Blog Archives
Frost Damage and Planting
Praising the Lord for some rain! It’s incredible how quickly planting occurs and how much is done. This past week was mostly spent looking at frost damage to wheat, rye, oat, and cover crop forages. Frost damage is worse in fields that are drought and/or moisture stressed and those that have poor stands and/or a poor canopy.
- At 24°F for two hours during jointing in wheat can cause leaf yellowing/burning, death of the growing point, and splitting or bending of the lower stem.
- At 28°F for two hours during boot in wheat can cause the florets to be sterile, heads to be trapped in the boot, damage to the lower stem, leaf discoloration/burning, and odor.
What I’m looking for in the fields: Look for any new growth from the main stem and tillers in the small grains. Split some stems and look to make sure the growing point with the developing head is yellow-green and firm, not brownish and mushy. The good news is that while one tiller may be injured, others on the plant may be ok. The mixture of normal and late tillers can cause uneven maturity though and potential grain yield reduction. Also notice the stem nodes. I have seen even in the better areas of some fields, if the wheat was fairly tall, that some of the lower stem nodes are becoming discolored and splitting. This can cause those tillers to fall over. Those tillers can still provide some nutrient transport to the head, but the lodging can be a pain at harvest and yield reduction will occur. For more information, the following is an article from 2020, but the info. on damage and what to look for is still relevant: https://go.unl.edu/2h7z.
Looking at the week ahead, for those who are planting, be aware of planting windows. We have some cold nights coming after some cold rains this weekend where soil temps have dropped. We say to avoid planting corn 48 hours before a cold snap and soybeans 24 hours before a cold snap. That’s assuming the seed is planted into moisture and begins the germination process. Corn seed needs to absorb 35% of its weight in water and soybean seed needs to absorb 50% of its weight in water in order to complete the initial imbibition (water uptake phase) and be capable of withstanding drops in soil temperatures after that.
Drone Dispatch: Dirk Charlson, our Extension Educator for Digital and Precision Ag, is releasing a newsletter called the Drone Dispatch. Published on the first Tuesday of each month, this newsletter is a product of Nebraska Extension, created to support producers, professionals, and communities using unmanned aerial systems (UAS). Across Nebraska, drones are already transforming agriculture, infrastructure, and emergency response. With that growth comes both opportunity and responsibility and this newsletter is here to help you navigate both. Let’s fly safe, fly smart, and keep Nebraska on the leading edge of drone innovation. If you would like to subscribe to The Nebraska Drone Dispatch, suggest a story or upcoming event, or would like your business or organization featured, please complete the contact from at go.unl.edu/TheNEDroneDispatch.
Forage Resources for Drought and Wildfire: We continue to hear of the need for forage resources between the drought and wildfire impacted areas in Western Nebraska. If you have available pasture and/or cover crop or other forages that you’re willing to custom graze cattle on, please list those resources on both of these places: https://www.pasturematch.com/ and https://nebraskagrazingexchange.com/.
UNL Agronomy/Horticulture Retirements will be celebrated on May 8th with a reception from 2-4 p.m. at the Goodding Learning Center, Plant Sciences Hall at UNL East Campus. Rhae Drijber retires June 30 after 32 years of service. Daren Redfearn retires May 6 after 12 years and Jerry Volesky retires June 30 after 31 years of service to the University of Nebraska–Lincoln. The online guestbooks can be signed at:
https://go.unl.edu/redfearn-retire
https://go.unl.edu/drijber-retire
https://go.unl.edu/volesky-retire
JenREES 4/17/22
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.
JenResources 