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Angie Peltier


Angie Peltier
Former Extension Educator, Commercial Agriculture



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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Grain yield for continuous corn planted at four different planting dates in 2013, 2014 and 2015 (source: Brian Mansfield, Northwestern IL Ag R&D Center Research Agronomist).
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Trends in Continuous Corn and Corn-Soy Rotation Planting Dates


Although Twitter came alive this spring with reports of farmers near Pearl, IL (in Pike County) planting corn on March 8, and I spoke with a farmer in Knox County that planted corn on March 22, most people wait for the 'earliest plant' dates dictated by the USDA Risk Management Agency (RMA). RMA sets these dates based upon historical weather patterns, balancing the risks associated with frost and lost yield potential due to delaying planting. Earliest plant dates are county-specific. In Warren County, and much of central Illinois, the RMA earliest plant date for corn is April 5. If a person were to plant before the earliest plant date, those acres would not be eligible for replant payments.

Planting date research. Each year, personnel at the Northwestern Research and Demonstration Center establish a replicated planting date trial. The data that will be collected from the trial established this year will tell us, given the conditions that will be experienced by the crop from planting until harvest, when was the best time to plant corn in Monmouth in 2016. Over a number of years and locations, these data can provide us with clues about the effect of planting date on grain yields.

Brian Mansfield, Research Agronomist at the Northwestern Illinois Ag R&D Center, recently summarized the results of two adjacent corn planting date trials planted in 2013, 2014, and 2015: one planted into continuous corn and one in rotated corn. The tables and figures and the indented text below is the summary that he prepared.

Trends in Continuous Corn and Corn-Soy Rotation Planting Dates

In Illinois, several studies investigating the effect of planting date on corn and soybean yields have been conducted at the NWRC as well as other locations across the state. Results from these long-term studies have identified mid- to late April as the best time to plant corn. As planting is delayed, yield reductions can be approximately 1 bu/day during the first third of May, 1.5 bu/day during the second third, and 2 bu/day during the last third of May (Nafziger, 2009).

Dr. Emerson Nafziger has conducted research trials at the NWRC that evaluate hybrid response to both planting date and a R1 (silking) foliar fungicide application. In both 2013, 2014, and 2015 a similar study was established, differing only by being planted in a continuous corn rotation rather than after soybean in a corn-soybean rotation. These separate experiments are located in adjacent fields. The hybrid and planting dates have been identical in both studies (Table 1). According to seed company literature the hybrid that was used is recommended for both rotations, is suitable for early planting/tolerant of cold soils, and has an average to above average resistance score for common diseases.

Table 1 Recorded Planting Date

Date

2013

2014

2015

Date 1

4/4/2013

4/9/2014

4/1/2015

Date 2

4/26/2013

5/5/2014

4/21/2015

Date 3

5/15/2013

5/19/2014

5/12/2015

Date 4

6/4/2013

5/30/2014

6/4/2015

Although there weren't always statistically significant differences among planting date treatments in each year in both rotations, when compared to the more 'typical' planting dates in mid-April or early May, the earliest planting dates and latest planting dates sometimes resulted in lower yields (Table 2).

Table 2

Corn Yield Response to Planting Date

Corn-Soybean Rotation

Continuous Corn

2013

2014

2015

2013

2014

2015

Date 1

212.2B

220.4A

235.5A


214.2A

210.8A

223.7AB

Date 2

221.6A

212.7AB

234.3AB


234.0A

223.0A

234.7A

Date 3

220.9A

212.6AB

228.1AB


228.4A

217.3A

208.3BC

Date 4

227.5A

178.7C

197.0C

218.5A

179.8B

194.7C

*Planting dates with the same letter are not significantly different from one another at alpha = 0.05.

Table 3 presents the mean yields for each of the planting date ranges combined across years. In continuous corn production, the mid-April to early-May planting date window resulted in the numerically highest yield (230.6 bu/A), followed by the mid-May (218.0 bu/A) and early-April (216.2 bu/A) planting dates, with the early-June planting date being the only treatments averaging below 200 bu/A (197 bu/A). Residue left from previous corn crops may have reduced soil temperatures in these trials, which could have significantly delayed crop growth and development. Research from Iowa State University showed that soil temperatures differed by as much as 2.2 to 2.5 degrees between soil with and without residue (Licht and Al-Kaisi, 2005). Although there was likely residue in the rotated corn trial, there was likely much less than in the continuous corn trial. Research has shown that there is nearly three times the amount of crop residue left after corn is grown than after soybean (Shrratt and Goesch, 2008). Residue also has the potential to impede seed to soil contact or physically impede seedling emergence.

In the rotated corn, the mean yields for the first three planting dates, from early-April until mid-May, were very similar, yielding within 2.4 bu/A of one another. With rotated corn, only planting in early June significantly reduced yields (Table 3).

Table 3

Corn Yield Response to Planting Date 2013 - 2015

Corn-Soybean Rotation

Continuous Corn

Date

Bu/A

Date

Bu/A

Date 2

222.9A


Date 2

230.6A

Date 1

222.7A


Date 3

218.0A

Date 3

220.5A


Date 1

216.2AB

Date 4

201.0B

Date 4

197.7B

*Planting dates with the same letter are not significantly different from one another at alpha = 0.05.

Literature Cited.

Licht, M.A. and Al-Kaisi, M. 2005. Strip-tillage effect on seedbed soil temperature and other soil physical properties. Soil & Tillage Research. 80:233-249.

Sharratt, B.S. and Gesch, R.W. 2008. Emergence of polymer-coated corn and soybean influenced by tillage and sowing date. Agronomy Journal. 100:585-590.


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