist from Mexico, and a Ph.D. student from Brazil all of whom worked for periods ranging from 2 months up to one year in my laboratory. The research output for this project year has been disseminated in nine technical journal articles, and in a series of oral presentations at workshops in China and Brazil, and in a workshop on soil salinity deliverd to avocado growers at the California Avocado Commission. Outputs related to teaching include dissemination of knowledge via courses taught in Soil Ecology and Soil Conditions and Plant Growth. PARTICIPANTS: J.P. Baquiran Ph.D. student (awarded Ph.D. December 2010) Richard Belcher Ph.D. candidate (fourth year) Lauren Hale Ph.D. candidate (second year) Lindsey Saum Ph.D. candidate (second year) Sun Ran (Ph.D. candidate, visiting student from Northwest A and F University Yangling, Shaanxi, China) Xiayu Wang (Visiting scientist, Northeast Normal University, Changchun,Jilin Province, China) Macario Bacillio (Visiting scientist, CIBNOR, Baja Mexico) Oscar Martinez (visiting Ph.D. candidate, Universidad de la Fronterra, Temucco, Chile Milko Jorquera (visiting professor, Universidad de la Fronterra, Temuco, Chile Gisele Nunes Lopes (visiting Ph.D. student, University of Sao Paulo, ESALQ campus, Piracicaba, S.P. Brazil Partner organizations: California Avocado Commission TARGET AUDIENCES: This research is ultimately aimed at both the academic research community (students and soil scientists)and farmers. Soil quality is dependent on biological processes and there is considerable interest in how to best manage soils to improve the soil biological functions, whether for cleanup of contaminated soils, or for improving agricultural yields. A unifying approach in this research is the application of artificial neural network models to link soil chemical, physical, and biological properties and enable predictions of the rates of specific biological processes, or effects on plant growth and yields. During this project year, advanced lectures on ANN modeling were delivered at the Universidad de la Fronterra in Temucco Chile, The University of Sao Paulo in Brazil, and to scientists at the Chinese Academy of Sciences at Beijing Agricultural University, and in Xinjiang Province, West China. Likewise, applications of ANN models were presented to avocado growers in S. California at a workshop aimed at salinity management of soils in which we are examining the effects of soil chemical, physical, and biological properties on avocado fruit yields. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project has supported the generation of fundamental and applied knowledge on the relationships between soil chemical, physical, and biological properties that shape microbial community structure and function in soil media. This project has contributed directly to advancement of the discipline of soil microbiology, and also to the development of human resources through the training of graduate students, and visiting scientists. Fundamental knowledge generated from this research include methods for the design and analysis of DNA microarrays for use in characterizing microbial communities in different soils, basic knowledge on the ecology of plant growth promoting rhizobacteria in different soils, the influence of biochar soil amendments on microbial communities, the use of artificial neural networks for modeling the effects of soil chemical and physical variables on soil microbial communities and plant salinity tolerance. This research also advances our knowledge of how chemical contamination of soils by petroleum hydrocarbons results in selection of specific microbial communities, and the types of genes that are carried by microbial communities in oil contaminated soils.
Publications
- Jorquera, M.A., D.E. Crowley, P. Marschner, R. Greiner, M.T. Fernandez, D. Romero, D. Menezes-Blackburn, M.L. Mora. 2010. Identification of Beta-propeller phytase-encoding genes in culturable Paenibacillus and Bacillus spp. from the rhizosphere of pasture plants on volcanic soils. FEMS Microbiol. Ecol. In press.
- Dmitriev, V.., D.E. Crowley, V.V. Rogachevsky, C.M. Negri, T.G. Rusakova, S.A. Kolesnikova. L.I. Akhmetov. 2010. Microorganisms form exocellular structures, trophosomes, to facilitate biodegradation of oil in aqueous media. FEMS Lett. In press.
- Navia, R. and D.E. Crowley. 2010. Closing the loop on organic waste management: biochar for agricultural land application and climate change mitigation. Waste Management Research 28: 479-480.
- Zhang, A, L. Cui, G. Pan, L. Li, Q. Hussain, X. Zhang, J. Zheng, and D. Crowley. 2010. Effect of biochar amendment on yield and methane and nitrous oxide emissions from a rice paddy from Tai Lake plain, China. Agric. Ecosys. Environ. 139:469-475.
- Chapman, R., H.L. Hayden, T. Webster, D.E. Crowley, P.M. Mele. 2010. Development of a microarray approach for measurement of microbial functional genes associated with soil health in Australian agroecosystems. In review.
- Kim, J-S, D.E. Crowley, A. Buerkert. 2010. Bacterial communities from deep sediments near an oasis in northern Oman. Catena. 82:102-111.
- Park, J-W and D.E. Crowley. 2010. Nested PCR bias: A case study of Pseudomonas spp. in soil microcosms. J. Environ. Monitoring. 12:985-988.
- Martinez, O., M. Jorquera, D.E. Crowley, G. Gajardo, and M.L. Mora. 2010. Mechanisms and practical considerations involved in plant growth promotion by rhizobacteria. J. Soil Sci. Plant Nutr. 10:293-319.
- Marschner, P., D.E. Crowley. Z. Rengel. 2010. Rhizosphere interactions between microorganisms and plants govern iron and phosphorus acquisition along the root axis: model and research methods. Soil Biol. Biochem. In press.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: This project year my research group has continued to explore relationships between microbial community structure and environmental variables that determine the relative abundances of different bacterial species. In one avenue that has been especially productive, our experimental work has been facilitated by a grant from the California Avocado Commission in which we are collecting data on all soil physical and chemical variables at 14 orchard locations across S. California. This enables us to study the community structure under one plant species, which is critical for separating out plant species effects from soil effects on microbial communities. In addition to surveys of community composition and bacterial fungal ratios, this research is focusing on the distribution of a key functional gene encoding the enzyme, ACC deaminase, which is involved in the lowering of ethylene concentrations in the rhizosphere of plants. In this manner, we can not only study the influence of soil chemical factors on the species composition, but also how such changes in community structure may influence the activity of plant growth promoting bacteria. Along with soil data, we are monitoring temporal variation over the year, and in different locations along the root axes. A second line of research continues a long-term project in which I have been working with colleagues in Brazil to study factors affecting the species composition and structures of microbial communities that colonize soils and plant surfaces in the Atlantic forest of Brazil. Our most recent work focuses in particular on the relationship between plant community composition and microbial community composition, with plants being the primary selective determinant. These ongoing studies are exploring the hypothesis that there is deep phylogenetic selection that has driven the coevolution of particular genera, families, and even bacterial divisions across different genera and families of plants. A large study was completed and the data have been analyzed using discriminant analyses, and with a neural net model that enables detection of patterns and correlations between variables that have nonlinear relationships. A new project underway in 2010, supported by the state of Sao Paulo (FAPESP), will enable us to further model the soil and chemical factors that serve as determinants of bacterial community structure and selected soil biological functions. Lastly, collaboration has been initiated with visiting scientists from Chile and Mexico who are working in my lab on projects that fall under the guiding themes of our umbrella Hatch project. These studies include an analysis of the community structures under one of the world's oldest plants (11,500 year old Larrea tridenta) in the Mohave Desert, and studies on the interactions of soil inoculants, plant growth promoting rhizobacteria, and indigenous microbial communities in different soils. PARTICIPANTS: David Crowley (PI) Ian Balcom (Graduate Student) Kun Liu (Graduate Student) Rosario Pineda (Postdoctoral Associate) Stephen Qi (staff research associate) Krisna Songco (undergraduate research assistant) Opportunities for training and professional development included participation in the Copernicus Program at UCR, which provides training to community college students who are considering a career in teaching or research in Science and Mathematics. Our lab hosted two groups of students who took part in a three day workshop on microbial diversity in the summer of 2009. A second training opportunity was provided during my service as a Fulbright Specialist during November 2009, when I went to the Universidad de la Fronterra in Temuco Chile. There I gave a series of lectures on surveys of microbial diversity, and environmental factors that affect the development and function of microbial communities, along with an overview of neural network statistical modeling methods that I am using to analyze the relationship between community structure and environmental variables. International colleagues who have contributed to this work or who are working as visiting scientists in my lab include Marcio Lambais (Professor Univ. Sao Paulo, Brazil), Karen Maciel (undergraduate student UCR), Milko Jorquera (visiting scientist), Macario Bacillio (visiting scientist). TARGET AUDIENCES: Target audiences that have benefited from this research include members of the California Avocado Society to whom I delivered lectures at 3 different locations in California, and UCR graduate and undergraduate students who took my class in soil conditions and plant growth, where I presented and discussed the latest details of this research project. The audience with the California Avocado society grower meetings ranged from 100 to 200 people at each location. Another target audience included students and faculty at the Universidad de la Fronterra in Temuco Chile, with whom I interacted for one month in November 2009. Other international venues where this work was presented included two presentations at Beijing Agricultural University and a seminar at Nanjing Agricultural University. The titles and dates for these presentations include: (1) Management of avocado in relation to soil chemical and physical properties. Ventura, San Luis Obispo, and Temecula. (3 presentations: June 9, 10, 11, 2009) (2). Applications of EcoInformatics and Neural Net Models for Analysis of Environmental Data. Beijing Agricultural University. June 2009. Lastly, my expertise in this subject area led to an invitation to conduct a one week project review (March 16-23, 2009) for the Department of Primary Industries in Victoria Australia, to evaluate a new multimillion dollar program entitled: Assessing the influence of climate and soil class on the condition and functionality of Australia's soil resource using microarray technologies. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In research publications generated from this project, we have examined the influence of soil contamination with polycyclic aromatic hydrocarbons (PAH) on bacterial communities in the rhizosphere of different plant species. In addition to providing an analysis on the impact of soil contamination on community structures, this research revealed that PAH degradation is rarely carried out by single organisms, but instead involves consortia of bacteria that vary in species composition depending on the plant species and location on the root axes. Another publication was a review paper that I prepared to accompany my presentation (plenary speaker) at the 5th Mtg on Interactions of soil minerals, organic matter, and microorganisms (ISMOM) in Pucon Chile. That paper examines the utility of different methods offering hierarchical levels of resolution on community structures. A third publication summarized one of my students dissertation research on the impacts of nitrogen on microbial community structure across different soils comprising a nitrogen deposition gradient from urban sources extending into the coastal sage scrubland of S. California. In my international work, our data analysis has shown that our hypothesis on the deep phylogenetic coevolution of plant and microbial species, genera, and families is strongly supported for bacterial communities associated with the phyllosphere, the dermasphere (bark surfaces) and the rhizosphere of trees in the Atlantic Forest of Brazil. This is a highly fundamental result that suggest evolution of microorganisms at the subdivision level within the Proteobacteria has tracked and perhaps even been driven by their the coevolution of their plant hosts. This research will provide an invaluable tool for guiding the surveys and inventories on microbial species that inhabit terrestrial ecosystems. Finally, our new work started this year which examines the distribution of plant growth promoting rhizobacteria in relation to soil chemical, physical, and biological variables may allow us to better manage PGPR bacteria populations in soils, either by use of soil amendments or inoculation. If we are successful, the long term impact from this latter project will be the development of management tools to improve root growth under saline and drought stress conditions for irrigated crops in soils having different physical and chemical properties. The enhance root growth in turn should lead to improved water use efficiency, thus addressing the urgent problem for farmers in the desert southwest.caused by long term drought, water shortages, and increased use of saline ground water.
Publications
- Balcom, I. and D.E. Crowley. 2009. Pyrene effects on rhizoplane bacterial communities. Int. J. Phytoremediation 7, 609-622.
- Crowley, D.E. 2008. Impact of metals and metalloids on microbial diversity and ecosystem function. Special Issue. J. Soil. Sci. Plant Nutrition 8, 6-11.
- Liu, K. and D.E. Crowley. 2009. Nitrogen deposition effects on carbon storage and fungal:bacterial ratios in semiarid, coastal sage shrubland of southern California. J. Env. Qual. 38, 2267-2272.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The primary output of this research project is the generation of fundamental knowledge on the relationships between soil chemical, physical, and biological variables, and the development of appropriate criteria for use of soil biology parameters for use in monitoring soil quality. To date, outputs from this research include two journal articles, training of two Ph.D. students (J.P. Baquiran and R. Belcher, a postdoctoral research associate (R. Pineda), and a series of seminar and lecture events where results of this project have been presented to the scientific community. One significant output has been a training course on soil quality, which was delivered as two separate 1 week sessions for approximately 40 students in Brazil. This workshop was sponsored by a Fulbright Senior Specialist Program award to Crowley. Other notable events include: Invited Talk. Bioindicators of Soil Quality. Institute of Soil Science. ZAAS, Hangzhou, China. Nov. 27, 2007; Invited Talk. Applications of Microbial Community Analysis for Evaluation of Soil Quality and Bioremediation. Nanjing Agricultural University, Nanjing China. Dec 1, 2007; Instructor for Third Int. Course on Biological Aspects of Soil, Plants, and the Environment (Two Lectures) Universidad de la Fronterra, Temuco, Chile 19-20 Nov, 2008; Plenary Talk. Impacts of Metals and Metalloids on Microbial Diversity and Ecosystem Function. 5th Int. Symposium of Interations of Soil Mineral with Organic Components and Microorganisms. Pucon, Chile Nov. 26, 2008. PARTICIPANTS: Jean Paul Baquiran, Ph.D. candidate; Richard Belcher, Ph.D. candidate; Rosario Pineda, postdoctoral associate; Pauline Mele, Department of Primary Industries Rutherglen, Australia; Hugo Zunino, University of Chile, Santiago, Chile; Milko Jorquerra, Universidad de la Fronterra, Temuco, Chile; Marcio Lambais, University of Sao Paulo, ESALQ Brazil; Milt McGiffen, University of California TARGET AUDIENCES: This research has relevance for a broad audience including land managers, farmers, and soil scientists. Soil biology data are an integral in determining soil quality and the impacts of management practices on soil biological processes, as well as organic carbon accumulation, and for disease management. Other areas of interest are related to plant growth promoting rhizobacteria that can increase plant yields. The ability to predict factors that affect different functional groups and biological processes is a major gap in our present knowledge. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Soil biological properties are extremely dynamic, and reflect short term changes in management practices that ultimately have long term implications for protection of soil quality. To develop bioindicators of soil quality, it is necessary to understand the factors that shape microbial communities in different soils. The objective of this project is to examine the relationship between soil chemical, physical, and biological properties and to evaluate the use of neural network modeling procedures for study of these relationships and their use for soil quality monitoring. In the experimental component of this project carried out in 2008, field samples of benchmark soils were collected and brought to the laboratory for growth chamber experiments to examine the effects of different plant species and environmental variables on microbial community structures. A total of 19 soils from benchmark locations across S. California were contrasted. Subsamples from each location were analyzed to determine texture, pH, salinity and other chemical and physical properties. The resulting data were analyzed using neural network modeling procedures using the program Synapse. Statistical analyses of the resulting data yielded data that enabled characterization and comparison of microbial community structures in each soil and in relation to specific chemical and physical variables. Initial analyses compared the effects of 3 plant species on microbial community structures and examined possible interactions with soil physical and chemical variables. Results showed that fescue, corn, and bean produced different microbial community structures. Soils planted with fescue had communities that were also highly sensitive to pH, texture, and salinity as determinants of community structure. By comparison, soils planted with corn showed nearly identical biological properties irrespective of differences in the soil chemistry and physical properties. Results of this research to date strongly support the hypotheses that soil chemical and physical variables are reliable determinants of soil microbial community structure. As part of this research, Crowley has become involved in a project with researchers in Australia to analyze their national soil data sets. Other impacts have been the establishment of working relationships with scientists in Chile, with the aim of examining soil quality parameters in virgin volcanic soils. Lastly, Crowley is now interacting with soil and plant scientists in the United States to develop a USDA proposal that proposes to examine soil biological parameters during crop rotations in vegetable production systems in the United States.
Publications
- Kim, J-S, R. Dungan, and D.E. Crowley. 2008. Microarray analysis of bacterial diversity and distributio in aggregates from a desert agricultural soil. Biol. Fert. Soils. 44:1003-1011.
- Crowley, D.E. 2008. Managing soils for avocado production and root health. In: California Avocado Society Yearbook 2007-2008. pp. 107-130. California Avocado Society
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: This research is investigating the relationship between physical, chemical, and biological properties of soil using California benchmark soils. Preliminary field collections and experiments were conducted in the first project year, reported here, and were used to leverage extramural funding to support the research in a project that was begun in January 2008. Experiments examined fatty acid methyl ester (FAME) and phopholipid fatty acid (PLFA) signatures for microbial communities from 14 benchmark soils in S. California. Research protocols were developed to compare soils under standardized conditions, which entail establishment of microcosms in plant growth chambers in which the soils are planted with reference plant species and are maintained under standard moisture and temperature conditions. Data analysis includes use of principal components analysis along with artificial neural network statistical analysis to extract relationships between chemical, biological, and
physical variables. In addition to completion of the first survey, experiment sites have been selected for quarterly monitoring of the dynamics of microbial community structures in soils with different chemical and physical properties. A subset of locations has also been identified to determine whether there is greater similarity in community structures within competing soil series in the same benchmark groups than between benchmark groups. Coooperative research related to this project is also in progress with soil scientists in Australia in which we are evaluating determinants of soil quality using biological markers. This research is directly relevant to the objectives of this proposal and is providing insight into the applicability of biological markers for assessing soil quality.
PARTICIPANTS: Dr. Pauline Mele, Department of Primary Industries, Rutherglen Research Institute, Victoria, Australia
Impacts
This research will establish an approach for inclusion of soil biological data into national soil databases that have been generated for providing landholders and policy makers with tools for soil quality assessment. The research will further identify soil types in which microbial communities and their biological functions are sensitive to specific management practices and changes in environmental variables. The long term goal of this research is to provide internet accessible decision support tools that are linked to the US soil database that can be used for better managing and protecting the soil resource.
Publications
- Mele, P. and D.E. Crowley. 2008. Application of self organizing maps for assessing soil biological quality. Ag. Ecosystems Environ. in press.
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Progress 01/01/06 to 12/31/06
Outputs
This research examining the linkages between soil chemical, physical, and biological properties and their relevance to soil quality. Microbial communities are known to vary in their phylogenetic compositions in different soil types, but to date there is very litte understanding of the chemical and physical factors that function as determinants of microbial community species composition and biological functions in soils. In the first six months of this project, we have begun surveys of local benchmark soils to examine their community structures using phospholipid fatty acid signatures. This method provides a microbial community biochemical fingerprint that describes broad differences in species composition. A grant proposal was submitted to the USDA Soil Biology program to obtain funding for the full project described in the Hatch proposal, and elaborates on specific hypotheses that were developed this year. Collaborative studies directly relevant to this research were
also continued with the Department of Primary Industries in Victoria Australia and in Brazil, both of which involve mapping and correlation of soil chemical, physical, and biological data.
Impacts
This research will establish a rational approach for inclusion of soil biological data into the national soil databases that have already been generated for providing landholders, policy makers, and scientists with a tool for soil use and quality assessment. Our research will further identify soil types in which the microbial communities are more or less sensitive to particular management practices and changes in environmental variables. The long term goal of this research will be to provide internet accessible decision support tools that are linked to the U.S. soil database that can be used for better managing and protecting the soil biological resource.
Publications
- Siquenza, C., D.E. Crowley, and E. Allen. 2006. Soil microorganisms of a native shrub and exotic grasses along a nitrogen deposition gradient in southern California. Appl. Soil Ecol. 32:13-26.
- Kim, J.S., G. Sparovek, R. deLongo, W. deMelo, and D.E. Crowley. 2006. Bacterial diversity of terra preta and forest soil from the western Amazon. Soil Biol. Biochem. 39:684-690.
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