Monthly Archives: April 2022
Signs of spring are all around with tulips and flowering shrubs budding or beginning to break forth in blossom! Have heard of a range of planting conditions and received a variety of questions last week. The following are some considerations as you begin planting or continue to plant this year. Also, John Mick, Pioneer Hi-Bred field agronomist, had excellent planter setting and planting season tips in his agronomy newsletter this week and a team of us share more detail in this CropWatch article.
Honestly, for many of us as agronomists, this spring is a new territory. We’ve dealt with dry conditions and wet ones before, but this situation of not receiving rains, the high winds, and availability of products presents a new challenge for many of us. There’s the saying ‘plant in the dust and your bins will bust’, but there’s also difficulty surrounding herbicide activation and potential ammonia burn from fall/spring applied anhydrous in the seed row.
Soil temps, depth, pops, conditions: We have one chance with planting to start the season off right, so soil conditions fit for planting, seeding depth for corn and soybeans close to 2”, and soil temps in the mid-40’s on a warming trend with no chance of a cold snap within 8-24 hours for soybean and 48 hours for corn are important components to achieving this. I prefer removing one more stress off corn by putting it in the ground when temps will stay over 50F for 5-7 days. It’s been interesting to see the shift in the number of soybean acres planted before corn in the several county area this year. I’m hearing the need for very high down force and difficulty getting planters in the ground, particularly down in the Nuckolls, Webster, Clay, Adams-county areas. Some have shared that no-till ground is working amazing and others have shared the wind removing residue has made the ground extra hard.
Finding moisture has been of concern to both non-irrigated and irrigated farmers as the winds continue. Bob Nielsen at Purdue shared that corn can be planted 3-4” deep based on their research. I wouldn’t put soybean past 2.5”. Regarding seeding rates, I haven’t recommended changing them unless the soybean germination percentage is less than 85%. We do have growers conducting soybean seeding rate studies again this year, and if you’re interested in trying that as well, please let me know.
Some have wondered about planting non-irrigated crops or waiting for a rain. This ultimately will be a grower by grower and field by field decision. We’re only setting at April 25th as I write this and as we think of planting windows vs. planting dates, we are still setting good. Many have asked about watering prior to planting. In general, we’re not recommending it at this time; if we don’t get rains as this planting season continues, we may need to adjust that thinking. Ultimately, we’d say to water before planting if the ground isn’t fit due to extra cloddy or hard soils. For those who applied anhydrous via strip till whether fall or spring, watering prior to planting may help with ammonia burn damage to the seed and to the plant when the roots reach the application zone.
I’ve also been asked about pre-plant herbicides. With the colder soil temps, several have mentioned not seeing weeds thus far. I’m concerned about a few things regarding PREs. One, activation. Most need at least 0.5-0.75” of moisture 5-7 days after application. Some can last on the ground up to 14 days with partial activation. With the wind, my concern is soil particles containing herbicide not staying on the soil surface (depending on tillage practice). Another concern is the moisture levels in soybean fields, planting depth, and PPO-inhibiting herbicides. This is a great chemistry. The challenge can be damage to seeds and seedlings can occur if they come in contact with the herbicide by the seed vee not closing, seed trench cracking, or rain/water-splash onto hypocotyls and cotyledons. Planting soybeans deeper, at least 1.5” (UNL research found best yield at 1.75”), will help allow the soybean to imbibe water from soils that have moisture at that depth. By planting shallow into dry soil, applying herbicide and then having rain or irrigation activate the herbicide, the herbicide can potentially enter the seed when completing the water-uptake process, damaging it. For those concerned about these different situations with pre-plant herbicides, an alternative could be to use a Group 15 product once the corn or soybean emerges. Just know those products won’t kill any weeds that have emerged but will provide residual for ones that come later.
Reminder of York Co. Tire Collection April 30 and May 1 at the York Co. Landfill from 8 a.m.-5 p.m. No tires on rims and participants must show proof of residency. More info: 402-363-2690.
Hope you had a blessed Easter weekend! Reminder that soil temperatures can be viewed at: https://cropwatch.unl.edu/soiltemperature.
Hay and Forage Resources: Resources for buying/selling hay, corn residue, and other forages can be found at the following:
- Nebraska Hay & Forage Hotline: https://nda.nebraska.gov/promotion/hay/index.html
- Nebraska Hay Exchange: http://www.hayexchange.com/ne.php
- Crop Residue Exchange: https://cropresidueexchange.unl.edu/
Fire Damage to Crop Residue: With the dry conditions and various fires that have occurred, have received questions regarding the nutrient value in the residue and/or soil impacts. When residue is burned, most nitrogen and sulfur in the residue are lost; however, the phosphorus and potassium are retained in the ash (as long as they don’t blow away).
In spite of this, short-term nutrient loss from the residue is none to minimal. Research from the University of Wisconsin looked at the need to replace nitrogen to the succeeding corn crop when soybean residue was either removed or not removed. They found no difference in nitrogen impacts to the corn crop regardless if the residue was removed; this suggests there is no need to replace the nitrogen in burnt soybean residue. Research from USDA-ARS in Nebraska, when looking at corn residue removal prior to corn planting, also suggested no need to replace the nitrogen lost from the residue. They found increased mineralization due to the change in C:N ratio when residue was removed. Previous research compiled in this resource from South Dakota State shared the same sentiments: https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1365&context=extension_extra. The SDSU resource is also helpful when walking through a dollar value of other loss considerations.
Regarding longer-term nutrient loss, a UNL NebGuide shares for every 40 bu/ac of corn or sorghum, approximately one ton of residue is produced. Each ton of corn and sorghum residue contains approximately 17 lb N, 4 lb P2O5, 37 lb K, and 3 lb S. For every 30 bu/ac of soybean residue, approximately one ton of residue is produced with 17 lb N, 3 lb P2O5, 13 lb K, and 2 lb S for each ton of residue produced.
Perhaps the greatest losses to consider are organic matter, soil loss, and soil moisture. Regarding organic matter, the soil holds the greatest portion of this. One year of residue is minimal, attributed with the potential of increasing organic matter 0.03-0.06%, depending on tillage type, crop, etc. Soil erosion due to wind/water can result in organic matter loss and loss of more productive soil. This is hard to quantify. Perhaps the more important factor is the soil moisture losses in no-till, non-irrigated fields, particularly in a dry year such as this. Paul Hay, Extension Educator emeritus, years ago shared with me several documented situations where yield losses due to moisture loss were estimated. Corn planted into burned no-till, non-irrigated soybean stubble ranged from 15-28 bu/ac yield loss in two situations. There was 0-3 bu/ac yield loss associated with soybean planted into burned, no-till, non-irrigated corn residue in two situations. Use of soil moisture probes can give an indication of soil moisture differences between burned and non-burned areas of fields or between fields. Direct yield comparisons between fields are difficult to make due to planting dates, hybrids/varieties, agronomic practices, etc., but important to still collect and assess.
Crabgrass Preventer timing: Crabgrass germinates when soil temperatures are maintained at 55F for 5-7 consecutive days. You can watch the CropWatch soil temperature maps at the link listed above. Or, use a meat thermometer (that you dedicate to only taking soil temperature!) for your own lawn situation at a 2-4” depth. Typically, towards the end of April/beginning of May is a good time for the first application, but it will vary by year. So far, this timing is holding true for 2022. When crabgrass preventer is applied too early, it can move out of the zone where the crabgrass seed is germinating. Would also recommend that you consider splitting your crabgrass herbicide application. Apply half of the highest labeled rate when soil temps warm and the other half 6-8 weeks later. Often there’s a flush of crabgrass later in the season and splitting the application can help with that It’s helpful for the products to be watered in within 24 hours for best results.
Cover Crop Termination including Planting Green
Cover Crop Termination: I always enjoy seeing new life and the seasons, so enjoying seeing wheat/rye greening up! Grateful for the excellent discussion around termination timing at the February practical cover crop management meeting! Pictures with more details each farmer shared is at jenreesources.com.
In a column last year, I shared detailed considerations for termination timing (prior to planting vs. planting green). That info. can be found at: https://jenreesources.com/2021/03/28/jenrees-3-28-21/. For this column, sharing key tips from the discussions that may be helpful for this year.
Key points I gleaned:
- While rye may die slowly depending on the temperature and year, it will die.
- Two farmers consistently killed rye with only 20-22 oz/ac of Roundup Powermax (even when headed). For those who planted vetch with rye, the vetch will survive the Roundup application allowing it to grow longer, produce more nitrogen, and be killed by a post-application containing a Group 27 herbicide (like Callisto) later (if want it to die).
- Clethodim vs. glyphosate: Two farmers and a Pioneer rep shared sentiments of clethodim providing a slower kill and allowing the rye to stay greener longer for weed/erosion control. This is of benefit especially for farmers who need to terminate prior to corn or seed corn planting.
- Regarding clethodim rates, several are aiming for the mid-range this year by using 12 oz/ac. Another farmer used 10 oz clethodim + warrant. Many use 8-10 oz/ac to kill volunteer corn in soybean, so a few are also trying the lower rate. When going into corn, clethodim needs to be applied to rye to kill it at least 7 days prior to planting corn. For soybeans, it can be applied anytime after planting/emergence if desired.
- When rye is greater than 12”, consider increasing gallonage to 15-20 gal/ac for better coverage.
- When considering planting corn green into rye on subsurface drip irrigation (SDI), need the ability for higher capacity well to get moisture up to the seedbed. Potential yield loss otherwise.
- When planting soybeans green, the goal is often to off-set the PRE herbicide cost with the cover crop seed and application cost. A residual is necessary at some point either at time of termination or up to a week after termination when planting soybean green. Plan on irrigation or rainfall to get the residual to the ground, especially on rye taller than 12”.
My key points for planting green include: plan on some form of nitrogen at planting if planting corn green into rye, have the pivot ready to go if need moisture for the seedbed, don’t use a PRE in soybean if can’t get seed vee closed, plan to water residual application as soon as label allows to get residual to ground, and if non-irrigated, consider seedbed moisture for termination timing.
Lawns: Lawns are slowly greening up and for those with fall armyworm damage last year, overseeding and/or replanting may be necessary. Consider overseeding now as Kentucky bluegrass overseeding is recommended from April 1-30th and tall fescue from Apr. 15-June 15. The full seeding rate for 1000 sq ft is 3-4 lbs for Kentucky bluegrass and 8-10 lbs for tall fescue; for overseeding, use ½ these rates. Small amounts of sawdust or sand can be mixed with the seed to aid spreading. The area should be prepared prior to seeding by raking to loosen the soil and excess dead growth. Areas can also be aerated or power raked (power raking should only be used if ½” thatch or greater is present). Scotts TurfBuilder Starter for New Lawns can be spread either immediately after seeding or one can wait till the seedlings emerge. Either way, it is safe for the seed/seedlings. Spring rains in April will greatly help with emergence, but otherwise, irrigation by mid-April will be necessary to keep the soil moist until germination occurs. Then apply water deeply and infrequently to encourage rooting. Also check out this excellent brochure for Lawn care in Eastern NE: https://go.unl.edu/mhkd.
Thank You to the following for their contributions to this information: Gabe Bathen, David Cast, Chad Dane, Jay Goertzen, Marvin Linhorst, Ron Makovicka, Kevin Medow, Brad Morner, Scott Richert, Todd Schmeiding, Stuart Spader, and Mike Spray. The photos are mostly mine from field visits other than the ones taken by the farmers from their tractor cabs.