Tackling Nitrogen as Necessary Evil: Impacts on Nebraska’s Cropping System and Water Quality

JAVED IQBAL, assistant professor and extension specialist of soil nutrient management and water quality, Department of Agronomy and Horticulture, University of Nebraska–Lincoln Author

11/10/2022 Added

25 Plays

Description

Efficient nitrogen management is imperative in improving crop production while protecting the environment. Iqbal will share his team’s collaborative research and extension efforts with stakeholders in improving nitrogen use efficiency and groundwater quality in Nebraska.

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[00:00:00.810]The following presentation
[00:00:02.250]is part of the Agronomy and Horticulture Seminar series
[00:00:05.850]at the University of Nebraska Lincoln.
[00:00:08.340]Good afternoon everyone,
[00:00:09.960]and welcome to the Agronomy and Horticulture
[00:00:13.020]Fall seminar series.
[00:00:14.820]My name is Dan Union and I'm an assistant professor
[00:00:17.220]here in the department,
[00:00:19.333]as well as in the School natural resources.
[00:00:21.270]Before I introduce this afternoon speaker,
[00:00:25.290]I wanna make a quick announcement about schedule.
[00:00:28.740]Next week, October 28th,
[00:00:31.830]we've had a scheduling conflict,
[00:00:33.750]and unfortunately, it's been necessary to cancel
[00:00:36.000]next week's seminar,
[00:00:36.900]so we will not meet next week.
[00:00:39.690]However, we will be back the following week, November 4th,
[00:00:43.140]Friday, November 4th.
[00:00:45.120]That'll be Dr. Keenan Edmondson from here in the department.
[00:00:49.920]So again, we'll send out reminder emails
[00:00:52.890]for that on Monday,
[00:00:54.630]get it all changed on the calendars.
[00:00:56.640]But I wanted to announce it here as well.
[00:01:01.230]Also, a note about kind of the interface
[00:01:05.010]for asking questions and interacting both online.
[00:01:09.570]We, of course have a nice online group
[00:01:11.940]as well as here in the room.
[00:01:14.070]Just so that the online crowd can hear well
[00:01:19.650]what we're saying in the room,
[00:01:22.410]those of you in the room can pose your questions verbally.
[00:01:25.920]Speaker, Javed, will repeat those
[00:01:28.200]so that those of you online can hear.
[00:01:31.710]Those of you online can also please enter your questions
[00:01:34.890]in the Q&A box, not the chat.
[00:01:37.440]You'll see a chat box, but chat is...
[00:01:39.810]If you see a chat box, it's disabled.
[00:01:43.110]But enter your questions in the Q&A
[00:01:45.600]and that's how we'll interact there.
[00:01:48.570]Okay. Now, that we have that out of the way.
[00:01:51.750]This afternoon on behalf of the entire seminar committee,
[00:01:55.020]it's my honor to introduce this afternoon speaker,
[00:01:59.280]Dr. Javed Iqbal.
[00:02:01.470]Javed is an assistant professor
[00:02:04.200]here in the Department of Agronomy and Horticulture,
[00:02:06.630]a nutrient management and water quality specialist,
[00:02:09.750]who works on complex challenges at the intersection
[00:02:13.470]of our soils and nutrients and production systems,
[00:02:17.520]which of course, as we all know
[00:02:19.020]is very important area with local to global relevance.
[00:02:25.320]Dr. Iqbal joined the department in late 2019,
[00:02:29.550]and today he's going to be talking
[00:02:34.290]about some nitrogen issues with us.
[00:02:36.180]So again, thank you Javed.
[00:02:39.090]The mic is yours.
[00:02:41.640]Thanks, Dan.
[00:02:42.990]Is it okay? Can you hear us?
[00:02:44.820]Hey, thanks Dan.
[00:02:45.900]And thank you for inviting me to this seminar series.
[00:02:49.680]I really appreciate this opportunity.
[00:02:52.140]And thanks all of you for coming here for this seminar.
[00:02:56.160]So in today's presentation,
[00:02:59.010]I'm going to share with you some of the work
[00:03:02.487]and some of the projects that we have been doing
[00:03:04.950]with some stakeholders to improve nitrogen management
[00:03:09.240]and water quality in Nebraska.
[00:03:13.800]So as you can see in the title, some of you,
[00:03:17.010]you may think nitrogen is an evil, but it's not.
[00:03:20.310]Actually it is a necessarily evil.
[00:03:22.950]Because nitrogen is definitely necessary
[00:03:26.670]to increase crop production
[00:03:29.070]to feed the growing world population.
[00:03:32.100]But at the same time,
[00:03:33.240]it has some adverse environmentally impact,
[00:03:38.010]and then impact on the human health.
[00:03:57.480]All right, sounds good now.
[00:03:59.580]All right. So you can see here the map from USGS
[00:04:02.730]showing the state at the risk of nitrate contamination
[00:04:07.230]with the shallow groundwater table depth.
[00:04:10.650]And then this map with groundwater nitrate violations
[00:04:16.140]kind of resembles with a map of America
[00:04:20.130]with the most high value farm regions.
[00:04:22.890]So as you can see here in Central Valley,
[00:04:26.837]in California to Washington,
[00:04:31.110]and then from Texas to North Dakota,
[00:04:33.540]from Nebraska, to all the way New York, and Pennsylvania.
[00:04:38.340]So you can see that there is a increasing risk
[00:04:41.340]of nitrate contamination in some of those states.
[00:04:45.030]When we look in Nebraska, more than half of the state
[00:04:49.470]is under this increasing risk
[00:04:51.510]of groundwater nitrate contamination.
[00:04:54.270]When we further look into the Nebraska stage,
[00:04:56.550]you can see that some of the townships here,
[00:04:59.490]they are more vulnerable to groundwater nitrate
[00:05:02.130]contamination than the other one.
[00:05:04.800]And then some of the towns,
[00:05:06.907]they are even reaching up to 100 parts per milligram
[00:05:11.401]nitrate in ground water,
[00:05:12.420]which is far above the EPA drinking water limit
[00:05:16.740]of 10 parts per million.
[00:05:18.810]And we know that these commercial nitrogen fertilizer
[00:05:23.670]is one of the source that has been contributing
[00:05:26.280]to this nitrate concentration in the ground water.
[00:05:31.170]And then that is more evident in areas
[00:05:33.630]where there are sandy soil or shell depth to groundwater
[00:05:37.260]or are irrigated corn fields.
[00:05:41.490]So this nitrate nitrogen fertilizer
[00:05:44.070]that is ending up in the groundwater
[00:05:46.890]is not only a cost to the farmer,
[00:05:51.059]this is also a cost to the community.
[00:05:55.036]So a medical team from UNMC,
[00:05:58.590]they recently found that the increasing
[00:06:01.500]nitrate concentration,
[00:06:03.960]whether in the streams or the groundwater,
[00:06:07.800]those are playing a role in increasing
[00:06:10.170]pediatric cancer in Nebraska.
[00:06:13.080]And Nebraska has the most cases of pediatric cancer
[00:06:18.600]than anywhere in the states
[00:06:20.656]except the northeast portion of USA.
[00:06:23.850]And then in addition, population in several of those towns,
[00:06:30.088]they are paying millions of dollars
[00:06:30.921]to remove that nitrate from the groundwater.
[00:06:35.340]And especially for the smaller community,
[00:06:37.800]this cost is really high.
[00:06:40.230]For smaller community,
[00:06:41.370]this cost of removing that nitrate
[00:06:44.790]ranges from $90 to $650 every year,
[00:06:49.110]which is really a big cost.
[00:06:52.738]So we definitely need to take immediate action,
[00:06:56.220]immediate measures to prevent this nitrate contamination
[00:07:00.717]in the groundwater.
[00:07:01.740]And then we know some of the reasons those are contributing
[00:07:04.920]to this increasing united concentration. Right?
[00:07:08.526]And one of the reason is increasing nitrogen fertilizer
[00:07:13.230]into the crop plants.
[00:07:15.210]There are several reports those have suggested
[00:07:18.173]that there is surplus nitrogen or extra nitrogen
[00:07:20.850]being used on the farm lands.
[00:07:24.265]For example, data from Upper Big Blue
[00:07:26.520]have suggested that about 50% of the field
[00:07:31.170]they have received excess nitrogen for last few years.
[00:07:35.280]And on the same note,
[00:07:38.033]about 70% of the field received excess node
[00:07:41.070]that was reported by lower Naborera and RD.
[00:07:44.310]So that really indicates that more than required, you know
[00:07:49.800]excess nitrogen is being applied
[00:07:52.770]on the crop land in Nebraska.
[00:07:57.309]And in our department, Patricia Group has done a great job.
[00:08:00.953]They evaluated, benchmark of nitrogen with surplus nitrogen,
[00:08:06.090]and they found that about more than 50%
[00:08:10.140]of the irrigated field, those are receiving
[00:08:14.010]extra nitrogen within nitrogen balance are nitrogen surplus
[00:08:18.406]surplus of more than 75 kilogram nitrogen per hectare
[00:08:22.502]which is again a big number.
[00:08:24.660]And then a recent study in the USA by Magno
[00:08:30.990]has found that they,
[00:08:33.852]they reported that nitrate leaching
[00:08:35.548]was closely related to the surplus nitrogen in the soil.
[00:08:40.960]So that really indicates that how this surplus nitrogen
[00:08:43.470]is really contributing
[00:08:45.972]to increasing nitrate contamination in the groundwater.
[00:08:50.010]Now, the question is how can we bring these farmers
[00:08:54.660]to use the reduced nitrogen rate,
[00:08:58.680]or at least the recommended nitrogen rate
[00:09:00.868]so that we can get rid of this excess nitrogen.
[00:09:05.232]University of Nebraska with several producers
[00:09:08.084]and stakeholders, our state head agencies
[00:09:11.592]have been doing a great job of implementing
[00:09:14.340]some of the best management practices
[00:09:17.188]to reduce this nitrogen contamination
[00:09:19.140]in our water resources.
[00:09:21.000]But the scope and the scale of the work
[00:09:23.070]has not met the challenge that our Nebraska state
[00:09:26.548]is facing at this point.
[00:09:30.026]So earlier last year,
[00:09:33.600]UN water Center and then the UN extension
[00:09:37.620]led by Crystal Power and Katie Pekarek,
[00:09:41.340]they called for this group.
[00:09:43.800]They called for an action to reduce nitrate leaching or
[00:09:46.920]united contamination to ground water.
[00:09:49.680]So they called this meeting with the leaders in the state
[00:09:53.790]that those were from agriculture
[00:09:56.220]as well as from the water management.
[00:09:58.890]So in this group, our overall goal
[00:10:03.120]was that all the Nebraskans will have access to safe water.
[00:10:08.981]Yes.
[00:10:10.475]Where's (indistinct)
[00:10:11.850]That was taken by Katie Pekarek.
[00:10:14.850]They posted this on the Crowd Watch articles.
[00:10:19.327]I don't know exactly the place.
[00:10:26.370]I'm not sure. So this was published in one of the article
[00:10:31.854]from where I took this picture.
[00:10:36.452]So this group set three priorities
[00:10:41.370]with three topics, awareness, education, and policies.
[00:10:46.127]And then they listed out these kind of activities
[00:10:47.880]within those three topics
[00:10:50.071]that we need to do to reduce this united contamination
[00:10:53.640]in the groundwater.
[00:10:55.291]I think that this is really a good,
[00:10:57.735]this was really a good call
[00:10:58.568]where stakeholders from different institute,
[00:11:02.987]they can really come together,
[00:11:03.930]connect with each other,
[00:11:05.490]and work far with the shared goal
[00:11:08.070]to reduce nitrate contamination
[00:11:10.140]in the groundwater of Nebraska.
[00:11:13.980]So my team has been involved directly, indirectly
[00:11:16.650]with some of those activities,
[00:11:18.540]but I am not going to cover all of the activities
[00:11:21.240]in today's presentation.
[00:11:23.147]I will be mainly focusing on the research part,
[00:11:26.280]and then collaboration with the stakeholders
[00:11:28.110]that we have been having in some of the projects.
[00:11:31.440]So coming back to those projects, we were looking to answer,
[00:11:36.719]how can we improve nitrogen use efficiency,
[00:11:39.571]and at the same time reduce
[00:11:41.819]this negative environmental impact.
[00:11:44.611]So I think that this is a million dollar question, right?
[00:11:48.855]And then, however, there's not a simple answer
[00:11:50.790]to this question.
[00:11:52.710]But think that there are different steps
[00:11:55.711]that we need to take to answer this question.
[00:11:58.831]First of all, I think that we need to understand
[00:12:00.450]the processes in the soil
[00:12:03.360]those are affecting nitrogen balance,
[00:12:05.400]those are affecting nitrogen dynamics
[00:12:07.920]or nutrient dynamics in the soil.
[00:12:10.613]And then we want to better understand those processes
[00:12:14.513]and then not only to increase crop production
[00:12:17.310]and also protect our environment.
[00:12:21.150]So once we know those processes
[00:12:23.100]those are affecting the nutrient dynamics,
[00:12:25.020]then we can refine our models
[00:12:30.450]nitrogen recommendations using those processes.
[00:12:34.140]When I'm talking about those processes,
[00:12:36.576]those apply to different nitrogen management practices
[00:12:42.320]or nutrient management practices,
[00:12:43.860]for example the next generation fertilizer
[00:12:47.520]that we are having in the market,
[00:12:49.800]how those next generation fertilizer,
[00:12:51.750]those are behaving in the soil.
[00:12:53.070]We need to understand those processes.
[00:12:55.140]And then we need to include in our models
[00:12:58.290]and our recommendations
[00:12:59.850]and then quantify the impact
[00:13:01.500]of those nitrogen management practices,
[00:13:04.530]their impact on improving nitrogen use efficiency
[00:13:07.530]profits in environment.
[00:13:10.260]So once we do that, we can again go back
[00:13:13.106]to understanding the processes until we can really refine
[00:13:17.640]our model or refine the management practices
[00:13:20.640]that can help us to optimize our nutrient management
[00:13:25.110]in the soil.
[00:13:27.300]So as a next step,
[00:13:28.500]once we know that when we have our recommendation,
[00:13:31.650]once we have refined models,
[00:13:33.750]I think that the next step is we need to implement that.
[00:13:37.470]But we need to set the priorities
[00:13:40.830]for those management practices, our BMPs,
[00:13:44.280]to reduce these negative environmental impact.
[00:13:46.440]Because some of those practices,
[00:13:49.527]they are more related with the nitrogen balance
[00:13:51.450]than the other practices.
[00:13:53.160]So adopting those, you are prioritizing those practices
[00:13:57.660]is really critical to improve nitrogen use efficiency
[00:14:01.320]and decrease and negative environmental impact.
[00:14:06.000]So my research and extension program
[00:14:08.760]has been mainly focusing around these steps
[00:14:13.050]for improving nitrogen use efficiency.
[00:14:16.260]And then to understand those processes,
[00:14:19.260]to refine those models,
[00:14:21.570]my team has been studying different
[00:14:24.150]nutrient management practices.
[00:14:26.770]For example, for our management practices
[00:14:28.230]with the right source, right rate,
[00:14:30.330]right time, and right place.
[00:14:31.800]Those are well known practices
[00:14:33.210]to improve nutrient management
[00:14:34.620]and improve raw production, improve sustainability.
[00:14:39.060]So we are studying these four Rs practices in our projects.
[00:14:44.220]In addition, some of the conservation practices
[00:14:46.770]including cover crop or perennial filter strips menu,
[00:14:50.182]no-till, irrigation, crop rotation,
[00:14:53.730]those are the other practices that can help us. Yes.
[00:15:05.610]So right rates or time in place.
[00:15:08.250]So yeah, that would be place.
[00:15:11.940]Yep. So right, I think that I'm missing place here.
[00:15:16.980]So these conservation practices,
[00:15:18.720]those can also help us to improve crop production
[00:15:23.370]or reduce the negative environmental impact.
[00:15:27.210]So when these two practice data,
[00:15:29.430]those are combined as an integrated
[00:15:32.370]nutrient management approach,
[00:15:35.430]This can really help us
[00:15:38.190]to improve crop production or increase ecosystem services,
[00:15:46.740]and then reduce the negative environmental impact
[00:15:49.500]that we are seeing in Nebraska.
[00:15:51.600]So today I will be sharing research findings
[00:15:56.610]from couple of our projects that we have been collaborating
[00:16:00.270]with the stakeholders.
[00:16:01.800]And then we'll also sharing introduction
[00:16:03.750]with some of the other projects as well.
[00:16:08.060]So our first project was at the
[00:16:11.460]Bazile Groundwater Management area.
[00:16:14.340]If you don't know about this area,
[00:16:16.020]this is the first federally approved
[00:16:19.740]groundwater management plan
[00:16:22.980]that addresses nonpoint source pollution in the nation.
[00:16:27.570]So this area is facing increasing nitrate contamination
[00:16:32.880]in the groundwater over time.
[00:16:34.650]As you can see that almost all of the townships,
[00:16:37.980]they have nitrate nitrogen
[00:16:39.937]above the 10 parts per million that is the EPA
[00:16:43.080]drinking water limit.
[00:16:45.390]So we have worked with four NRDs
[00:16:47.970]to participate in one On-Farm research in that area.
[00:16:53.550]In fact, UNL has been collaborating
[00:16:56.550]with these for last couple of years.
[00:16:58.860]And then faculty from different department
[00:17:02.520]then snow jet under crystal, power Crystal,
[00:17:06.300]Christopher Proctor from here,
[00:17:08.250]we have all been working
[00:17:09.660]on the three On-Farm Research demonstration in that area.
[00:17:17.070]So one of the On-Farm research demonstration
[00:17:20.730]have been led by my group.
[00:17:23.490]We have looked to answer some questions
[00:17:26.730]regarding the nitrogen management.
[00:17:28.650]So this On-Farm research trial was located atray in the BGMA
[00:17:34.710]where the nitrate concentration in the irrigation well
[00:17:37.650]is above 10 parts per million is 20 parts per million.
[00:17:44.873]That what we found in 2020.
[00:17:47.229]So it has a loamy sand soil.
[00:17:49.020]We did this study for two years.
[00:17:51.390]Today I will be presenting data just from the first year,
[00:17:54.630]and we are still working on the data for the second year.
[00:17:58.200]So this soil has low organic matter.
[00:18:00.510]As you can see here,
[00:18:02.730]my student, a PhD student Ashdi Sigh,
[00:18:05.760]he has been doing a fantastic job of collecting data
[00:18:09.360]and leading the research project at this site.
[00:18:13.800]So at this site we had a pivot with VRI system.
[00:18:18.660]So we were able to create different maps for irrigation,
[00:18:22.470]we were able to apply nitrogen
[00:18:24.120]through in application for irrigation.
[00:18:28.350]At this side we were looking...
[00:18:31.259]We had couple of projects and we were looking to answer
[00:18:33.000]a few questions.
[00:18:34.799]For example, in one of our experiment,
[00:18:37.350]we were looking to evaluate
[00:18:38.910]different nitrogen recommendation tool
[00:18:41.310]and see how these nitrogen recommendation tools
[00:18:44.640]can help us to optimize nitrogen management,
[00:18:47.940]improve nitrogen use efficiency,
[00:18:50.010]and decrease nitrate leaching.
[00:18:52.380]So we tested different nitrogen recommendation tools
[00:18:56.520]including university as well as industrial tools.
[00:18:59.730]For example, here we use UNL-N nitrogen calculator,
[00:19:03.480]Maize-N, Crop canopy sensor,
[00:19:05.490]and we used two industrial model Adapt-N and Granular.
[00:19:09.060]So again, as I shared earlier
[00:19:10.950]we had a VRI system at this location.
[00:19:15.270]So we were able to create different maps
[00:19:19.020]for preplan nitrogen fertilizer application
[00:19:22.910]or side dress application.
[00:19:25.046]Here is an example for irrigation
[00:19:28.231]as needed for those treatments.
[00:19:32.280]So I will go into a little detail for the treatments
[00:19:35.250]that we use in this study.
[00:19:37.740]So we had a set of treatments in this study,
[00:19:40.080]we have Nramp with six nitrogen rates
[00:19:43.440]that we use to calculate economic optimum nitrogen rate
[00:19:47.310]and its effect on nitrogen we use efficiency
[00:19:51.214]and nitrate leaching.
[00:19:52.530]So all of those treatments that I have here,
[00:19:54.870]those were split applied.
[00:19:56.490]Those are either nitrogen was applied as a pre-planned
[00:19:59.640]side-dressed or using for irrigation.
[00:20:03.724]So all the treatments here, those received for irrigation.
[00:20:08.490]And then we had university nitrogen recommendation tool
[00:20:12.180]UNL-N, Maize-N, sensor-based irrigation
[00:20:15.483]based on the crop canopy sensor,
[00:20:17.880]Adapt-N, and granular.
[00:20:20.010]So here are the recommendations by these models.
[00:20:24.327]For example, UNL-N nitrogen model
[00:20:27.270]recommended 237 pounds nitrogen,
[00:20:31.230]Maize-N recommended 253,
[00:20:34.500]sensor-based for fertigation
[00:20:35.790]each recommended 171 pounds nitrogen.
[00:20:39.960]But due to our limited capacity for fertigation,
[00:20:44.370]we were only able to apply 164,
[00:20:47.160]that was seven pounds less than recommended by this model.
[00:20:53.460]So Adapt-N they recommended,
[00:20:55.410]and Granular actually they both recommended
[00:20:57.960]kind of same amount of nitrogen,
[00:21:00.630]but we recommended nitrogen from the irrigation
[00:21:03.918]and then we ended up applying less nitrogen
[00:21:06.210]than what it was recommended.
[00:21:09.210]So we applied 164 pounds nitrogen in each of those models.
[00:21:18.720]So at this site, my research team,
[00:21:23.220]they had been doing a tremendous job.
[00:21:25.350]There was a lot of work.
[00:21:27.180]This was three hours drive from here.
[00:21:30.330]And we installed a lot of equipment,
[00:21:32.310]we installed about two suction cup lysimeter
[00:21:36.030]at five foot depth in each plot.
[00:21:39.660]So we have about 75 plot and we ended up applying
[00:21:42.840]more than 170 suction cup lysimeter.
[00:21:46.569]That was a lot of work,
[00:21:47.402]but I really appreciate my team Richard Little, Sigh,
[00:21:51.990]William Nills, and undergrad student,
[00:21:54.030]they have been really working hard to install equipment.
[00:21:57.600]And then during the season,
[00:21:59.730]after they install equipment and Christopher Misar is here,
[00:22:04.230]who is installing the suction cup lysimeter.
[00:22:06.810]And then during the season,
[00:22:10.290]our group was going there at least twice every week
[00:22:14.250]or sometime three times every week.
[00:22:17.091]So they were applying suction on those suction cup lysimeter
[00:22:19.860]and then they were collecting water samples.
[00:22:21.870]So there was a lot of effort
[00:22:24.818]and 14 hours work every day.
[00:22:27.990]So they had been doing a great job
[00:22:31.320]in collecting the data throughout the season.
[00:22:33.690]So we also installed some other equipment
[00:22:36.870]As you can see here there is a tube here
[00:22:40.050]where we installed in exchange raisins.
[00:22:42.930]That was kind of site project we were looking to estimate,
[00:22:48.660]we were looking to test different methods
[00:22:52.560]for nitrate leaching.
[00:22:53.910]So we were comparing in exchange raisins with soil testing,
[00:22:57.840]soil nitrate ammonium and nitrate leaching
[00:23:01.380]through suction cup lysimeter.
[00:23:03.660]And then we also had these moisture sensors installed
[00:23:08.700]at different depth
[00:23:10.450]so we can see the moisture change every day.
[00:23:13.950]Right now I will search to the results.
[00:23:17.340]So here is our first results.
[00:23:18.870]You can see a crop yield response
[00:23:20.700]with six different nitrogen rates.
[00:23:22.950]You can see a typical crop yield response here.
[00:23:25.950]And then using a quad plate function,
[00:23:28.470]we were able to calculate economic optimum nitrogen rate
[00:23:31.530]for this site, which was 230 pounds nitrogen per acre.
[00:23:38.813]And then the yield at this EONR was 259 bushels per acre.
[00:23:44.490]And this was actually a continuous corn.
[00:23:47.250]This was a second year for the corn at this site.
[00:23:51.270]And then once we calculated this EONR,
[00:23:54.600]we compared the nitrogen rate from EONR
[00:23:59.040]with other models and the yield with other models
[00:24:02.010]and the nitrate leaching, as I would share later.
[00:24:04.950]So here we have the first graph showing the nitrogen rate,
[00:24:15.090]from EONR compared to the rest of the models.
[00:24:18.600]So this baseline is just like our EONR,
[00:24:21.600]and then there are differences of those nitrogen rates
[00:24:24.090]from those different models with EONR.
[00:24:27.000]So first, as you can see here EONR nitrogen,
[00:24:31.181]it has 3% higher nitrogen recommendation than the EONR.
[00:24:36.150]And the crop canopy sensor,
[00:24:41.160]it had 171 pounds nitrogen,
[00:24:44.970]which was 2% less than the EONR.
[00:24:50.400]For Maize-N, Maize-N recommended 10% more nitrogen rate
[00:24:55.290]than the EONR.
[00:24:57.960]These two models recommended 29% less nitrogen
[00:25:02.910]than the EONR.
[00:25:05.393]So here the main point is you can see that
[00:25:09.720]we have been having some questions
[00:25:11.340]about the EONR nitrogen recommendations.
[00:25:13.850]So this site has shown that these results
[00:25:16.740]have shown that the nitrogen recommendations
[00:25:20.550]from EONR nitrogen calculator
[00:25:22.883]was really close to EONR that we have for this site
[00:25:28.680]for this year.
[00:25:30.090]While the other models,
[00:25:31.920]they either underestimated or overestimated
[00:25:35.409]the nitrogen rate.
[00:25:38.863]So here is the graph for the corn yield
[00:25:41.850]with those different models compared to EONR.
[00:25:46.626]As you can see from UNL nitrogen calculator,
[00:25:48.660]we have got the same yield
[00:25:51.360]from this UNL-N nitrogen calculator
[00:25:54.240]as we got from EONR.
[00:25:56.637]For crop canopy sensor,
[00:25:58.350]there was 16% less grain yield than the EONR.
[00:26:02.190]This was expected because there was less nitrogen applied
[00:26:05.400]with the crop canopy sensor.
[00:26:07.260]With the Maize-N, both nitrogen was applied.
[00:26:09.450]So there was 2% more nitrogen,
[00:26:12.030]more grain shield with Maize-N.
[00:26:14.580]And then there was some yield penalty
[00:26:17.040]from Adapt-N and Granular with 3% and 6% less grain yield.
[00:26:23.310]But grain yield from Adapt-N, Granular,
[00:26:28.140]Maize-N and UNL-N nitrogen,
[00:26:30.360]it was not statistically different,
[00:26:32.280]it was statistically same.
[00:26:34.350]So indicating that even if you're applying nitrogen,
[00:26:38.640]about 40 to 60 pounds,
[00:26:41.040]40 to 50 pounds less nitrogen,
[00:26:44.220]you are going to get some yield penalty.
[00:26:46.350]But there was no statistically significant difference
[00:26:49.500]of grain yield among those tubes.
[00:26:54.540]Crop canopy sensor has 16% less nitrogen.
[00:26:59.490]So these crop canopy sensor and these two models,
[00:27:03.300]they actually received similar nitrogen rate
[00:27:07.650]as I showed earlier.
[00:27:09.450]But the only difference between these was,
[00:27:13.021]I will just point out here,
[00:27:14.430]that for this Adapt, these two models,
[00:27:17.640]we applied nitrogen and split at five times
[00:27:20.730]with three fertigation, side-dress and pre-planned.
[00:27:24.120]But the sensor-based fertigation,
[00:27:25.980]we just applied nitrogen at pre-plant.
[00:27:28.980]We did not sidedress.
[00:27:30.660]So we applied the rest of the,
[00:27:32.970]after we scanned the crop canopy at V8 stage,
[00:27:37.380]we applied nitrogen after we scanned those crop canopy
[00:27:41.850]with that crop canopy sensor.
[00:27:43.710]So we applied nitrogen just through fertigation.
[00:27:46.890]We did not side-dress at crop canopy sensor treatment.
[00:27:51.840]So that's why you can see here
[00:27:54.450]that that indicates that these three treatments,
[00:27:58.261]they got the same kind of rate
[00:27:59.580]but just missing the side-dress
[00:28:01.950]really resulted in less grain yield
[00:28:04.740]as we can see with this treatment.
[00:28:09.510]All right. So there is a lot of data to show today.
[00:28:12.630]So here we have the nitrate concentration
[00:28:16.650]from the suction cup lysimeter
[00:28:19.169]that we collected throughout the growing season.
[00:28:21.480]So here I'm just showing the nitrate concentration
[00:28:25.050]just from the six nitrogen rates.
[00:28:27.660]We divided the whole season into three period,
[00:28:31.680]early vegetative, late vegetative,
[00:28:33.420]and reproductive stage.
[00:28:35.040]So you can see irrigation and precipitation
[00:28:37.410]in each of those panels.
[00:28:40.201]And then this is flow weighted nitrate concentration
[00:28:42.810]from the suction cup lysimeter.
[00:28:45.090]And then so you can see that the higher the nitrogen rate,
[00:28:49.890]the higher the nitrogen leaching is so simple.
[00:28:53.250]So that indicated that this side was really a good side
[00:28:56.640]to test the effect of different products
[00:29:00.465]on nitrate leaching.
[00:29:02.730]So generally, we found higher nitrate concentration
[00:29:06.990]during the early vegetative stage,
[00:29:09.120]followed by late vegetative, and reproductive stage.
[00:29:13.560]And then we averaged nitrate concentration
[00:29:17.430]from each of those periods.
[00:29:19.140]As you can see here for during the early vegetative stage,
[00:29:22.680]nitrate concentration increased
[00:29:24.450]with increase in nitrogen rate.
[00:29:27.330]During late vegetative stage we found the same effect,
[00:29:30.240]though the magnitude were lower,
[00:29:31.890]but we found a linear increase in nitrate concentration
[00:29:35.100]with increase in nitrogen rate.
[00:29:37.200]But during the reproductive stage
[00:29:39.270]we found that there was increase in nitrate concentration
[00:29:43.349]with increasing nitrogen rate up to a certain point.
[00:29:46.680]And after this, there was an exponential increase
[00:29:49.890]in nitrate concentration.
[00:29:52.110]So that indicates that after this rate,
[00:29:56.070]we had our actually economic optimum nitrogen rate,
[00:29:59.220]but that was 230 pounds nitrogen.
[00:30:02.580]That lies somewhere here.
[00:30:04.170]So that indicates that above that economic optimum
[00:30:07.740]nitrogen rate,
[00:30:08.573]any extra nitrogen that you are going to apply,
[00:30:10.980]you are going to lose that up.
[00:30:12.480]You are going to lose that nitrogen into the groundwater.
[00:30:18.570]So then we calculated the cumulative nitrate leaching
[00:30:22.890]throughout the growing season,
[00:30:24.240]and we again compared those nitrate leaching
[00:30:27.330]from those models compared to EONR.
[00:30:31.230]So you can see from the UNL-N nitrogen calculator
[00:30:33.750]there was 5% higher nitrate leaching from this tool.
[00:30:40.020]And then Maize-N has 29% higher nitrate leaching.
[00:30:46.140]And crop canopy be sensor, as expected,
[00:30:49.310]it has lower nitrogen rate,
[00:30:50.970]it decreased nitrate leaching by 41%.
[00:30:54.330]Adapt-N and granular,
[00:30:56.250]these decreased nitrate leaching by 22 and 18%.
[00:31:00.750]So we did not find a significant difference
[00:31:03.420]of nitrate leaching among the four models
[00:31:06.060]except crop canopy sensor.
[00:31:08.190]Crop canopy sensor has less nitrate leaching
[00:31:12.360]compared with other models.
[00:31:13.920]Again, we were expecting this
[00:31:15.690]because there was less nitrogen applied in this treatment.
[00:31:21.440]So overall, we can say that UNL-N nitrogen calculator
[00:31:26.760]was really performing well among all the models.
[00:31:31.410]It has almost same nitrate leaching compared to EONR.
[00:31:36.030]However, decreasing nitrogen rate by 40 to 50 pounds
[00:31:40.920]as you can see with Adapt-N and Granular end,
[00:31:44.400]you can decrease nitrate leaching kind of significantly.
[00:31:49.710]But you would have a little yield penalty with those models.
[00:31:53.340]So you really want to see where you want to be.
[00:31:56.070]And then we still have to calculate the range of EONR,
[00:31:59.430]which can be maybe 20 pounds less or more
[00:32:02.670]than the EONR value,
[00:32:04.710]so that you really want to know where you want to be.
[00:32:08.280]Do you want to be at the upper bound of the EONR
[00:32:11.150]or lower bound of the EONR?
[00:32:13.200]If you are at the lower bound of the EONR,
[00:32:15.769]you may have a little yield penalty
[00:32:18.600]but you can significantly reduce nitrate leaching.
[00:32:26.010]So on the same side, we had another experiment
[00:32:30.570]where we were looking to evaluate
[00:32:33.960]next generation nitrogen fertilizers.
[00:32:36.540]So we were looking to see if those fertilizers
[00:32:39.330]can help us to reduce the nitrogen rate
[00:32:42.330]or improve nitrogen use efficiency profits
[00:32:45.600]and decrease nitrate leaching.
[00:32:47.310]So in this study, we tested four different nitrogen sources
[00:32:52.290]including Urea, Agrotain, SuperU, and UAN,
[00:32:56.940]and different combination with different timing
[00:32:59.310]of nitrogen application.
[00:33:01.290]So here are the treatments for this experiment.
[00:33:04.050]So we have three kind of treatments here.
[00:33:08.490]So we had Urea that was pre-planned, 100% preplanned.
[00:33:13.530]We used a sub-optimum nitrogen rate here.
[00:33:17.100]Then for this side,
[00:33:18.360]so we use 194 pounds nitrogen.
[00:33:22.447]And then second set of treatment
[00:33:23.400]we have actually Urea coated with Agrotain.
[00:33:26.640]So it is just like written as Agrotain
[00:33:29.130]but this is Urea quoted with Agrotain.
[00:33:31.110]So we had Agrotain, 100% preplanned
[00:33:34.620]and Agrotain split applied with UAN
[00:33:38.790]throughout the growing season.
[00:33:40.350]And then we also tested SuperU as 100% preplan,
[00:33:45.180]and then SuperU split with UAN
[00:33:47.850]throughout the growing season.
[00:33:49.440]So we were looking to have the same nitrogen
[00:33:53.430]at all of the size but unfortunately our equipment
[00:33:59.430]was not calibrated for SuperU,
[00:34:02.190]so we ended up applying more nitrogen at this site.
[00:34:05.880]So 248 pounds nitrogen was applied
[00:34:09.834]for the last two treatments.
[00:34:11.340]So here again here are the results
[00:34:14.910]from the suction cup lysimeter.
[00:34:17.190]So you can see here the nitrate concentration
[00:34:19.680]from the suction cup lysimeter.
[00:34:21.170]So you cannot really differentiate across the treatments.
[00:34:24.360]But generally you would see that there were higher
[00:34:26.730]nitrate concentration
[00:34:29.070]during the early vegetative stage
[00:34:30.510]compared to the late vegetative, and the reproductive stage.
[00:34:34.530]But I really want you to focus on these graphs
[00:34:37.680]that can provide the kind of neat comparison
[00:34:40.890]among the treatments.
[00:34:42.690]So when you look at the first two treatments,
[00:34:45.180]So this nitrate leaching is reported as pounds,
[00:34:48.300]nitrogen per acre.
[00:34:50.190]So you can see that as expected a 100% Urea,
[00:34:53.733]straight Urea preplan has the highest nitrate leaching.
[00:34:58.090]And our second treatment,
[00:34:59.250]which was a 100% Agrotain preplan,
[00:35:03.180]it has a lowest nitrate leaching.
[00:35:05.160]It has the lower nitrate leaching than the Urea treatment.
[00:35:10.560]And for the next two pairs,
[00:35:13.170]you can see Agrotain preplan,
[00:35:15.360]again has lower nitrate leaching
[00:35:17.730]compared to Agrotain UAN split application
[00:35:23.520]For next treatment, SuperU had lower nitrate leaching
[00:35:29.303]compared to SuperU and UAN split application.
[00:35:33.600]So overall you can see from this first set of treatment
[00:35:39.480]that generally split application
[00:35:43.080]are the use of those nitrification inhibitor
[00:35:45.660]decreased nitrate leaching compared to straight Urea
[00:35:50.520]that was pre-planned.
[00:35:54.210]So if we look for the next section
[00:36:00.870]in the late vegetative state,
[00:36:02.730]so with the differences that we see among these treatments,
[00:36:05.880]those differences started to disappear.
[00:36:08.970]As you can see that there was less nitrate leaching
[00:36:11.490]with the Urea treatment,
[00:36:14.340]but there was more nitrate leaching
[00:36:16.110]from Agrotain UAN compared to Urea and Agrotain.
[00:36:20.580]But it was really interesting to see even here and here,
[00:36:23.880]especially here though we applied higher nitrogen rate
[00:36:29.250]with this SuperU treatment compared to the other treatment
[00:36:32.370]we still had lower nitrate leaching
[00:36:35.220]with the SuperU treatment
[00:36:36.510]because this SuperU has both nitrification inhibitor
[00:36:39.900]and Urea's inhibitor.
[00:36:41.130]So those are really effective in reducing nitrate leaching.
[00:36:45.990]So when we looked at the reproductive stage,
[00:36:48.930]it was really interesting to see here that Urea
[00:36:52.147]and Agrotain those had lower nitrate leaching,
[00:36:55.680]but Agrotain with UAN split application
[00:36:58.920]had higher nitrate reaching. Yes.
[00:37:13.620]Right, that's true, yes.
[00:37:14.910]So statistically, there is not much difference
[00:37:17.760]for example for these four treatments,
[00:37:22.380]there is not statistically much difference there.
[00:37:25.200]Yes, you can see by magnitude there is difference.
[00:37:31.920]So you can, again, see there was less
[00:37:35.040]statistically difference here in the second phase.
[00:37:38.610]And here there was a huge variability in nitrate leaching.
[00:37:42.720]So that's why we didn't see statistical difference
[00:37:46.890]in some of the treatment,
[00:37:48.540]but we definitely saw some pattern there.
[00:37:52.380]So here you, you saw that Agrotain UAN split
[00:37:56.904]in magnitude had higher nitrate leaching
[00:38:00.360]than Urea and Agrotain,
[00:38:01.590]but though it was not statistically different.
[00:38:04.710]And then SuperU also had no difference
[00:38:09.660]than the other treatment.
[00:38:11.190]But in magnitude it has higher nitrate leaching.
[00:38:16.290]So we then calculated the cumulative nitrate leaching
[00:38:21.330]throughout the growing season.
[00:38:23.580]So you would see here as you also saw in the last slide
[00:38:28.980]Urea had the higher nitrate leaching compared to Agrotain.
[00:38:33.090]And it has statistically higher nitrate leaching
[00:38:36.450]than the Agrotain.
[00:38:38.760]But when we looked at the next treatment,
[00:38:43.840]so Agrotain UAN split application
[00:38:46.170]has statistically higher nitrate leaching than the Agrotain.
[00:38:52.200]And then it was really interesting
[00:38:53.910]to see that Urea preplan had statistically
[00:38:58.110]similar nitrate leaching compared to Agrotain UAN split,
[00:39:02.820]Which is a kind interesting
[00:39:04.680]that we know that split application can decrease nitrate,
[00:39:09.120]but here we are not seeing any effect here.
[00:39:11.940]So there could be some reasons.
[00:39:14.250]For example, we really need to know
[00:39:16.950]different nitrogen sources.
[00:39:18.750]We applied nitrogen at Side-dress,
[00:39:21.960]we applied UAN at Side-dress,
[00:39:23.730]and then we got four inches of rain within one week.
[00:39:27.210]So that four inches of rain would have flushed that profile
[00:39:35.160]with the nitrate leaching going down.
[00:39:37.710]So this is just one year data.
[00:39:41.520]And next year when this is more dry, just like 2022,
[00:39:44.730]we don't know how the data is going to look like.
[00:39:48.532]In one of 10 cases, we may see there is no difference
[00:39:51.030]or who knows we may see differences
[00:39:53.610]or we may not see differences for this year.
[00:40:03.180]So then we looked at again these last two applications,
[00:40:08.190]SuperU and UAN split.
[00:40:09.720]There was no statistical difference
[00:40:12.120]between these preplan and split application.
[00:40:14.820]And then actually there was no difference
[00:40:16.560]of these two treatments compared to straight Urea preplan.
[00:40:22.680]But this again kind of indicates
[00:40:24.780]that even when you are applying more nitrogen,
[00:40:27.480]we applied about more than 50 pounds nitrogen with this...
[00:40:31.080]We ended up applying more nitrogen
[00:40:32.610]with these two applications.
[00:40:34.320]But even then we had comparatively less nitrate leaching
[00:40:39.000]compared to straight Urea.
[00:40:40.710]So that indicates that if we would have applied
[00:40:44.686]the same rate in these two treatments,
[00:40:47.970]we may have seen less nitrate leaching with a SuperU
[00:40:51.960]compared to other treatments.
[00:40:57.920]So here I wanted to compare a couple of treatments
[00:41:01.950]from those two studies that I shared.
[00:41:05.580]So EONR that we had 230 pounds nitrogen per acre,
[00:41:12.060]versus Agrotain where we applied
[00:41:14.430]194 pounds nitrogen per acre.
[00:41:17.070]So we were looking to compare these two treatments,
[00:41:19.470]and then as you can see here
[00:41:23.372]with Agrotain preplan there was 15% less nitrogen
[00:41:27.360]that was used at this site.
[00:41:29.730]But we did not see any difference
[00:41:32.430]in grain yield between these two treatments.
[00:41:36.360]But we found 53% lower nitrate concentration
[00:41:42.180]with Agrotain compared to EONR value.
[00:41:46.740]So that indicates that these nitrogen stabilizers
[00:41:51.480]they can help to reduce nitrogen rate
[00:41:55.380]just like we had 36 pounds less nitrogen rate
[00:41:59.160]with the Agrotain,
[00:42:00.420]and this can reduce nitrate leaching
[00:42:03.304]without impacting grain yield.
[00:42:08.132]So in conclusion from this study,
[00:42:10.680]I would say that selecting an economic optimum nitrogen rate
[00:42:14.250]can definitely help us to get the most profit.
[00:42:19.080]However, if we can reduce nitrogen rate by 40 to 50 pounds,
[00:42:23.610]there could be a little yield penalty,
[00:42:25.740]or we can be at the lower bound
[00:42:27.780]of that economic optimum nitrogen rate.
[00:42:29.790]We still have to do those calculations.
[00:42:32.160]We have got a lot of data,
[00:42:33.450]we will be coming up with more calculations
[00:42:35.430]with uncertainty in UNR.
[00:42:38.940]So reducing nitrogen rate by 40 to 50 pounds
[00:42:43.470]may result in little yield penalty to no yield penalty,
[00:42:46.592]but it can significantly reduce nitrate leaching.
[00:42:51.870]And then next generation nitrogen fertilizer,
[00:42:55.428]they can really help to cut down
[00:42:58.170]some of the nitrogen rate, reduce nitrate leaching,
[00:43:01.680]and then without impacting crop yield.
[00:43:07.770]All right. So that was the one study
[00:43:10.380]that I was looking to share with you.
[00:43:12.810]Now I will switch to another study
[00:43:18.210]that we did at South Central LA lab.
[00:43:20.340]So in this study my MS student William means he,
[00:43:25.188]he led on this study.
[00:43:26.021]So in this study, we were looking to compare
[00:43:27.810]different nitrogen sources.
[00:43:29.550]We know that these nitrification inhibitor,
[00:43:32.490]they are really getting popular
[00:43:34.650]and nowadays are recommending
[00:43:37.040]these to stabilize nitrogen and reduce nitrate leaching,
[00:43:40.170]especially during the early part of the growing season.
[00:43:43.020]But we were looking to see that,
[00:43:45.720]okay, we know these nitrification inhibitors,
[00:43:47.880]those are effective,
[00:43:49.200]but how about our conventional nitrogen sources
[00:43:53.850]that we have,
[00:43:54.930]how effective these nitrification inhibitors are
[00:43:58.410]compared to those our conventional nitrogen sources?
[00:44:01.650]And then we also know that herbicide
[00:44:05.820]has some effect on nitrification.
[00:44:08.040]And then some lab studies have shown
[00:44:10.440]that these herbicide can inhibit nitrification.
[00:44:13.530]But those studies have just been conducted at the lab scale.
[00:44:17.760]So in this study we were looking to see
[00:44:21.150]and evaluate if this nitrification inhibitor,
[00:44:24.750]they conserve less or more nitrogen
[00:44:27.990]compared to conventional nitrogen sources or herbicide.
[00:44:32.460]So we tested Urea versus Anhydrous two nitrogen sources
[00:44:37.590]with and without nitrification inhibitor
[00:44:39.990]and with no pre-emergence herbicide
[00:44:42.690]versus Acuron and Resicore.
[00:44:44.610]We tested two herbicide in this trial.
[00:44:48.210]So this trial was connected at south central leg lab.
[00:44:53.460]I skipped that slide.
[00:44:55.200]And this was gone following soybean,
[00:44:58.140]we had the same nitrogen rates for all the treatments.
[00:45:03.610]So to test the effect of all of those treatments
[00:45:06.810]on nitrification,
[00:45:09.150]we collected weekly soil sample
[00:45:11.850]during May and June,
[00:45:19.440]during the two years.
[00:45:20.880]So because those are the two months
[00:45:22.680]which are more, you can get more precipitation
[00:45:26.940]and then there are more chances for nitrate leaching
[00:45:30.570]during those early season
[00:45:32.850]if you are getting heavy precipitation events.
[00:45:35.700]So we collected those samples
[00:45:41.430]and we analyzed those samples
[00:45:43.410]for soil ammonium and soil nitrate during those two seasons.
[00:45:48.030]So here you can see that this graph
[00:45:50.550]is showing soil ammonium for the two shares.
[00:45:54.570]AA stands for Anhydrous ammonia
[00:45:57.210]plus I, with inhibitor,
[00:45:59.400]and plus no, that means anhydrous ammonia
[00:46:02.220]without any inhibitor.
[00:46:04.020]Urea plus I is Urea with inhibitor.
[00:46:06.630]Urea no is without any inhibitor.
[00:46:10.620]So you can see here that anhydrous ammonia with inhibitor
[00:46:16.980]had comparatively higher ammonium nitrogen
[00:46:21.390]compared to anhydrous ammonia without inhibitor.
[00:46:25.320]So we saw on most of the sampling dates
[00:46:27.870]for the anhydrous treatment.
[00:46:29.700]But for Urea treatment, there was just a couple of days
[00:46:32.880]where Urea with anhydrous with inhibitor
[00:46:36.030]had higher ammonium nitrogen compared to without inhibitor.
[00:46:40.500]And we found the similar effect for the next year.
[00:46:44.310]But it was most interesting to see these reserves
[00:46:49.752]that nitrogen source had either a bigger effect
[00:46:52.830]on nitrification.
[00:46:54.840]You can see that anhydrous ammonia
[00:46:56.790]has significantly higher ammonium nitrogen
[00:47:00.750]compared to Urea treatment with or without inhibitor.
[00:47:04.560]And then we see the same pattern for the next year.
[00:47:08.160]When we looked at the soil nitrogen data,
[00:47:11.130]we saw the opposite effect.
[00:47:13.470]So there was some effect of nitrification inhibitor
[00:47:17.585]and reducing information of nitrate in the soil.
[00:47:21.150]However, we saw a significant effect of nitrogen source.
[00:47:25.290]So nitrogen source has a significant effect
[00:47:27.570]on nitrate formation.
[00:47:28.950]You can see that here and anhydrous ammonia
[00:47:31.590]had lower nitrogen compared to Urea.
[00:47:35.790]So that really indicates that nitrogen source
[00:47:38.190]is even more important.
[00:47:40.350]It has more effect on reducing nitrification
[00:47:43.650]compared to nitrification inhibitor.
[00:47:46.500]And then we also saw the effect of herbicide
[00:47:49.500]on nitrification or soil ammonium
[00:47:53.430]and nitrate nitrogen during those two months.
[00:47:58.256]So we saw a variable effect of those herbicide
[00:48:00.750]on nitrification.
[00:48:02.790]Somehow we saw, for example,
[00:48:05.960]here Acuron retained more ammonium than the Resicore
[00:48:10.380]but there was no statistical difference
[00:48:12.240]with no pre-emergence herbicide.
[00:48:14.730]But we saw some effect in 2020 where both herbicides
[00:48:19.872]had higher ammonium nitrogen
[00:48:22.740]compared to no pre-emergence herbicide.
[00:48:26.220]And then we did not found any significant effect
[00:48:29.040]of nitrate formation with anhydrous ammonia in both years.
[00:48:33.360]But surprisingly, we saw lower nitrate nitrogen
[00:48:37.860]with low pre-emergence herbicide
[00:48:39.990]compared to the other two herbicides.
[00:48:42.630]So this is really interesting.
[00:48:44.280]Because here, in 2020, there were more weeds.
[00:48:50.160]We were not able to apply
[00:48:53.340]post-emergence herbicide on time.
[00:48:56.040]So that resulted in more weeds
[00:48:58.560]and then that took up more nitrate nitrogen
[00:49:02.188]from the soil.
[00:49:05.280]While in 2021 we applied pre-post-emergence herbicide
[00:49:09.480]that did not affect nitrate nitrogen concentration
[00:49:14.400]in the soil.
[00:49:16.020]So I think that I am really going, we have less time, right?
[00:49:20.100]How much time do we have?
[00:49:22.660](indistinct)
[00:49:28.020]Okay, sounds good.
[00:49:29.650]So I think that I will have to skip some slides here.
[00:49:33.600]So I will just go through this,
[00:49:34.980]and then I will take questions.
[00:49:37.950]Okay, so we did not see...
[00:49:39.690]So here are the grain yield from those two years,
[00:49:42.928]2020 and 2021.
[00:49:45.120]You would see here we did not see any effect
[00:49:48.120]of nitrification inhibitor on grain yield
[00:49:52.740]in either year with either nitrogen source.
[00:49:55.770]However there was some effect of,
[00:49:58.612]there was some interaction of nitrification inhibitor
[00:50:00.840]with a nitrogen source.
[00:50:02.400]Here you can see that those Acuron and Resicore
[00:50:07.440]those had higher grain yield
[00:50:10.530]compared to no pre-emergence herbicide
[00:50:12.900]and Urea treatment in 2020.
[00:50:15.960]This was probably because we had...
[00:50:23.947]This was probably because as I mentioned earlier,
[00:50:26.190]we did not apply both emergence herbicide at time
[00:50:30.090]so that the weeds probably took up more nitrogen,
[00:50:33.300]they were able to exploit surface applied nitrogen.
[00:50:37.110]But when you see the anhydrous ammonia,
[00:50:39.330]we did not see any effect of those nitrogen inhibitor
[00:50:43.380]or herbicide with anhydrous ammonia
[00:50:47.130]because probably because the weeds
[00:50:49.800]were not able to exploit nitrogen, those were in the band.
[00:50:54.110]So that really indicates that, again,
[00:50:57.090]banning nitrogen can really help to reduce
[00:51:03.480]nitrogen uptake by the weeds.
[00:51:07.129]But it definitely can help to improve
[00:51:09.930]top nitrogen uptake when there are more weeds.
[00:51:14.730]All right. So I think that with this
[00:51:17.070]I would be happy to take any question
[00:51:18.870]because I have other two slides
[00:51:20.490]that I don't have time for.
[00:51:25.175]So that excess nitrogen that we call nitrogen balance,
[00:51:31.643]So whatever nitrogen is applied
[00:51:33.720]minus nitrogen taken up by the crop.
[00:51:36.120]So whatever nitrogen would be left
[00:51:39.030]would be called surplus nitrogen.
[00:51:42.094](indistinct)
[00:51:44.095]That is, you can estimate at the end of the year, yes.
[00:51:49.091](indistinct)
[00:52:20.395]plus or minus 10% percent, what should that value be?
[00:52:24.510]Cause all the answer.
[00:52:26.100]Right. So that's very... Okay.
[00:52:31.170]Thanks for reminding me.
[00:52:32.490]So the question is when we are talking
[00:52:35.100]about the excess nitrogen, what does that mean?
[00:52:39.360]What is that excess nitrogen and how is that calculated?
[00:52:42.930]And then how about the...
[00:52:45.150]And then I replied the excess nitrogen
[00:52:47.070]is kind of nitrogen balance
[00:52:48.450]where nitrogen that you have applied,
[00:52:52.050]you can deduct nitrogen taken up by the crop,
[00:52:54.660]the difference would be excess nitrogen.
[00:52:56.940]But the follow up question was,
[00:52:59.010]how about the nitrogen that is coming from,
[00:53:01.590]either from the water or nitrogen coming from other sources?
[00:53:06.124]So how do you calculate where the boundary is?
[00:53:08.520]That's really a good question,
[00:53:10.020]because once, you know, I think that,
[00:53:14.644]we really need to set up the limits for excess nitrogen.
[00:53:17.760]So that's what we call uncertainty.
[00:53:21.000]Around your EONR economic optimum nitrogen rate.
[00:53:24.390]And then if you cannot get the same rate for EONR,
[00:53:29.850]you cannot hit the same rate every year.
[00:53:32.850]There would be always an error or uncertainty.
[00:53:35.910]And then different research
[00:53:38.640]have found different uncertainty values.
[00:53:42.810]But I think that if you are,
[00:53:45.608]for example, 15 or 20 pounds plus minus that EONR
[00:53:51.960]you should be happy that you are using EONR,
[00:53:57.030]you are within that range.
[00:53:58.530]But if you are exceeding that limit,
[00:54:02.809]for example, if you are applying
[00:54:04.492]more than 30 pounds nitrogen,
[00:54:06.509]and then some researchers
[00:54:08.820]have found that there was a nitrogen balance
[00:54:12.090]above 75 kilogram nitrogen per hectare,
[00:54:15.660]which is really above the EONR.
[00:54:18.410]So we really need to set up those values
[00:54:21.060]after taking into account nitrogen from those sources.
[00:54:24.540]I think that would be really a key.
[00:54:37.633](indistinct)
[00:54:46.831](indistinct)
[00:55:05.236]So the question is,
[00:55:06.300]because I shared one slide where we have one loop
[00:55:08.880]with four Rs practices
[00:55:11.027]and then I have the conservation practices as well.
[00:55:13.050]So Dan have asked me question
[00:55:15.150]what work if any my group is doing
[00:55:19.020]to evaluate those conservation practices.
[00:55:22.020]So actually I was supposed to you share some of the slides
[00:55:24.870]on those that I am missing here.
[00:55:28.560]So we are working, actually I'm working
[00:55:31.020]in lot of conservation practices
[00:55:32.790]like in city well had protection area,
[00:55:36.360]they reached out to us
[00:55:37.890]and they told us that the nitrate
[00:55:40.712]in their drinking water well is increasing over time.
[00:55:42.750]So we are doing some study with cover crop there.
[00:55:46.140]We drill cover crops so we are seeing,
[00:55:49.650]we are evaluating the effect of those cover crop
[00:55:51.780]on nitrate leaching.
[00:55:54.360]And then so I have got another grant from NRCS now,
[00:55:57.780]where we are going to evaluate the effect of cover crop
[00:56:01.830]on nitrogen balance
[00:56:03.480]at three of our long-term delay sites in Nebraska.
[00:56:06.960]And I have another project going on from USDA
[00:56:12.540]where we are evaluating different
[00:56:14.970]integrated nutrient management practices
[00:56:17.280]including the effect of manure
[00:56:20.640]versus inorganic fertilizer
[00:56:23.160]with or without cover crop,
[00:56:25.110]with and without wood chips.
[00:56:27.900]So those are some of the practice
[00:56:29.723]that we are also evaluating their effect
[00:56:33.152]on nitrate leaching nitrogen efficiency.
[00:56:37.488](indistinct)
[00:56:46.892]And concentration (indistinct)
[00:56:49.888]What about the variability (indistinct)
[00:56:56.824](indistinct)
[00:56:58.848]Yes.
[00:56:59.852]So which of the two
[00:57:02.238]did you show some the variability on the concentration?
[00:57:05.735]how that affected (indistinct)
[00:57:09.860]They have that same variability
[00:57:11.404]or maybe you start to catch some of the licenses.
[00:57:15.995]So yeah, I think that's really a good question.
[00:57:19.470]Great question because there is always variability
[00:57:22.410]whether you are doing greenhouse gas measurements
[00:57:24.570]or nitrate leaching.
[00:57:26.370]There is always temporal variability,
[00:57:29.704]special as well as temporal variability.
[00:57:31.532]So to catch up special variability
[00:57:33.870]we install multiple suction cup lysimeter in each plot.
[00:57:38.970]For temporal variability,
[00:57:41.040]I think that the more frequent measurements are,
[00:57:44.940]the more better it would be.
[00:57:46.080]Because at the end through linear interpolation
[00:57:49.800]you want to calculate the estimate the nitrate leaching
[00:57:53.912]with the other days when you are not doing the measurements.
[00:57:56.250]But in our study what we did,
[00:57:58.260]we tried to collect frequent measurements
[00:58:00.810]so we were going there twice every week.
[00:58:03.150]That really gives us more sampling points
[00:58:06.570]to do the linear interpolation
[00:58:08.700]and get some kind of accurate estimate
[00:58:10.890]for nitrate low to ground water.
[00:58:13.110]I know it's really hard to get the exact,
[00:58:18.480]but there is always an estimate
[00:58:20.790]to compare among the treatments.
[00:58:24.860]Yeah, my question was,
[00:58:26.919]so flow (indistinct)
[00:58:33.997]So we are not calculating the flow
[00:58:36.120]with the moisture sensor actually.
[00:58:38.040]We are just, you know...
[00:58:40.020]So we are using that data from the moisture sensor
[00:58:42.500]in our water balance equation to calculate the flow.
[00:58:47.400]So yeah, we use the water balance equation.
[00:58:53.644](indistinct).
[00:59:02.898]Yes
[00:59:04.368](indistinct)
[00:59:06.117]So those were actually done all the treatments,
[00:59:08.280]but these industrial models,
[00:59:10.320]they do not include that sometime in their recommendations.
[00:59:13.920]So all of our models, they were accounting for that,
[00:59:16.560]so that's why we ended up accounting their nitrogen
[00:59:19.290]from their recommendations too.
[00:59:31.568](indistinct) earlier
[00:59:33.188]that had the nitrate concentration in groundwater.
[00:59:36.330]Yes.
[00:59:37.163]And you know if we (indistinct)
[00:59:42.060]bring all of the ground water down below the parts of perion
[00:59:47.700]within some reasonable amount of time,
[00:59:50.717]let's say a decade or something.
[00:59:54.136]From your studies and your work up there
[00:59:58.680]justify adjusting nitrogen fertilizer rates.
[01:00:04.860]Okay, that's great question.
[01:00:08.588]It's a mixing question.
[01:00:09.696]Yes.
[01:00:11.016]With the leaching low enough in that.
[01:00:15.080]So the question from Aaron is,
[01:00:17.310]so we have this nitrate in the groundwater
[01:00:21.090]from different townships in Nebraska,
[01:00:23.940]and then the concentration
[01:00:26.092]are above 20 parts per million or so.
[01:00:30.892]So how can we bring those down?
[01:00:33.412]So with the practices that we are,
[01:00:34.320]for example for evaluating cutting nitrogen rate,
[01:00:38.490]can that bring that value down
[01:00:41.040]to 10 parts per million that we want?
[01:00:43.740]That's a good question.
[01:00:45.900]And then I think that to bring that value down,
[01:00:51.450]we really have to answer the questions
[01:00:56.366]in the right way.
[01:00:57.660]And you really have to know if the practices
[01:01:01.440]that you are implementing,
[01:01:04.050]are those really helping to reduce the nitrate leaching
[01:01:08.702]and not making it worse?
[01:01:09.600]And that's one thing. We want to know the reality.
[01:01:11.490]We don't want to stay on our assumptions.
[01:01:14.430]For example, we know this great application
[01:01:17.130]is one way to reduce nitrate leaching.
[01:01:22.830]But we don't have that study in Nebraska
[01:01:25.710]to really show applying UAN which is already nitrate
[01:01:30.600]applying UAN, can that...
[01:01:34.183]Is better applying UAN with other fertilizers,
[01:01:35.730]can that reduce nitrate leaching?
[01:01:37.140]Probably it can, but we don't know what extent.
[01:01:40.170]That's one part.
[01:01:41.003]The other one is using these nitrification inhibitor,
[01:01:43.680]how much nitrogen can we cut down?
[01:01:45.720]So using four Rs is one practice
[01:01:49.230]to cut down that nitrogen rate.
[01:01:51.600]Probably that would not reduce the nitrogen
[01:01:54.420]to the level that we want.
[01:01:56.160]Again conservation practices are the other option
[01:01:59.040]to kind of refine our nitrogen rates
[01:02:03.210]and reduce the nitrate leaching into the groundwater.
[01:02:07.920]So I would say again, as I presented earlier,
[01:02:10.740]a combination of these practices,
[01:02:13.050]we really need to use a combination of these practices
[01:02:17.640]to reduce these nitrate leaching leaking.
[01:02:19.110]Especially like we need to prioritize practices.
[01:02:24.840]If one practice is really can help us to reduce
[01:02:28.110]nitrate leaching more than the other,
[01:02:30.915]we really need to set up those priorities.
[01:02:32.313]Because if we are, for example, talking about one practice,
[01:02:36.240]just to give you an example, if we are thinking that,
[01:02:41.323]if you can do improved soil health
[01:02:42.900]to reduce nitrate leaching,
[01:02:44.670]I don't know how long it's going to take
[01:02:46.950]to reduce nitrate leaching just by growing cover crop.
[01:02:50.310]So cover crop can reduce nitrate leaching to some extent,
[01:02:53.700]but varies the cover crop compared
[01:02:55.470]to other best management practices.
[01:02:57.480]We really need to set the priorities
[01:02:59.460]and then see how those practices can contribute.
[01:03:05.340]But when there's a question for you Aaron,
[01:03:09.000]you have to answer that question first.
[01:03:12.599]So when are we going to see that effect?
[01:03:13.980]Probably I think that we need to do some modeling
[01:03:18.538]and see the timeline when this nitrate,
[01:03:24.390]how long it takes for the nitrate
[01:03:26.250]to move from the surface to groundwater
[01:03:28.740]and what's the leg effect and how long would it take?
[01:03:34.050]Does that answer your question? Okay.
[01:03:42.899](indistinct) practices
[01:03:45.900]Yes.
[01:03:47.340]Someone working which chips
[01:03:51.207]would bring down nitrogen levels (indistinct)
[01:03:54.884]nitrogen ratio funnel the activities
[01:03:59.563]into bring down those chips.
[01:04:03.418](indistinct)
[01:04:18.599]So yeah, continue.
[01:04:19.650]And I just wanted to bring this slide up.
[01:04:22.500]Someone is working.
[01:04:24.210]Oh yes actually you know Amy Smith,
[01:04:28.590]she's the associate professor.
[01:04:31.200]She has worked some on research trial
[01:04:34.140]with the wood chips.
[01:04:35.340]And then in this USDA CARE Project,
[01:04:38.100]we are also looking the effect of the wood chips
[01:04:40.440]on nitrate leaching.
[01:04:42.570]Yes. We are looking into that.
[01:04:48.810]in con we are looking in con.
[01:04:55.220](indistinct)
[01:05:08.040]Stop there, for a great presentation
[01:05:10.620]and we've run out of time
[01:05:12.060]Lots of great discussions.
[01:05:13.860]So thank you again.
[01:05:15.540]And again reminder, no seminar next week,
[01:05:17.730]but we will be back November 4th.
[01:05:21.912](audience clapping)

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Tackling Nitrogen as Necessary Evil: Impacts on Nebraska’s Cropping System and Water Quality

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