Progress 10/01/10 to 09/30/15
Outputs
Target Audience:Target audiences include graduate and undergraduate students, for whom research opportunities have been provided. An internship program at Russell Ranch targets undergraduates in particular and gives them an opportunity to become involved in different aspects of sustainable agriculture and ecosystem service analysis. Other target audiences include other faculty members and staff from different discipline, who bring in different perspectives to my research program and are broadened by learning from my perspective. In addition, farmers and producers are engaged with, both through field days, but also by working together on collaborative research projects. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Project provided opportunity for two visiting graduate students from Pakistan, two visiting undergraduate student from Brazil, and visiting scientists from Korea, Brazil and Spain, to be involved in scientific research on sustainable agriculture. In addition eight UC Davis undergraduate student interns and five graduate students were trained on projects at Russell Ranch Sustainable Agriculture Facility. How have the results been disseminated to communities of interest?Some of the results of this project were presented at the annual field day of the Russell Ranch Sustainable Agricultural Facility (170 participants) which was focused on nitrogen management. In addition results were disseminated to visiting scientists, to UCD students (total of 190 in three academic courses) and to local farmers during visits and research meetings Russell Ranch. The Russell Ranch Sustainable Agricultural Facility website hosts information about our research findings and some of their implications. What do you plan to do during the next reporting period to accomplish the goals?Research will be conducted at the Russell Ranch Sustainable Agriculture Facility in the long term plots of the Century Experiment to measure impacts of different irrigation systems (drip with single or double lines versus furrow) on soil health, microbial communities, soil structure, soil fertility and yields in processing tomatoes. We will continue to analyze soil samples, measuring total C, N, S and other elements, which were collected at 8 depths to 3 meters deep in 72 plots of the RR Century Experiment representing different crops and management systems in place for 20 years. Also we will evaluate the negative (costs) and positive (benefits) impacts of agricultural soil amendments (e.g. dairy biodigestate, compost, manure, biochar) on microbial communities, key agricultural services, and resilience of agroecosystems.
Impacts
What was accomplished under these goals?
Our study explored the long-term effects of walnut shell biochar on crop productivity and soil quality in conjunction with both organic and mineral fertilizers. The one-time addition of biochar to a high fertility, clay loam, agricultural soil showed positive yield and fertility effects only in the second of four seasons. These delayed but short-lived effects can be attributed to significant increases in exchangeable K, Ca, and PO4-P one year after biochar application. Based on the elemental composition of the biochar itself, greater concentrations of these nutrients is most likely due to direct additions from this high-ash biochar rather than from indirect mechanisms, such as increased nutrient retention or solubility of non-biochar sourced ions. However, the mechanisms should be explored further. The fertilizer type used did not alter the biochar's effects for any of the parameters measured, though the mineral vs. compost fertilizer treatments had their own effect independent from the biochar factor. Additionally, plots with biochar showed no significant changes in inorganic N pools, indicating that this biochar will not prevent nitrification or help to retain N in this soil. The WS biochar's effects clearly faded in subsequent years as the excess nutrients leached and were taken up by crops. Therefore, in our temperate system, we conclude that this biochar has no positive long-term impacts, though the biochar particles are still clearly visible in the soil. There do not appear to be any negative effects of the biochar in the soil, though it will be important to continue this evaluation beyond four seasons. The ability of soil to retain water under drought and other extreme hydrological events is critical to the survival and viability of both crops and microbes in soil. We investigated the impact of biochar on water retention properties of two typical California agricultural soils using pressure plate apparatus and also a neutron imaging method to study spatial and temporal distribution of biochar amended sample. The impact of biochar type (Walnut Shell biochar, WS, and Enhanced biochar, EB), application rate (0, 0.5, 1%), and particle diameter (0-0.25, 0.25-0.5, 0.5-1, 1-2 mm) were also investigated. Our results indicate that high surface area biochar (WS biochar) can increase field capacity of sandy soil, while low surface area biochar (EB biochar) had no significant impact. Neither biochar had an impact on the field capacity of the high clay content soil. The data, for the sandy soil, also revealed a positive correlation with increasing biochar particle diameter and field capacity. No impact of biochar on soil wilting point was observed across treatments. Thus, biochar potential to increase plant available water in soil is limited to increasing field capacity in a coarse textured soil. Our results also indicate that biochar can hold more water than the surrounding material due to its pore structure and can spontaneously release water to the surrounding material during drying. Moreover, the biochar moisture content remained higher than the surrounding soil. Generally, the moisture distribution in the biochar amended sample was greatest for biochar interiors, followed by biochar exterior surfaces, and finally the surrounding sand. The impact of biochar's influence on surrounding soil moisture content was dependent on its own moisture content and reduced with time. These data demonstrates that biochar has limited potential for use to increase water holding capacity of soils under conditions of drought, with limited benefits only observed in a course textured soil. It is important to note that this current study does not consider biochar impacts on soil aggregation and organic matter storage, which are also important for soil-water relations. Inefficient phosphorus (P) use in intensive agriculture is common in both organic and conventional systems, resulting in P over-application and soil P build-up. Increasing crop P removal and P recycling within farming systems (e.g., via cover crops) and reducing P inputs lower P surpluses, resulting in more balanced P budgets. Lowering P inputs to reduce soil P surpluses is easier with mineral fertilizers for which N and P inputs can be decoupled, whereas reducing inputs of organic amendments with a constrained stoichiometry (manures, composts) often results in N under-fertilization and lower yields. We computed farm-gate P budgets for several vegetable and grain cropping systems in two long-term California agricultural experiments that vary in terms of inputs (mineral fertilizers, organic fertilizers, manure, yard compost), cash crops (corn, wheat, tomato, broccoli, lettuce), cover crops (type, frequency) and cropping intensity (biennially, annually or biannually). In organic systems, using manure or compost resulted in high P surpluses, whereas using pelleted or liquid organic fertilizers with higher N:P ratios resulted in smaller P surpluses. Systems receiving mineral fertilizers were often very close to P balance when fertilized regularly. Grain rotations generally had small P deficits whereas vegetable rotations had P surpluses due to lower crop P removal in vegetables. Phosphorus uptake by cover crops was important (12-25 kg P ha-1), but their benefits to soil fertility will depend on the magnitude and timing of P release during residue decomposition. Overall, using organic nutrient sources with low N:P ratios resulted in significant P surpluses, confirming the need to use complementary N sources such as N-fixation or N-rich fertilizers to balance P budgets.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Maltais-Landry, G., K. Scow, E. Brennan, and P. Vitousek. "Long-term effects of compost and cover crops on soil phosphorus in two California agroecosystems." Soil Science Society of America Journal 79, no. 2 (2015): 688-697
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Zhang, Nan Nan, Yan Mei Sun, En Tao Wang, Jin Shui Yang, Hong Li Yuan, and K. M. Scow. "Effects of intercropping and Rhizobial inoculation on the ammonia-oxidizing microorganisms in rhizospheres of maize and faba bean plants." Applied Soil Ecology 85 (2015): 76-85.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Pereira, Engil Isadora Pujol, Emma C. Suddick, Fungai ND Mukome, Sanjai J. Parikh, Kate Scow, and Johan Six. "Biochar alters nitrogen transformations but has minimal effects on nitrous oxide emissions in an organically managed lettuce mesocosm." Biology and Fertility of Soils (2015): 1-10.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Cohen, Craig R., Rachel L. Steinfeld, Elly Weke, Elizabeth A. Bukusi, Abigail M. Hatcher, Stephen Shiboski, Richard Rheingans et al. "Shamba Maisha: Pilot agricultural intervention for food security and HIV health outcomes in Kenya: design, methods, baseline results and process evaluation of a cluster-randomized controlled trial." SpringerPlus 4, no. 1 (2015): 122.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Geisseler, D., and K. M. Scow. "Does long-term use of mineral fertilizers affect the soil microbial biomass?." Better Crops with Plant Food 98, no. 4 (2014): 13-15.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Target audiences include graduate and undergraduate students, for whom research opportunities have been provided. An internship program at Russell Ranch targets undergraduates in particular and gives them an opportunity to become involved in different aspects of sustainable agriculture and ecosystem service analysis. Other target audiences include other faculty members and staff from different discipline, who bring in different perspectives to my research program and are broadened by learning from my perspective. In addition, farmers and producers are engaged with, both through field days, but also by working together on collaborative research projects. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Project provided opportunity for a visiting graduate student from China, visiting undergraduate student from Brazil, and visiting scientists from Turkey and Spain, to be involved in scientific research on sustainable agriculture. In addition five UC Davis undergraduate student interns and five graduate students were trained on projects at Russell Ranch Sustainable Agriculture Facility. How have the results been disseminated to communities of interest? Some of the results of this project were presented at the annual field day of the Russell Ranch Sustainable Agricultural Facility (170 participants). In addition results were disseminated to visiting scientists, to UCD students (total of 190 in three academic courses) and to local farmers during visits and research meetings Russell Ranch. The Russell Ranch Sustainable Agricultural Facility website hosts information about our research findings and some of their implications. What do you plan to do during the next reporting period to accomplish the goals? Research will be conducted at the Russell Ranch Sustainable Agriculture Facility in the long term plots of the Century Experiment to measure biochar effects on water relations, soil fertility and yields in processing tomatoes to provide a second year of field data. Investigations of the impact of biochar on specific soil microbial communities involved in nitrification and denitrification, as well as biomass and community composition, will be measured in different size fractions of soil, as well as along the depth profile, in organic and conventional farming systems (tomato-corn rotation). We will analyze soil samples collected at 8 depths to 3 meters deep in some of the 72 plots of the Century Experiment representing different crops and management systems in place for 20 years. Comparisons of archaea and bacterial communities, including those responsible for nitrogen cycling, will be made in wheat-fallow, wheat-tomato, and tomato-corn rotations.
Impacts
What was accomplished under these goals?
Increasing nutrient inputs into terrestrial ecosystems affect not only plant communities but also associated soil microbial communities. Studies carried out in predominantly unmanaged ecosystems have found that increasing nitrogen (N) inputs generally decrease soil microbial biomass; less is known about long-term impacts in managed systems such as agroecosystems. We analyzed the responses of soil microorganisms to mineral fertilizer using data from long-term fertilization trials in cropping systems. A meta analysis based on 107 datasets from 64 long-term trials from around the world revealed that mineral fertilizer application led to a 15.1% increase in the microbial biomass above levels in unfertilized control treatments. Mineral fertilization also increased soil organic carbon (C) content and our results suggest that increases in organic carbon is a major factor contributing to the overall increase in microbial biomass C with mineral fertilization. The magnitude of the effect of fertilization on microbial biomass C was pH dependent; while fertilization tended to it in soils with a pH below 5 in the fertilized treatment, it had a significantly positive effect at higher soil pH values. Duration of the trial also affected the response of microbial biomass C to fertilization, with increases most pronounced in studies with a duration of at least 20 years. The input of N per se does not seem to negatively affect microbial biomass C in cropping systems. The application of urea and ammonia fertilizers, however, can temporarily increase pH, osmotic potential and ammonia concentrations to levels inhibitory to microbial communities. Even though impacts of fertilizers are spatially limited, they may strongly affect soil microbial biomass and community composition in the short term. Long-term repeated mineral N applications may alter microbial community composition even when pH changes are small. How specific microbial groups respond to repeated applications of mineral fertilizers, however, varies considerably and seems to depend on environmental and crop management related factors. Soil water-stable aggregate structure is one of the critical properties impacting agricultural soil productivity and soil organic matter dynamics. Biochar soil amendments have the potential to support a low cost soil carbon sequestration strategy. We investigated the long term impact of biochar amendment on soil microbial community and soil water-stable aggregate formation in two California agricultural soils. Our results indicated that incompletely carbonized organic residue in low-temperature biochar can be a carbon source for microbes and increase soil microbial biomass to varying degrees, which in turn can benefit soil water-stable aggregate formation. Soil water-stable aggregate analysis indicated that the impact of biochar on soil water-stable aggregates depended more on soil texture than biochar surface properties. Carbon stable isotope analysis indicated that biochar carbon can contribute to the carbon in water-stable aggregates despite not impacting the mean weight diameter of soil aggregates. Most biochar-carbon was found in small macroaggregates and barely detected in large macroaggregates. As part of a long-term management strategy, it is important to consider various impacts of biochar amendments, and consider their trade-offs, under different environmental conditions. Extreme hydrological events exacerbated by climate change, such as prolonged drought or frequent wet-dry cycles, could interfere with interactions of biochar amendments with soil properties including soil organic matter (SOM). We investigated the interrelationships among soil moisture history, biochar and biosolid amendment on water extractable organic matter (WEOM) in an agricultural soil. A soil incubation experiment was carried out for 52 weeks (23 ± 1 °C) with three soil moisture treatments: simulated wet, dry, and wet-dry cycles, three biochar amendment treatments of 0, 0.5, 1% biochar (w:w) and two biosolid amendment treatments of 0, 0.5% biosolid (w:w) under each of the soil moisture treatments. Biochar and biosolid amendments increased the amount of WEOM, as did the dry and wet-dry cycle treatments. Specific Ultraviolet Absorption (SUVA) and carbon stable isotope analysis indicated that, on a per unit WHAT? basis, biochar releases more WEOM than does soil (up to 5.6 times), and biochar amendment can increase the release of WEOM from agricultural soil (from 52.9% to 87.9%). In the extreme soil moisture treatments, biochar can enhance WEOM release increase due to water treatments, which may benefit soil microbial communities, but also increase the risk of SOM loss. This impact of biochar on SOM mobility needs to be considered in using biochar as a soil amendment and potential trade-offs associated with biochar use need to be evaluated.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Maltais-Landry, G., Scow, K., & Brennan, E. (2014). Soil phosphorus mobilization in the rhizosphere of cover crops has little effect on phosphorus cycling in California agricultural soils. Soil Biology and Biochemistry, 78, 255-262.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Geisseler, D., & Scow, K. M. (2014). Long-term effects of mineral fertilizers on soil microorganismsA review. Soil Biology and Biochemistry, 75, 54-63.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Hicks, K. A., Schmidt, R., Nickelsen, M. G., Boyle, S. L., Baker, J. M., Tornatore, P. M., Hristova, K & Scow, K. M. (2014). Successful treatment of an MTBE-impacted aquifer using a bioreactor self-colonized by native aquifer bacteria.Biodegradation, 25(1), 41-53.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Park, I., Zhang, N., Ogunyoku, T. A., Young, T. M., & Scow, K. M. (2013). Effects of Triclosan and Biosolids on Microbial Community Composition in an Agricultural Soil. Water Environment Research, 85(12), 2237-2242.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
North, K. P., Mackay, D. M., Annable, M. D., Sublette, K. L., Davis, G., Holland, R., & Scow, K. M. (2012). An ex situ evaluation of TBA-and MTBE-baited bio-traps. Water research, 46(12), 3879-3888.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Key, K. C., Sublette, K. L., Duncan, K., Mackay, D. M., Scow, K. M., & Ogles, D. (2013). Using DNA?Stable Isotope Probing to Identify MTBE?and TBA?Degrading Microorganisms in Contaminated Groundwater. Groundwater Monitoring & Remediation, 33(4), 57-68.
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: Target audiences include graduate and undergraduate students, for whom research opportunities have been provided. An internship program at Russell Ranch targets undergraduates in particular and gives them an opportunity to become involved in different aspects of sustainable agriculture and ecosystem service analysis. Other target audiences include other faculty members and staff from different discipline, who bring in different perspectives to my research program and are broadened by learning from my perspective. In addition, farmers and producers are engaged with, both through field days, but also by working together on collaborative research projects. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Project provided opportunity for visiting graduate student from Shanghai, China to be involved in many aspects of scientific research, from experimental design to data analysis and writing. In addition three undergraduate students were trained on internships that involved participating in different aspects of the research study. How have the results been disseminated to communities of interest? Some of the results of this project were presented at the annual field day of the Russell Ranch Sustainable Agricultural Facility (160 participants). In addition results were disseminated to visiting scientists, and also to students (in two academic courses) and to local farmers during visits or tours of Russell Ranch, and in two research meetings. The Russell Ranch Sustainable Agricultural Facility website hosts information about our research findings and some of their implications. What do you plan to do during the next reporting period to accomplish the goals? Research will be conducted at the Russell Ranch Sustainable Agriculture Facility in the long term plots to measure biochar effects on agroecosystems, particularly focusing on how to manage with fertilizers in both conventional and organic farming systems. Investigations of the impact of biochar on specific soil microbial communities involved in nutrient transformations, as well as biomass and community composition, will be measuredin different farming systems. The spatial distribution of different microbial communities in different size fractions of soil, as well as along the depth profile, will be studied in organic and conventional farming systems (tomato-corn rotation).
Impacts
What was accomplished under these goals?
Biochar is stable, carbon-rich material produced by pyrolysis of biomass materials and potentially of use in remediation. We evaluated the sorption of three phenyl-urea herbicides--linuron, diuron, monuron-- to five kinds of biochar: enhanced biochar (wood and algal digestate), hog waste (soft wood), turkey litter, walnut shell, and wood feedstock. Biochars were characterized via elemental analysis, BET-N2 surface area (SA) and FTIR. Walnut shell biochar, with the greatest surface area, most strongly sorbed all pesticides and reduced the potential for leaching to groundwater. Long term biochar agricultural plots were created at the Russell Ranch Sustainable Agriculture Facility to be able to investigate the long term effects of biochar on soil, fertility management, crop productivity, and contaminant levels. We investigated the impacts of the antibiotic, ciprofloxacin, present in biosolids, on microbially-mediated nitrogen cycling processes in soil and tested whether co-amendment with biochar can reduce potential negative effects. Nitrification is carried out by both ammonia-oxidizing bacteria (AOB) and archaea (AOA). At high concentrations (100 ppm), ciprofloxacin negatively affected particularly AOB and to some degree AOA population growth. These results add support to growing observations that archaea often show less sensitivity to pharmaceuticals and other chemicals in biosolids than do bacteria, and this may help soils be more resistant or resilient to disturbances caused by exposure to these chemicals. Biochar appeared to mitigate negative effects caused by antibiotic disturbance, perhaps through sorption of the antibiotic and a resulting decrease in bioavailability and toxicity. In a greenhouse study examining the effects of co-amending biosolids with biochar, we find that biochar had a positive growth effects on plants, possibly due to the sorption of growth-limiting contaminants that were contained in biosolids. A bioanalytical (CALUX) examination of endocrine-disrupting activity in the biosolid- and biochar-amended soils suggests that biochars might also be a source of such activity.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Pujol Pereira, Engil Isadora, Haegeun Chung, Kate Scow, and Johan Six. "Microbial Communities and Soil Structure are Affected by Reduced Precipitation, but Not by Elevated Carbon Dioxide." Soil Science Society of America Journal 77, no. 2 (2013): 482-488
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Rasa, Ehsan, Barbara A. Bekins, Douglas M. Mackay, Nicholas R. Sieyes, John T. Wilson, Kevin P. Feris, Isaac A. Wood, and Kate M. Scow. "Impacts of an ethanol?blended fuel release on groundwater and fate of produced methane: Simulation of field observations." Water Resources Research 49, no. 8 (2013): 4907-4926.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Rasa, Ehsan, Laura Foglia, Douglas M. Mackay, and Kate M. Scow. "Effect of different transport observations on inverse modeling results: case study of a long-term groundwater tracer test monitored at high resolution." Hydrogeology Journal 21, no. 7 (2013): 1539-1554.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Garc�a-Orenes, Fuensanta, Alicia Morug�n-Coronado, Raul Zornoza, and Kate Scow. "Changes in Soil Microbial Community Structure Influenced by Agricultural Management Practices in a Mediterranean Agro-Ecosystem." PloS one 8, no. 11 (2013): e80522.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Outputs completed during the reporting period were results of activities of the Russell Ranch (RR) Sustainable Agricultural Facility at UC Davis, a facility that I direct. Both my research and outreach programs have evolved in collaboration with stakeholders from different sectors in order to reflect the needs of the diverse community associated with agriculture. In the past year, I hosted at Russell Ranch more than 380 visitors and 21 groups from California, the US and throughout world to discuss sustainable agriculture and agroecology. We hosted three meetings on various topics to link university farm-based research programs with farmers and other stakeholders from the food system network. Dissemination of results occurred through the annual Russell Ranch Field Day on nitrogen and water that attracted over 150 students, faculty, farmers, extension and community members. This was the largest number of attendees of the RR Field Day and it exceeded capacity.The website for Russell Ranch (http://asi.ucdavis.edu/rr) is continually updated to report on new information that is derived from the main RR experiment and from other smaller experiments at the site. PARTICIPANTS: Radomir Schmidt, a postdoctoral fellow, and Priya Singh and Daoyuan Wang, both graduate students, were very involved in the research accomplished this past year. Emma Torbert, Specialist, and Israel Hererra, Field Superintendent, were also key collaborators. Other partners included the farmer, Scott Park, and farm advisor, Gene Miyao. TARGET AUDIENCES: Target audiences include graduate and undergraduate students, for whom research opportunities have been provided. An internship program at Russell Ranch targets undergraduates in particular and gives them an opportunity to become involved in different aspects of sustainable agriculture and ecosystem service analysis. Other target audiences include other faculty members and staff from different discipline, who bring in different perspectives to my research program and are broadened by learning from my perspective. In addition, farmers and producers are engaged with, both through field days, but also by working together on collaborative research projects. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We found that combining manure and inorganic fertilizers produced up to 26 % higher biomass and 40 % higher market value of leafy green vegetables than if they received fertilizer or manure alone. Furthermore, the input ratio of manure to fertilizer appears to be flexible and thus could be easily adjusted to price fluctuations. Our research provides a clear basis for small scale farmers to better allocate soil fertility investments and enhance incomes from market vegetable production. Our research also highlighted the importance of involving farmers in agricultural research for efficient evaluation of new technologies, building local capacity and yielding rapid impacts (Kearney et al., 2012). It is essential to consider the ecosystem services and natural capital of soils and to offer a conceptual framework for valuing soil that goes beyond performance indicators of soil health and quality, and recognizes the broad value that soil contributes to human wellbeing. Our approach encompassed links and synergies between soil science and other disciplines such as ecology, hydrology, and economics, recognizing the importance of soils alongside other natural resources in sustaining the functioning of the Earth system. We developed an argument for why an ecosystems approach is important for soil science in the context of natural capital, ecosystem services, and soil change. Soil change was defined as change on anthropogenic time scales and important to consider in current political decision-making time scales. We identified four important areas of research: (i) framework development; (ii) quantifying the soil resource, stocks, fluxes, transformations, and identifying indicators; (iii) valuing the soil resource for its ecosystem services; and (iv) developing decision-support tools (Robinson et al., 2012). We investigated the combined effect of soil moisture potential and plant residue addition on soil enzyme activities and phospholipid fatty acid (PLFA) profiles. Soil respiration was positively correlated with soil moisture potential and significantly increased with the addition of residue. In the unamended soil, enzyme activities were not very affected by soil moisture potential, nor did they change much over time. The addition of residue, however, significantly increased enzyme activity at each moisture level. Bacteria were more sensitive than fungi to differences in soil water potential. Our results suggest that under dry conditions, potential enzyme activities may be decoupled from microbial biomass and respiration in the presence of substrates (Geisseler et al., 2011).
Publications
- Kearney, S, SJ Fonte, A Salomon, J Six, KM Scow. 2012. Forty percent revenue increase by combining organic and mineral nutrient amendments in Ugandan smallholder market vegetable production Agronomy for Sustainable Development 1:9
- Robinson, DA, N Hockley, E Dominati, I Lebron, KM Scow, B Reynolds, BA Emmett, AM Keith, LW de Jonge, P Schjonning, P Moldrup, Scott B Jones, M Tuller. 2012. Natural capital, ecosystem services, and soil change: Why soil science must embrace an ecosystems approach. Vadose Zone J. 11:1
- Tomich, TP, S Brodt, H Ferris, R Galt, W Horwath, E Kebreab, J Leveau, D Liptzin, M Lubell, P Merel, R Michelmore T Rosenstock, K Scow, J Six, N Williams, and L Yang. 2011."Agroecology: A review from a global change perspective." Annual Review of Environment and Resources 36:193-222.
- Geisseler, D., W. R. Horwath, and K M. Scow. 2011 Soil moisture and plant residue addition interact in their effect on extracellular enzyme activity. Pedobiologia 54: 71-78
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: A number of outputs related to outreach were associated with activities of the Russell Ranch (RR) Sustainable Agricultural Facility at UC Davis, a facility that I direct. Both my research and outreach programs have evolved in collaboration with stakeholders from very different sectors in order to reflect the needs of the diverse community associated with agriculture. In the past year, I hosted at Russell Ranch more than 480 visitors and 29 groups from California, the US and throughout world to discuss sustainable agriculture and the role of microbial communities in numerous soil processes. Currently, I am involved in developing a network (web-based and also working group) that will link university farm-based research programs on climate change to monitoring on commercial farms, and involve multiple interested stakeholders. Dissemination of results occurred through the annual Russell Ranch Field Day on biodiversity, that included a specific emphasis on soil biodiversity, which reached maximum capacity this year, and attracted over 120 students, faculty, farmers, extension and community members. A Russell Ranch website (http://asi.ucdavis.edu/rr) that I played a major role in developing includes information about the overall field experiment and facility, as well as data from experiments conducted at the site. PARTICIPANTS: Radomir Schmidt, a postdoctoral fellow, and Priya Singh and Mike Matiasek, both graduate students, were very involved in the research accomplished this past year. Emma Torbert, Specialist, and Israel Hererra, Field Superintendent, were also key collaborators. Other partners included the farmer, Scott Park, and farm advisor, Gene Miyao. TARGET AUDIENCES: Target audiences include graduate and undergraduate students, for whom research opportunities have been provided. An internship program at Russell Ranch targets undergraduates in particular and gives them an opportunity to become involved in different aspects of sustainable agriculture and ecosystem service analysis. Other target audiences include other faculty members and staff from different discipline, who bring in different perspectives to my research program and are broadened by learning from my perspective. In addition, farmers and producers are engaged with, both through field days, but also by working together on collaborative research projects. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Changes in knowledge that resulted from research findings from my group and collaborators include discovering that nitrous oxide fluxes from agricultural soils can be linked to presence of several bacterial functional genes responsible for different metabolic steps in the denitrification pathway and the diversity of these genes varies among soils with different rates of nitrous oxide emissions (Kong et al., 2010; Pereira et al., 2011). Research on carbon cycling revealed that microsites within soil aggregates where added carbon is assimilated into microbial cells vary in organic versus conventionally managed soils (Kong et al., 2011) and there is potential, though limited, for C sequestration in California's agricultural soils using currently available management practices. Composition of soil microbial communities was governed by differences in land uses on a regional scale (Drenovsky et al., 2010) but did not vary substantially among different habitats within a single agricultural landscape (Smukler et al., 2010). Similarly we found that, despite large differences in microbial biomass, differences in microbial diversity in soils managed using organic or conventional practices, or receiving no fertilizer (at Russell Ranch), are not very substantial (Briar et al., 2011), confirming the greater importance of soil type and specific land uses, than short term management practices, in shaping the composition of communities of soil microorganisms. Our research on the role of microorganisms in the ecosystem service of contaminant degradation included development of a method for detection of functional genes for biodegradation on perchlorate, modeling the biodegradation of volatile organic chemicals, and measuring relationships between microbial community composition and mercury methylation across a landscape (Kristensen et al, 2010). We also developed molecular tools for and quantified human pathogenic bacteria that persist in soil in agricultural soils (Nozawa-Inoue et al., 2008; Son et al., 2010).
Publications
- Pereira, E., H. Chung, K. Scow, M. J. Sadowsky, C. van Kessel, J. Six. 2011. Soil nitrogen transformations under elevated atmospheric CO2 and O3 during the soybean growing season. Environmental Pollution 159: 401-407.
- Briar, S., S. J. Fonte, I. Park, J. Six, K. Scow, H. Ferris. 2011. The distribution of nematodes and soil microbial communities across soil aggregate fractions and farm management systems. Soil Biology and Biochemistry 43: 905-914
- Kong, A.Y.Y., K.M. Scow, A.L. Cordova-Kreylos, W.E. Holmes, and J. Six, 2011. Microbial community composition and carbon cycling within soil microenvironments of conventional, low-input, and organic cropping systems. Soil Biol. Biochem., 43, 20-30
- Smukler, S., S. Sanchez-Moreno, S.J. Fonte, H. Ferris, K. Klonsky, A.T. O'Geen, K.M. Scow, K.L. Steenwerth, L.E. Jackson. 2010. Biodiversity and multiple ecosystem functions in an organic farmscape Agriculture, Ecosystems & Environment:139: 80-97
- Kong, A.Y.Y., K. Hristova, K.M. Scow, and J. Six, 2010. Impacts of different N management regimes on nitrifier and denitrifier communities and N cycling in soil microenvironments. Soil Biol. Biochem., 42, 1523-1533
- Son, A., I. M. Kennedy, K. M. Scow and K. R. Hristova. 2010. Quantitative gene monitoring of microbial tetracycline resistance using magnetic luminescent nanoparticles. Journal of Environmental Monitoring 12:1362-1367
- Yang, J., E. Rasa, P. Tantayotai, K. M. Scow, H. Yuan and K. R. Hristova. 2010. Mathematical model of Chlorella minutissima UTEX2341 growth and lipid production under photoheterotrophic fermentation conditions. Bioresource Technology 102:3077-3081.
- Geisseler, D., W. R. Horwath and K. M. Scow. 2011. Soil moisture and plant residue addition interact in their effect on extracellular enzyme activity. Pedobiologia 54:71-78.
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