Remote Sensing and Variable Rate Nitrogen

Luqi Li Author

07/30/2020 Added

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Michael Carlson - Remote Sensing and Variable Rate Nitrogen

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[00:00:06.253](upbeat music)
[00:00:26.643]Hi, my name's Michael Carlson.
[00:00:28.590]I'm a research tech here
[00:00:30.927]and a P2 student studying precision nitrogen management
[00:00:34.620]on golf course fairways.
[00:00:36.270]Work for Bill Kreuser.
[00:00:38.240]I'm gonna talk about some work I'm doing here
[00:00:40.030]at our east campus plots
[00:00:42.230]as well as some spatial variability work I'm doing
[00:00:45.620]out at the Jim Ager Memorial Golf Course in Lincoln.
[00:00:50.970]Hopefully what I'm trying to figure out
[00:00:52.300]with my dissertation project,
[00:00:54.060]how to precisely at variable rate apply nitrogen
[00:00:57.980]on golf course fairways using NDRE reflectance
[00:01:03.060]to make the prescription rates.
[00:01:06.480]At our east campus plots,
[00:01:07.670]I'm continuing some of the work
[00:01:09.430]that I've been doing over the past two years.
[00:01:11.720]We can see that on this creeping bentgrass fairway,
[00:01:15.910]we've been varying the growth in quality
[00:01:18.440]by applying different rates of nitrogen
[00:01:20.730]and also altering the irrigation
[00:01:24.690]on the large plots of the fairways.
[00:01:28.480]So that way we're applying nitrogen anywhere
[00:01:32.380]from absolutely nothing,
[00:01:33.940]so zero pounds of N per thousand square feet
[00:01:36.930]every two weeks, up to 0.4 pounds,
[00:01:41.430]so anywhere from under,
[00:01:43.370]vastly under-applying to over-applying.
[00:01:45.800]You know, we're stacking this nitrogen on there
[00:01:47.280]so that we can see the varying qualities
[00:01:51.900]and then reflectance values
[00:01:54.710]from a couple of different sensors
[00:01:56.200]to hopefully be able to build some sort of model
[00:01:58.970]to precisely apply nitrogen
[00:02:02.350]for creeping bentgrass fairways needs.
[00:02:06.390]Can see Craig Ferguson and I collecting clippings
[00:02:09.530]from my plots out on east campus to quantify growth.
[00:02:14.530]This is a pretty standard way that we collect clippings.
[00:02:19.270]We change from using the buckets to that PVC pipe system
[00:02:23.960]so that we can maintain our distance between the two of us.
[00:02:28.320]So similar to what we've done out at Ager
[00:02:31.160]where we've collected clippings
[00:02:33.250]from specified locations on each fairway,
[00:02:36.320]that way we can relate some of that data to the growth rate
[00:02:42.220]to the reflectance that we have collected from that sensor
[00:02:45.870]to make sure that the model that I build
[00:02:50.410]works in that when we applying different rates of nitrogen,
[00:02:55.240]we can relate that back to different qualities and growth.
[00:02:58.060]Measuring reflectance from it
[00:03:00.300]using the same mower sensor setup
[00:03:02.270]that we use out at Ager here,
[00:03:04.960]as well as using two handheld sensors,
[00:03:07.400]so the Holland Scientific RapidSCAN sensor
[00:03:11.990]that measures in the same wavelengths
[00:03:14.570]as the mower attach sensors,
[00:03:17.470]so the red, red edge, and near infrared wavelengths,
[00:03:20.270]as well as using a Spectrum FieldScout TCM 500 NDVI meter.
[00:03:26.530]So that's just a handheld unit
[00:03:29.480]that anybody can easily go out and buy.
[00:03:31.360]And that measures reflectance in the red, green,
[00:03:35.900]and near infrared wavelengths.
[00:03:38.010]And from that, I'm just gathering,
[00:03:39.800]we're just recording the NDRE data.
[00:03:42.790]That way seeing if we can see a similar response
[00:03:45.540]in reflectance from a couple different sensors,
[00:03:48.690]as well as if a mower base unit
[00:03:52.130]may not be feasible at the moment,
[00:03:55.190]some of these handheld units might be able to be used
[00:03:58.350]on different courses in the meantime.
[00:04:01.690]So in 2019, when we looked at our handheld scanner data
[00:04:05.420]from both the NDVI data
[00:04:09.040]as well as NDRE,
[00:04:10.500]we found that NDRE had a bigger variation in,
[00:04:15.960]or a bigger range in values
[00:04:18.870]from the lowest growth and lowest quality
[00:04:22.530]up to the highest growth and highest quality plots
[00:04:25.690]out here on east campus.
[00:04:26.870]Whereas NDVI was a little bit, had a shorter range.
[00:04:31.140]And so what we're thinking is that
[00:04:36.360]as NDRE is more sensitive to the changes in growth
[00:04:40.110]and quality that we're forcing the grass to do,
[00:04:47.260]using NDRE can be a better method to prescribe nitrogen
[00:04:53.020]on creeping bentgrass fairways than using NDVI
[00:04:57.660]because of a lot of the issues relating to saturation
[00:05:02.390]of the red band in NDVI
[00:05:04.990]from 100% canopy cover that we see in turf grass systems.
[00:05:14.800]In early July, we're collecting clippings
[00:05:18.570]from three different fairways
[00:05:19.790]out at Jim Ager Memorial Golf Course here
[00:05:21.590]in Lincoln, Nebraska from fairways one, five, and seven.
[00:05:27.800]Fairway one is right outside the clubhouse,
[00:05:29.930]has some water issues as well as some shade issues
[00:05:33.410]on one side of the fairway.
[00:05:35.020]That's why we're interested in looking at it.
[00:05:36.840]It usually performs pretty fine
[00:05:38.710]and has a lower amount of annual bluegrass
[00:05:40.180]than some of the other fairways.
[00:05:42.800]Whereas when we look at fairway five,
[00:05:45.400]that on this video Ferg is at blowing off the dew,
[00:05:50.330]this one has a range and topography,
[00:05:53.320]has a low spot where there's often water found
[00:05:55.810]after heavy rains.
[00:05:58.930]It's pretty highly shaded during the day,
[00:06:01.970]especially in the morning,
[00:06:03.160]as well as has quite a bit of disease issues
[00:06:06.600]and historically has.
[00:06:08.910]So that's when we chose this one
[00:06:09.950]when we're looking at the variation
[00:06:11.770]in spatial clipping content
[00:06:14.550]or the spatial variability or clippings.
[00:06:18.690]We thought this one would be good
[00:06:21.090]'cause we can see just how much variability there is
[00:06:23.860]within one fairway.
[00:06:25.660]And then seven is the last fairway,
[00:06:27.700]and that one doesn't have much shade cover.
[00:06:32.200]It really honestly has minimal problems
[00:06:34.250]throughout the past two years
[00:06:36.710]that I've been working with Dr. Bill Kreuser in his lab.
[00:06:47.690]So if we look in some of the videos,
[00:06:49.800]you'll see that there we spray-painted dots.
[00:06:52.410]They look to be about 15 feet wide from each dot,
[00:06:57.000]and that is important
[00:06:59.380]'cause we've been able to set out 15-foot square grids
[00:07:03.450]on each fairway.
[00:07:05.350]And then rather than just relying
[00:07:07.900]on high spatial resolution GPS unit that we have,
[00:07:13.540]while we were collecting,
[00:07:15.100]I decided to go out and dot each of these grid spots
[00:07:19.480]so that when we're out there collecting,
[00:07:20.700]we can visually see where we need to start
[00:07:22.290]and stop that mower
[00:07:23.640]and reduce the amount of time that we're on that course
[00:07:26.460]and disturbing other golfers.
[00:07:30.000]Looking at spatial variability here on Ager,
[00:07:33.660]'cause we've been using a sensor,
[00:07:36.110]as we can see, on the back of this mower
[00:07:37.950]and in a couple other videos, the fairway mower,
[00:07:41.040]to collect reflectance data,
[00:07:43.420]specifically looking at NDRE
[00:07:46.770]to see if we can variable-rate apply nitrogen applications
[00:07:51.100]on fairways, especially creeping bentgrass fairways
[00:07:54.730]throughout a growing season.
[00:07:57.590]In this video, we can see our clippings collection process
[00:08:01.480]out here at Ager.
[00:08:03.370]It's honestly really quite similar
[00:08:04.710]to what we do on east campus
[00:08:06.280]when we're collecting clippings.
[00:08:07.680]We're just using the fairway mower that they use every day,
[00:08:10.770]collecting clippings from the central bucket
[00:08:13.470]in the front of the mower.
[00:08:17.860]And then, as we can see in subsequent videos,
[00:08:21.990]we're able to,
[00:08:23.490]we dumped the clippings into just a tub,
[00:08:27.580]sweep all those clippings into a labeled bag
[00:08:30.480]where they would go later that day to get dried
[00:08:33.390]as well as for to collect or to measure our dry biomass.
[00:08:39.310]And then I also took an extra set of clippings
[00:08:43.730]from each of these plots to measure chlorophyll content
[00:08:46.940]in the lab from a DMF solvent extraction.
[00:08:51.910]It went by pretty quick.
[00:08:52.850]We were able to get over the three fairways, 110 plots,
[00:08:57.640]done in less than two hours.
[00:09:01.510]Thanks for watching my video about some of my work
[00:09:04.340]in the precision nitrogen applications
[00:09:06.450]on creeping bentgrass fairways.
[00:09:07.720]If you have any questions,
[00:09:09.910]feel free to contact me.
[00:09:11.641]I'll be more than glad to provide you some information,
[00:09:15.310]or it'd be great if you have some specific thoughts
[00:09:17.824]on my project.
[00:09:18.950]Have a good day. (upbeat music)

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Remote Sensing and Variable Rate Nitrogen

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