22 - Soybean Management Field Days - Soy Varietal Maturity Group – Cover Crop
Soy Varietal Maturity Group – Cover Crop - Jim Specht, UNL Emeritus Professor of Agronomy and Horticulture covers the following: Inserting a Winter Annual Cover Crop into a soybean-corn crop rotation involves two considerations, the first of which we have already discussed (delaying the soybean planting date to allow more CC dry matter), but one must also consider using an earlier varietal MG to permit better establishment of the CC after soybean harvest. Let’s consider some tools for making decision to use an earlier MG.
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[00:00:07.730]Okay, my name is Jim Specht, professor of agronomy,
[00:00:11.300]now retired at the University of Nebraska
[00:00:13.600]and my specialty was soybean physiology
[00:00:17.320]and production in addition to genetics genomics,
[00:00:20.090]but today we're going to focus on physiology
[00:00:22.260]and production of soybean.
[00:00:23.730]So, how does the impact of inserting a cover crop
[00:00:27.830]influence your choice of bridle maturity group?
[00:00:31.680]Here again is where you're going to insert it.
[00:00:33.810]But notice that when we stop talking about
[00:00:36.520]just before the soybean crop is planted
[00:00:38.377]until after the soybean crop is planted.
[00:00:41.440]Can you reduce the maturity group of your planted soybean
[00:00:44.810]to allow you to get more time to plant your cover crop
[00:00:48.470]for the next season corn crop before then?
[00:00:52.360]And one advantage here is that you can take a look at
[00:00:55.734]Iowa's tool, selection tool, it's a very nice tool
[00:01:00.930]because it allows you to compare planning dates
[00:01:04.356]and maturity groups together.
[00:01:07.210]So if you're a cover crop person,
[00:01:09.360]you want to know how you can best insert a cover crop
[00:01:12.480]and modify your planting date for soybean
[00:01:15.080]and maturity group you can use this slide.
[00:01:18.280]So this particular slide from the tool
[00:01:21.400]which you can get by yourself shows if
[00:01:22.870]for the maturity of groups one, two, and three on the left
[00:01:26.953]for southwest Iowa which is directly across from Lincoln.
[00:01:31.890]And you can see that if your plant on May, April 30th here,
[00:01:39.330]you can get all the three of those maturity groups done
[00:01:42.520]by the likely frost date.
[00:01:45.380]And so you would naturally choose
[00:01:47.150]the longest maturity group.
[00:01:49.420]Now if you move your planting date to May 15
[00:01:52.240]and you still have the same maturity groups,
[00:01:54.130]you see the maturity group three is running into
[00:01:56.370]a risk problem with fall frost.
[00:01:59.400]And so you might jump into a group two or two five.
[00:02:03.840]And here again, if you're planning on May 30 late,
[00:02:07.380]you can see that your maturity group threes
[00:02:10.320]are definitely not to the years
[00:02:11.870]and maturity groups twos are getting close
[00:02:14.281]to being a problem but and you're spreading out the season
[00:02:17.364]a little bit on maturity group ones.
[00:02:22.330]Sell for cover crop planting.
[00:02:25.100]So, we just chose the April 30th to May 15th planting,
[00:02:29.397]because you can either will delay your planting,
[00:02:33.579]soybean planting to May 15th
[00:02:35.640]to get a higher cover crop biomass.
[00:02:37.887]But what maturity groups will be best for you then
[00:02:41.370]and you can see this is from maturity group three.
[00:02:43.990]Twos and threes are a bit, three is definitely are falling
[00:02:47.580]into the high risk frosting date.
[00:02:51.410]But here again you can see you can get by with,
[00:02:54.080]by going with maturity group two, it should be two.
[00:03:00.620]And the reason for making that soybean maturity group
[00:03:05.080]just a bit earlier is to allow you to plant the cover crop
[00:03:09.650]in the fall of winter rye, a little bit earlier.
[00:03:13.200]As Chris Proctor showed in his presentation,
[00:03:16.890]you can accumulate more dry matter
[00:03:19.390]to start out with in the in the fall and then again
[00:03:22.900]in the spring to get your cover crop off to a good start.
[00:03:26.240]So, soybean planting must be delayed to mid-May
[00:03:29.960]to get the cover crop biomass you need that carbon.
[00:03:32.850]But when you're doing that you also have the possibility
[00:03:35.500]of seeing whether you can plant the cover crop
[00:03:39.210]that goes in after the soybean crop a bit earlier
[00:03:41.870]by choosing a little bit earlier maturity group.
[00:03:44.200]So you can use this too to do that.
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