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Welcome to the Crop and Soil Sciences Seminar Series. Following is a list of the seminars scheduled for the Fall of 2005 and Spring 2006. Unless otherwise noted, all seminars are on Thursday, from 12:20 PM to 1:10 PM in 135 Emerson Hall.
Crop and Soil Sciences
SPRING 2006
5/11/06 - Growing Trees in Concrete: CU-Structural Soil (Nina Bassuk, Professor, Urban Horticulture Institute, Department of Horticulture, Cornell University) . Abstract: The major impediment to establishing trees in paved urban areas is the lack of an adequate volume of soil for tree root growth. Soils under pavements are highly compacted to meet load-bearing requirements and engineering standards. This often prevents roots growth and reduces drainage to critical levels. Subsequently, urban trees with most of their roots under pavement grow poorly and die prematurely. It is estimated that an urban tree in this type of setting lives for an average of only 7-10 years, where we could expect 50 or more years with better soil conditions. Those trees that do survive within such pavement designs often interfere with pavement integrity. Older established trees might cause pavement failure when roots grow directly below the pavement and expand with age. . As a result, the potential for legal liability compounds expenses associated with pavement structural repairs. Moreover, pavement repairs that significantly damage tree roots often result in tree decline and death. 'CU-Structural soil' is a medium that can meet or exceed pavement design and installation requirements while remaining root penetrable and supportive of tree growth. Cornell's Urban Horticulture Institute has been testing a series of materials over the past 14 years. The materials tested are gap-graded gravels that are made up of crushed stone, clay loam, and a hydrogel stabilizing agent. The materials can be compacted to meet all relevant pavement design requirements yet allow for sustainable root growth. The new system essentially forms a rigid, load-bearing stone lattice and partially fills the lattice voids with soil. Structural soil provides a continuous base course under pavements while providing a material for tree root growth.
5/4/06 - Microbial Community Analysis using Two dimensional Gel Electrophoresis of Bacterial Ribosomal Internal Transcribed Spacer Regions – Methodology and Application (Chris Jones, MSc Candidate, Crop and Soil Sciences, Cornell University) . Abstract: Molecular microbial community analysis techniques that use polymerase chain reaction (PCR) amplification of phylogenetic marker genes are powerful methods for use in microbial ecology studies, but are prone to several different biases. In particular, overlap of operational taxonomic units (OTUs), caused by the co-migration of amplicons with identical electrophoretic properties, often results in a loss of resolving power as more common members of a community mask those that are less abundant. One possible way to resolve this problem would be to separate DNA fragments amplified from community DNA extracts in two dimensions; size and G+C content. To test the feasibility of this, bacterial ribosomal internal transcribed spacer regions (ITS) from a sequence database were analyzed in-silico, then ITS fragments amplified from both a defined community of individual isolates as well as soil community DNA were separated using two dimensional polyacrylamide gel electrophoresis (2D-PAGE). Community analysis using 2D-PAGE was compared with three different community analysis methods, DGGE, T-RFLP, and ARISA in order to determine consistency as well as to compare OTU resolution. It was found that 2D-PAGE of ITS regions resulted in a three-fold increase in the number of detected OTUs in comparison to other methods, and gels could be compared using standard spot-matching software typically used in protein gel analysis. Fluorescently end-labeled primers used in conjunction with laser-based gel scanning technology further enhanced spot detection as well as facilitated gel analysis and multivariate statistical comparisons. The method was then used to compare soil samples taken along a naturally occurring Zinc and Cadmium concentration gradient to determine the effects of elevated heavy metal levels on bacterial community structure and diversity.
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Improving Soil Organic Matter in Smallholder Farming Systems of Western Kenya (Joseph Kimetu, PhD Student, Crop and Soil Science, Cornell University) . Abstract: Soil fertility and the production potential of highly weathered tropical soils are intricately linked to the amount and quality of soil organic matter (SOM). Maintaining sufficient amounts of SOM will largely depend on (i) the status of soil organic matter degradation; (ii) the quality of the applied organic matter; and (iii) the soil texture. Trajectories of soil organic matter build-up and time needed to reach new equilibrium levels of SOM as a function of those three factors are not currently known. Therefore, we propose to determine the effects of quality of organic matter additions on its stabilization in soil and to investigate the interaction of this stabilization with texture and the soil organic matter status along a chronosequence of soil degradation. Organic matter of vastly differing quality such as tithonia, animal manure, sawdust and charcoal was applied to soil with SOM contents ranging from 100 to 15 mg C g-1, both on a sandy and clayey soil. The gradient of SOM contents is a result of different lengths of cropping of maize stretching from recent forest conversions (two years) to conversions done in the late 19th century (over 100 years). This false-time series was established on farmers’ fields that have the same parent material, soil type and climate identified based on official and private records, Landsat imagery, and farm interviews. Three replicate farms were selected on two soil types (sandy and clayey) per conversion age and 6 tons C ha-1 added to soil with and without nitrogen (N) fertilization. In addition to total soil carbon (C) and N, OM stabilization will be assessed using physical fractionation and incubation studies combined with measurements of in-field CO2 evolution. Farmers will use the obtained research outputs to adapt the management of their cropping systems to mitigate soil C losses or even increase SOM, conserve N capital, increase use efficiency of fertilizer nutrients and sustain food production.
4/27/06 - Do US Air Quality Standards Protect Human and Environmental Health? An Environmental Researcher’s View of the Standard Setting Process for Ozone (Peter Woodbury, Research Associate, Crop and Soil Sciences, Cornell University) . Abstract: Ozone in the stratosphere protects us from ultraviolet radiation. However, ozone at the ground surface is the most important air pollutant damaging plant health in the USA and probably worldwide. Ozone is also a serious air pollutant damaging human health. During coming decades, ozone concentrations are expected to increase significantly in most temperate and sub-tropical regions of the world. In the USA, the Clean Air Act requires the US Environmental Protection Agency to set National Air Quality Standards for each criteria pollutant including ground-level ozone. The primary standard protects human health and the secondary standard protects crops and other vegetation. These standards must be revisited periodically to assure that they are protective based on the available scientific data. For the past several years, I've been involved in writing a portion of the ozone criteria document which forms the technical basis for the air quality standards. I synthesized data from thousands of articles in the scientific literature to quantify effects of ozone on vegetation. This criteria document has gone through extensive peer review, and the USEPA is now determining whether the current standards are adequately protective. I will review what kind of research did and did not contribute to this standard-setting process, how uncertainties are dealt with, how risks are assessed, and what steps the USEPA takes to make a recommendation of a specific standard. I will also present evidence that the current standard for ozone may not protect sensitive plant species such as soybean from significant damage and yield loss.
4/20/06 - Synthetic Fibers as a Marker for Land-application of Wastes (Brian Richards, Senior Research Associate, Soil and Water Group, Biological and Environmental Engineering, Cornell University) . Abstract: Habib et al. (1998) first proposed the use synthetic fabric fibers as an indicator of wastewater sludge and sewage effluent in the environment using water extraction followed by polarized light microscopy. The purpose of our study was to more widely test this approach by taking advantage of a broad and unique array of archived wastewater sludge and soil samples generated in long-term sludge application studies. Specific objectives were to 1) test the effects of different methods of processing (dewatering, pelletization, composting, alkaline-stabilization) on fiber detectability in sludge products, and 2) determine long-term fiber detectability in sludge-applied soils from both experimental columns and field sites. Fibers were detectable in sludge products, with variations in fiber recoverability and condition resulting from the different processes. Fibers were also detected in long-term soil columns over 5 years after application, retaining fiber characteristics observed in the applied sludge. Surprisingly, fiber concentrations mirrored (within a factor of 2) predictions based on soil dilution. Fibers were visible in field site soils after intervals of up to 15 years after application, again retaining the characteristics seen in the applied sludge products. Concentrations correlated with residual sludge metal concentration gradients in a well-characterized field site. Synthetic fibers were thus shown to be semi-quantitative indicators of past sludge application.
4/13/06 - Colloid Transport in Unsaturated Porous Media: Visualization, Modeling, and Experiment. (Bin Gao, Research Associate, Biological and Environmental Engineering, Cornell University) . Abstract: Subsurface transport of colloids is important to groundwater quality because most of the colloidal particles have high sorption capacities for various contaminants, also some of the biocolloids such as microbial pathogens are pollutants themselves. This study is aimed at improving current understanding of the mechanisms that govern colloid mobilization, transport, and deposition in unsaturated porous media. Laboratory columns packed with quart sand were used to study the influences of flow and pore-water chemistry on colloid transport in homogeneous and heterogeneous porous media. And the governing mechanisms of colloid deposition and mobilization were investigated in details through pore-scale observations of colloid movements within partly saturated micro-flow cells. Results of the experiments with homogeneously packed sand columns indicate that colloid deposition rates are sensitive to colloid mineralogy, vary directly with porewater pH, and decrease with increasing moisture content. Increases in flow rate and porewater pH can mobilize colloidal particles trapped in partly saturated homogeneous porous media. The mechanisms that control colloid mobility within homogeneous media also influence colloid transport through partially saturated columns containing structured heterogeneity. Colloids were found mainly transported within the fine porous media in the partly saturated heterogeneous sand columns, and there were almost no flow and transport within the coarse media. Observations from experiments with micro-flow cells reveal that colloid deposition in the column experiments is controlled by attachment to air-water interfaces, straining within thin-water films that surround mineral grains of partially saturated pores, and storage within stagnant-water zones that branch from advecting porewater regions. Although release of retained colloids is slow during steady flow, mobilization is rapid during transient flow and reflects the release of strained colloids from expanding thin-water films and from immobile-water zones that reconnect with advecting porewater regions during porous-medium imbibition. The knowledge gained from this research illuminates the complexity of colloid deposition and mobilization processes and can be used to inform the refinement of modeling approaches for colloid transport through the vadose zone.
4/6/06 - Effects of Urbanization on Delaware Basin Streams Identifying Key Landscape Variables, and Improving their Quantification. (Rachel Riemann, Research Forester, USDA Forest Service, Troy, NY) . Abstract: Many Delaware River Basin watersheds are undergoing rapid urbanization. Effective management ultimately requires knowledge of specific landscape characteristics that influence stream ecosystems. A multi-agency study was undertaken to assess the effects of urbanization on streams, identify the landscape characteristics that influence stream ecosystem responses in this area, and evaluate the suitability of satellite-based landscape data for characterizing relevant land use, land cover, and pattern variables. Characteristics of 32 catchments were quantified through photo-interpretation of 1:40,000 digital orthophotography and related to stream biological, physical, and chemical data collected in 2000-01. Accuracies of National Land Cover Datasets (NLCD) from 1992 and 2001 for deriving the identified management relevant variables were evaluated through comparison with photo-interpreted values. Stream condition was related in large part to factors associated with urbanization. Increased urbanization was related to declines in sensitive invertebrates and increases in nutrient, pesticide, and chloride concentrations, with stream condition changing even at low levels of urbanization. Landscape variables contributing to multiple-regression response models included the spatial extent of urban land, the type of urban land use and land cover (e.g. impervious), location in relation to stream, and configuration of remaining forest. NLCD-based values of many variables differed markedly from their photo-interpreted counterparts, particularly in heavily forested catchments. In particular, the form of the observed biological response to urbanization factors depends largely on the landscape dataset used. Road-based NLCD correction improved comparability for many, but not all, variables. Evaluation and correction of NLCD can substantially improve its utility in water-quality and forestry studies.
3/30/06 - Spatial Microheterogeneity of Copper in Contaminated Soils (Astrid Jacobson, Post-doctoral Associate, Crop and Soil Sciences, Cornell University). Abstract: Most studies of metal contaminated soils have been limited to assessments of bulk concentrations with little regard for the spatial distribution of the metals. The spatial distribution of a metal, however, has important consequences for the bioavailability and mobility of the metal. In this study we investigate the spatial distribution of copper in thin sections of intact surface soils that had been contaminated by repeated applications of copper sulfate over many years. The thin sections were analyzed by SEM-EDX, electron microprobe, and synchrotron micro-Xray fluorescence to map copper and associated trace elements. Traditional bulk physico/chemical analyses of Cu, pH, organic matter content, texture and mineralogy were use to characterize the soils and complement the elemental maps. The results suggest that the copper is largely associated with organic matter.
3/23/06 - SPRING BREAK
3/16/06 - Supporting Soil Health Management with On-farm Measurements (John Idowu, Project Coordinator, Soil Health Initiative, Departments of Plant Pathology, Horticulture and Crop and Soil Sciences, Cornell University) . Abstract: Soil quality assessment is important for the purpose of monitoring soil degradation and providing a useful basis for soil and crop management planning. Since soil quality focuses on integrated assessment of soil physical, chemical and biological functions, the challenge has been to define soil quality status based on appropriate indicators. The soil health initiative has brought together a multi-disciplinary group of scientist working with growers and extension staff to address the issue of soil quality assessment for the past three years. This seminar will focus on results and interpretation to address grower’s concerns related to soil management.
3/9/06 - NO SEMINAR.
3/2/06 - NO SEMINAR.
2/23/06 - Government Policies, the Coca Economy and Lanscape/Forest Fragmentation in Bolivia (Andrew Millington, Professor, Department of Geography, Texas A&M University) .
2/16/06 - NO SEMINAR.
2/9/06 - Ecological Footprint of Iowa Row Crop Agriculture (Ricardo Salvador, Program Director for Food Systems and Rural Development, WK Kellogg Foundation, Battle Creek MI; Associate Professor of Agronomy and Sustainable Agriculture, Iowa State University, Ames IA). Abstract: A variation of a technique first developed by community regional planners permits estimation of the land area required to supply the resources and absorb the wastes of agricultural production. This is the "footprint" of agricultural activity. We have measured the ecological footprint of corn/soy production and estimated the area required to supply the energy embodied in inputs (fertilizers, machinery and pesticides) and to absorb the nitrates and other wastes generated by cropping. We have compared the footprint of industrial corn/soy production with an organic alternative and are in the process of conducting similar comparative assessments (rain-fed vs. irrigated, monoculture vs. polyculture). Comparison of apparent productivity (simple yield) of various agricultural systems with their ecological footprint is one way of examining the ultimate sustainability of the systems assessed.
2/2/06 - Traditional and New Approaches for Rainfed Field Crops Improvement in Israel (David Bonfil, Professor, Agricultural Research Organization, Gilat Research Center, Israel). Abstract: Yields of dryland crops in semi-arid and arid zones are limited by precipitation. Since precipitation is a fixed, un-controlled and varies by season, their optimal utilization by rainfed crops is most important. Traditional and new approaches have been tested and developed for rainfed field crops during past years. New varieties with better performance are always a key for success. No tillage was found to be the best management practice in these regions, as it increases rain use efficiency, reduces drought risks, and could increase income by $100/ha. Crop rotation and precise fertilization are also very important for rainfed wheat. Currently wheat fertilization is based on bioassay. The last ongoing research tests site specific nitrogen application for base fertilization, and decision support system for decision making at heading to ensure high wheat yield quality. Multi and hyperspectral data are used for biotic and abiotic stresses diagnosis. All these options have assisted the success of rainfed crop production.
Spring 2006 Special Seminars
FALL 2005
12/01/05 - Bio-char as a Soil Amendment: Nutrient Leaching and Carbon Biogeochemistry (Julie Major, Graduate Student, Crop and Soil Sciences, Cornell University) . Abstract: Biomass-derived black carbon (bio-char) is a promising organic matter source for soil application that combines chemical recalcitrance with high surface area and cation exchange capacity. Field experiments have shown significant yield increases in highly weathered, acid soils. I propose to evaluate the potential of black carbon to reduce nutrient leaching when fertilizers are applied to a savanna Oxisol in the Colombian Llanos and to examine the fate of black carbon and its biogeochemistry. Field experiments have been installed in a collaborative effort between Cornell University and the Centro Internacional de Agricultura Tropical (CIAT) in Cali, Colombia. Preliminary data show that soil water dynamics are significantly affected by bio-char additions.
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Mechanisms of ZnS Dissolution in Naturally Metalliferous Peat Soils (Tarah Sullivan, PhD Student, Crop and Soil Sciences, Cornell University) Abstract: Naturally occurring peat soils in Western NY contain anomalously high concentrations of Zn and Cd. Under reducing conditions these trace metals are not readily available (as sulfides and thiol-compounds), but when the peat soils are drained for agriculture, availability increases and patches of phytotoxicity are observed. Previous studies suggest that the availability and cycling of these metals may be driven primarily by microbial populations. New data on spatial variations across a field at a time when the field is drained in preparation for spring planting exhibit patterns in both the soil chemistry as well as soil microbial communities that may help begin to explain the mechanisms involved in metal cycling. Proposed is a research plan that would examine dissolution mechanisms within the inherent microbial populations at the site as well as within the rhizosphere of Zn-tolerant willows at the site.
11/24/05 - THANKSGIVING RECESS
11/17/05 - Evaluation of Phosphorus Accumulation and Loss Dynamics in Manure Amended Soils: From Process to Landscape Scales (Liz Brock, MSc Candidate, Crop and Soil Sciences, Cornell University) . Abstract: Application of animal manure beyond crop uptake can lead to accumulation of phosphorus (P) in the plow layer. It is uncertain whether resulting high levels of soil test P represent an increased risk of P loss due to other effects of manure addition on soil chemistry. We quantified P losses via subsurface vertical leaching in undisturbed soil cores from naturally acidic soils with a dairy or poultry manure application history of up to 40 yr. One background, 4 poultry litter (PL) and 4 dairy manure (DM) amended fields were selected and three intact cores (50 cm height, 30 cm diameter) were collected per field. Soils were Wellsboro or Oquaga channery silt loams and ranged in Mehlich-3 extractable P (M3P) from 79 to 2924 mg P kg-1. Cores were irrigated once every week for 7 mo with deionized water at a rate matching a New York Southern Tier 1 hr -1 yr storm. In the first week, average leachate dissolved reactive P (DRP) from DM soils and PL soils ranged from 0.073 – 1.83 mg L-1 and 0.073 – 1.11 mg L-1 respectively. In DM soils, average leachate DRP concentrations returned to background levels after three weeks of irrigation. Leachate from the poultry field with the highest M3P increased in DRP over time, peaking at 10.34 mg L-1, possibly due to dissolution of calcium phosphates and lowering of soil pH. Results show that leaching can be a significant mechanism of P loss which may increase over time if soils are taken out of cropping rotations and allowed to return to their naturally acidic state. Simple, reliable indicators to predict these losses will also be discussed.
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Soil Fertility Degradation and Management in Smallholder Farms of the Highlands of Kenya” (Solomon Ngoze, Graduate Student, Crop and Soil Sciences, Cornell University) Abstract: High population growth and rapid depletion of soil fertility in smallholder farms are the main causes for decline in per capita food production in sub Saharan Africa. Decreasing soil fertility in the highlands of Kenya is a result of an imbalance between nutrient inputs and harvest removal, erosion and leaching. Using maize yields as an indicator, farms in this region exhibit contrasting soil fertility degradation levels based on the time of land conversion from primary forest to agriculture. Because small-scale, low-fertility farms in this region cannot be expanded, due to limited frontiers and shrinking arable land, we examine whether land use and socio-economic factors significantly effect the soil fertility of these farms. In addition, we evaluate the impact of soil fertility amendments, including manure, green manure, and inorganic N, on maize yield on farms at various levels of soil fertility degradation in this region. The implications of our results for understanding the dynamics of soil fertility degradation, the impact of soil fertility management, and the challenges of soil fertility restoration on smallholder farms in the highlands of Kenya are discussed.
Current research interests: -To understand the dynamics of soil fertility degradation and the impact of soil fertility management strategies for sustainable agricultural production in the smallholder farms of sub Saharan Africa. In particular, looking at nitrogen and phosphorus dynamics of soils amended with organic and inorganic fertilizers to restore fertility on a chronosequence of soil fertility degradation in the smallholder agriculture of the highlands of Kenya.
11/10/05 - NO SEMINAR
11/03/05 - Exploring Microbial Communities in Soil: A Tale of Two Approaches (Dan Buckley, Assistant Professor, Crop and Soil Sciences, Cornell University) . Abstract: Every pinch of soil contains billions of microbes whose activities regulate terrestrial nutrient cycles and influence the evolution of our biosphere. Despite their importance many aspects of soil microbial communities are still a mystery and soil remains a fertile habitat for discovery. This seminar will provide a brief overview of microbial diversity in soils and describe two complementary approaches to explore the ecological significance of soil microbial communities: a phylogenetic approach and a functional approach. An example of each approach will be given focusing on both the diversity of soil Planctomycetes and the use of stable isotope probing to target free-living nitrogen fixing microorganisms in agricultural soils.
10/27/05 - Developing a Biological Control Program for Invasive Swallow-worts (Vincetoxicum spp.) (Lindsey Milbrath, Research Entomologist, USDA-ARS, US Plant, Soil and Nutrition Laboratory, Ithaca, NY) . Abstract: Swallow-worts (Vincetoxicum rossicum, pale swallow-wort, and V. nigrum, black swallow-wort) are exotic, herbaceous, perennial, twining vines in the milkweed family (Asclepiadaceae) that are becoming invasive in North America. Classical biological control, which involves the introduction of host-specific insects and/or pathogens that attack the invasive plant in its native range, can be a sustainable, effective, environmentally-sound and economical management tool. Dr. Milbrath will discuss current and proposed research in the development of a biological control program targeting swallow-wort.
10/20/05 - Farming for Health: the Global HarvestPlus Biofortification Program (Ross Welch, Professor, Plant Physiologist/Lead Scientist,USDA/ARS, US Plant, Soil and Nutrition Laboratory and Professor of Plant Nutrition (Courtesy), Crop & Soil Sciences, Cornell University) . Abstract: Micronutrient malnutrition afflicts over 50% of the world's population especially among resource-poor families in the Global South resulting in increased morbidity and mortality rates, reduced labor productivity, lower intellectual attainment, meager family incomes which greatly contributes to sluggish national development efforts and poor health and livelihoods for those affected. One of the leading contributing factors to this global health crisis is the low bioavailability of micronutrients in diets comprised of common staple food crops (e.g., rice, wheat, maize, and beans) that feed the poorest of the poor. Most of these crops, as commonly eaten, can contain high levels of antinutritive substances (i.e., phytate, polyphenols, certain fibers, etc.) that greatly reduce the bioavailability of micronutrients in ordinary diets. What sustainable approaches can be used to improve the bioavailable micronutrient output of agricultural systems? The HarvestPlus biofortification program is an agricultural tool that focuses on plant breeding as a way to improve the micronutrient density of staple food crops, and as such, is the first global health intervention to employ agriculture to improve human health. This review will discuss potential solutions to micronutrient malnutrition focusing on sustainable food system approaches. The roles that plant breeding, agronomy, and biotechnology can play in improving the output of bioavailable micronutrients in food systems will be discussed as will as means to increase the levels of those factors [e.g., ascorbate, cysteine, the "meat factor(s)", etc.] that promote the bioavailability of micronutrients from diets based on staple plant foods. The possible negative effects of reducing certain antinutrients (e.g., phytate) on both crop productivity and consumer health will be presented. The potential importance of the hindgut, and associated microorganisms, in determining micronutrient bioavailability will also be explored.
10/13/05 - Response of Cassava (Manihot esculenta Crantz) to terminal water stress: ABA, sugar and starch accumulation/partitioning and root growth under different water regime treatments (Luis Duque, MS Student, Crop and Soil Sciences, Cornell University) . Abstract: Cassava is an important staple crop for developing regions worldwide and is valued for its reliable yield in environments subject to abiotic stresses. Although cassava is one of the best crops for drought-prone environments it is also among the most productive crops in well-watered situations. The mechanisms it uses to regulate growth and stress tolerance activities in such contrasting conditions are not well understood. The objectives of this research are to evaluate the hypothesis that cassava tolerates drought primarily by employing a conservative resource-use and partitioning strategy, accumulating carbohydrate reserves in stems and storage roots prior to a drought episode, conserving resources during stress by limiting vegetative growth, shedding leaves, and restricting root branching, such that carbohydrates are available to initiate rapid regrowth when rainfall resumes. To test this hypothesis we determined the effects of a water stress (without rewatering) on ABA, sugar, starch accumulation and partitioning in different plant parts and evaluated new adventitious root growth as affected by different water regimes. Cassava plants grown in one meter high pots were subject to four different water regimes during 30 days. Apical, basal leaves and adventitious roots were sampled during the drought episode. Leaf senescence/abscission and biomass were also quantified.
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Trehalose alters carbohydrate partitioning and utilization, which increases drought tolerance in rice plants (Tomohiro Kurai, Master Degree Candidate, Crop and Soil Sciences, Cornell University) Abstract: Trehalose is non-reducing disaccharide, which can be found in many species and kingdom including bacteria and fungi. The function of trehalose is known as compatible solutes to stabilize cellular structure in bacteria and yeast, yet its function in plants is unknown. Our study reports that trehalose alters carbohydrate partitioning under water stress condition and increases drought tolerance. Escherichia coli trehalose biosynthetic genes are introduced and regulatory overexpressed in rice plants by tissue-specific and stress-dependent promoters. It is found that biomass, transpiration level as well as abscisic acid concentration are not significantly different between transgenic and non-transgenic control rice. It is also observed that glucose concentration is maintained at the same level in all genotypes. However, it is found that transgenic lines can maintain higher sucrose and starch level under stress. Sucrose may serve as compatible solutes for higher drought tolerance, and starch serves as carbohydrate supply for maintaining cellular activity under drought condition. The result confirms suggested role of trehalose in modulating sugar sensing and carbohydrate metabolism.
09/29/05 - Evolving Oxygenated Surface Functional Groups through Biotic and Abiotic Oxidation on the Wood Char (Chih-Hsin Cheng, Graduate Student, Crop and Soil Sciences, Cornell University) . Abstract: We compared biotic and abiotic oxidation on the effects of wood char. After 4 months incubation, the wood char showed significant alternations. They increased acidity and exchange cation adsorption ability, especially in higher temperature treatment, by evolving oxygenated surface functional groups via chemisorption. Fourier transform infrared (FTIR), Boehm's titration, and X-ray photoelectron spectroscopy (XPS) indicated that the carboxylic functional groups were most prominent. The higher temperature abiotic oxidation, 70C, was more important than biotic oxidation at beginning phase when wood char was produced.
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Rice Cultivar Trait Differences and Their Effect on Weed Tolerance and Weed Suppressive Ability: An Application for Integrated Weed Management in the System of Rice Intensification (SRI) (V Ryan Haden, MS Candidate, Crop and Soil Sciences, Cornell University) . Abstract: Increased susceptibility to weeds and hence more laborious weeding requirements are among the primary constraints to SRI’s profitability and adoption. Other weed-prone rice systems (i.e. direct seeded and upland) have successfully used weed competitive cultivars as a means of reducing the intensity of both weeding operations and herbicide applications. This study seeks to apply this strategy to SRI in Indonesia. In addition to evaluating the differential weed tolerance and suppressive ability of 6 diverse rice cultivars, we attempt to explain how various plant traits can influence the weed-crop relationship.
09/22/05 - Fagopyritols, Insulin Mediators, NIDDM, and PCOS (Ralph Obendorf, Professor, Crop and Soil Sciences, Cornell University) . Abstract: Fagopyritols are galactosides of D-chiro-inositol found in seeds of buckwheat and some other species. Fagopyritol A1 is isosteric with an insulin mediator believed to be limiting in subjects with non-insulin dependent diabetes mellitus and polycystic ovary syndrom. Consumption of fagopyritols may be a dietary treatment for NIDDM and PCOS. Our recent and current research on fagopyritols will be reviewed.
A list of some recent publications:
09/15/05 - Root Development and Soil Nitrogen Availability as Drivers of Maize-weed Competition (Andres Berger, Graduate Student MS, Crop and Soil Sciences, Cornell University). Abstract: A mechanistic understanding of crop-weed interaction is required to develop dynamic simulation models of crop-weeds growth that can be used to estimate the outcomes of competition, predict yield losses or evaluate the effects of management practices. Due to the complexity of studying competition for resources, our understanding of these processes is limited. This study: i) quantifies early season root system growth for maize and four weed species and determines the effects of above and below ground maize competition on maize and weed root system development; ii) compares the early and exponential growth phases of four weed species to maize; and iii) identifies and quantifies the changes in plant architecture and morphology induced by N stress that could be important in determining success in resource competition in a maize-weed mixture.
09/08/05 - Cover Crop Evaluation and Soil Nutrient Budget Evaluation Tools Across an Elevation Gradient in the Bolivian Andes (Steven Vanek, Graduate Student, Crop and Soil Sciences, Cornell University). Abstract: Steve has just returned from preliminary community and research site surveys with World Neighbors, a development organization that along with local communities is hosting this research in a project funded by the McKnight Foundation. Steve will describe the research setting and goals, including the evaluation of a range of promising green manure species over an elevation gradient, the use of cover crops to keep nitrogen and phosphorus more available in the rotation, and the use of nutrient budgeting approaches as a tool for evaluation of existing practice compared to proposed innovations.
9/1/05 - Relationships Among Legume Residue Use, Soil Fertility Characteristics and Soilborne Bean Seedling Pests in Trans Nzoia District Kenya (Beth Medvecky, PhD Candidate, Crop and Soil Sciences, Cornell University) . Abstract: Poor soil fertility, soilborne pests, and farmers' economic inability to afford fertilizer inputs hinder the productivity of maize and beans on smallholder farms in the densely settled highland regions of Kenya. Research and development efforts aimed at improving crop and soil productivity have focused on increasing farmers' utilization of organic inputs, especially residues from herbaceous legumes and agroforestry species. However, it is not well understood how these inputs might impact farmers' pre-existing pest problems. In my dissertation research I studied both short and longer-term effects of legume residue use on a soilborne bean seedling pest complex in Trans Nzoia district Kenya. In this seminar I will present the key research findings, which point to a complex web of interrelationships among the legume residue management practices, soil fertility characteristics, and bean seedling pests.
8/25/05 - Alfalfa-grass Forage Quality Prediction in New York State (David Parsons, MS/PhD Student, Crop and Soil Sciences, Cornell University)
. Abstract: Timing of spring alfalfa cutting is critical to obtain the optimal forage quality for animal production. There is a relatively small range in optimal alfalfa neutral detergent fiber (NDF), emphasizing the need for quick and accurate methods for determining NDF. A number of methods have been developed to estimate alfalfa NDF, including models based on weather, chronological age and plant morphology. However, the situation in New York, where a high proportion of forage stands are a mixture of alfalfa and grass, is more complex. The study focused on the following objectives: (i) Determination of whether current prediction equations for pure alfalfa are valid for alfalfa in mixed stands; (ii) Development of new models for prediction of grass NDF and total stand NDF; (iii) Development of farmer-usable tools to aid prediction of mixed stand NDF.
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Modeling Smallholder Crop-livestock Systems in Yucatan Peninsula, Mexico (David Parsons, MS/PhD Student, Crop and Soil Sciences, Cornell University) . Abstract: Sheep production is a growing agricultural enterprise in the tropical Yucatan Peninsula. Because of their accessibility to smallholder farmers and the growing demand for sheep meat, they represent a significant development opportunity. However in addition to livestock production there exist seemingly competing goals for land use, including agriculture and preservation of forests for biodiversity. The proposed research involves developing a system dynamics model of Yucatan crop-livestock (sheep) systems, to aid in understanding the implications of current land use practices.
Fall 2005 Special Seminars
12/15/05 - Effect of Crop Production Innovations on the Upstream Efforts of Agronomy Research (Clay Mitchell, Innovative Farmer) . Abstract: Clay Mitchell Farms in Northeast Iowa and his innovative combination of no-till controlled-traffic farming, farm wide wireless LAN, centimeter-level automation of seed, fertilizer, and chemical application, root-zone banding of fertilizer, and strip-intercropping, represent a particular dedication to soil conservation and to a farming culture that favors farmers’ management skill and traditional family and community cooperation. As such, The Mitchell Farm stands at a crossroads equally relevant to the ancient farms of Europe and Asia and the innovation and entrepreneurial spirit in Australia and South America. This farm was recently featured in a Time magazine article on cutting-edge farming.
10/07/05 - Turnover of Soil Organic Matter - bulk soil, lignins, lipids and black carbon (Michael Schmidt, Professor, Department of Geography, Physical Geography, University of Zurich) . Abstract: This presentation tries to give an overview of the recent research from Soil Biogeochemistry group, Univ Zurich. Further information and reprints can be found here: www.geo.unizh.ch/~mschmidt. Soils store about twice as much carbon (C) than exists in the atmosphere as carbon dioxide (CO2). Global warming probably will affect soil organic carbon (SOC) decomposition and will determine how much carbon will be transferred to the atmosphere or sequestered in soils. Lignin and lipids are some of the the main contributor to soil organic matter (SOM) and are generally believed to be relatively resistant against microbial degradation. However, analytical information on biodegradation has mostly been addressed in short-term (days to weeks) in-vitro experiments. In-vivo experiments mimic natural processes in soils over many years much better but are sparse. Direct molecular-level information on long-term turnover could come from field studies using the natural stable isotopic difference between C4 plant and C3 plant isotopes. Results show that in agricultural and grassland soils n-alkanes, n-carboxylic acids and lignins turn over faster than or (similar to) bulk SOM. Black carbon, derived from the incomplete combustion of biomass, is ubiquitous in the environment. A review summarizes the analysis, formation, and fate of black carbon in boreal forest.
Conferences
Other Related Seminars
Biogeochemistry and Environmental Change
Department of Natural Resources
Fall 2005 and Spring 2006 Seminars
Fall 2004 and Spring 2005 Seminars
Fall 2003 and Spring 2004 Seminars
Fall 2002 and Spring 2003 Seminars
Spring 2002 Seminars
Fall 2001 Seminars
Spring 2001 Seminars
Fall 2000 Seminars
Spring 2000 Seminars