12 - 2020 Soybean Management Field Days - Influence of Soil and Residue Management on Herbicide Carryover and Subsequent Crop Development
Chris Proctor, Nebraska Weed Management Extension Educator discusses the following: Carryover of residual herbicides can limit productivity of subsequent crops in a rotation. He also discusses persistence of residual herbicides is greatly influenced by soil properties such as texture, organic matter, water content, organic matter content and temperature regimes
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[00:00:07.030]Chris Proctor, I'm a weed management extension educator
[00:00:09.670]with the University of Nebraska.
[00:00:11.340]I'm gonna highlight a study that was conducted
[00:00:14.250]in both Wisconsin and Nebraska,
[00:00:16.690]looking at how soil and residue management
[00:00:21.310]might influence herbicides
[00:00:23.010]that were applied to a previous crop,
[00:00:25.510]and how they might carry over to the next season's crop
[00:00:28.600]and how that might influence the development
[00:00:32.610]and yields of those next crops.
[00:00:35.780]So certainly, how herbicides persist in the soil,
[00:00:39.790]and their ability
[00:00:41.150]to maybe negatively influence the next crop in rotation
[00:00:45.840]is something to pay attention to,
[00:00:48.910]in terms of carryover in our systems.
[00:00:52.210]And so, we wanted to look at,
[00:00:54.100]particularly, how soil management might influence that.
[00:00:56.820]So there's been a little bit of work
[00:00:58.120]investigating just the idea of carryover
[00:01:00.780]from one crop to another, but we wanted to maybe evaluate
[00:01:06.740]if managing soil differently would influence that.
[00:01:09.307]And so, as I mentioned, this was a study done
[00:01:11.650]both in Wisconsin and in Nebraska
[00:01:15.240]at a research farm outside of Lincoln, Nebraska.
[00:01:19.120]We had a number of different soil textures.
[00:01:21.750]So that kinda helps give a broad swath of how this might,
[00:01:26.020]how soil texture might influence the study.
[00:01:29.130]But ultimately looked
[00:01:29.963]at three different soil management practices,
[00:01:31.650]and then five different herbicide treatments.
[00:01:34.607]And our soil management practices compared tillage
[00:01:37.220]versus a no-till system, versus a no-till plus cover crop.
[00:01:42.410]And our cover crop for this study was cereal rye grass.
[00:01:49.270]And then we looked at two different herbicide,
[00:01:52.390]sets of herbicides.
[00:01:53.340]One was herbicides that would've been applied to corn.
[00:01:57.550]And then we looked at how that would influence
[00:02:00.710]the next year's soybean.
[00:02:01.820]And so, we had two herbicides, Callisto and Stinger.
[00:02:05.280]So, mesotrione and clopyralid.
[00:02:07.280]And those were applied at two different rates.
[00:02:08.730]So we had a quarter of the full-label rate,
[00:02:11.090]as well as half the full-label rate.
[00:02:12.970]And these were applied in the fall.
[00:02:15.370]And so we were trying to mimic a full rate,
[00:02:17.900]a spring application, that went through an entire season,
[00:02:21.420]and then how much might be left the subsequent year
[00:02:25.520]when the next crop was planted.
[00:02:26.980]And so, a quarter rate and a half rate in the fall
[00:02:30.100]was trying to represent maybe how much would be left
[00:02:32.440]after the cropping season
[00:02:33.980]that could potentially carry over the winter
[00:02:35.620]to the next year.
[00:02:36.453]And so that's how we designed the study.
[00:02:38.950]And then we also evaluated a couple of soybean herbicides.
[00:02:43.190]So, Reflex and Pursuit.
[00:02:45.470]And those were, again, applied
[00:02:46.810]at the quarter and half rate in the fall.
[00:02:48.740]And then we evaluated how those soybean herbicides
[00:02:50.870]might carry over
[00:02:51.970]into the corn cropping system the next season.
[00:02:57.370]We also selected a corn hybrid and a soybean cultivar
[00:03:01.320]that were kinda known to have a sensitivity
[00:03:03.960]to some of these herbicides.
[00:03:05.030]So we were wanting to exaggerate some of the effect
[00:03:08.260]if we could pick it up.
[00:03:09.400]We wanted some corn and soybean plants
[00:03:12.320]that might be more easy to detect some of these symptoms.
[00:03:16.830]And then we also evaluated kinda the development
[00:03:21.710]of the crop canopy at V3.
[00:03:23.910]And then we also evaluated yields at the end of the year.
[00:03:29.710]So I'll start highlighting some of the soybean results here.
[00:03:34.530]We'll jump right into it.
[00:03:35.363]And so this is looking at one of the sites in Wisconsin.
[00:03:39.810]And what we saw is at V3,
[00:03:41.850]we were able to detect a difference in canopy development
[00:03:44.550]where tillage had a more developed canopy
[00:03:48.100]relative to the no-till and the cover crop.
[00:03:50.240]But when we got to the end of the year,
[00:03:51.650]there was no difference
[00:03:52.810]in terms of soybean yield at that site.
[00:03:56.700]For our Lincoln, Nebraska location, it was very similar,
[00:04:00.040]where we had earlier development of canopy under tillage
[00:04:04.440]compared to the no-till and cover crop treatments,
[00:04:08.070]but that didn't show up in the yield at the end of the year.
[00:04:12.190]For the Lancaster location, the same story.
[00:04:14.890]So, earlier development of canopy under tillage,
[00:04:17.880]but no difference in yield at the end of the year.
[00:04:21.730]And then for one of the locations, Arlington,
[00:04:25.570]there was a small effect of the herbicide treatment.
[00:04:29.560]So for the previous ones I showed,
[00:04:30.830]there was really no effect of the herbicide.
[00:04:32.260]There was only differences between soil management.
[00:04:34.670]So, tillage, no-tillage, cover crop.
[00:04:37.430]But for this location, there was.
[00:04:38.780]There was a slight difference
[00:04:40.160]in terms of canopy development,
[00:04:43.330]where the half rate, the 50% rate of the mesotrione
[00:04:47.770]did decrease the canopy development at Arlington at V3.
[00:04:53.270]But then, by the end of the year,
[00:04:55.149]that didn't translate into a yield reduction.
[00:04:58.750]So this would just be an image
[00:04:59.850]showing some of the mesotrione injury
[00:05:02.450]that we saw at that V3 stage.
[00:05:05.200]So we could detect a little bit of injury in the soybean,
[00:05:09.660]but it ultimately didn't, we didn't see any effect
[00:05:12.750]in terms of yield.
[00:05:15.220]And so now I'm just gonna highlight
[00:05:16.920]some of the soybean herbicide carryover into corn.
[00:05:22.288]So I'll just highlight a few of the results
[00:05:24.490]of our soybean herbicides,
[00:05:27.230]and the influence they had on canopy development
[00:05:30.920]and yield in corn.
[00:05:31.867]And so looking at the first site, at Arlington,
[00:05:36.860]we saw early canopy development in tillage was higher
[00:05:40.050]than the no-till and the cover crop.
[00:05:42.660]And we did see even a decrease in yield
[00:05:45.050]under the cover crop plots here in corn.
[00:05:49.000]For the Lincoln, Nebraska site, in this instance,
[00:05:52.740]the no-till had a little bit slower canopy development
[00:05:55.780]at V3, and it did translate
[00:05:58.470]into a slight yield decrease for the no-till,
[00:06:00.880]and the cover crop plots did have slightly lower yield,
[00:06:04.350]relative to the tillage treatment.
[00:06:07.620]And then for the Lancaster site,
[00:06:10.720]again, canopy development was delayed
[00:06:12.510]for the higher-residue treatments.
[00:06:14.730]So the no-till and the cover crop
[00:06:16.320]did have lower canopy development at V3.
[00:06:19.510]And then also, that did translate across
[00:06:22.110]into lower yields for that location.
[00:06:26.440]And we did see a little bit of a difference
[00:06:28.350]for our Lincoln, Nebraska site, in terms of difference
[00:06:30.650]for the different herbicide treatments.
[00:06:34.170]This was the only location
[00:06:35.220]that had differences in herbicide treatment.
[00:06:36.770]So you can see that the imazethapyr, for example,
[00:06:41.640]at 50%, had a little bit lower canopy development
[00:06:47.310]compared to some of the other herbicide treatments at V3.
[00:06:51.720]And, ultimately though, that didn't translate
[00:06:54.480]into any yield differences for that location,
[00:06:57.690]relative to the herbicide treatments.
[00:07:00.190]And this was just an example of some of the injury
[00:07:03.390]that we did see in corn.
[00:07:04.223]So we did see some early injury symptoms
[00:07:07.760]in some of the corn.
[00:07:08.920]It wasn't persistent, it wasn't widely persistent,
[00:07:10.930]but we did see a little bit early on.
[00:07:15.684]And so really, what we did see is,
[00:07:18.600]under tillage conditions for soybean,
[00:07:20.360]the canopy developed quicker than the no-till
[00:07:23.940]and the cover crop treatments.
[00:07:28.270]And, ultimately, it was the cover crop.
[00:07:33.600]The cover crop treatments really had no effect
[00:07:37.470]on soybean yield, ultimately, for, across the treatment.
[00:07:41.790]So, while we did see some early differences,
[00:07:43.630]it didn't translate into yield for the soybean.
[00:07:46.530]However, in corn, it was a little different story.
[00:07:48.500]So, ultimately, it was not a carryover effect
[00:07:53.430]due to herbicides, but the cover crop treatments
[00:07:56.310]across all of our study locations did have lower yields
[00:07:58.760]relative to the no-till.
[00:08:02.293]And so, soil treatment, if you will,
[00:08:05.910]so, no-till versus tillage, versus cover crop,
[00:08:09.090]that had a stronger influence on the next year's crop
[00:08:11.980]than herbicide carryover did, in this instance.
[00:08:14.950]And so, we think the level of rainfall
[00:08:17.310]that we had during the study,
[00:08:19.560]and kinda the soil conditions, the soil type,
[00:08:21.940]probably had a stronger influence
[00:08:23.870]on not seeing carryover for this particular year.
[00:08:26.930]So, it's certainly possible,
[00:08:28.420]but we didn't see a strong effect of that
[00:08:31.610]for this particular study.
[00:08:35.080]The comment being, in Nebraska,
[00:08:37.310]we have a range of irrigated versus rain-fed environments,
[00:08:40.710]and a whole range of soil types.
[00:08:44.170]And so that can have a pretty strong influence
[00:08:46.070]on how likely an herbicide is to carry over
[00:08:48.730]from one year to the next.
[00:08:50.120]Certainly the last number of years in Nebraska,
[00:08:52.160]we've had pretty adequate rainfall, either fall or spring.
[00:08:56.190]And so I think it's limited carryover,
[00:08:58.950]or it's been pretty small pockets of the state
[00:09:02.540]where conditions were just right to see it.
[00:09:05.320]But we haven't seen widespread carryover
[00:09:08.070]in Nebraska in recent years.
[00:09:10.180]Yeah, so the question being that the yield decrease
[00:09:12.460]that we saw in the corn
[00:09:14.170]that was tied to the cover crop treatment,
[00:09:17.370]is that something that just 'cause the cover crop,
[00:09:19.170]it was kinda the part of that establishing cover crops
[00:09:22.180]into a system, and it might decrease over time,
[00:09:25.750]versus, is this just always gonna be an issue?
[00:09:31.610]Yeah, I think tillage environments, in the short term,
[00:09:36.520]are gonna favor corn yields, right?
[00:09:39.460]It's just, it's an environment where corn tends to thrive.
[00:09:43.050]But when you look at the big picture,
[00:09:46.910]there's real advantage to the no-till and the cover crop.
[00:09:49.130]And it does seem to regulate.
[00:09:51.740]So if you look at the adoption of no-till over time,
[00:09:54.900]there tends to be that yield lag
[00:09:56.410]during the adoption of no-till.
[00:09:58.220]They talk about the five-year adoption lag.
[00:10:00.670]And so, those yields have tended to stabilize
[00:10:03.010]and increase over time.
[00:10:04.490]And I think we're starting to see
[00:10:05.660]more and more cover crop data that would suggest the same,
[00:10:07.970]that as those systems mature
[00:10:09.850]and are utilized over the course of time,
[00:10:15.530]those yields tend to stabilize as well.
[00:10:17.160]And so, I think that's probably most likely to occur.
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