March 1, 2002
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Crop Production Fertility Alfalfa Research Management Resources
Select crops based on available water
Crop producers in some areas of Nebraska may be facing limited water for irrigation in 2002. In
addition, the timing of water deliveries may not work well for some crops, making crop selection
even more important. For example, soybeans need most of their water during pod fill; if water is
not available then, yields are greatly affected.
To operate efficiently, many irrigation districts plan to deliver a minimum of 1 inch of water per week. For example, if 6 inches of irrigation water is available for the summer, the maximum length of the irrigation season would be six weeks - less if water demands are greater than one inch per week.
The Bureau of Reclamation has estimated that the amounts of water listed in Table 1 will be available for 2002. The district uses these estimates to estimate how much to supply water users. In districts where water is expected to be short, the estimates would need to be adjusted if the district does not plan to deliver one inch of water each six to seven days.
As of February 7, snow pack in the North Platte Valley drainage area is approximately 60% of normal. As a result, water supplies are forecast to be near 75% of normal. This forecast assumes that average snow and rain occur this spring. Below normal precipitation will cause this forecast to be reduced even further. We hope that spring and summer moisture will help this situation, but of course we can't count on that.
What are a crop producer's best options? First, check with the appropriate Farm Service Agency, CRC coverage, etc. before making any cropping decisions. Second, when selecting crops, look at when they need water as well as how much water they need. If water is not expected to be available during a critical growth period, consider another crop.
Remember, most tillage operations reduce soil water by 1/3 to 1/2 inch. Reducing tillage operations conserves soil water and the crop residue on the soil surface can help suppress weed growth. Crop residues also will improve infiltration rates of the soil and reduce soil crusting from raindrop impact. Both are especially important when precipitation finally comes in torrents with summer thunderstorms. Also avoid soil moisture loss to weeds. Control weeds on a timely basis by selecting the right herbicide and applying it at the right time.
If corn is selected, stay away from full season hybrids if water is limited. Adjust fertility rates for a lower yield goal. Reducing plant population for corn can reduce water use, but populations must be planted below approximately 16,000 plants per acre before substantial water savings can be expected. Also, studies have shown that water stress early in corn has much less of an impact on yield than water stress during tasseling. If supplies are limited, you may want to delay water application until the crop begins to tassel.
For soybean, if there is a chance water may not be available at pod fill, consider planting the soybean earlier (although frost and some insects may increases risks). Planting early may not gain you a lot on maturity, but it can help some. Soybean flowering is more closely related to photo period (the length of the daily light and dark periods) than with this stage of either corn or sorghum. The shift in soybean from the vegetation to the flowering stage is caused mostly by changes in length of darkness. Soybean flowering is also influenced to some extent by temperature. High temperatures hasten flowering. Given a very warm vegetative period, flowering can start before the dark period begins to lengthen. Since flowering response of corn and sorghum is more temperature dependent than that of soybean, accumulated growing degree days are more reliable for estimating corn and sorghum growth stages than they are with soybean growth stages.
At the Rogers Memorial Farm, 10 miles east of Lincoln, Paul Jasa, Extension Engineer, no-till planted soybean on dryland to evaluate planting date and whether late planted soybean would have adequate rainfall or soil moisture during August for the important pod fill period, the main determinate of yield. In 2000 it rained in July but not in August during pod fill. Table 2 lists planting dates and soybean yield for two maturity dates.
In western Nebraska, dry bean is another good crop choice when facing limited supplies of water. Dry bean needs about 16 inches of water. Early water stress on dry bean has been shown to depress yields somewhat; however, maintaining soil water during flowering can still produce respectable yields.
Most areas of the state have the greatest potential for precipitation in early spring. Even though conditions are dry, excess rain during the spring can result in water loss to deep percolation. Planting a crop such as spring wheat or having winter wheat planted may allow irrigators to take better advantage of the spring rains. The crop is actively growing in the spring and can use the water before being lost.
Conditions may change, but it looks more and more likely that at least some areas will face a shortage of irrigation water. Again, always check with the appropriate agency before selecting crop, planting dates, and other production practices which may affect eligibility for programs.
Robert Klein
Extension Cropping Systems Specialist
West Central REC
Dean Yonts
Extension Irrigation Specialist
Panhandle REC
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After analyzing precipitation trends across the state from Sept. 1, 2001 to now, it is evident that
considerable variability exists from west to east. In general most of the eastern half of the state
remains in the normal range (80-120% of normal), while the western half appears to be much
drier (less than 80% of normal). The worst hit areas are the northern two-thirds of the Panhandle
and western half of the Sandhills.
One and two month precipitation trends are even more ominous as many areas of western
Nebraska have failed to receive 30% of normal precipitation since the beginning of January.
Exceptionally dry areas include the Panhandle, most of the Sandhills, the southwestern corner of
the state, and much of central Nebraska.
In addition to the lack of precipitation, temperatures have been exceptionally warm. Unless the
recent infiltration of arctic air continues through March, Winter 2002 will probably rank as one
of the five warmest in the last 100 years. Because of the unusual warmth, frost depths have been
virtually nonexistent and surface drying has been a persistent problem, with little in the way of
moisture replenishment.
The upper air pattern for most of the winter caused low pressure systems to come ashore in the
Pacific Northwest and move into the northern Great Plains. We have seen a persistent lack of
low pressure systems emanating from the four corners region. It is these types of systems that
give us the Colorado lows that produce widespread heavy precipitation events in winter.
Almost all areas of the state have received less than 50% of their seasonal snowfall. In fact, if it
wasn't for the late January snow, most of the state would have received less that 20% of the
snowfall it typically receives. The lack of major snowstorms across western Nebraska indicates
stream flow rates are likely to be lower than normal this spring. Based on US Geological Survey
stream flow projections, flow rates on the northern and southern branches of the Platte River are
expected to be about 50% of normal this spring. These projections are based upon the idea of
receiving normal precipitation through the end of April.
Snowfall along the front range of the Rocky Mountains has been miserable. In fact, most of
Wyoming has moderate to severe drought conditions. If moisture doesn't materialize soon, all of
Wyoming may be upgraded to a severe drought status.
The lack of snows along the front range also means that reservoir recharge will likely be poor for
Lake McConaughy. Projections indicate ample water supplies for two seasons of irrigation from
Lake McConaughy, however water level declines through summer may force a reevaluation of
allocations.
Enders and Swanson reservoirs face a greater problem. These systems can recharge more quickly
than McConaughy, but would require several extreme snow events within their watersheds this
spring to make up for the past several years of drought conditions. There is a high probability
that irrigation water restrictions will continue through 2002.
Long-lead model outlooks don't offer much in the way of help for the upcoming growing season,
especially for western Nebraska. The models show a bias to warmer than normal conditions
through the first half of the winter.
Although no precipitation tendencies are projected for the Central Plains during the growing
season, above normal temperatures would indicate that crop water demands should be higher
than normal. In addition, a building El Nino may add additional problems as we progress
through summer. There has been a consistent trend toward drier conditions during the late
summer and early fall during the last few El Nino events.
The State Climate Assessment Response Committee was to meet Thursday (Feb. 28) to discuss
many of these issues. I'll provide an update in the next CropWatch.
Al Dutcher
Water levels likely low after warmer, drier winter
As the 2002 production season edges closer, it's time to evaluate factors which may affect
planting decisions. A multitude of potential problems exist, including a lack of precipitation,
low reservoir levels, high wind events, above normal winter temperatures, and the looming El
Nino event predicted to mature by the end of this year.
State Meteorologist
Agricultural MeteorologyNU research: Adoption of GMO soybeans grows quickly, secondary system changes lag
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University researchers conducted an exploratory study in a 21-county area of southeast Nebraska in 1997-1998 to determine why farmers had adopted the new technology and whether they were taking full advantage of the potential crop management benefits that could result from using transgenic soybeans. They surveyed producers identified by their local Extension educators as likely to have planted Roundup Ready soybeans.
In an article to be published in this month's Journal of Extension, the findings were described by the authors: Jim Peterson, Extension educator in Washington County; Ken Cassman, head of the UNL Agronomy and Horticulture Department, and Randy Cantrell, then director of the Southeast Research and Extension Center. Of those responding to the survey, in 1997 65% were using Roundup Ready soybeans and 52% were using Bt corn. In 1998 92% of the respondents were using Roundup Ready soybeans and 78% were using Bt corn. Respondents could be typified as full-time, experienced farmers -- average time farming ranged from 22 (1997) to 24 (1998) years. The average farm size of respondents -1311 acres (1997) and 1411 (1998) - is three times the average farm size of 414 acres for southeast Nebraska. (The average farm size for southeast Nebraska as reported by Nebraska Ag Statistics is likely relatively small due to the number of acreages and small farms near the metropolitan areas.)
Not surprisingly, more than half of the respondents said they had switched to Roundup Ready soybeans because of the expected benefits of better weed control, reduced weed control costs, reduced crop injury and ease of application. In 1997 almost half (49%) tried the new transgenic seed out of curiosity, while by 1998 only 31% cited curiosity as a factor. In the first year of the study 89% eliminated pre-plant and pre-emergence or post emergence herbicides. In 1998 respondents were less apt to eliminate (69% did) preplant and preemergence herbicides and slightly fewer (76%) eliminated postemergence herbicides.
When respondents were asked about disadvantages of using GMO soybeans, they cited expense, expected yield reduction, not being able to use bin run seed and fear of a foreign government ban.
While using the glyphosate-based system does provide the opportunity for changing practices, more than 90% of the respondents said they had not changed planting practices.
Peterson, et al., concluded that the producers who were early adopters of the new technologies were conservative in making changes in management that would allow them to take full advantage of the benefits from planting transgenic crops. Although those responding to the survey indicated that they had eliminated most pre-plant and postemergent herbicides on Roundup Ready soybean, tillage and planting practices basically remained unchanged in 1997 and 1998.
The authors were surprised that "relatively few producers switched to no-till or narrow row practices as they adopted RR soybeans. Because weed control is clearly much easier with the RR soybeans, a greater shift to some form of conservation tillage and narrow row production systems may occur in the future as equipment changes occur on the farm."
Since Peterson's original surveys, producers may have become more comfortable making major changes in their tillage or planting systems. They may've needed to buy new planting equipment, making possible the adoption of a different tillage or planting system. Gradually, as new equipment is purchased, there may be a shift to no-till, narrow row (15-inch) or drilled (7-inch) soybeans.
Please take a few moments to answer the few survey questions. Please include your name if you would like to be included in a drawing for a selection of NU Cooperative Extension publications.
Lisa Jasa
Crop Watch Editor
Jim Peterson
Extension Educator
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While you can't lower the price of anhydrous ammonia, you can manage your fertilizer application to avoid paying for nitrogen the crop won't use. The University of Nebraska has an extensive database of nitrogen field research and demonstrations where various nitrogen rates have been applied to corn and the yields have been measured. These studies can help producers make more informed decisions on nitrogen application. Through 20 years of on-farm testing, NU Institute of Agriculture and Natural Resources scientists have developed a specific method for determining optimum nitrogen rates for corn. There always is some yield variation, but the data is fairly consistent throughout Nebraska.
The NU recommendations put producers very close to maximum yields. At today's prices, the savings easily could add up to more than $10 per acre. Using a realistic yield goal is part of the recommendations. Use a five-year average plus 5%. Our research shows that many farmers use a yield goal higher than that, but fail to reach the yield goal 50% of the time.
NU recommendations indicate that applying 75% to 80% of what was previously applied may actually be the most profitable option, especially at today's nitrogen prices.
When fertilizer prices fluctuate, nitrogen use can be increased or reduced accordingly. Research shows that when corn is $2 per bushel and nitrogen is less than 13 cents per pound or $210 per ton of anhydrous ammonia, it is profitable to add 50 pounds of nitrogen to NU's recommended rate. However, when anhydrous ammonia prices rise above 22 cents per pound of nitrogen or $364 per ton, it is profitable to reduce the recommended rate by 50 pounds. This analysis doesn't include application costs.
Using data from 35 nitrogen demonstrations on sandy soils, average yields were 156 bushels per acre when the total nitrogen applied was 50 pounds less per acre than the NU recommended rate. At the recommended rate, yields were 162 bushels, and at 50 pounds more than recommended, the yields were 165 bushels. Other researchers have found similar results in other areas of the state. (Many of these demonstration sites were on irrigated fields which may have had high nitrate levels. If your field situation is different, adjust the recommended rate accordingly.) Reports indicate anhydrous ammonia supplies are limited and the cost of nitrogen, if available, will be near the point where reducing nitrogen by 50 pounds per acre from the recommended rate will be profitable. If prices rise to 30 cents per pound of nitrogen, use 75% of the university's recommendation for nitrogen, then monitor the crop and add more nitrogen by side-dressing if deficiency symptoms appear.
Charles Shapiro
Extension Soils Specialist
Northeast REC
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Irrigation water
Sample and test groundwater samples for nitrogen. The amount of nitrogen available depends on
the nitrate concentration in the water and the amount of irrigation water expected to be applied by
mid season or later.
Manure
Livestock manure can be a major source of nitrogen; however, the nitrogen content of manure is
highly variable and can deviate widely from book values. To estimate the amount of nitrogen
actually being applied, have a representative manure sample analyzed for ammonium and total
nitrogen, and calibrate the applicator accordingly.
To get complete use of the manure nitrogen, it's necessary to incorporate the manure during application. Ammonium is readily lost when exposed to air. If incorporated two days after application, 50-75% of the ammonium-N is lost. If the manure is not incorporated, ammonium nitrogen losses may be 80-95%.
Manure will continue to contribute nutrients for several years. Organic nitrogen becomes available as manure decomposes. The residual supply of manure nitrogen is estimated to be 12-15% at one year and 5% two years after application. For more information on estimating the value of manure, see the following NebGuides: Determining Crop Available Nutrients from Manure, G97-1335, and Estimating Manure Nutrients from Livestock and Poultry, G97-1334.
Legumes
If the previous crop was a legume, NU recommends that fertilizer nitrogen can be reduced by 45
lb/A for corn and sorghum. This is a conservative estimate -- generally the soybean nitrogen
benefit to a subsequent grain sorghum crop is more than 70 lb/A. If the previous crop was a good
stand of alfalfa, plan for 150 lb residual nitrogen per acre.
Charles Wortmann
Extension Soils Specialist
Weeds like pennycress, downy brome, mustards, cheatgrass, and shepherd's purse are common in first cut alfalfa. They lower yields, reduce quality, lessen palatability, and slow hay drydown. If you walk over your fields today, you probably will be able to see their small, green, over-wintering growth.
You can't do much to control these weeds once alfalfa starts growing; however, if you treat your alfalfa as soon as possible during the next burst of spring-like weather, you can have cleaner, healthier alfalfa at first cutting.
Several herbicides can help control winter annual grasses and weeds in alfalfa. They include Karmex, Sencor, Velpar, Sinbar, and Pursuit. They all control mustard and pennycress. Karmex and Pursuit do not control downy brome very well, but Karmex has some residual soil activity that helps control a few summer annual grasses like foxtail and barnyardgrass.
To be successful, though, you must apply these herbicides soon - before alfalfa shoots green-up this spring - to avoid much injury to your alfalfa. If you wait and alfalfa shoots are green when you spray, your alfalfa growth might be set back two or three weeks.
Bruce Anderson
Extension Forage Specialist
Cutworms feed on newly emerging leaves near the crown of alfalfa. This often slows or delays alfalfa green-up. If your alfalfa seems slow to get started, examine fields closely for cutworms. During daylight they often are found in the loose soil surrounding the plant. If you don't seem them right away, scratch around a little to find them.
Count the number of cutworm larvae per square foot in several areas. The economic threshold for spraying is four or more army cutworms per square foot on established alfalfa, but just two larvae in fields seeded last year. Once alfalfa is four to six inches tall, spraying won't be beneficial unless there's a lot of active leaf feeding.
The best insecticides for controlling army cutworms in alfalfa are the synthetic pyrethroids. These include Ambush, Pounce, Baythroid, and Warrior. Lorsban also works well. Before spraying, read and follow label directions to safely apply the correct rate.
Bruce Anderson
Extension Forage Specialist
This year, the October average daily closing price for December Chicago Board of Trade futures contracts will determine the harvest price for corn crop revenue coverage. In the past, for corn crop revenue coverage, the U.S. Department of Agriculture Risk Management Agency used the November average daily closing for harvest price, said Doug Jose, NU farm management specialist. This change makes corn crop revenue coverage consistent with soybean crop revenue coverage, which already uses October for the harvest price discovery month.
The reason for the change is that, in the cornbelt, corn and soybean yields often are influenced by the same weather events. Under the previous approach, loss adjusters often had to settle soybean losses at one time and corn losses at a later date, Jose said. Under the new plan, both harvest prices will be known by Nov. 1 and loss adjusters can settle claims for corn and soybeans during the same trip to the farm.
In some years this change may help farmers and in others it may not, Jose said.
"Mostly it's just something to be aware of. It probably will not affect producers significantly."
The planting price determination process will remain the same. For corn, that is the average of the December futures contract price during February. The harvest price is used to calculate the actual revenue and to calculate the revenue guarantee in the event that harvest price is higher than planting price.
The same price calculations apply to the grain sorghum insurance contract for this year, except grain sorghum prices are 95% of the respective corn prices.
In addition to the market-based prices for crop revenue coverage policies, the Risk Management Agency (RMA) establishes prices for the multiple peril crop insurance program. The prices, as announced on Nov. 30, 2001, are $2 for corn, $4.92 for soybeans and $1.85 for grain sorghum.v "This year, RMA did not announce additional price elections by the usual Jan.15 deadline," Jose said. "This is due to the potential changes on 2002 commodity prices caused by Congressional deliberations on a new farm bill. The farm bill is currently being negotiated in a Congressional conference committee."
The agency has yet to announce additional price elections this year. That will happen when RMA has sufficient information and no later than July 1. Producers will be notified of any additional price elections by their insurance provider. They then will have 10 business days to notify the provider if they want to change their price.
"Producers may be concerned over the late announcement of price selections, because the sales deadline is March 15," Jose said. "Producers may select an additional price provided they have not suffered a loss, were not prevented from planting before the additional prices were announced or do not suffer a loss within 10 days of the announcement."
Heather Corley
IANR Newswriter
As more people begin to adopt integrated weed management practices, the Guide has begun to reflect these practices. Improvements include:
Corrections
As with any publication of this size, a few errors turn up and we would like to correct those here.
Page 2 - Drs. Pat Shea and Steve Comfort are with the School of Natural Resources.
Page 39 - The rate for Roundup UltraMax postemergence in corn is 26 oz not 25.6 oz.
Page 40 - Paramount and atrazine rate a 5 on triazine-resistant kochia and waterhemp.
Page 77 - Reglone should replace Diquat; use the same rates.
Page 102 -- The footnotes are missing for the replant table in the first printing run and can be printed from the web site.
Page 113 - In the box, the reference to the list of restricted use herbicides should be to page 133.
Page 119 - Extreme CP is registered only for use in RR soybean not conventional soybean.
For those individuals interested in buying the 2002 Guide For Weed Management in Nebraska, please contact your local University of Nebraska Cooperative Extension office. The cost is a very affordable $3/copy. The Guide is also on the Web.
Brady Kappler
Weed Science Educator
WeedSOFT is a decision support system designed to help growers, consultants, and extension educators make both proactive and reactive weed management decisions. This comprehensive and ecologically sound tool will help farmers in every step of their weed management decision. WeedSOFT provides the treatment information you need for your specific field conditions while factoring in economic and environmental principles. Whether you are considering early season soil-applied treatments or control of mid-season infestations or comparing treatments requiring additional costs for herbicide resistant crops, WeedSOFT provides a powerful tool for your weed management decisions.
WeedSOFT treatment data is maintained through annual database updates. Periodic updates also are provided through this Web site to keep the program interface and data as up-to-date as possible. WeedSOFT consists of four modules; Advisor, EnvirFX, MapView, and WeedView. ADVISOR is the heart of the WeedSOFT suite of decision-support tools. ADVISOR provides information to help growers better manage weeds by providing a bioeconomical analysis based on weed biology, weed management efficacy, and production costs. Through query statements, the program generates a list of allowable treatments from an extensive database of possible treatments and control practices. The gain in expected yield resulting from applying a particular treatment is determined and becomes the criteria used to rank the allowable treatments. Treatments may be ranked by expectations of percent maximum yield or "net gain".
EnviroFX is intended to provide information on the potential environmental impact of specific herbicide treatments. EnviroFX estimates relative herbicide leaching and potential for groundwater contamination based on soil and herbicide properties and water table depth. The user may input site-specific values for organic matter content, pH, and cation exchange capacity (CEC) or select default values from one of 17 soil series.
MapVIEW provides a first step in the process of evaluating the risk of groundwater contamination by herbicides. This module is a collection of digitized Nebraska county maps (1:20000) that are color coded to display the vulnerability of certain sites to groundwater contamination from herbicides. Once wite vulnerability is determined, EnviroFX may be used to determine the relative potential of a specific herbicide to reach groundwater. These tools allow the user to make informed management decisions based on soil properties and depth to ground water.
WeedVIEW is a visual library containing color images and line drawings for each of 46 common weed species found in Nebraska. This module facilitates the correct identification of weed species. Images represent a portion of the photographs contained in the book "Weeds of Nebraska and the Great Plains" (Stubbendieck et al. 1994).
WeedSOFT 2002 incorporates:
Brady Kappler
Weed Science Educator
Avoid overapplying nitrogen. Test soils now for residual nitrogen by sampling down to four feet, unless crop-rooting depth is limited due to soil conditions such as coarse sand or a high water table. In these cases a minimum depth of two feet may be appropriate. See story on page 6 and the latest NU recommendations in the NebGuide, Fertilizer Suggestions for Corn.
March 1 or April 15: Which date should you use to file your taxes? How can you use the Deemed Sale Election when computing taxes? To learn more check out these NU Market Journal video interviews on "Tax Planning for 2002" with Gary Bredensteiner, director of the Nebraska Farm Business Assn. The archived Feb. 14 show features information on weed management strategies for 2002.
Seconds are critical when someone is sprayed with liquid ammonia. Immediately flush the exposed body areas with water. Keep five gallons of fresh water in the vehicle carrying the NH3 and another five gallons in the tractor. Carry a six- to eight-ounce eye wash bottle in your pocket to be used in the first few seconds after exposure.
The March 14 edition of UNL's Market Journal will focus on planning grain marketing strategies in light of current market conditions. It also will feature the third video in a series on taxes, produced in cooperation with the Nebraska Farm Business Association. The Market Journal Web site also is featuring a video on UNL research to detect insects in stored grain more quickly and economically. Market Journal is presented by University of Nebraska Cooperative Extension in cooperation with the Nebraska Feed and Grain Association and the Risk Management Agency of USDA.A new University of Nebraska web site offers information for students interested in attending UNL's College of Agricultural Sciences and Natural Resources. See what current students have to say about the value of their experiences at http://grow.unl.edu.
Crop Genetic Engineering
March 19-20, 8 a.m. – 5 p.m., UNL East Campus in Lincoln; $200/$220
Topics: understand the steps required to develop a genetically engineered crop; compare key
differences between developing new traits with genetic engineering technology and conventional
methods; determine the basis for potential problems such as yield drag, allergenicity or pest
resistance; predict the limits of genetic engineering; understand the differences among various Bt
or herbicide resistance events. Registration fee includes resource materials, lunch, refreshments,
parking, CD-Rom of materials. If taking for academic credit, completion of Internet lessons and
an exam after the workshop required. More details available at: http://agronomy.unl.edu/distance_ed. CCA credits: five integrated pest management and nine crop
management.
Farm Level Mapping With GIS/GPS Technology – Introduction
March 19, 9 a.m.– 4 p.m., UNL East Campus, Lincoln; $100/$110
A “lat/long” doesn’t by itself tell you where you are. Make sure you know your “UTM” from
your “WGS84” from your “NAD27” and find out where to get data for your farm base map. If the
weather is right participants will go outside for GPS exercises. (Bring your hand-held GPS if you
like.) CCA credits: six soil and water management.
Farm Level Mapping With GIS/GPS Technology - Applications
March 20, 9 a.m. – 4 p.m., UNL East Campus, Lincoln; $100/$110
How do farmers make money with GIS/GPS technology? This workshop considers “farmer
decisions” — rates of inputs, strategies for soil/plant sampling, variety selection, land leveling,
etc. — and explores how mapping technology helps manage crops better. Look at how
Internet-based information services can play a role in precision agriculture and how to use
weather services and crop models. CCA credits: three in soil fertility and three in water management.
Farm Level Mapping With GIS/GPS Technology - Introduction
March 21, 9 a.m. - 4 p.m. UNL East Campus, Lincoln; $100/$110
Already doing on-farm trials? Working with the Nebraska Soybean and Feed Grain Profitability
Project and have a yield mapping combine? Curious about the possibility of contract research? If
so, this course is for you. We will start with the basics (randomization, replication, statistical
tests) and end “playing” with some advanced techniques (e.g., kriging, multivariate analysis).
CCA credits: six in crop production.
Atrazine and Non-Atrazine Herbicide Comparisons in Conventional Till Corn (NF02-503): Research report: Sequential herbicide applications (preemergence followed by postemergence) were more consistent in weed control across four environments because the postemergence treatments controlled weed escapes and second flushes. Singular herbicide treatments were less effective in that regard. Several single applications gave good control but not the excellent control of the sequential treatments. Atrazine in the preemergence application failed to control velvetleaf, but provided good control when used postemergence. The non-atrazine herbicides were at least as effective as the atrazine herbicides. (Free)
Atrazine and Non-Atrazine Herbicide Comparisons in No-Till Corn (NF02-504): Research report: Although not all herbicides were completely effective in this study, various ones performed well, including atrazine and non-atrazine treatments. The atrazine treatments cost less than most other treatments. The sequential application strategy was consistently better than a single application because the postemergence followup treatment controlled the escapes and second flushes. Single treatments were at a disadvantage in that regard; however, several preemergence, non-atrazine herbicide treatments were noteworthy in their performance. (Free)
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