1. Planting tips for wheat planted after row crop harvest 1 2. Sunflower preharvest treatments 2 3. Fertilizer management for cool-season pastures 3

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1 Number 106 September 14, Planting tips for wheat planted after row crop harvest 1 2. Sunflower preharvest treatments 2 3. Fertilizer management for cool-season pastures 3 1. Planting tips for wheat planted after row crop harvest When planting wheat after row crop harvest, it s important to use the proper nitrogen (N) rates and seeding rates to maximize yield potential. Planting dates are usually on the later side of the recommended range when planting after row crop harvest, which means that tillering will likely be reduced and roots will not have as much time to develop before winter sets in. This means that producers will have to take special care to make sure the plants get off to a good start and have everything they need in the upper layer of topsoil. In general, producers should apply at least part of their N at planting time when planting late after row crop harvest. The amount of N that can be applied with the seed was discussed in e-update No If producers want to apply 30 lbs N per acre or more down with the seed at planting time, that s hard to do with starter fertilizers such as , , or unless they are spiked with UAN or urea, which can damage the seed. So if higher rates of N are desired at planting time, it s often best to surfaceapply the fertilizer. When planting wheat into grain sorghum stubble, producers will need an extra 30 lbs N per acre over their normal N rate. When planting wheat into soybean stubble, producers should not reduce their N rates since the N credit from soybeans doesn t take effect until the following spring. If the wheat is being planted no-till after row crop harvest, N rates should be increased by 20 lbs N per acre over the normal N rate. Seeding rates should be increased when planting wheat late after row crop harvest. It s best to use a seeding rate of 90 to 120 lbs per acre in central and eastern Kansas, and 75 to 100 lbs per acre in western Kansas. When planting more than three week s after the Hessian fly-free date, producers should use a seeding rate of 120 lbs per acre. 1

2 If planting that late or into heavy residue, it s probably a good idea to use a fungicide seed treatment, even on seed that has high test weight and good germination. -- Dale Leikam, Nutrient Management Specialist dleikam@ksu.edu -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 2. Sunflower preharvest treatments Application of a preharvest treatment to sunflowers can speed the drydown time to harvest, help control weeds, and allow earlier planting of fall seeded crops following sunflower harvest. Three treatments are now labeled for preharvest application to sunflowers, including Gramoxone Inteon, sodium chlorate (Defol 6), and Roundup products (Roundup Weather Max, Roundup Original Max, Roundup Power Max, and RT3). Preharvest treatments should not be applied until after the sunflowers reach physiological maturity and the seed moisture is less than 35%. This generally corresponds to the time when the back of the sunflower heads have turned yellow and the bracts are turning brown. The florets on the face of the flower also brush off easily near 35% moisture. Earlier application could result in illegal residues, yield reduction, and loss of quality. Therefore, seed moisture testing is also advised. Gramoxone Inteon and sodium chlorate can provide a little quicker desiccation and drydown of the sunflower seed than the Roundup products, but generally won t be as effective for weed control. Roundup products were just approved for preharvest treatment in sunflowers during the past year under a supplemental label. The only labeled application rate of the Roundup products as a preharvest treatment is 22 oz/a. Sunflowers should not be harvested for seed for at least 7 days after application with any of the three approved treatments. Sunflowers treated with Gramoxone Inteon or sodium chlorate should not be grazed, or the treated forage fed to livestock. Sunflower treated with Roundup products can be grazed or fed to livestock 7 days after application. For more information on preharvest treatments in sunflowers, see the following articles on the National Sunflower Association website: Jeanne Falk, Sunflower District Extension Specialist jfalk@oznet.ksu.edu 2

3 -- Dallas Peterson, Weed Management Specialist 3. Fertilizer management for cool-season pastures Smooth bromegrass and tall fescue (cool-season grasses) require annual fertilization for optimum production. Nitrogen (N), phosphorus (P 2 O 5 ), potassium (K 2 O) and sulfur (S) are the nutrients which most commonly limit cool-season grass production in Kansas. If cool-season grass pastures have not been sampled yet for soil test analysis, this should be done at once. Balanced fertility is essential to optimum yield and high quality hay. For example, adding N will not produce optimum yields if the soil P level is low. Plant and root growth will be limited if the soils ability to provide adequate P to cool season grasses is limited. Likewise for potassium. While the November-February time-frame is optimum for most fertilizer applications to many cool-season grass pastures, there are situations where it might be best to split applications between an August-September application and a November-February application. If split applications are used, it is best to apply P and K during the August- September time period, along with lbs N per acre while applying the remaining N and S fertilizer during the November-February time period. If split applications will not be used, it is best to apply all of the needed fertilizer in the November-February time period. Under what conditions would a split application be preferred? * If the cool-season grass is to be grazed/harvested in both the fall and spring, it is best to make split applications in order to maintain adequate growth and quality for the fall crop. * If the cool-season grass stand has been subjected to drought or overgrazing stress, split applications are preferred in order to provide optimum nutrition for the recovering crop. * If the field is to be used for seed production. Do not apply N fertilizers to frozen soils, however, since there is a real potential of N washing off the field in runoff. Kansas research over the years has demonstrated that urea, ammonium nitrate, and ureaammonium nitrate solution (UAN) are equally effective for cool-season grass production. During the course of many studies conducted over several years, there have been a few years where urea was better than ammonium nitrate and a few years where ammonium nitrate has performed better than urea but the majority of years have found no differences among N sources when applied during recommended time periods. 3

4 The suggested rates of N are: Nitrogen recommendations for cool-season grass Area of state Annual N rate (lbs/acre) New Seeding: All Established stands: Eastern Central Over the years, large amounts of P and K are removed from cool-season grass pastures, and P and K soil test values are often low. Cool-season grasses are relatively responsive to applied P and K if soil tests are low. Crop removal is about 12 pounds of P 2 O 5 and 40 pounds of K 2 O per ton of cool-season grass. If maintaining soil test values is desired over time, then the amounts of P and K removed in the forage will be required. At a minimum, the following suggested P and K application rates should be applied, based on soil test values, for optimum cool-season grass production: Phosphorus suggestions for cool-season grass based on soil test values Mehlich 3/Bray P (ppm) Annual P 2 O 5 rate (lbs/acre) > 20 0 Potassium suggestions for cool-season grass based on soil test values Exch. K Soil Test (ppm) Annual K 2 O rate (lbs/acre) > If the N, P, and K needs of the crop are completely satisfied, sulfur would be the most likely nutrient to limit cool-season grass production. Application rates of pounds of S is the suggested rate of application. Soil ph is sometimes a consideration for cool-season grass pastures. Both forage production and stand longevity are reduced when the soil ph is less than 5.5. At higher soil ph levels, however, cool-season grass responses to lime have been inconsistent in K-State tests. If lime is to be applied, surface-apply no more than 2,000 lbs effective calcium carbonate (ECC) per acre at one time. 4

5 For more information on smooth bromegrass management, see K-State publication C-402 Smooth Brome Production and Utilization, at: -- Dale Leikam, Nutrient Management Specialist These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e-update Editor. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 5