Nitrification Inhibitors: For the next several weeks I will share data from on-farm research studies. Nitrification Inhibitors are best thought of as an insurance policy against loss of applied ammonium-based fertilizer due to excess rain in the first month or so after fertilization. For spring applications, some active ingredients have been proven by research to slow the conversion of ammonium to nitrate for at least two weeks, with a range of 1-6 weeks, depending on soil temperature. They are one tool (not a silver bullet), when used at right place and time, for aiding in nitrogen management. To summarize the research below, nitrification inhibitors are less likely to have a significant impact on increasing yield and reducing nitrate leaching in silt loam and silty clay loam soils as compared to sandy soils.
An ongoing study at UNL’s South Central Ag Lab (SCAL) near Clay Center is conducted on silt loam soils, common in the UBBNRD. The majority of the study at SCAL compared Spring pre-plant anhydrous vs. side-dress application with and without the use of nitrification inhibitor N-Serve® (nitrapyrin). A yield increase due to nitrapyrin applied pre-plant was observed in 6 of 28 years with a mean yield change of 2 bu/ac/year. Only 1 of 28 years was a yield increase observed when nitrapyrin was applied in season during side-dress application with a mean yield change of 0 bu/ac/year. In this study, they found delayed side-dress N with nitrapyrin could reduce plant N uptake and release N too late, thus it is not recommended to add an inhibitor to nitrogen applied in-season.
In 2019, two York Co. farmers compared spring anhydrous ammonia applications with and without the nitrification inhibitor (N-Serve®). At York location 1, 180 lbs N as anhydrous was applied on April 10, 2019 in ridge-till, silt-loam soil. At York location 2, 160 lbs N as anhydrous was applied on April 8, 2019 in no-till, silt-loam soil. These locations were around 4 miles apart and the previous crop in both was soybean. Soil samples were taken 2” off the anhydrous band down to three feet for both ammonium and nitrate concentrations at V7 growth stage. The results showed the nitrification inhibitor was still slowing the conversion of ammonium to nitrate in 1st foot at York 1 location (longer than would be anticipated for a spring-applied inhibitor treatment), but not at York 2. At both study locations, no yield difference occurred between the check and inhibitor treatments respectively (250 vs. 251 bu/ac at York 1 and 264 vs. 264 bu/ac at York 2).
In 2020, four farmers (3 in York Co. and one in Fillmore Co.) conducted on-farm research inhibitor studies. These studies were in partnership with the UBBNRD. Soil samples for ammonium and nitrate concentration were taken around 6 and 9 weeks post-application based on the protocol provided. Note: with these being inhibitor focused studies, future protocols will have soil tests taken closer to application. With farmers interested in what nitrogen distribution in the profile looks like in the late season, we will also sample then.
At York location 1, 150 lbs N as anhydrous was applied in the fall and spring with and without Centuro®. Soil tests in early May showed less total nitrogen in the third foot for the Spring anhydrous with Centuro® compared to Fall anhydrous with no inhibitor. There were no yield differences between treatments in 2020 (Fall and Spring check yielded 269 bu/ac, Fall with Centuro® 267 bu/ac, Spring with Centuro® 270 bu/ac). This study will continue. The other three locations had yields impacted by the July 9, 2020 wind event. At the Fillmore Co. location, 115 lbs spring applied 32% UAN with and without Instinct® II was compared. There was less nitrate and total nitrogen in the Instinct® II treatment at 2nd and 3rd foot vs. the check and there were no yield differences (both yielded 213 bu/ac). At the York 2 location, four products were compared (44 gal. spring applied 32% UAN as a check compared to the check plus either ammonium thiosulfate (ATS), Biovante™, or Instinct® II. The UAN+ Instinct® II had less nitrate and total nitrogen in the 3rd foot than the UAN+ Biovante™. The UAN+ATS treatment yielded significantly more than the check (215 bu/ac vs. 209 bu/ac) with no differences amongst the other treatments (212 bu/ac each). At the York 3 location, 45 gal spring applied 32% UAN was compared to a producer-developed concoction containing humic acid, sugar, and ATS. There was more nitrate, ammonium, and total nitrate in the inhibitor concoction than the check at the 3rd foot with no yield differences (220 bu/ac check vs. 221 bu/ac inhibitor concoction). These and other Nebraska on-farm research studies will be presented Feb. 25-26 both virtually and in-person. You can learn more and register here: https://go.unl.edu/h83j.
York County Corn Grower Plot Results and Banquet: The results of the York County Corn Growers plot can be found at: https://jenreesources.com/2019/11/03/2019-york-county-corn-grower-plot-results/. Special thanks to Ron and Brad Makovicka for their dedication and work in hosting! Also appreciate all the seed companies who participate! The York County Corn Grower’s Banquet will be held Tuesday, November 26 at Chances ‘R in York with social at 6:30 p.m. and dinner at 7:00 p.m. Tickets are $10 and may be purchased from any York Co. Corn Grower director or at the York Co. Extension Office.
Fall Nitrogen Application: With November here, a reminder to check soil temperatures before applying anhydrous ammonia to crop fields. Soil microbial activity and the rate of conversion of ammonium to nitrate is very low when the soil temperature is less than 50oF. Thus, apply fertilizer-N (and manure) when the soil temperature at the 4” soil depth is below 50°F and trending cooler. Daily and weekly soil temperatures (taken 4” below the surface of bare soil) can be found at: https://cropwatch.unl.edu/soiltemperature.
Extension Soil Fertility and Nutrient Management Specialists Javed Iqbal, Charlie Wortmann, Bijesh Maharjan, and Laila Puntel shared additional considerations for fall Nitrogen application in this week’s CropWatch: Apply anhydrous ammonia rather than other N fertilizers; Limit fall application of N to silt loam, silty clay loam, and finer textured soils; Use nitrification inhibitors to slow the conversion of ammonium to nitrate, especially on sand-dominant soils; Avoid fall application on wet soils; and Consider applying a lower base rate of nitrogen in the fall and plan on applying the rest at planting, or as a side-dress application.
On-Farm Research Protocols are available for anyone interested in fall vs. spring nitrogen management studies, inhibitor studies, or other potential on-farm research studies by contacting your local Extension educator. For growers within the UBBNRD interested in on-farm research studies that have a water quality focus, you may be eligible for additional support through the UBBNRD. In some instances it may cover district staff and equipment use; in others, it may cover a portion of the costs of lab analysis of soil, plant tissue, or water samples. If you’re a grower interested in this type of study, please contact the UBBNRD or your local Extension Educator to talk through your study idea and for additional information.
Farm Bill Meetings: Joint Nebraska Extension and Nebraska Farm Service Agency (FSA) producer education meetings are scheduled at 28 locations across the state from late November to mid-December in advance of the coming ARC/PLC enrollment deadlines in early 2020. The meetings are free and open to the public. Advance registration is encouraged for planning purposes for materials and facilities. Attendees can register for any of the meetings conveniently on the web at farmbill.unl.edu or by calling or visiting their county FSA or Extension office. The educational programs will feature information and insights from FSA specialists and Extension experts, as well as other relevant information from local agencies.
Nearest locations for this area of the State include: Nov. 25. Community Center, Red Cloud (1-4 p.m.); Dec. 3 ENREC near Mead (9-Noon); Dec. 4 Ag Park in Columbus (9-Noon); Dec. 5 College Park in Grand Island (1-4 p.m.); Dec. 5. Opera House, Bruning (1:30-4:30 p.m.); Dec. 6 Fairgrounds Cornerstone Building York (9-Noon); Dec. 16. Extension Office Lincoln (9-Noon); Dec. 17 Fairgrounds 4-H Bldg. Beatrice (9-Noon); Dec. 17 Fairgrounds in Kearney (1-4 p.m.).