Managing Cover Crops with Rolling and Crimping Techniques

Rolling hay, rye and other cover crops could be the fastest way for some farmers to prepare their fields for planting. That's thanks to rolling machines--developed by Agricultural Research Service (ARS) scientists--that can quickly flatten mature, high-biomass cover crops such as rye.

Each roller consists of a long cylinder adorned with a series of thick, blunt, steel crimping bars, each about one-quarter-inch thick. As a standard tractor pulls the roller over the field, pressure from the bars flattens and damages the cover crop without cutting or uprooting it. Within three weeks, the rolled cover crop dries out, forming a mat of dead biomass into which farmers can plant cash crops.

Since 2001, ARS has been conducting research to find the best crimping roller design for conditions in the southeastern United States, and the benefits from this research are gaining recognition.

ARS scientists Ted Kornecki and Randy Raper and their colleagues at the agency's National Soil Dynamics Laboratory (NSDL) in Auburn, Ala., compared three different roller designs. The first roller has a traditional design with long, straight, horizontal bars. The second has diagonal bars that curve around the roller. The third has a smooth drum attached to a crimping bar that mashes the rye as the machine moves forward.

NSDL scientists, who developed the curved-bar and crimping roller designs, found that all three models killed enough rye--90 percent or more--to enable farmers to begin planting cash crops in the field within three weeks. The crimping-bar roller yielded the best results.

The scientists also found that the curved-bar and the crimping rollers provided smoother rides than the traditional straight-bar roller. Future studies will help scientists maximize the efficiency and comfort of these machines.

The one-pass process saves money, reduces soil erosion and runoff, helps control weeds, conserves water in the soil and decreases or eliminates the need for herbicides.

Read more about the research in the September 2008 issue of Agricultural Research magazine.

ARS is a scientific research agency of the U.S. Department of Agriculture.

ARS Researchers Search for Casuarina Biological Control Agents

Australia's Outback and remote coastlines are home to insects that could be key biocontrols for a highly invasive weed threatening coastal areas of the United States, according to Agricultural Research Service (ARS) scientists and cooperators.

ARS entomologist Greg Wheeler and his ARS and university colleagues are touring the Outback and Australia's coastal areas in search of biological control agents for the highly invasive Casuarina species commonly called Australian pine.

This weed is infiltrating U.S. coastal areas, especially in south Florida, the Virgin Islands, Puerto Rico and Hawaii. Known for its rapid growth and dense coverage, Australian pine inhibits the growth of native plants.

The Australian pine problem includes three Casuarina species--C. equisetifolia (referred to in Australia as “coastal she-oak”), C. glauca (“swamp she-oak,” and arguably as big or a bigger problem than C. equisetifolia) and C. cunninghamiana (“river she-oak”).

In the past few years, the Australian members of the team--Matthew Purcell and Bradley Brown, researchers at the ARS Australian Biological Control Laboratory in Indooroopilly, Queensland, and Gary Taylor from the University of Adelaide, Australia--conducted five separate trips throughout Australia. Purcell, Brown, Taylor and John Gaskin, research leader of the ARS Pest Management Research Unit in Sidney, Mont., collectively comprise a Casuarina research team.

Wheeler served as the lead scientist for the project, coordinating the funding, surveys and plant-DNA testing. From a bounty of some 300 wasps, weevils, stem-borers, sap-suckers, seed-eaters and more, the scientists have narrowed the field of potential control agents to about 12 candidates.

Not only do these top candidates attack C. equisetifolia, but many also attack C. glauca and C. cunninghamiana. Among the top finds were the seed-feeding wasp Bootanelleus orientalis, which is host-specific to Australian pine, and the defoliator moth Zauclophora pelodes.

These insects are still undergoing testing by Purcell and colleagues in Australia to determine their suitability for use as biological control agents in the United States. Insects that decrease Casuarina reproduction and spread are being given the most attention.

Read more about the research in the September 2008 issue of Agricultural Research magazine.

ARS is a scientific research agency of the U.S. Department of Agriculture.

Database Documents Names for More Than 150,000 Diptera Species

Distinguishing between insect pests and partners starts with an ironclad identification. So Agricultural Research Service (ARS) entomologist Chris Thompson headed up efforts to accurately identify and name almost 157,000 flies, gnats, maggots, midges, mosquitoes and related species in the order Diptera.

Diptera is one of the four largest groups of living organisms on Earth, and its members are critical components in virtually all non-marine ecosystems. Carl Linnaeus, who devised the scientific classification system still in use today, compiled the first index of Diptera species names in 1758. But even though an average of 800 new Diptera names are proposed every year, the nomenclature has not been comprehensively updated since 1805.

Thompson works at the ARS Systematic Entomology Laboratory in Washington, D.C. For this research, he partnered with Neal Evenhuis, an entomologist at the Bishop Museum in Honolulu, Hawaii; Thomas Pape, an entomologist at the Natural History Museum of Denmark; and Adrian Pont, an entomologist at the Oxford University Museum of Natural History in Oxford, England.

The group assembled the tenth edition of the Biosystematic Database of World Diptera (BDWD). This massive index contains nomenclature data for 156,599 living and extinct Diptera species in 154 families and 11,671 genera—around 10 percent of the known biodiversity in the world today.

The BDWD, which is available at www.diptera.org, has two components. The Nomenclator allows users to check names, confirm species status, and obtain information about type, family classification and sources for all names in the collection. The Species database is being designed to answer queries about different species, including their distribution, biological associates and economic importance.

The BDWD provides a framework for organizing and integrating current and future data that is accessible by researchers around the globe. Scientists can obtain a wealth of information that will help them fine-tune Diptera’s evolutionary tree and track the migration, increase and decline of economically-important Diptera species worldwide.

The team presented their research at the 20th International Congress of Zoology in Paris, France, in August.

ARS is a scientific research agency of the U.S. Department of Agriculture.

Grain Moisture Measurements May Divert Mold, Insect Infestation

Grain storage bins are routinely monitored for temperature to control insect and mold problems. Now an Agricultural Research Service (ARS) scientist and his colleagues at Kansas State University (KSU) have preliminary research findings showing that monitoring carbon dioxide--along with humidity and temperature--also may help detect problems more effectively.

Grain moisture content and temperature are the primary factors affecting grain deterioration in storage. If these factors are not properly monitored and controlled, grain quality can deteriorate quickly due to mold growth and insect infestation.

ARS engineer Paul Armstrong at the agency's Grain and Marketing and Production Research Center in Manhattan, Kan., and Haidee Gonzales and Ronaldo Maghirang at KSU monitored a simulated grain storage bin during aeration to determine if high-moisture grain, or adverse storage conditions, in the bin top could be detected using sensors to measure relative humidity, temperature and carbon dioxide levels.

Relative humidity and temperature can be used to estimate grain moisture, while carbon dioxide levels indicate the amount of respiration due, primarily, to molds. Current technology allows relative humidity and temperature sensors to be placed at multiple points within the grain mass. Carbon dioxide sensing is more feasible at an aeration duct.

In the study, sensors were placed at different depths in the bin. High-moisture grain-- comprising about 11 percent of the volume--was placed at the top of the bin and produced high amounts of carbon dioxide, which in most cases was easily detectable during aeration.

Lowering grain temperature with aeration diminished the amount of carbon dioxide produced, making it more difficult to detect unless the carbon dioxide sensor was located very close to the wet grain.

Relative humidity and temperature sensing gave good estimates of grain moisture for all conditions, but under some grain conditions, high carbon dioxide levels persisted for grain considered to be at safe moisture and temperature conditions. Combining relative humidity, temperature and carbon dioxide measurements gave reasonably accurate measurements of grain moisture content as well as overall storage conditions.

ARS is the U.S. Department of Agriculture's scientific research agency.

ARS Scientists Test MRI Device to Measure Body Fat in Piglets

A new magnetic resonance imaging (MRI)-based device--more advanced than the technology used today for body composition tests--can accurately and precisely measure total body fat in piglets using the principles of quantitative magnetic resonance (QMR), according to Agricultural Research Service (ARS) scientists who evaluated the new technology.

The new device, called EchoMRI, was tested by ARS researchers to measure not only total body fat, but lean tissue mass, free water mass and total body water in piglets. The research was done under a grant from the National Institutes of Health, which wants to know if the new technology could have future applications for human pediatric use.

Standard MRI systems are commonly used to scan and visualize tissue in humans. However, when used for body composition analysis, imaging systems are subject to substantial error rates caused by the interpretation of visual images using software that relies on population averages.

EchoMRI uses a new type of QMR methodology to obtain body composition results. Its measurement principle depends on the density of hydrogen nuclei and the physical state of the tissue.

ARS animal scientist Alva Mitchell at the Animal Biosciences and Biotechnology Laboratory in Beltsville, Md., tested the device, developed by Echo Medical Systems, to determine EchoMRI's precision and accuracy in piglets as compared to dual x-ray (DXA) technology and chemical analysis.

Twenty-five piglets, each weighing between 3.5 pounds and 8 pounds, were screened live, anesthetized, and post-mortem, using a prototype EchoMRI device for infants. The piglets were also scanned using DXA and then subjected to chemical analysis.

After DXA scans, EchoMRI screenings, and chemical analyses were completed, EchoMRI was found to be a precise and accurate method suitable for measuring piglet whole body composition, total body fat, lean tissue mass, free water mass, and total body water. While these studies were conducted on piglets, EchoMRI may be transferable to market-weight pigs.

EchoMRI allows for measurements to be conducted in only a few minutes without anesthesia or sedation, is radiation-free, and does not require the subject to remain completely motionless. This facilitates convenient, low-stress repeated tracking of small changes in body composition and can be advantageous to researchers to optimize feed utilization. It could also help researchers identify high-value hogs for breeding.

ARS is a scientific research agency of the U.S. Department of Agriculture.

“Fingerprinting” Helps Make Great Grapes

At about this time next year, nearly all of the 2,800 wild, rare and domesticated grapes in a unique northern California genebank will have had their "genetic profile" or “fingerprint” taken. These fingerprints may help grape breeders pinpoint plants in the collection that have unusual traits--ones that might appeal to shoppers in tomorrow's supermarkets. Other grapes might be ideal for scientists who are doing basic research.

That’s according to Agricultural Research Service (ARS) plant geneticist Mallikarjuna Aradhya. He's heading the grape fingerprinting venture.

The grape collection that Aradhya is fingerprinting encompasses vineyards and screened enclosures, called “screenhouses." It is part of what’s officially known as the ARS National Clonal Germplasm Repository for Tree Fruit and Nut Crops and Grapes, in Davis, Calif.

To glean a distinctive genetic fingerprint of each member of the collection, Aradhya uses pieces of genetic material--or DNA--known as microsatellite markers. Eight markers are all that are needed for a genetic fingerprint of more familiar grapes, like close relatives of those already used for making wine or raisins or for eating out-of-hand.

But the lesser-known ones--wild grapes and some prized types from China, for instance--require twice as many markers for reliable identification. That’s due, in part, to the fact that the taxonomy, or relatedness of one kind of grape to another, is quite jumbled, Aradhya noted.

He has already fingerprinted 1,100 better-known grapes and 300 wild specimens.

ARS is a scientific research agency of the U.S. Department of Agriculture.

Hydrogen-Producing Bacteria Provide Clean Energy

A new "green" technology developed cooperatively by scientists with the Agricultural Research Service (ARS) and North Carolina State University (NC State) could lead to production of hydrogen from nitrogen-fixing bacteria.

Renewable sources of energy—such as hydrogen—that don't produce pollutants or greenhouse gases are needed to solve global energy shortages. Fossil fuels such as coal, oil and natural gas are nonrenewable energy sources implicated in global warming.

The invention holds promise as a source of hydrogen for use in fuel cell technology. Fuel cell devices combine hydrogen and oxygen to produce electricity and water, and are considered efficient, quiet and pollution-free. Fuel cells are now being tested in a range of products, including automobiles that release no emissions other than water vapor.

ARS inventors Paul Bishop and Telisa Loveless and NC State inventors Jonathan Olson and José Bruno-Bárcena developed the patent-pending technology.

Nitrogen-fixing bacteria play a key role in agriculture. They live in soil and on certain plant roots, and convert nitrogen from the air into a chemical form that plants can use to grow. The researchers developed a way to identify strains of these bacteria that produce hydrogen gas.

Bishop first demonstrated novel aspects of bacterial nitrogen-fixing more than two decades ago. Building on that work, the team developed a method that uses a selecting agent to identify these special hydrogen-producing strains. The selecting agent allows researchers to identify these bacterial strains without the need for genomic sequencing or genetic modification.

Using the selecting agent, the inventors identified a gene that inactivates the bacteria's hydrogen uptake system so that all of the hydrogen produced is released. Because the bacterial cells cannot recycle the hydrogen, the hydrogen they produce can be captured and used as a fuel whose byproduct is water and heat.

Licensing information can be obtained by contacting the ARS Office of Technology Transfer or the Office of Technology Transfer at NC State.

ARS is a scientific research agency of the U.S. Department of Agriculture.

Scientists Tie Chickpea Disease to Fungal Culprit

The fungus Sclerotinia trifoliorum plagues legume crops worldwide. But chickpeas seem to have escaped its wrath, with the exception of Australia's crop. Now, that's no longer the case, report Agricultural Research Service (ARS) and collaborative university scientists.

During the 2005-06 chickpea growing season in central California, the team observed stem and crown rots reminiscent of Sclerotinia infection. But subtle irregularities in the symptoms led the researchers to believe their prime suspect—S. sclerotiorum, which infects more 400 plant species—had an accomplice, namely S. trifoliorum.

ARS research plant pathologist Weidong Chen led the team, which included Fred Muehlbauer (now retired) with the ARS Grain Legume Genetics Physiology Research Unit in Pullman, Wash., and University of California-Davis and Washington State University researchers.

They examined 10 Sclerotinia isolates from their collection from chickpea stems and subjected each to three identification criteria: growth rate, ascospore morphology and DNA markers indicative of S. trifoliorum. The team's analysis showed that S. trifoliorum isolates were slower-growing, displayed "ascospore dimorphism," which is the formation of two versions of the same spore type, and harbored a set of group I intron markers while S. sclerotiorum did not.

Chen suspects S. trifoliorum's occurrence on central California chickpeas stems from prior plantings of alfalfa—another legume host—and not an accidental introduction from Australia, the only continent where the fungus has previously been reported on chickpea. Identification of this new chickpea pathogen should aid in improving disease-management practices and developing resistant chickpea cultivars for farmers.

The research is part of the ARS National Sclerotinia Initiative. More information on this initiative is available at:

http://www.whitemoldresearch.com

The research study was published recently in the journal Plant Disease, and is available online at:

http://apsjournals.apsnet.org/doi/interp/10.1094/PDIS-92-6-0917

ARS is a scientific research agency of the U.S. Department of Agriculture.