Monthly Archives: August 2019
Reducing Nitrogen Losses: Most growers I’ve interacted with desire to be good stewards of the land and leave it better for future generations. Economically, they also need to be increasingly efficient in how they farm. One of these stewardships and efficiencies comes in preventing nitrogen losses and individual farm situations may differ in how the risk of those losses is reduced.
Nitrogen losses occur three primary ways: Leaching, Denitrification, and Ammonia Loss.
1-Leaching: All nitrogen fertilizer eventually converts to the nitrate-Nitrogen (nitrate-N) form. This form has a negative charge and is not held by negatively charged soil particles. Thus excessive rains can allow for leaching of nitrogen below the plant root zone, particularly in sandier soils. Fertilizers that are already in the nitrate form such as urea ammonium nitrate (UAN) and ammonium nitrate are susceptible to leaching upon application. Soil microbes can convert urea to nitrate-N within two weeks in late spring, making it susceptible to leaching loss. Anhydrous ammonia takes longer to convert to nitrate-N because it initially kills soil microbes that would convert it. Less conversion occurs once soil temperatures consistently reach 50°F and lower without excess soil moisture.
2-Denitrification occurs in saturated soil conditions where certain soil bacteria can survive and thrive. The bacteria convert nitrate-N to oxygen and nitrogen gases resulting in nitrogen lost to the atmosphere. Heavy, poorly drained, compacted soils are most susceptible to loss via denitrification.
3-Volatilization occurs primarily in urea based products such as dry urea or liquid urea-ammonium nitrate (UAN) when applied on the surface and not incorporated via rain or tillage. The urea in these situations is converted to ammonia gas via urease enzymes in the soil and plant residues. Up to 15-20% of urea can volatilize within a week after application if the conversion occurs at the soil surface during warm, sunny days, particularly in high residue situation, pH levels greater than 7.0 and on light textured soils. If the urea is injected or incorporated after application, or if half-inch of rain/irrigation is received within 24 hours after application, volatilization risk is essentially eliminated.
In general, to reduce the risk of leaching or denitrification, our Extension Soil Fertility Specialists recommend considering applying the majority of nitrogen close to when crop demand is high with more nitrogen applied during the growing season vs. pre-plant. Research has included in-season and split applications including side-dress with and without use of crop sensors, and/or fertigation. The use of inhibitors is not advised in season as research showed they can release N too slowly for the crop demand resulting in yield loss and/or resulting in increased leaching of nitrogen when it was released too late in the growing season for crop uptake. Inhibitors may help reduce risk of leaching or denitrification pre-plant, but they are not a silver bullet and need to be well targeted in order to aid in reduced nitrogen losses. In general, the research is more supportive for inhibitor use in sandy soils vs. heavier textured soils; yield benefit to a nitrification inhibitor may be none to a few bushels/acre for silt loam or silty clay loam soils. The duration of inhibitor effects depends on soil temperature and may be as little as 1-2 weeks or as much as 6 weeks with spring pre-plant applications. Split application was likely more effective than use of most inhibitors to reduce leaching loss.
Places where inhibitors could be well-targeted to high risk nitrogen loss situations include: urease inhibitor reducing ammonia volatilization with delayed rainfall after urea or UAN broadcast to no-till fields, wheat and pastures, and/or soil pH >7.2; nitrate leaching in a wet spring, especially with sandy soil; denitrification and nitrous oxide emission for poorly drained soil subject to flooding. Other research-based recommendations include considering the addition of alfalfa in rotation 5 of 10 years and including a cover crop in situations where excess nitrate-N may occur, such as seed corn. Two tools developed by UNL for helping quantify the risk of nitrogen loss include the Nitrogen-Loss Assessment Tool (N-LAT) and Maize N which can be accessed at: https://cropwatch.unl.edu/soils.
Crop Update and Hail Damage: While I don’t remember numbers as well, calendar dates are something I tend to remember. And, in agriculture, there’s numerous dates that accumulate over one’s life from hail, tornado, blizzard, flood, and wind events. I was reflecting on the Aug. 6th hail storm that occurred in Merrick, York, and Seward counties in 2018. This past week on August 7th, some woke up to hail/wind damage in Adams, Clay, and Nuckolls counties. The tree damage was incredible. Michael Sindelar, Clay Co. Educator, and I surveyed damage a day later. My estimation of the worst hit crops: corn around 80% defoliation with varying percentages of greensnap above/below ear and soybeans around 50% defoliated/broken off/with at least 50% pods on the ground. Where hail stones hit the ears, the kernels are mushy and mold is already setting in on corn at milk stage. There’s also mold setting in on soybean pods hit with hail stones. It’s hard to receive crop damage any time. The good news is that nothing appears to be a total loss; the majority of what we looked at was less than 40% defoliated and in general, the hail did not seem to penetrate the stalks, thus early stalk rot doesn’t appear to be setting in. Pictures at https://jenreesources.com.
Tree Problems: The majority of my questions the past 10 days were regarding tree leaves turning yellow and dropping from trees. They look stark against green grass. In general, what’s happening is the fact that we’ve had high humidity for a period of time now and we’ve had rain throughout spring and summer. Fungal pathogens thrive in these conditions. So, ornamental/flowering pears have pear rust; crabapples and apples have scab and also cedar-apple rust (depending on varieties); maples, ash, sycamores are showing anthracnose; and a number of other fungal leaf spots are observable on shade trees in general. Evergreen trees show various fungal needle spots. Ultimately, we don’t recommend doing anything for these diseases this time of year. We typically don’t recommend to spray shade trees in general, but fruit and evergreen trees should be sprayed in the spring if fungal diseases have occurred in the past. So, fungal diseased leaves may drop early and you may or may not observe a new flush of leaves yet this year. These fungal diseases won’t kill deciduous trees. They can kill evergreen trees over a period of years.
Oak leaves turning brown in clusters was also observed this past week. Sometimes
browning of leaves can be due to a fungal disease called anthracnose. Most of what I’m seeing, I believe, is environmental. It could be due to changes in hot/cool and periods of heavy moisture followed by lack of moisture on trees that had a huge flush of leaves due to moisture this spring. I really don’t know the cause for sure, but it doesn’t appear to be disease related from what I can tell. We wouldn’t recommend doing anything for the trees at this time.
UBBNRD Public Hearing: The Upper Big Blue NRD will hold a public hearing and informational open house on Aug. 19 at 7:00 p.m. at the Holthus Convention Center. The purpose is to receive comments on proposed changes to District Rule 5 – Ground Water Management Area Rules and Regulations. A complete copy of Rule 5 and the proposed changes are available at the district office and at www.upperbigblue.org/publichearing. The public will have the opportunity to learn more about these proposed changes and their effects, and address NRD board members about their concerns or support.
The proposed changes would stipulate that an approved nitrification inhibitor must be applied at the manufacturer’s recommended rate with pre-plant nitrogen fertilizer in the following situations: The application of anhydrous ammonia prior to March 1; The application of all nitrogen fertilizers other than anhydrous ammonia after February 29. In addition to these requirements, in Phase II and Phase III areas pre-plant application of nitrogen fertilizer shall not exceed 120 lbs. per acre. The remaining nitrogen fertilizer may be applied post plant. Prior to applying nitrogen fertilizer, but no later than April 1 of each year, each operator in the management area will be required to report information regarding the use of best management practices. For more information, visit www.upperbigblue.org or call (402)362-6601.
York County Corn Grower Plot Tour will be held Aug. 20th from 5-7 p.m. at 1611 Rd. 14 east of York. Pizza and refreshments will be provided and check out the latest hybrids. Guess the winning yield without going over and win a $50 gas card. All are welcome!
*End of News Column. Hail damage photos below.
Thank you to everyone who “pulled together” to make the 2019 York County Fair a success! Reminder of the Seward County Fair in Seward August 8-11 and you can find details at: http://sewardcountyfair.com/.
Cash-Rent Workshops: Nebraska Extension land specialists will address common agricultural landlord and tenant questions such as: What does an equitable rental rate look like for my land? How do I manage a farmland lease? How could the lease be adjusted for recent flood damage? What should I expect for communications between the landlord and tenant? What are key pasture leasing considerations including stocking rates? Who is responsible for cedar tree removal from grazing land? What does it cost to raise crops on my ground? The closest locations to our area are listed below. Registration is 15 minutes prior to start time. The cost is $15 per person or $25 per couple. Registration will include refreshments and handouts.
- Aug. 8, 10 a.m. – 2 p.m.: Eastern Nebraska Research and Extension Center near Mead (includes lunch). RSVP: 402-624-8030 or email@example.com
- Aug. 19, 10 a.m. – 2 p.m.: St. Paul Community Library, 1301 Howard Ave., St. Paul (includes lunch). RSVP: 308-754-5422 or firstname.lastname@example.org
- Aug. 20, 9 a.m. to noon: Saline County Extension Office, 306 W 3rdSt. Wilber. RSVP: 402-821-2101 or email@example.com
- Aug. 21, 1 – 4 p.m.: Lancaster County Extension Office, 444 Cherrycreek Rd., Lincoln. RSVP: 402-441-7180 or firstname.lastname@example.org
Nebraska Soybean Management Field Days will be held August 13-16 and will offer farmers research-based information to improve their soybean profitability. Locations are Sargent on Aug. 13; Pilger on Aug. 14th; Plymouth on Aug. 15; or Waverly on Aug. 16. The field days begin with registration at 9:00 a.m. and conclude at 2:30 p.m. More details at: https://go.unl.edu/2019smfd. Topics include: Making Sense of Production Costs and Policy Changes; Soybean Insects & Cover Crops; Hail Damage Impact on Growth & Development of Soybeans; Management of Cover Crops & Soybean Insects and Pathogens; Soybean Weed Control & Cover Crops; Cover Crop – Pros & Cons Associated with Soybean Production; Soybean Production & Agronomic Topics Associated with Cover Crops – Planting Rates, Row Spacing, Planting Dates, Maturity Groups, Irrigation Management. CEUs available for Certified Crop Advisors.
Soil Health Workshop will be held on August 22 at the Eastern Nebraska Research & Extension Center near Mead. This hands-on workshop is geared for anyone interested in learning more about soil health including home and acreage owners, farm operators, and industry consultants. Topics include: management considerations to improve soil health; measuring bulk density, porosity and infiltration and the impact on soil health; physical soil properties – the foundation for soil health; cover crops for improving soil health; what is soil biology – active carbon test; soil characteristics, productivity and landscape position; and chemical soil properties. CCA credits have been applied for (6.5 Soil & Water Mgt.). Details at: https://enrec.unl.edu/2019MidwestSoilsClinic.pdf or call (800) 529-8030.
West Central Crops and Water Field Day will be held on Aug. 22 at the West Central Research & Extension Center in North Platte. Registration begins at 8 a.m. with program from 8:45 a.m.-5 p.m. This Field Day offers a unique opportunity for anyone interested in water to learn and see irrigation practices and cropping systems on a farm scale that maintain or increase crop production while conserving water. Approximately 25 commercial vendors will be on hand to provide live demonstrations of how their products can help farmers manage their fields. UNL-TAPS updates and field tours will be included. Details at: https://extension.unl.edu/statewide/westcentral/water-crops-field-day/.