South Dakota Walking Your Fields newsletter-June


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The June issue of Walking Your Fields newsletter contains articles about: Nitrogen loss after excessive rainfall, glyphosate restrictions, corn stand evaluation, and early season sunflower management.

Articles are written by DuPont Pioneer agronomists in South Dakota and distributed on behalf of DuPont Pioneer account managers and Pioneer sales reps.

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South Dakota Walking Your Fields newsletter-June

  1. 1. Heavy spring rainfall causes concerns about nitrogen (N) losses in corn fields and raises questions about the need for supplemental N applications. In general, leaching losses are more likely on sandy soils where water can move through the profile quickly. Denitrification is more likely on medium and fine textured soils that are not well drained. The exact extent of N losses through leaching and/or denitrification following the heavy rains is difficult to determine. Both of these loss processes occur through the nitrate form of N, so the potential for significant loss is determined by the amount of the crop N supply that was in the nitrate form when the excess rainfall occurred. Losses depend on many factors such as when the N was applied, the forms of N applied or expected to provide N for the crop, soil characteristics, and soil moisture. Where fertilizer N was applied before planting, the timing of the application and the form of N used are important in determining the risk of loss. Keeping in mind that losses occur through the nitrate form of N, the timing of nitrate formation is an important consideration in evaluating po- tential losses. Fall-applied fertilizer N has a high risk for loss following excess rainfall because most or all of the N would be in the nitrate form by mid-May. For spring pre- plant applications, ammonium forms of N such as anhy- drous ammonia or urea are converted to nitrate-N in about 4 to 6 weeks. Urea usually is converted to nitrate more rapidly than anhydrous ammonia. Nitrogen solu- tions (28% UAN) contain half of the N as urea and the remainder as ammonium nitrate. Essentially, this fertilizer contains 75 percent of the N as ammonium and 25 per- cent as nitrate when it is applied. Denitrification losses can occur within a few days if the soil remains saturated or flooded and nitrate-N is present. Warm temperatures and extended periods of saturated conditions favor high losses. Work in Illinois suggests that four to five percent of the nitrate-N present can be lost each day the soil remains saturated. Table 1 from the University of Nebraska provides some estimates of deni- trification losses at various temperatures and times of saturated soil conditions. WALKING YOUR FIELDS® newsletter is brought to you by your local account manager for DuPont Pioneer. It is sent to customers throughout the growing season, courtesy of your Pioneer sales professional. The DuPont Oval Logo is a registered trademark of DuPont. PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents. ®, TM, SM Trademarks and service marks of Pioneer. © 2013 PHII. Kyle Christensen Field Agronomist Ryan Nuttall Product Agronomist Jim Ruhland Field Agronomist June 10, 2013 - Issue 3 NCGA National Corn Yield Contest For nearly a half century, the National Corn Grower‟s Association‟s corn yield contest has provided corn grow- ers an opportunity to compete with colleagues to grow the most corn per acre ~ helping feed and fuel the world. This NCGA contest has given participants the recognition they deserve as well as an opportunity to learn from their peers.  June 15: Early entry deadline. Cost per entry $80.  July 12: Final deadline to have all entries submitted. Cost per entry $110 Do you have a nice looking field of Pioneer corn? Enter a Pioneer® brand hybrid in the yield contest and all entry fees and membership dues are paid by Pioneer directly to NCGA. Talk to your Pioneer Sales Representative about your entry. On-line entries are available by following this link: N Losses Following Excessive Rainfall Continued on pg 2 Table 1. Estimated denitrification N Loss- es as influenced by soil temperature and days saturated. Soil Temp (°F) Days Saturated N Loss (% of applied) 55-60 5 10 10 25 3 60 75-80 5 75 7 85 9 95 Source: Shapiro, University of Nebraska.
  2. 2. Options for applying supplemental N when it is needed include traditional side-dressing with anhydrous ammonia or N solutions. Where the entire crop N requirement has not yet been applied, side-dress or other post-emergence applications should contain the balance of the crop N re- quirement plus 25-50 percent of the N that was already applied. Urea-ammonium nitrate solutions (28%) can also be applied as a surface band or as a broadcast spray over the growing crop. Dry N fertilizers such as urea or ammonium nitrate can also be broadcast applied to the crop. Leaf burning from solution or dry broadcast applica- tions should be expected. Applying the dry materials when foliage is dry will help to minimize burning. Basical- ly, broadcast N rates should be limited to 90 lbs. N/acre for corn with four to five leaves and to 60 lbs. N/ acre for corn at the 8-leaf stage. Under N deficient conditions, corn will respond to supplemental N applications through the tassel stage of development if the N can be applied. To help you assess potential fertilizer N losses, download the simple and reliable Supplemental Fertilizer N Work- sheet from the University of Minnesota. http:// (Source: Schmitt and Randall, U of MN) (Source: Portions of this article are from Dr. Larry G. Bundy, U of WI Extension Service, „Evaluating Nitrogen Losses Following Excessive Rainfall.‟) Glyphosate on Corn Corn can be damaged by spraying glyphosate too late in the growing season. Ears appear to have aborted ker- nels or scattered pollination. It can be easy to diagnose when only part of the field has been sprayed. There is a distinct line and difference between sprayed and un- sprayed portions of the field.  Corn may be sprayed broadcast or over the top with glyphosate until it reaches V8 stage or 30 inches in height (whichever comes first).  Corn can be sprayed be- tween 30 and 48 inches with a ground rig employ- ing drop nozzles that direct the spray to the base of the corn plants and avoids direct application of spray solution into the whorl of the corn plant. Glyphosate on Soybeans Spraying soybeans with glyphosate can occur through R2 stage. Reproductive phases are as follows:  R1--Plants have at least one flower on any node.  R2--Plants have at least one flower open on one of the two uppermost nodes (Four days after R1).  R3--A 3/16 inch pod at one of the four uppermost nodes (Ten days after R2). After you see the first flower, you have approximately two weeks to spray glyphosate to stay on label. This recom- mendation is a clarification of previous definitions of spraying glyphosate on soybeans throughout flowering. The average yield of corn in the U.S. and Canada has tripled over the last half-century. Yield gains have result- ed from improved hybrid genetics, more precise soil fertil- ity practices, better weed control, and advances in other production methods. Among these factors, genetic im- provements have contributed the most to yield gains, adding from 1.0 to 1.5 bu/acre each year. To accomplish these increases, corn breeders have selected for superior tolerance to drought and other stresses, and yield stabil- ity across diverse growing environments. A key result of enhanced stress tolerance is adaptability of hybrids to higher plant populations. Optimum economic returns of- ten require plant populations of 35,000 plants/acres or more, depending on the hybrid and environment. Obtain- ing these higher plant populations is essential, especially at higher yield levels. Corn stands can be reduced by many issues such as cold or wet soils, insect feeding, poor seedbed, and equipment issues. The best time to evaluate stands and the effectiveness of planter equipment, residue manage- ment and seedbed preparation is shortly after emer- gence. Stand counts. Take several sample counts to represent the field or area under considera- tion. For ease of calcu- lation, a sample size of 1/1000th of an acre is recommended (Table 2). Measure off the dis- tance appropriate for your row width, count the number of live plants and multiply by 1000 to obtain a reasonable es- timate of plants/acre. Restrictions on Spraying Glyphosate Ear on left shows irregular kernel set resulting from a late glyphosate application. Ear on right is from unsprayed plant in same field. Photo by Clyde Tiffany, DuPont Pioneer. Evaluate Corn Stands: Identify Areas for Improvement Table 2. Row lengths equal to 1/1000th of an acre. Row Width Length of Row 38 inches 13 ft. 9 in. 36 inches 14 ft. 6 in. 30 inches 17 ft. 5 in. 22 inches 23 ft. 9 in. 20 inches 26 ft. 2 in. 15 inches 34 ft. 10 in. Continued from pg 1
  3. 3. Stand counts should be taken randomly across the entire area of the field. The accuracy of your stand estimate will improve with the number of locations sampled within the damaged area. Stand uniformity. Evaluate whether plants are evenly distributed or if the stand is uneven. Gaps and doubles indicate an equipment or seedbed problem and reduce yield. Identify Problems and Plan for Solutions. After you have evaluated stands and uniformity, make every effort to identify the causes of any observed problems. Were metering devices working properly? Were row cleaners set properly and working effectively? Was planting depth proper and consistent? Was residue managed effective- ly? Were monitors effective in identifying metering devic- es or other equipment problems when they occurred? Was pre-plant tillage uniform, and did it create a quality seedbed? Continuously improve your planting operation by making sure to implement solutions to any problems observed. Of all the crops grown around the world, only one was domesticated from North America, the sunflower. Sun- flowers are a key crop for the northern and western plains of the U.S. In central and western South Dakota, sunflow- ers are a great fit in the cropping rotation. Other attractive characteristics include a relatively short growing season, shorter than most fall crops to help spread out work load during planting or harvest, and excellent drought toler- ance. Planting Depth. Proper planting depth is critical in es- tablishing strong lateral roots for nutrient and moisture uptake. The ideal planting depth is 1.5 to 2 inches deep, similar to corn. The seed should be placed into moisture but not deeper than 3 inch- es as percent emergence will decrease. Sunflowers have a “woody hull” so ex- cellent seed to soil contact is critical and closure of the furrow becomes more im- portant than for corn and most other crops. Planting Date. Sunflowers can be planted from May 1 until late June. Best yields are usually obtained from late May to early June planting dates. More important than the calendar date is having soil temperature of 50°F or more at seed depth. 65°F is better suited for optimal germina- tion and growth. Scout for Early Season Insects and Weeds. Typically the only insect to keep an eye on in the early seedling stage is an infestation of cutworms. These caterpillar-like larvae are usually cream color to gray-brown, often with dark mottling or stripes as seen in photo. Cutworms damage can be observed by chewing at, or slightly above, ground as the plant emerges. The eco- nomic threshold is one per square foot or 25-30 percent stand reduction. Management options include several different post applied insecticides that are registered for cutworm control. Early weed control is essential to maximizing yield poten- tial in sunflowers. Knowing the field‟s weed history will help plan for successful weed control options. For emerged weeds, apply a burndown (glyphosate) in conjunction with a residual herbicide (sulfentrazone) as a pre-plant application. For in-season weed control, utilize the Pioneer® brand sunflower hybrids with the DuPont™ ExpressSun® trait for tolerance to DuPont™ EXPRESS® herbicide with TotalSol® soluble granules. EXPRESS herbicide can be applied as a post application, controlling Canadian thistle and many other broadleaf weeds. DuPont™, Express® , ExpressSun® and TotalSol® are trademarks of DuPont or its affiliates. Photo:TomDoerge,DuPontPioneer Early Season Sunflower Management Photo: NDSU Extension Photo: NDSU Extension Entomology Department
  4. 4. WALKINGYOURFIELDS® KA Christensen, Ruhland, Nuttall DuPont Pioneer Sales & Marketing PO Box 466 Johnston, IA 50131 ADDRESS SERVICE REQUESTED PRESORTED FIRST-CLASS MAIL U.S. POSTAGE PAID PHI CUSTOMER INFO Follow your DuPont Pioneer Agronomist @PioneerSDakota In this issue:  NCGA Yield Contest  Nitrogen Management  Spraying Guidelines  Evaluate Corn Stands  Sunflower Management This Walking Your Fields® newsletter is brought to you courtesy of your Pioneer Sales Representative and DuPont Pioneer Account Manager. Joel Bierman Account Manager Scott Johnson Account Manager Kyle Kayser Account Manager Cole Cotton Account Manager Tye Kjeldgaard Account Manager Pat VanLith Account Manager Troy Boomsma Account Manager Lance Kuehl Account Manager