Oct. 10, 2003

Wheat planting was virtually completed across most of Nebraska with corn and soybean harvest underway. Photo by Brett Hampton

Sample wheat fields this fall for residual nitrate-nitrogen

Soil sampling

Prepare to counter wind erosion in western wheat

Wheat plants may go into the winter stressed, increasing the likelihood for crown and root rot and winter kill. Dry, loose soils are susceptible to wind erosion, which will only be made worse by poor wheat growth and winter kill.

Although we do not know what this fall and winter will bring, it would be wise to be prepared to deal with blowing soil conditions. Emergency tillage may be used to create a rough, ridged, cloddy surface that will be more resistant to wind erosion. If erosion is anticipated, focus efforts on areas in the field most vulnerable to erosion before the wind reaches a critical speed.

If soil conditions are too dry to form clods, crop residues, such as hay, straw, or corn stalks, or livestock manure may be used to prevent blowing from starting in vulnerable areas.

Protect stored grain from deterioration

Rotating temperatures Al Dutcher, UNL state climatologist, says that in the next 10-14 days Nebraska will see two series of rotating temperature trends with highs ranging from the mid 60s to upper 70s and nightly lows sometimes dropping to the mid 30s. A frost isn’t expected during this period.

To understand the importance of both grain moisture content and temperature on safe storage times, consider the results of experiments conducted with corn held at a constant temperature and moisture level in the laboratory.

At 15% moisture the shelf life of corn decreased from 414 days at 55°F, to 206 days at 65°F degrees, to 115 days at 75°F. A rule of thumb is that for each 10 degree increase in temperature, storage time is cut in half when held at a given moisture content.

Fall is also an excellent time to treat musk and plumeless thistles with herbicides. Both plants act as biennials or winter annuals and rarely as summer annuals. Almost all of the plants that flower and produce seed next year will be present as rosettes this fall. That means controlling weeds this fall will usually substitute for a spring treatment. This can help move the workload away from the spring “crunch”. There is one qualification with fall treatments. Examine the area to make certain there are enough plants to justify treatment; a dry summer and fall reduce seed germination and treatment may not be warranted.

With fall herbicide applications, some weather related factors will need to be heeded. Soil moisture must be adequate to support active growth. In drought stressed plants herbicide absorption and translocation can be greatly reduced. With a drought stress situation it is more cost effective to forego treatment until more favorable conditions exist next season. Questions often arise regarding the impact of frost on weed response to herbicides. Frost does not automatically signal the end of the season for applying foliar active herbicides. Many of our most serious biennial and perennial weeds are quite frost tolerant. The key is to examine the foliage. Healthy green foliage indicates active growth and favorable conditions for treatment. If the foliage has become discolored due to low temperatures, the herbicide effect will be reduced.

With leafy spurge the key is to break the stem and check for the presence of the white latex like substance. Bob Masters, formerly at UNL with the Agricultural Research Service, determined that the presence of latex indicated a plant actively growing and responsive to herbicide. Some plants may actually become more susceptible to herbicides after a frost.

Maverick® and Beyond™ herbicides are both effective at selectively controlling downy brome when applied postemergence in winter wheat. Beyond can only be used with herbicide-tolerant wheat varieties in the Clearfield Production System. Beyond herbicide is used primarily to control jointed goatgrass, but is also fair to good at controlling feral rye when applied early postemergence.

Maverick is a sulfonylurea herbicide similar to other common wheat herbicides such as Ally and Amber, with the exception that it may also provide excellent control of grasses in the Bromus genus such as downy brome, Japanese brome and cheat.

Like may of the other sulfonylurea herbicides, Maverick has a long persistence in the soil. Sunflower, grain sorghum, and corn (except for imidazolinone-resistant hybrids) should not be planted for at least 22 months after herbicide application. Soybean should not be planted for at least 12 months after application. Proso millet, sulfonylurea-tolerant soybean (STS™), and imidazolinone-resistant corn, may be planted three months after herbicide application.

Maverick should be applied at a rate of 2/3 ounce of product in 5 to 20 gallons of water per acre per cropping season. It may be applied preemergence or postemergence in winter wheat. A non-ionic surfactant should be applied to postemergence treatments at 0.5% on a volume basis.

In testing by the University of Nebraska, Maverick has given good efficacy on downy brome in wheat when applied early postemergence, that is shortly after the downy brome has emerged in the fall. Control during this time period has ranged from 80% to 100%. Sufficient rainfall prior to late October improved soil activation and root uptake of the herbicide, providing for excellent downy brome control. Without the fall precipitation following application, downy brome control has been closer to 80%.

Applications after Nov. 1 have tended to have much reduced control, probably due to reduced precipitation and a slowing down of plant growth. Spring applications to downy brome have been more inconsistent, with an occasional control rating as high as 85%, but more typically control in the spring has been in the 35% to 70% range. These plants are usually significantly stunted, but still produce seed. Again, precipitation after application appears to be important for improved herbicide activity.

While crop rotation using summer crops is an excellent way to reduce the impact of downy brome in winter wheat, Maverick herbicide may help wheat growers who find themselves with a downy brome infestation despite their bests efforts at cultural control. Growers should be aware of the rotation restrictions with this product and the effects of weather and timing of application on its downy brome efficacy.

The Clearfield Production System for Wheat combines the use of Beyond herbicide with a wheat cultivar containing a gene that confers tolerance to this herbicide. This allows for selective control of winter annual grass weeds such as jointed goatgrass, downy brome, and feral rye in winter wheat.

Wheat cultivars with this gene may be treated with Beyond herbicide with minimal risk of crop injury. Beyond will seriously injure or kill winter wheat cultivars without the tolerance gene. Remember that this is tolerance and not resistance. Tolerance means it can withstand the amount of herbicide recommended but will not tolerate excessive rates. In fact a 2X rate (for example overlap when spraying) may cause crop response. The cost of 4 ounces of Beyond herbicide is approximately $16.70/acre plus cost of application. A grower must take the necessary steps to prevent goatgrass resistance when using this program.

In field research in western Nebraska and throughout the western winter wheat belt, the Clearfield Production System provided excellent (95%+) control of jointed goatgrass and downy brome when weeds were treated with 4 ounces of product per acre in the fall or early spring. Fair to good (80%+) control of feral rye required an early fall application with 5 ounces of product per acre. It provided optimum control of feral rye with little wheat injury when Beyond was applied before rye plants had produced a tiller and wheat had at least three leaves emerged.

Listen to the . . . Oct. 10 Market Journal interview with Bob Klein on "Managing Risk: Skip-Row Planting." Real One player, which is available free on-line, is required to listen to either the video or audio recording of the interview.

The whole idea behind skip-row planting is to keep developing corn plants from using all of the available soil moisture in a field too early in the growing season, said Bob Klein, NU cropping systems specialist, who conducted the trials. Because moisture in the soil between widely spaced rows can’t be reached by the maturing plants until later in season, there is more moisture available to the plants in July and August -- usually the driest months of the summer in Nebraska.

In the trial, they planted two rows to rainfed corn and skipped two rows. With drought conditions prevailing again this year, he said “it looks like there’s quite an advantage to the skip-row planting here in 2003.”

Skip-row planting also should provide some cost savings related to reduced seed, starter fertilizer and in-row insecticide treatments. These savings should more than offset the cost of a postemergence herbicide to kill weeds that develop where there is no crop canopy, Klein said. Roundup Ready corn is an ideal selection for this system because it will allow for the use of glyphosate, a relatively inexpensive herbicide. Potential weed problems also could be limited by planting in a field with a lot of crop residue to suppress weeds.

Two versions of the skip row trial provided 17% and 32% increased yields over the traditionally planted control plot, Klein said.

Following is a breakdown of the yield results:

• Control plot: 19,500 population with 41 bu/ac yield;
• Removing approximately every third plant, 14,700 population with 41 bu/ac yield;
• Thinned with every other plant removed, 11,200 population with 45 bu/ac yield;
• Series of two rows in corn followed by one row removed; 13,700 population with a 48 bu/ac yield (17% above the control);
• Series of two rows in corn with the next two rows removed with a 54 bu/ac yield (32% above the control).

For the trials, plants were removed July 2. Klein estimates that three more inches of soil water would have been available if the plant two rows, skip two rows system had been used from the start of the season. To test this theory, Klein will conduct further trials in 2004.

"Soil structure has greatly improved, that's probably number one," Douglas said.

That soil improvement is a result of Douglas' willingness to stick with no-till for the long haul, said University of Nebraska Cooperative Extension Educator Paul Hay.

No-till methods improve soil structure by allowing surface residue to accumulate, but "it's actually quite difficult to build up the residue very fast because just the natural decay process rots it down," Hay added.

Douglas and Hay discuss the benefits of no-till farming on the Oct. 17 edition of NU Cooperative Extension's "Market Journal Extra."

No-till's long-term impact on soil structure is significant, Hay said. "If you actually measure the bulk density (the weight) of the soil for volume, you find out that in a lot of places in the field, the volume doesn't weigh as much simply because there is so much more space in it," he said. "Even though it looks firm, the amount of air and the amount of water spaces available in that soil are high because of the structure, or aggregate, of the soil."

No-till also can increase earthworm populations, Hay said. He conducted an experiment in which he dug one-square-foot holes at random locations in both tilled and no-till fields. In seven tilled fields, he found an average of one worm per sample. In 16 no-till fields, he found an average of six worms per sample. More worms, said Hay, means better soil.

"Earthworms will make a track up through the soil, come to the surface, grab a piece of residue, and then drag that residue back down into the soil to digest it and eat it," Hay said. The tracks they create becomes a path in the soil through which water and nutrients can move.

Douglas said the improved soil structure has other impacts.

"The structure helps support the machinery so you don't spin and dig around in the mud," Douglas said. "Also, you can go out (to plant) slightly earlier because the soil has internal drainage. It's a little drier."

Sally Mackenzie, a UNL plant geneticist, inspects tiny transgenic plants growing in her lab. She heads a research team that has identified a genetic key that triggers male sterility in plants. Male sterile plants don't produce pollen, which makes it easier to breed improved hybrids and produce hybrid seed. Scientists think their techniques should work on a broad range of crops and vegetables.

Scientists have long tried to develop male sterile plants through a variety of techniques, from tapping natural mutations to inducing sterility through radiation and chemical methods. However, sources of male sterility are nonexistent in some crops, such as soybeans, or limited in others, such as corn. And this characteristic can be unstable -- some types of sterile plants can revert to fertility, which causes problems for growers.

Sally Mackenzie, a University of Nebraska-Lincoln plant geneticist, thinks she's found a genetic key to sterility. It promises to work for a wide range of crops and horticultural products.

Scientists have long known that, in nature, changes in the cells' mitochondrial DNA cause the sterility mutation. Mackenzie and her team followed that genetic trail to recreate the mutation in the lab. They found a gene in the cell's nucleus that controls genetic changes in the mitochondria, which are the cell's energy producers and also contain DNA. By inserting foreign DNA into this gene, they turned it off, observed changes in the mitochondria and pinpointed which change actually triggers male sterility.

They tracked down the gene in Arabidopsis, which they use as a model plant because its genetic code is known, but their findings have broad potential. Because all plants carry this gene that affects the mitochondria, these NU Institute of Agriculture and Natural Resources scientists can use their technique to trigger male sterility in others.

Mackenzie now is growing transgenic soybeans and tomatoes to search for additional male steriles.

"The really cool thing about this is that once I induce a male sterile, it's stable," Mackenzie said. After removing the foreign DNA that caused the original genetic change, the plant remains sterile. But by eliminating the foreign DNA, the plant is no longer considered transgenic.

"That's the beauty of it," she says. "Nobody has to have any qualms about using GMO technology."

Agriculture would benefit if this method of inducing male sterility proves successful. Mackenzie wants consumers to benefit, too. She's applying her findings to develop a sterile, seedless green bean that vegetable buyers should appreciate. Without seeds, the pod is tenderer and more easily digestible. Sterility also tricks the plant into producing three times the number of pods, increasing yields.

While genetically modified crops have helped reduce the need for agricultural pesticides, consumers have yet to benefit directly, she said.

"If we hit the market with our male steriles and, at the same time, come up with our new seedless bean," said Mackenzie, "I think the consumer is going to say, 'this is nice engineering'."

Researchers hope to work with an agribusiness to make sterile males commercially available in a variety of crops. The university has filed for a provisional patent on their technique.

Mackenzie also is looking toward human diseases.

"The recombination that we're looking at in plant mitochondria may actually occur in us as well," she said.

Diseases such as diabetes, Parkinson's and heart conditions may stem from mitochondrial defects that affect one in 8,000 people. As she did in Arabidopsis, Mackenzie is looking for a similar gene in humans that causes mitochondrial changes. If she finds it, researchers could use the same transgenic technique to recreate the genetic defects in mice, a discovery that could launch new explorations in medicine.

Earlier this year, the Nebraska team reported some of its findings in the Proceedings of the National Academy of Sciences. The National Science Foundation and U.S. Department of Energy helped fund this research, which is conducted in cooperation with IANR's Agricultural Research Division.

Gillian Klucas
IANR News Service

2003 corn production up in Nebraska

Soybean production is forecast at 175.5 million bushels, down 3% from last month and slightly below last year. Yields are expected to average 39 bushels per acre, unchanged from last month and just above the 38.5 bushels per acre of 2002. Area for harvest, at 4.5 million acres, is down 150,000 acres from September and down 2% from 2002.

Sorghum production is forecast at 30.1 million bushels, double the production of last year. Yields are expected to average 59 bushels per acre, up 6 bushels from last month and 9 bushels above last year.

Sunflower production of 69.1 million pounds is well above the 24.7 million pounds of last year.

Sugar beet production of 898 thousand tons is up 18% from 2002.

Dry edible bean production of 2.94 million cwt. is down 15% from last year.

Alfalfa hay production is forecast at 5.0 million tons, up 24% from 2002, and all other hay production is up 22% from a year earlier.

Soybean condition rated 13% very poor, 25%, 35% fair, 21% good, and 6% excellent. Ninety-three percent of the crop had dropped leaves, behind 94% last year and 97% average. Harvest progressed to 32% complete, ahead of last year at 31% but behind average at 38%.

Sorghum condition improved and rated 19% very poor, 31% poor, 35% fair, 14% good, and 1% excellent. The crop was mature on 67% of the acreage, behind 88% last year and 89% average. Harvest was 13% completed, although nearly two weeks behind last year at 30% and average at 28%.

Dry bean harvest progressed to 83% complete, ahead of 73% last year but the same as average. Wheat planting progressed to 93% sown, ahead of last year and average at 90%. Seventy-one percent had emerged, ahead of last year at 69% and average at 65%.

Proso millet harvest advanced to 88% complete, ahead of 72% last year.

Alfalfa condition rated 15% very poor, 23% poor, 34% fair, 25% good, and 3% excellent. Fourth cutting activities continued where growth permitted with 86% harvested, ahead of both last year at 83% and average at 80%.

Speakers will include Horst Caspari, Colorado State University viticulturist, who will discuss vineyard irrigation and plant-water interactions based on his lengthy experience with vineyards in New Zealand and Colorado. Speakers from the University of Nebraska-Lincoln will include Wayne Woldt, environmental engineer in the Biological Systems and Engineering department, who will discuss soil-water relationships, and Garald Horst, professor in the Agronomy and Horticulture department, who will discuss the physiology of plant-water uptake. The workshop, which will begin with registration at 8 a.m. and a program at 9 a.m., also will cover drip irrigation methods and equipment, soil moisture measurement, how water moves in the soil, and irrigation timing and techniques. Irrigation companies will display equipment and give brief presentations.

A concurrent session during the morning program will feature vineyard establishment and provide key information for novice grape growers or those planning to start a vineyard. The day will conclude with a sampling of some of Nebraska's finest wines. The workshop is being presented by the University of Nebraska Viticulture Program in cooperation with UNL Cooperative Extension and the Nebraska Winery and Grape Growers Association (NWGGA).

Old crop soybeans stored in all positions on September 1, 2003 totaled 11.9 million bushels, down 10% from last year. On-farm stocks are 4.6 million bushels, up 64% from last year. Off-farm stocks are 7.3 million bushels, down 30% from 2002. Wheat stored in all positions on September 1, 2003 totaled 86 million bushels, up 20% from a year ago. On-farm stocks of 16 million bushels are up 23% from 2002. Off-farm stocks are 70 million bushels, up 20% from last year. Old crop Sorghum stored in all positions on September 1, 2003 totaled 5.9 million bushels, down 47% from last year. On-farm stocks are 400 thousand bushels, down 80% from a year ago and the lowest since 1954. Off-farm stocks are 5.5 million bushels, 40% under 2002. Oats stored in all positions on September 1, 2003 totaled 4.5 million bushels. On-farm stocks totaled 2.3 million bushels, 44% above last year.

Policy Challenges Facing the Livestock Industry

Ag at the Crossroads

The morning sessions will address general trends and legislative and government initiatives related to the livestock industry. Morning speakers will include: John Allen, UNL Department of Agricultural Economics, on "Current Conditions and Trends in Rural Nebraska"; Dave Buchholtz of David and Associates on "Promoting Nebraska Agriculture"; Cheryl Stubbendieck and John McChesney of the Nebraska Farm Bureau on "Nebraska Policy Institute/teVelde Dairy Study"; Sen Curt Bromm of Wahoo on "State Legislative Initiatives Affecting the Livestock Industry"; and Greg Ibach, deputy director of the Nebraska Department of Agriculture, on "Executive Branch Initiatives Affecting the Livestock Industry."

Afternoon sessions will address production and marketing alternatives and country of origin labeling. Speakers will include: Monte Hemenover, consultant, on "Avenues of Change: Alternative Production and Marketing Approaches"; Bob Hilger, a David City producer, on "A Producer Approach to Market Development"; and an audience discussion of production and marketing alternatives.

Speakers addressing country of origin labeling will include: Darrell Mark, UNL Department of Agricultural Economics, on "Potential Economic Impacts from Country of Origin Labeling"; Bill Bullard from R-CALF USA on "The R-Calf Perspective"; and Mark Dopp of the American Meat Institute on "The American Meat Institute Perspective."

The conference is sponsored by the Nebraska AgRelations Council and the UNL Department of Agricultural Economics. Registrations are $30 for members of the AgRelations Council or $35 for non-members. For more information or to make a reservation, contact the Nebraska AgRelations Council, 104 ACB, P.O. Box 830918, University of Nebraska, Lincoln, NE 68583- 0918 or call (402) 472-2821. The registration deadline is 5 p.m. Tuesday, Nov. 4.

Interseeding alfalfa on the Northern Plains: Flowering alfalfa breaks barriers

Recently, since word has spread of the plant's success, falcata has received interest from farmers, ranchers, and researchers who want more information.

Falcata covers about 1,500 known acres east of Lodgepole, South Dakota, on the ranch owned by Norman "Bud" Smith and his son, Tim. They are descendants of the homesteader who received the original seeds nearly a century ago.

"My great uncle started with just a small packet of seeds," says Bud Smith. "Over several decades, it survived on the plains with virtually no help whatsoever." Some time after taking over the land in the 1950s, Smith recognized the potential of falcata and nurtured it to harvest 5 pounds of seeds to plant. "I interseeded it, meaning I placed the alfalfa among my existing shrubs and grasses to increase forage production and palatability," he says.

Alfalfa has long been known as a high-protein feed source for cattle. Trouble is, the hay varieties wither on the Northern Plains under nonirrigated conditions.

According to legend, the traveling scientist first noticed cows and sheep grazing the bright- yellow falcata on the Siberian plains near the Arctic Circle and brought the original seeds back home. Today, the Smiths attribute increased livestock numbers and weight gains without bloat to the fine-stemmed and fine-leaved falcata alfalfa, which they say the cattle prefer.

At home on the range

A day in the life of a rangeland plant is marked by fierce competition for life-sustaining water. Some rangelands receive as few as 10 inches of rain per year. Ten years ago, scientists at the Cheyenne lab concluded that interseeding available varieties of alfalfa would be a good way to increase forage production and quality. But early attempts to interseed legumes on the rangelands showed little promise. "You could get it started, but it wouldn't persist very long," says Schuman. "Within three or four years it would die out."

Then three years ago, Schuman visited the Smith ranch and saw the proliferating, interseeded areas of falcata alfalfa. Since then, Smith has become an eager volunteer collaborator in helping ARS scientists unlock the mysteries of falcata's success.

It seems that most U.S.-grown alfalfa varieties have a long, main root——called a taproot——that grows deep into the soil. Since 80 percent of neighboring plant species sink their roots in a more shallow, distributed network, those plants usurp water that otherwise could sustain alfalfa. "But falcata has a more fibrous root system that's unlike other alfalfas and more like grass," says Schuman. "Falcata's root system allows it to compete with native grasses and forbs for limited moisture."

The lab has since been evaluating the effects of falcata on forage production, forage quality, and soil quality.

Increases in soil nitrogen

Schuman's team includes ARS physical science technician Matthew C. Mortenson and postdoctoral research associate Lachlan J. Ingram. They studied the Smiths' various interseeded acres and found a large increase in forage production——at times nearly double——when compared to noninterseeded rangeland.

For Schuman, the find revived a stalled effort to pursue interseeding alfalfa into rangelands because of the legume's natural ability to replenish nitrogen-poor soil. Alfalfa is able to obtain its nitrogen directly from the air, and under the right conditions, alfalfa's nitrogen can boost nearby grass and forb production.

"A bacterium called Rhizobium forms nodules on roots of the alfalfa, and they convert nitrogen gas in the soil into a form of nitrogen that the plant can use," says Schuman. On farmland where falcata had been interseeded for more than three years, large increases in soil nitrogen have been measured. And plant protein content in these areas has increased by as much as 30%.

Closing in on carbon

In addition to nitrogen fixation, the scientists are interested in the extent to which falcata influences carbon storage in the soil. The more carbon dioxide (CO₂) that plants assimilate -- which increases soil organic carbon and improves soil quality -- the lower the levels of atmospheric CO₂.

Schuman's team found a substantial increase in soil carbon -- by more than 5 tons per acre on some falcata-interseeded rangelands -- when compared to noninterseeded areas.

Plants take CO₂ out of the atmosphere and convert it, using sunlight and water, into carbohydrates. That process produces plant material, nearly half of which is carbon. "If a plant had a skeleton, it would be made out of carbon," says plant physiologist Jack Morgan, who is the research leader of the Cheyenne station. "It's the backbone of all organic material."

By increasing the soil's organic matter through plant residue decomposition, falcata essentially improves soil quality. "Carbon sequestration is the process in which CO₂ from the air is made into plant and root material and then eventually deposited into the soil during decomposition," says Schuman. "We call that form soil organic carbon."

Winter-weather forage

Because falcata has been grazed successfully in winter, the researchers plan to take vegetation samples in late November to test its off-season forage quality.

Schuman says that unlike other alfalfas, falcata's stems are finer, providing cattle with forage in the chilly winter air. The researchers will test the November samples to measure falcata's protein content and gauge its nutritional quality as a feed source for cattle in the winter months.

"We'll continue to study falcata on the Smiths' ranch because of its tremendous potential to increase production and forage quality and to increase the amount of carbon that is stored in soil," says Schuman.

In the meantime, as word of the proliferating yellow-flowering alfalfa spreads, more ranchers are interested in using falcata as a means of increasing forage production.

Rosalie Marion Bliss
USDA ARS Information Staff

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