Soybean Management Strategies to Facilitate Timely Winter Wheat Establishment in 2017

Article written by Dr. Adam Gaspar and Dr. Shawn P. Conley
 
Winter wheat acres across WI have declined over the past few years due to late grain harvests, disease concerns (FHB or scab) and poor wheat prices, however anyone that lives and works in WI knows that a base number of cereal acres are needed to support the dairy industry (straw and land to summer haul manure). As farmers get ready to kick off the 2017 growing season here are a few suggestions to help get your 2017/18 winter wheat crop established on time.

• Plant early. If weather and soil conditions allow for it plant the acreage you intend to go to winter wheat first. This is regardless of which crop you plan to follow (soybean, corn silage or field corn). Remember the optimal planting date window for most of our WI winter wheat acres is the last week of September through the first week in October. In table 1 below you will notice that for every 3 days planting is delayed we see ~1 day delay in beginning maturity (R7), so delaying planting by one week equates to about 2 days later maturing. However when planting is delaying past June 1^st it turns in to more of a 1: 1 relationship. Also remember in WI it normally takes another 5-8 days for the soybean crop to move from R7 to R8 (full maturity). 

Table 1. Calendar date for reaching R5 (beginning seed fill) and R7 (beginning maturity) growth stage by planting date and maturity group for the 2014, 2015, and 2016 growing seasons at Arlington and Hancock, WI.

		Date of Growth Stage Initiation
		R5		R7
Planting Date	Maturity Group	Arlington	Hancock	Arlington	Hancock
May 1st	2.5	3-Aug	4-Aug.	14-Sept.	15-Sept.
	2.0	30-July	1-Aug.	9-Sept.	14-Sept.
	1.5	26-July	29-July	3-Sept.	9-Sept.
May 20th	2.5	7-Aug.	9-Aug.	18-Sept.	20-Sept.
	2.0	3-Aug.	7-Aug.	14-Sept.	18-Sept.
	1.5	3-Aug.	4-Aug.	6-Sept.	15-Sept.
June 1st	2.0	11-Aug.	12-Aug.	18-Sept.	24-Sept.
	1.5	10-Aug.	9-Aug.	16-Sept.	18-Sept.
	1.0	7-Aug.	8-Aug.	10-Sept.	14-Sept.
June 10th	2.0	15-Aug.	17-Aug.	25-Sept.	30-Sept.
	1.5	14-Aug.	16-Aug.	20-Sept.	25-Sept.
	1.0	11-Aug.	14-Aug.	16-Sept.	18-Sept.
June 20th	1.5	21-Aug.	21-Aug.	27-Sept.	2-Oct.
	1.0	18-Aug.	18-Aug.	24-Sept.	26-Sept.
	0.5	16-Aug.	16-Aug.	19-Sept.	22-Sept.

• Consider an earlier maturity group soybean. Plant a high yielding, earlier maturity group soybean to help get that soybean crop harvested on time. Though later maturing varieties "on-average" produce the greatest yields, data from our 2016 WI Soybean Variety Test Results show the maturity group range that included a starred variety (starred varieties do not differ from the highest yield variety in that test) was 1.8-2.8, 1.4-2.4, and 0.8-1.8 in our southern, central and north central regions respectively. This suggests that the "relative" maturity group rating is trumped by individual cultivar genetic yield potential. Therefore growers have options to plant an early maturity group soybean that will be harvested on time and not sacrifice yield.
• Crop rotation matters. Our long-term rotation data suggests winter wheat yields are greatest following soybean, followed by corn silage and lastly corn for grain.  Therefore plan your rotation accordingly to maximize yield and system efficiency.
• Manage for the system not necessarily the crop. If you are serious about maximizing wheat grain and straw yield on your farm one of the biggest contributing factors for both of these in WI is timely wheat planting. Make management decisions to facilitate that. *We all know what inputs can extend maturity that don't necessarily guarantee greater yields. So instead of listing them and fielding angry emails I am being strategically vague here*  As a producer is it better to sacrifice 0-2 bushels of soybean yield or 10-20 bushels of wheat grain yield and 0.5 tons of straw?  

As we all know mother nature holds the ultimate trump card on whether we will get our winter wheat crop established in that optimal window. These aforementioned strategies are relatively low risk to the farmer and regardless of what weather patterns we run into are agronomically sound.

Planting Date and Maturity Group Considerations Moving into a Potentially Early Spring 2017.

Article written by Dr. Adam Gaspar and Dr. Shawn P. Conley

Early May planting in Wisconsin has been documented to increase yield due to increased light interception (Gaspar and Conley, 2015).  Earlier planting dates are able to increase light interception in two ways, which are both demonstrated in Figure 1. First, the reproductive growth period between R1-R6 occurs during longer days with the May 1^st (Green line) compared to June 1^st (Orange line) planting date.  Secondly, the time spent in the R1-R6 growth stages is increased with the earlier planting date. As Figure one shows, the May 1^st planting date spent ~60 days from R1-R6 compared ~45 days for the June 1^st planting date.  Therefore, early plated soybeans experience both longer duration in reproductive growth (more days) and reproductive growth during the longest days of the summer. 

Figure 1. Blue lines represent day length at various latitudes. Most WI soybeans are grown between 43 and 45 degrees latitude. The vertical lines represent the time spent from R1 through R6 for May 1^st (Green Lines) and June 1^st (Orange Lines) planting dates. WI soybeans are mainly grown between 43 and 45 degrees latitude.

Yet, in some instances (weather or logistical problems) planting can be delayed or replanting may be needed. Therefore, investigating the effect of different MG’s at multiple planting dates across the state would be useful.  Thus, DuPont Pioneer and the Wisconsin Soybean Marketing Board funded a 3-year study to examine proper MG selection at 5 different planting dates across the state to maximize yield.  So let’s look at the 2014-2016 data.

Trials were conducted at Arlington, Hancock, and Spooner, WI.  The five planting dates at each location were planting roughly on: (1) May 1^th, (2) May 20^th, (3) June 1^st, (4) June 10^th, and (5) June 20^th.  Planting after June 20^th is generally not recommended in WI.  Two varieties within each realistic MG from a 2.5 all the way down to a 00.5 were tested depending upon the location and planting date and are displayed in Table 1.  

Table 1. Maturity Group’s tested within each location and planting date.
Planting Date		Arlington	Hancock	Spooner
1 (May 1th)		2.5, 2.0, 1.5	2.5, 2.0, 1.5	1.5, 1.0, 0.5
2 (May 20th)		2.5, 2.0, 1.5	2.5, 2.0, 1.5	1.5, 1.0, 0.5
3 (June 1st)		2.0, 1.5, 1.0	2.0, 1.5, 1.0	1.0, 0.5, 0.0
4 (June 10th)		2.0, 1.5, 1.0	2.0, 1.5, 1.0	1.0, 0.5, 0.0
5 (June 20th)		1.5, 1.0, 0.5	1.5, 1.0, 0.5	0.5, 0.0, 00.5

We will start with the easy and redundant part, get your soybeans in the ground ASAP to maximize yield.  This is very evident again in this trial as shown in Figure 2 and 3. If the soil is fit, soil temps are near 50 ˚F, and the forecast is favorable….. get that soybean planter rolling! As you would expect we found some very interesting synergies between early planting and longer MG’s.  Figure 2 contains MG 1.5 soybeans which at the May 1^st planting date only achieved ~85% of max yield.  Figure 3 contains the longest maturing soybean varieties (>1.5) for each location where soybeans reached 99% of max yield, with May 1^st planting.  Furthermore, as planting is delayed, the earlier MG bean’s (Figure 2) do not show a quick and dramatic yield decline compared to the later maturing beans (Figure 3).  Therefore, those that may have not experienced yield loss from delayed planting are likely planting varieties from a MG too short for their respective area.  Clear yield synergies are demonstrated in Figure 2 and 3 from planting early and using a longer MG soybean variety.  Both management practices add no additional cost, meaning any yield increase is direct profit. 

Figure 2. Yield of planting date from May 1^st (120) into June of 1.5MG soybean varieties.

Figure 3. Yield of planting date from May 1^st (120) into June for longest maturing soybean varieties at each location.

 Table 2. Effect of Maturity Group on Yield tested within each location and planting date, during 2014, 2015, and 2016

Planting Date		Arlington	Hancock	Spooner
1 (May 1th)		2.5	2.5	1.5
2 (May 20th)		2.5	2.5	1.5
3 (May 30th)		2.0	2.0	1.0
4 (June 10th)		2.0	2.0	0.5
5 (June 20th)		1.5	1.5	0.5
The numerically highest yielding MG for each planting date and location.  MG that are bold and colored red were significantly higher at the  P ≤ 0.10

Table 2 agrees with the conclusion from Figures 2 and 3, that early planting and longer maturity groups maximize yield. However, due to no significant MG effect at the Spooner location, the synergy of early planting and longer MG’s, may not be as consistent in Northern WI where the growing season is condensed. Planting date 5 at Arlington and Hancock was not significant for MG effects, but the longest MG planted there still yielded the highest numerically.  This was also the case at Spooner, but the 0.5 MG significantly out yielded the 0.0 and ultra-early 00.5 MG varieties.   

These results suggest planting a portion of your acres to slightly longer MG than normal within May can result in greater yields with no additional dollars spent.  In addition, when planting is delayed into June, switching to a variety much more than 0.5 MG earlier than a full season variety (2.5 MG) may limit yield potential.  However, if planting is delayed until mid to late June or more likely replanting is needed, a variety that is at least a full MG earlier should be considered to avoid fall frost damage.

In conclusion, early planting is critical for higher yields through increased light interception, and can be further maximized by planting longer MG’s. However, variety selection heavily based upon the MG is not the “silver bullet” for increasing yields. Yet, it does provide a strong “potential” for higher yields with no additional dollars spent, especially in early planting situations. Therefore, growers should give consideration to MG when selecting varieties, but past local and regional performance, disease package, scn-resistance, etc. should also strongly be considered.

References:

Gaspar, A.P. and S.P. Conley. 2015. Responses of canopy reflectance, light interception, and soybean seed yield to replanting suboptimal stands. Crop Sci. 55:377-385.