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The Field Narrows For Cover Crops In Biofuel Production

Posted by [email protected] on April 21, 2014 at 4:35 PM Comments comments (0)

An Agricultural Research Service (ARS) scientist is looking for cover crop perennials that provide the best balance in biofuel production between agronomic success and environmental sustainability. This work is being supported by the Sun Grant Initiative, a national network of land-grant universities and federally funded laboratories working together to study, produce, and commercialize renewable, biobased energy technologies.

 

ARS agronomist Jeremy Singer, who works at the National Soil Tilth Laboratory in Ames, Iowa, is conducting this research as part of a three-component study of optimizing corn cultivation for biofuel production. He’s evaluating perennial grass crops to assess their potential for mitigating soil erosion and enhancing soil organic matter even in fields where every bit of corn and stover—stalk, leaves and all—is harvested either for grain or cellulosic ethanol production.

Perennial groundcovers’ root systems may contribute enough carbon to the soil to offset the loss of carbon when stover is removed. Cover crops also provide habitat for beneficial insects, facilitate water infiltration, help hold nitrogen in the soil, suppress weeds and reduce the runoff of agricultural chemicals.

Results from Singer’s first season in the field indicated that white clover or Kentucky bluegrass were promising cover crop candidates worthy of additional study. On the other hand, creeping red fescue added notable amounts of carbon to the soil, but was very competitive with corn.

When the optimum groundcover has been identified, using no-till and strip-till cultivation practices in the corn-groundcover system will reduce the amount of fossil fuel needed to prepare and plant the crops. This reduced tillage, in turn, will decrease greenhouse gas emissions and require fewer energy inputs than using conventional tillage—another prospective plus for farmers and fields alike

Estimate Soil Texture-by-feel

Posted by [email protected] on April 21, 2014 at 4:05 PM Comments comments (0)

The ability to estimate soil texture-by-feel is an important skill that students and registered soil scientists should learn.

Many soil properties depend largely on soil texture, and texture impacts most land-use decisions. Soil texture strongly influences the nutrient holding ability of a soil, the amount of water the soil can store, the amount of this water that is available to plants, how fast water moves through the soil, the effectiveness of soil in cleaning up waste water, the shrink-swell nature of soil, and many other properties.

D.P. Franzmeier and P.R. Owens, Purdue University, write about how soil texture can be determined by using the texture-by-feel method in an article in the Journal of Natural Resources and Life Sciences Education.

"Soil texture can be determined in the field using the texture-by-feel method or the samples may be sent to a laboratory for particle-size analysis. The laboratory option is more accurate, but it is more expensive and slower because it can take weeks or months to get the results," explains Owens.

The field method is less accurate but much faster. Soil scientists use texture-by-feel to provide quick reliable estimates of soil texture in the field. This method is used by researchers where numerous samples are required to capture variability, developing soil surveys, and consultants for sizing on-site wastewater disposal systems.

When the texture-by-feel method is used, the estimator takes a soil sample about the size of a marble up to the size of a golf ball. The person estimates the texture by rolling, squeezing, flattening, and pressing the soil between his fingers. Each person develops his own technique for estimating texture. The important point is that while learning the technique, he must always compare his results with laboratory data.

A computer program assesses student performance for estimating particle-size distribution and soil texture. If the estimate coincides exactly with laboratory results, the score is 100%. If the estimate and laboratory results are as far apart as possible, at opposite corners of the texture triangle, the score is zero.

“Students appreciate the fairness of grading. Also, we can use the method to let a student or professional know if their estimates are consistently above or below the laboratory values, which helps them calibrate their fingers,” says Owens.

“We have used this tool to help registered soil scientists improve their field skills and they seem to enjoy the challenge,” says Franzmeier

Pesticides make the life of earthworms miserable

Posted by [email protected] on April 17, 2014 at 5:10 PM Comments comments (0)

Pesticides are sprayed on crops to help them grow, but the effect on earthworms living in the soil under the plants is devastating, new research reveals: The worms only grow to half their normal weight and they do not reproduce as well as worms in fields that are not sprayed.

Pesticides have a direct impact on the physiology and behavior of earthworms, a Danish/French research team reports after having studied earthworms that were exposed to pesticides over generations.

"We see that the worms have developed methods to detoxify themselves, so that they can live in soil sprayed with fungicide. They spend a lot of energy on detoxifying, and that comes with a cost: The worms do not reach the same size as other worms, and we see that there are fewer of them in sprayed soil. An explanation could be that they are less successful at reproducing, because they spend their energy on ridding themselves of the pesticide," the researchers, Ph. D. student Nicolas Givaudan and associate professor, Claudia Wiegand, say.

Claudia Wiegand is from the Department of Biology at University of Southern Denmark, and she led the research together with Francoise Binet from University Rennes 1 in France. Nicolas Givaudan is doing his Ph. D. as a joint degree between University of Southern Denmark and University of Rennes 1 in France. They researchers reached their findings by metabolomic profiling and energetic parameters.

The researchers set up an experiment to study the behavior of the earthworm species Aporectodea caliginosa. They moved two portions of farmed soil with worms into the lab. One portion was taken from a local organic field, the other from a local conventionally cultivated field that had been sprayed with fungicide for 20 years. This soil had remnants of the internationally commonly used fungicide Opus® at a level common in fields. When crops are sprayed with fungicide, only a small part of the chemical is absorbed by the plant. The waste can be up to 70 per cent, and much of the fungicide ends up in the soil.

In the laboratory, the researchers could see how the fungicide-exposed worms adapted to the toxic environment. Over generations the worms have developed a method to detoxify themselves.

"The fungicide increased metabolism rate in the worms, both the adapted worms and the not adapted worms. In the not adapted worms we saw that their energy reserve of glycogen was used faster. Contrastingly, only in the adapted worms we saw that amino acids and protein contents increased, suggesting a detoxification mechanism. "They also increased their feeding activity, possibly to compensate for the increase in energy demand," the researchers said.

Often there are 2 -- 3 times more earthworms in unsprayed soil than in sprayed soil.

"The reason for this may be that earthworms in sprayed soil do not reproduce as successfully as worms in unsprayed soil, because they need to spend more energy on detoxifying," the researchers say.

They also weighed the worms in the experiment and found that the worms exposed to fungicide weighed only half of the worms in organic soil. Worms in organic soil had an average weight of 0.6 grams, worms in conventionally cultivated soil had an average weight of 0.3 grams

Can one-time tillage improve no-till?

Posted by [email protected] on April 17, 2014 at 5:05 PM Comments comments (0)

A one-time tillage has no adverse effects on yield or soil properties on no-till land, according to field research conducted at the University of Nebraska-Lincoln. Although tillage is another expense for farmers and generally increases the risk of soil erosion, a one-time tillage may be performed to correct some problem, such as a perennial weed problem.

The feasibility study was conducted for five years at two locations in eastern Nebraska. Charles Wortmann led the interdisciplinary team in examining the effects of a one-time tillage on no-till land for grain yield, reducing stratification of soil properties, increasing soil organic matter, and improving soil physical properties. The results were published in the July-August 2010 edition of Agronomy Journal.

Continuous no-till crop production has been widely adopted for reduced fuel consumption and labor requirement, erosion control, improved surface soil properties, increased profitability, and often increased yield. Crop yields have generally increased in the western and southern parts of the U.S., although northern agricultural lands have seen some declines in yield. Nebraska occupies a transition zone, with little change in yield due to no-till.

The researchers were testing whether one-time tillage of no-till could help manage certain perennial weeds, and reduce phosphorus stratification and runoff. They also wanted to determine if a one-time tillage, by burying the enriched surface soil and bringing deeper, less improved soil to the surface, improve soil structure and the distribution of soil nutrients.

Tillage did reduce stratification of phosphorus, soil organic matter and soil bulk density for the first years, but by the end of the five year experiment there was no difference between one-time till and no-till treatments. One-time tillage had no effect on soil organic matter content in the surface one foot of soil after five years. One possible negative effect of tillage was reduced microbial biomass at one site, but it did not affect grain yield.

The study areas consisted of one plot of grain sorghum rotated with soybean and corn with soybean at the other location. Tillage treatments included deep plowing with moldboard plows or a mini-moldboard plow, and disk tillage, and was done in late fall or very early spring to have low soil temperature and microbial biomass preceding and following tillage to minimize soil organic matter losses.

The authors concluded that one-time tillage of no-till can be done in eastern Nebraska without measureable long-term effects on yield or soil properties except for a change in soil microbial communities. Since tilling increases erosion risk, the authors recommend tilling only to address problems that cannot be cost-effectively managed with no-till practices.

Transitioning to organic farming

Posted by [email protected] on April 17, 2014 at 5:05 PM Comments comments (0)

As the organic food trend continues to grow; more farmers are converting from conventional agriculture to organic production. One of the fastest growing markets in the U.S. is the production of organic milk. The growth of this industry has prompted many farmers to transition their land to organic feed grain production. With transition on the rise, it is necessary for these farmers to have effective and economical organic management practices.

A research team led by scientists from Penn State University and University of New Hampshire conducted a four-year study examining the impact of reduced-tillage and cover crops managed for hay and forage production on the agronomic and economic performance of feed grain production.

Two cropping system experiments were carried out in central Pennsylvania from 2003 to 2007. For the first year both plots rotated between a cover crop, corn and soybeans; one plot was managed with full tillage and the other with reduced tillage. Changes in weed populations, crop yields, and economic returns over the three year rotation were monitored by the research team.

From a weed management perspective, the results indicate that utilizing reduced tillage for organic production could present a challenge for some farmers. Weed populations were less responsive to the choice in cover crop than to the reduction in tillage. Weed populations dramatically increased in reduced tillage systems.

"This is a troubling result because the weed populations that increased included perennial species such as Canada thistle and bindweed which are very difficult to control without tillage once they become established. In a way, these perennial weeds can actually act as 'management drivers,' forcing organic growers to have to periodically utilize more intensive tillage practices to reduce their populations," says Richard Smith, University of New Hampshire.

The study also suggests that growers who want to transition to organic production while minimizing tillage may experience variable economic success depending on how they begin their rotation. Costs associated with manure and compost, which was purchased off-farm, also strongly influenced the economics of the systems. The authors conclude that integrated systems that include field crop and dairy production, where manure sources are available on-site or locally, would improve the economics of these systems. While tillage did not have a significant effect on cumulative net returns in either experiment, there did appear to be a trend for higher returns in the rotations that utilized full-tillage

Invasion of the slugs; Halted by worms

Posted by [email protected] on April 13, 2014 at 5:55 PM Comments comments (0)

The gardener's best friend, the earthworm, is great at protecting leaves from being chomped by slugs, suggests research in BioMed Central's open access journal BMC Ecology. Although they lurk in the soil, they seem to protect the plants above ground. Increasing plant diversity also decreases the amount of damage slugs do to individual plants.

Spanish slugs (Arion vulgaris) are among the top 100 worst alien species in Europe and are considered a pest almost everywhere. A team of scientists from the University of Natural Resources and Life Sciences Vienna investigated what effect the presence of earthworms and plant diversity would have on the amount of damage these slugs caused.

Using large incubators to simulate grassland environments the researchers could regulate the diversity of plant species and time the introduction of earthworms and slugs. They found that the presence of worms increased nitrogen content of plants and reduced the number of leaves damaged due to slugs by 60%. Yet when they compared leaf area damaged the researchers found slugs also ate 40% less at high plant diversity than at low.

Explaining their results Dr Johann Zaller, who led the study, said, "Our results suggest that two processes might be going on. Firstly, earthworms improved the plant's ability to protect itself against slugs perhaps through the build-up of nitrogen-containing toxic compounds. Secondly, even though these slugs are generalists they prefer widely available food and in high diverse ecosystems slugs eat less in total because they have to switch their diets more often since plants of the same species are less available. Therefore gardeners are to help protect earthworms by increasing plant diversity in the garden in order to keep slug damage low. In order to elucidate the mechanisms behind these complex interactions, all parts of an ecosystem need to be investigated.

Pesticides make the life of earthworms miserable

Posted by [email protected] on April 13, 2014 at 5:45 PM Comments comments (0)

Pesticides are sprayed on crops to help them grow, but the effect on earthworms living in the soil under the plants is devastating, new research reveals: The worms only grow to half their normal weight and they do not reproduce as well as worms in fields that are not sprayed.

Pesticides have a direct impact on the physiology and behavior of earthworms, a Danish/French research team reports after having studied earthworms that were exposed to pesticides over generations.

"We see that the worms have developed methods to detoxify themselves, so that they can live in soil sprayed with fungicide. They spend a lot of energy on detoxifying, and that comes with a cost: The worms do not reach the same size as other worms, and we see that there are fewer of them in sprayed soil. An explanation could be that they are less successful at reproducing, because they spend their energy on ridding themselves of the pesticide," the researchers, Ph. D. student Nicolas Givaudan and associate professor, Claudia Wiegand, say.

Claudia Wiegand is from the Department of Biology at University of Southern Denmark, and she led the research together with Francoise Binet from University Rennes 1 in France. Nicolas Givaudan is doing his Ph. D. as a joint degree between University of Southern Denmark and University of Rennes 1 in France. They researchers reached their findings by metabolomic profiling and energetic parameters.

The researchers set up an experiment to study the behavior of the earthworm species Aporectodea caliginosa. They moved two portions of farmed soil with worms into the lab. One portion was taken from a local organic field, the other from a local conventionally cultivated field that had been sprayed with fungicide for 20 years. This soil had remnants of the internationally commonly used fungicide Opus® at a level common in fields. When crops are sprayed with fungicide, only a small part of the chemical is absorbed by the plant. The waste can be up to 70 per cent, and much of the fungicide ends up in the soil.

In the laboratory, the researchers could see how the fungicide-exposed worms adapted to the toxic environment. Over generations the worms have developed a method to detoxify themselves.

"The fungicide increased metabolism rate in the worms, both the adapted worms and the not adapted worms. In the not adapted worms we saw that their energy reserve of glycogen was used faster. Contrastingly, only in the adapted worms we saw that amino acids and protein contents increased, suggesting a detoxification mechanism. "They also increased their feeding activity, possibly to compensate for the increase in energy demand," the researchers said.

Often there are 2 -- 3 times more earthworms in unsprayed soil than in sprayed soil.

"The reason for this may be that earthworms in sprayed soil do not reproduce as successfully as worms in unsprayed soil, because they need to spend more energy on detoxifying," the researchers say.

They also weighed the worms in the experiment and found that the worms exposed to fungicide weighed only half of the worms in organic soil. Worms in organic soil had an average weight of 0.6 grams, worms in conventionally cultivated soil had an average weight of 0.3 grams

Using ground covers in organic production

Posted by [email protected] on April 13, 2014 at 5:35 PM Comments comments (0)

Studies by U.S. Department of Agriculture (USDA) scientists indicate that organic farmers who need to periodically amend their soils with compost after planting can still control weeds-and hold down costs-by using fabric ground covers. This will be welcome news to organic farmers who till composted manure into their crop fields after planting.

Agricultural Research Service (ARS) soil scientist Larry Zibilske, who works at the agency's Integrated Farming and Natural Resources Research Unit in Weslaco, Texas, set out to see how these ground covers limit water penetration and affect carbon and nutrient levels in soils. ARS is USDA's chief intramural scientific research agency, and this work supports the USDA commitment to supporting sustainable agriculture.

Zibilske conducted a soil chamber study using two types of commercial ground covers: a needle-punched, double-layer fabric, and a tightly woven material made of flat polypropylene strands. He used two types of compost-poultry litter pellets or a compost mix of cattle manure and other organic materials-in the research.

Zibilske monitored the movement of nutrients from the two types of composted materials through the two types of ground covers for 30 days. Water was able to pass freely through the fabric cover, but the polypropylene cover limited the movement of water for the first two weeks. However, water was able to pass through the polypropylene cover much more easily by the end of the study, perhaps because the cover was becoming coated with organic molecules from the compost.

Zibilske found that soil microbial activity indicators were essentially the same in soils protected by fabric covers, soils protected by polypropylene covers, and control soil samples where the movement of nutrients had not been impeded by a ground cover. This similarity suggests that these ground covers did not significantly alter or limit biological activities in the soil. Links were also observed between the use of fabric covers and reduced soil levels of nitrogen and phosphorus levels.

Mix-and-match cover cropping can optimize organic production, USDA scientists say

Posted by [email protected] on April 13, 2014 at 5:20 PM Comments comments (0)

Farmers can fine-tune their use of cover crops to help manage costs and maximize benefits in commercial organic production systems, according to U.S. Department of Agriculture (USDA) scientists.

Production expenses for high-value organic crops like lettuce and broccoli can exceed $7,000 per acre, so producers often try to streamline costs with an annual two- to three-crop rotation. Agricultural Research Service (ARS) horticulturalist Eric Brennan designed a long-term investigation that examined several different cover cropping strategies for an annual organic lettuce-broccoli production system. ARS is USDA's chief intramural scientific research agency, and this work supports the USDA priority of promoting international food security.

The researcher selected three winter cover crops often grown in the Salinas, Calif., area -- rye, mustard, and a legume-rye mix -- and planted each cover crop using either a typical seeding rate or a seeding rate that was three times higher. Seeding rates can influence a cover crop's ability to smother weeds.

During lettuce and broccoli production, Brennan ensured all systems received the same fertilizer and irrigation inputs and pest management. The harvest and sale of the crops, which met all USDA organic standards, were conducted by a commercial harvester.

Brennan's results indicated that all three cover crops yielded more dry matter than the two tons of crop residue per acre often recommended for maintaining soil organic matter. The legume-rye and rye cover crops produced approximately 25 percent more dry matter biomass than the mustard crops. But effectively suppressing weeds with the legume-rye crops required seeding at three times the typical rate, while rye and mustard crops appeared to suppress weeds adequately with typical seeding rates.

The long-term study also provided Brennan with more data about year-to-year yield variations in the legume-rye mix, including why legumes, which make up most of the seed costs, are not consistently abundant. Brennan thinks cooler early-season weather helps legumes compete with the rye. So when a hot and dry autumn is expected, producers might want to use a rye cover crop and skip spending the money on a cover crop with legumes

Paraquat resistance discovered in major weed

Posted by [email protected] on April 13, 2014 at 5:10 PM Comments comments (0)

Scientists at the University of Adelaide have discovered new cases of herbicide resistance in annual ryegrass, one of the world's most serious and costly weeds.

For the first time, researchers have found that annual ryegrass has developed resistance to paraquat, the second most important "knockdown" herbicide used by cropping farmers.

Weed management experts Dr Peter Boutsalis and Associate Professor Christopher Preston, from the University's Waite Research Institute, made the discovery in samples taken from two separate farming properties near the South Australian town of Naracoorte.

Annual ryegrass is a major weed worldwide. It is particularly damaging to crops in countries with a Mediterranean climate, with Australia, South Africa, Argentina, Spain and Italy among the worst affected.

Dr Preston says farmers should be concerned about the development of herbicide resistance.

"This discovery has major implications for farmers," Dr Preston says.

"Paraquat is the only viable herbicide alternative to the most commonly used herbicide, glyphosate. With more than 100 annual ryegrass populations in Australia already having developed resistance to glyphosate, the discovery of paraquat resistance means that none of the currently available knockdown herbicides can be guaranteed to control ryegrass," he says.

"The paraquat resistant ryegrass was discovered on sites where pasture seed crops have been grown for a long time and paraquat extensively used."

Dr Preston says farmers should rotate their knockdown herbicides in alternate seasons and adopt integrated weed management practices.

Dr Preston is the lead investigator on a research project investigating annual ryegrass resistance to glyphosate, which has been funded by Australia's Grains Research and Development Corporation.

Drs Preston and Boutsalis are based in the School of Agriculture, Food & Wine at the University of Adelaide's Waite Campus


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