The "official" publication season for Crop Watch has ended. Updates will be posted to this Web site and the Crop Watch Events page intermittently throughout the winter. Photo by Brett Hampton

Jan. 23, 2003

Early irrigation advised when temperatures warm

Any time soil temperature at the crown level (typically about 1 inch below the soil surface) is above 32^oF, winter wheat and alfalfa will grow, albeit slowly in most winters. Dry, windy conditions this winter have promoted winter growth while at the same time drying out the surface soil in many locations. Winter desiccation is the primary cause of winter kill in alfalfa and winter wheat.

Growers who can apply water, preferably 0.5 inch, to their wheat crop may benefit by using a three- to four-day warm spell of above freezing temperatures to replenish the surface moisture.

A winter irrigation can accomplish two things. It will reduce plant stress caused by dry conditions and moderate soil temperature fluctuations. Wet soil is more resistant to temperature fluctuations than dry soil. Large temperature fluctuations often create more problems for winter wheat than extreme cold weather. Applying water at this time of year could make a big difference in winter survival and spring plant vigor. Growers will need to turn off and drain their irrigation systems before night time temperatures drop below freezing or keep their systems running throughout the night to prevent damage to the system. (Running high-pressure irrigation systems with sprinklers above the pipes in freezing or near-freezing weather is not advised since ice may build up on the pipe and the weight may cause undue stress or damage. In this case you may want to wait until temperatures are expected to be clearly above freezing while it's running.)

Alfalfa has a deeper root system than wheat, but in many cases it also would benefit from preseason irrigation. University specialists have long advocated late fall or early spring irrigation of alfalfa to build up water in the soil profile. Apply only as much as the soil can rapidly absorb so that there is no standing water to freeze and form ice on or near the plant, potentially smothering it.

It can be a fine line between replenishing a critical water source and indirectly damaging the plant. Not applying too much at any one time also will allow for any precipitation to be absorbed. Another advantage of a light spring irrigation is that it will help maintain residue cover, helping to limit erosion from wind.

Drew Lyon
Extension Dryland Crops Specialist
Bruce Anderson
Extension Forage Specialist
Bill Kranz
Extension Irrigation Specialist

Snowfall throughout the Platte River water basins in Colorado and Wyoming got off to a tremendous start in November. By Thanksgiving, snow water equivalency (SWE) of the snowpack was at an average of 125% of normal. By the second week of December, however, the SWE had dropped to 90% of normal, and by Jan. 1, the SWE for the upper Platte watershed in Wyoming was at 52% of normal, for the lower Platte watershed in Wyoming it was at 71% of normal, and for the south Platte watershed in northcentral Colorado it was at approximately 60% of normal.

Streamflow estimates for the Platte watershed continue to be disappointing with projections varying widely. As of January 1, projected flow rates for the spring runoff in the upper Platte watershed range from 17% to 86% of normal. For the lower Platte watershed, spring runoff is projected to be 17%-72% of normal and for the South Platte watershed, 48%-71% of normal.

The high degree of variability in streamflow projections is due to the fact that it’s so early in the snowpack season. Using historical climate records, NRCS can make projections based upon the normal distribution of snowfall during the February-April period. Since most snowpack is accumulated during this period, the range of estimates in future reports will likely narrow.

To further put these numbers in perspective, the NRCS and hydrologists from western states have raised several issues. First, with each successive day without precipitation, the snowpack will lose 0.5% to 1.0% of its peak snowpack total. The snow is not melting, but they are measuring current status against an average peak value that occurs in April. Second, some hydrologists are estimating that up to 20% of the snowpack will be lost to ground absorption due to the extreme drought conditions last summer. If this is the case, snowpack would need to be 120% of normal just to achieve normal runoff.

The Nebraska State Climate Assessment Response Committee (CARC) will meet Jan. 30 to assess the drought situation in the state. I am hopeful that a clearer picture of the hydrological situation will be presented at that meeting. Results of this meeting will be presented in the next issue of CropWatch.

With recent snows the snow-water ratios were in the range of 15-1 to 20-1 so liquid water was relatively minor.

Al Dutcher
State Climatologist

"Though drought and even multi-year droughts such as we are experiencing now are a normal and expected climatic pattern, the current drought is rapidly setting records in a number of areas," said Mike Hayes, climate impact specialist with the National Drought Mitigation Center at UNL.

Moderate to extreme drought conditions extend across the High Plains and much of the West, including more than 30% of the continental United States. At the height of the drought last summer, more than half of the country was affected. Only droughts of the 1930s and late 1950s affected a greater percentage of the country's land mass, he said.

"Only the Dust Bowl years of 1934 and 1936 were drier in Nebraska than what we experienced in 2002," Hayes said.

Nebraska averaged only 20% of normal precipitation in the last 60 days and had about 40% to 80% of normal precipitation in the past year, he said.

The drought has had sweeping effects throughout the Great Plains, the Rocky Mountain West and the nation.

Nebraska's agricultural losses from drought last year are estimated at about $1.2 billion, Hayes said. South Dakota reported agricultural losses of $1.8 billion last year. Colorado estimated $1.1 billion in agricultural losses and $1.7 billion in losses to the state's tourism industry. Wyoming, Montana and Missouri reported similar agricultural losses for 2002.

Drought helped shrink last year's U.S. wheat crop to the smallest since 1972, he said.

• Feb. 10, Knights of Columbus Hall in O'Neill,
• Feb. 11, Jefferson County 4-H Building in Fairbury,
• Feb. 12 at the Ag Center in Holdrege,
• Feb. 13 at the West Central Research and Extension Center at North Platte, and
• Feb. 14 at the Eagles Lodge in Alliance.

"This course is especially important because so many areas are experiencing severe drought conditions," said Dean Yonts, NU irrigation engineer and course co-coordinator. "Producers need to be exposed to water management issues so they can possibly rethink the way they do things to improve for the future."

The central theme of the course will be managing water during drought. Other topics will include methods of monitoring soil water, how to improve water management with limited water supplies and issues surrounding surface and ground water use in the state.

Registration is $25. Certified Crop Advisor credits are available for a $75 registration fee. Up to five CEUs have been applied for in the soil and water area. Fees include lunch and a copy of the Central Plains Irrigation Workshop proceedings. For more information or to register, call Yonts at (308) 632-1246.

"Due to the structural changes in agriculture, cooperatives are increasingly facing challenges in redeeming member equity and generating new member investment," he said. "It is critical for cooperative management teams to address these issues."

In the morning, alternative equity investment and redemption programs will be discussed, including qualified and non-qualified allocations. Ideas for generating new capital will be covered, along with the future of traditional cooperatives investing in value-added processing and joint ventures. The afternoon will feature a panel of speakers addressing loss handling for cooperatives. University economists, attorneys and certified public accountants who specialize in agricultural cooperatives will be available to answer questions about handling losses passed down from regional cooperatives.

Registration is $30 per person before Feb. 7 and $40 after that date. To register, contact Sandy Sterkel at (402) 472-1742. For more information about the meeting, contact Mark at (402) 472-1796 or dmark2@unl.edu.

The seminars will be held at four locations:

• Feb. 24, Red Willow County Fair Community Building, McCook;
• Feb. 25, Orleans Ag Center;
• Feb. 26, City Auditorium, Hardy; and
• Feb. 27 Milligan City Auditorium.

Doug Nagel of Davey, NEGSPA president, said the seminars will include marketing, pricing strategies, risk management, the latest information on sorghum production and technology; value-added markets; the long-range weather and water outlook; and an update on ethanol expansion in the Midwest. Guest speaker Barney Gordon, associate professor of Agronomy at Kansas State University, will discuss production basics, rotation systems and irrigation scheduling.

Mean annual total recharge of groundwater (in mm) Map courtesy of the UNL Conservation and Survey Division. For more maps, including those showing various aspects of groundwater recharge, visit their web site at http://csd.unl.edu/csd.htm

The maps were produced by scientists at the University of Nebraska-Lincoln and are the first of their kind in the state. They should help modelers and resource managers investigating relationships between groundwater pumping, nonpoint-source water pollution, stream-aquifer interaction and streamflow allocation, said Joe Szilagyi, hydrologist with the Conservation and Survey Division and senior author of the map with groundwater geologists Ed Harvey and Jerry Ayers, both of CSD and the UNL School of Natural Resource Sciences.

The two digital maps calculate base recharge and total recharge for the state over 30 years. Recharge is the amount of water from precipitation that replenishes groundwater in storage.

"I think you get a good general picture of the recharge for the state with this technique," Szilagyi said.

The average annual total recharge for the state was 48 millimeters, or about 1.92 inches. However, as with most averages, this is somewhat misleading because the recharge ranges from 3-14 millimeters (0.12-0.56 inches) in an arc around the border with Colorado to a high of 120-140 millimeters (4.72-5.51 inches) in the far southeastern corner.

In addition to the gradient radiating from the border with Colorado and generally trending west to east, the highest recharge rates were in the valleys of the Elkhorn, Platte, Missouri and Big and Little Nemaha rivers and in the Sand Hills. These valleys have shallow depths to groundwater, and the Sand Hills have higher rates because water readily moves through the coarser, sandy soils.

Base recharge is essentially all water not running off the surface but infiltrating the soil and discharging from groundwater into streams over the long term, Szilagyi said. To obtain total recharge, water evaporating from groundwater-fed lakes and moisture taken straight from groundwater by subirrigated vegetation is added to base recharge.

Corn rootworms are the number-one pest of corn, costing farmers hundreds of millions of dollars a year in pesticides and lost crop yields. By being the first pest ever to evolve a way of foiling crop rotations, the corn rootworm may have given genetically modified (GM) crops their biggest boost ever. Now, Agricultural Research Service researchers are partnering with industry to test genetically modified corn's ability to curb this adaptable pest.

Adult western (left) and northern corn rootworms (Jim Kalisch, UNL Entomology) (Photo by Jim Kalisch, UNL Entomology)

Crop rotations are the standard nonchemical way farmers -- both conventional and organic -- limit pest levels. The idea is to plant a crop, like corn, in a field or garden one year and then rotate to a different crop, such as soybeans, the next year. Any corn rootworms that move in to breed and feed on the corn will survive, but their offspring will starve to death the next year, because they'll hatch in a field of soybeans. But a few years ago, something very new and strange happened. The western corn rootworms themselves began rotating fields, to make sure future generations were always born in a cornfield, not a soybean field. Adult beetles began flying out of cornfields just long enough to lay their eggs in soybean fields that would become cornfields the next spring, when their hungry larval offspring would hatch in the soil. Northern corn rootworms took another tack: They laid eggs that took two years to hatch, so they'd hatch when the fields were rotated back from soybeans to corn.

Changing the plant

Now, scientists are looking to control rootworm by using a GM corn that is moving through regulatory channels for possible use for spring 2003 planting. YieldGard Rootworm corn has been genetically modified to produce a protein toxin derived from Bacillus thuringiensis (Bt), a common and naturally occurring soil bacterium. This bacterial insecticide kills rootworms when they feed on corn plants. One concept that will be tested on a large scale is use of a mix of conventional and GM corn seed. The seed-mix concept is based on cooperative research by USDA ARS and Monsanto Company (the developer of the new corn variety). In the field, plants that grow from conventional corn seeds in the mix serve as a refuge for some of the beetles. This ensures there will be rootworm beetles not exposed to Bt available to mate with any Bt-resistant survivors. The offspring will likely not be resistant, which will slow the evolution of beetles resistant to Bt.

Under a five-year cooperative research and development agreement that is up for renewal in 2003, the researchers tested various seed mixtures. They found that those with 10% to 20% conventional corn seed provided the same rootworm control, on average, as 100% genetically modified seed. With rootworm control superior to that offered by a conventional insecticide, the seed-mix approach may provide an effective strategy to slow the evolution of resistance to Bt. While further research is required for seed-mix strategies, the U.S. Environmental Protection Agency is reviewing Monsanto's application to sell YieldGard Rootworm corn for three years only at first. This will allow Monsanto time to conduct additional studies with ARS and university scientists.

The Bt corn offers a way to reduce use of conventional insecticides, says Wade French, an ARS entomologist at Brookings, South Dakota. French and colleagues are researching the seed mix in cooperation with Monsanto and conducting other research on rootworms. The wormlike larvae cause most of the damage to corn by devouring plant roots — their dietary mainstay. French and colleagues evaluate feasibility of seed mixes by rating root damage and plant lodging (falling) and monitoring numbers of adult corn rootworm beetles caught with emergence cages.

So far, all seed mixtures tested have worked as well as conventional insecticide, and most of them did much better. But the mixtures with no more than 10% to 20% conventional corn seeds worked best.

"This makes us think that a seed mix will control rootworms while also slowing down the development of resistance," French says.

Protecting helpful predators

But will the Bt corn also kill beneficial bugs such as ground beetles, some of which are fierce predators of rootworms? The family Carabidae includes more than 20,000 species of ground beetles, making them the second largest group of beetles in the world. Ground beetles are ubiquitous and common in both rural and urban areas, where the larger beetles are often mistaken for cockroaches.

In a study designed to investigate the potential impact of Bt corn on ground beetle species composition, French's colleague Mike Ellsbury, also an ARS entomologist, set up 105 pitfall traps, each one a single plastic cup, or pit, for beetles to fall into. He placed the traps in experimental plots planted with a mix of YieldGard Rootworm corn and conventional corn. The plots were scattered over 40 acres of soybean fields on private farms. By keeping track of the numbers and species of beetles in the test plots, the researchers will have an indication of whether the corn harms the insects.

Ellsbury collected 20,000 ground beetles this past growing season — as many as 5,000 in 48- hours — representing 60 species.

French also placed pitfall traps to monitor ground beetles on private farms, where some farmers are growing another type of Bt corn to control corn borer pests. These farms are part of a national pest-management project designed to reduce the corn rootworm population across the Corn Belt with a variety of techniques, including nonchemical means.

Ellsbury also is experimenting with three nighttime traps created by modifying a commercial mosquito trap. He and colleagues converted the trap from one suspended on a pole in the air to one buried just beneath the soil surface. The trap nabs adult beetles as they race across the surface of cornfields at night, devouring rootworms — and just about everything else they encounter. The researchers attached the rotating trap mechanism to a circular panel of recycled plastic so they could cover it with soil and crop residue, completely disguising it, with only a single pitfall opening exposed at the ground surface.

The trap is like a clock, set to rotate every three hours, so that beetles fall into one of eight different collection bottles. Researchers can then see not only how many and what kind of beetles are present within a three-hour span. This tells researchers exactly when different species of beetles are active, which offers clues as to who or what they're eating.

With the decreasing effectiveness of the crop-rotation strategy in corn farmers' arsenals, growers must increasingly turn to conventional pesticides or beneficial insects to combat rootworms — or to a new weapon: corn plants genetically modified to produce a pesticide that affects only corn rootworms.

Don Comis
USDA Agricultural Research Service Information Staff

As Nebraska crop producers found out Jan. 10, relatively small changes in key supply and demand estimates can devastate prices.

Policy brief

Each year in January, the U.S. Department of Agriculture issues its final estimate of the previous year's crops. This year, the crop production summary was accompanied by a quarterly grain stocks report. Those hoping for a bull market found mostly disappointment in the two reports. By crop, here's a quick overview:

Corn production, at 9.01 billion bushels, only slightly exceeded USDA's November estimate. However, reduced livestock feeding and a slow export pace are taking their toll. Stocks on hand were 125 million bushels higher than the trade had expected. And next Aug. 31, when the marketing year ends, carryover stocks now are forecast at 924 million bushels. This compares to 843 million bushels in the previous estimate.

Soybean production increased 40 million bushels in the January report. While the 2002 crop is still 6% less than in 2001, the bump-up in production reduced fears of supplies running out before the next harvest. Carryover is now estimated at 190 million bushels.

Projected wheat carryover also increased in the January stocks report from 348 million bushels to 418 million bushels. In part, that's because wheat feeding has been less than expected. A relatively slow export pace has added to the problem.

So what happens to prices now that the January reports are behind us? Generally speaking, prices for Nebraska's major crops will be driven almost entirely by demand factors over the next three months or so. The supply side of the market will be relatively less important. We know how much we have on hand from 2002, and it's too early to be concerned much about 2003 crops.

A key for corn will be weekly export commitments. We expect lower feed use because of declining livestock numbers. Exports, however, are always somewhat unpredictable. Recently, export commitments have been disappointing, in no small part because of competition from other exporters. China, in particular, is pushing corn exports with a variety of government incentives.

For soybeans and soybean products, all eyes will be on South American crops in the weeks ahead. Record production is possible, even probable. Unlike corn, China has helped to support U.S. soybean prices with strong, sustained buying. But a huge South American crop and mediocre demand elsewhere in the world would not bode well for spring and summer prices.

Wheat stocks are quite low, both in the United States and around the world, but exports from Australia and Russia are larger than expected. This competition will keep U.S. exports from reaching the levels of the past two years, hardly a positive signal for prices.

Roy Frederick
Public Policy Specialist

About Crop Watch | Agricultural News Events | Archives | Markets Ag Links | Weather | Photos Contributors | Search Lisa Jasa, Crop Watch Editor Rural Routes | Publications | IANR

	Published by The Institute of Agriculture and Natural Resources Cooperative Extension, University of Nebraska-Lincoln, Cooperating with the counties and the U.S. Department of Agriculture
University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture.