Quick facts

To maximize profitability, the final plant population should selection from around 32,000 to 34,000 plants every acre. The economically optimum plant population varies v seed costs and also corn prices. As well high the a planting rate generally does not minimize corn yield, yet it does minimize net return.

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Optimum plant populace does not readjust if corn is planted by mid-May. However, once planting is delayed till late May, a higher plant populace is necessary to maximize yield.

Optimum plant populace is generally not influenced by row width. However, narrow rows can administer a modest yield boost for early-maturity hybrids.

Optimum plant populations are typically not influenced by relative maturity for mid- and also late-hybrids. However, optimum plant populaces for beforehand maturity hybrids have tendency to be close to or above the encourage planting rate guidelines.


With enhancing corn production costs and fluctuating serial prices, it’s critical that corn growers do sound decisions about planting come maximize profits. Decisions concerned planting price are specifically important, since seed represents about 15 percent of the total cost that corn manufacturing according to an Iowa State university report.

From 2005 to 2011, researchers evaluated exactly how corn yields in southern and central Minnesota responded to plant population, and whether planting date, hybrid maturity and also row width impacted this.

Maximizing profit

To maximize profit, research shows Minnesota growers require a final stand of 32,000 to 34,000 plants per acre (Figure 1), back this varies v the cost of seed and corn price. Corn yields were maximized close to a final stand of 33,000 plants per acre and were not diminished as plant populace increased to 44,000 plants per acre.


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Figure 1: Corn an answer to plant population in Lamberton, Morris, Rochester and also Waseca from 2009 come 2010. Each dot in the mean of 228 plots.

Planting rates

Planting rates need to be higher than the optimum plant populace to compensate for at an early stage season stand losses. Based upon Figure 1, planting prices of 34,000 come 36,000 seed per acre maximize net return in most fields.

Like the last stand essential to maximize profit, economically optimum seeding rates vary with corn price and seed costs. We calculated seeding rates (seeds per acre) to acquire within $1 of the maximum network return in Table 1. This seeding rates are 5 percent over the targeted population to compensate for at an early stage season losses.

 


Seed cost $4/bushel corn price $6/bushel corn price $8/bushel corn price
$225/bag 30,700 come 33,700 32,100 come 34,400 32,700 come 34,700
$275/bag 30,100 to 32,900 31,700 to 34,000 32,400 come 34,400
$325/bag 29,400 come 32,300 31,200 to 33,500 32,100 to 34,100

factors affecting optimum plant populace
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Planting date

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Figure 2: how corn responds come planting date and also plant population in Lamberton, Morris and also Waseca, indigenous 2009 to 2010.Research performed in Lamberton and also Waseca found that the optimum plant populaces were not impacted if corn was planted through mid-May (Figure 2). However, when planting was delayed till late May, a greater plant population was required to maximize yield.

Timely planting in an excellent soil conditions is the foundation for successful corn production. Studies display that tiny yield reduction wake up if corn is planted by mid-May. However, yield drops off conveniently when planting to be delayed beyond mid-May (Figure 3).


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Figure 3: an answer of corn grain yield to planting date in Lamberton, Morris and also Waseca from 2009 come 2011. Each dot is the mean of 6 hybrids.

Guide: when to tree corn in Minnesota

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Researchers evaluated how corn yield responds to 20- and 30-inch row spacings over a range of plant populations. They found that small rows go not substantially increase yield at any plant populace level and that the economically optimum plant populace of both heat widths was similar (Figure 4).


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Figure 4: Corn response to row width and plant populace in Lamberton and Waseca, native 2009 come 2010. Each dot is the mean of three hybrids.

Guide to narrow-row corn planting in Minnesota

Row width and relative maturity

Researchers likewise evaluated how hybrids in various maturity groups responded come the 20- and 30-inch row spacings in ~ different populace levels. The early-, mid-, and also late-maturity hybrids learned in southern Minnesota were 95-, 101- and 105-day family member maturities (RM). In west main Minnesota, the hybrid RMs to be 91-, 94- and 99-day.

Optimum planting rates and corn grain returns were normally not impacted by heat width for mid- to late-maturity corn hybrids.

However, early-maturity hybrids (less than 90-day family member maturity) planted in northwestern Minnesota developed 4 to 5 percent greater grain yield as soon as planted in rows narrower 보다 30 inches. These early-maturity hybrids additionally had optimum planting rates that were 3,500 seeds per acre better when planted in narrow rows.


These studies found greater corn yields with mid- and also late-maturity hybrids than early-maturity hybrids (Figure 5). The research evaluated 95-, 101-, and also 105-day RM hybrids in southern Minnesota, and also 91-, 94- and 99-day RM in west central Minnesota.


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Figure 5: Corn yield an answer to hybrid maturity and plant populace in Lamberton, Morris, Rochester and also Waseca, indigenous 2009 to 2010.

Optimum planting prices differed just slightly because that the different maturity team hybrids. For early maturity hybrids, the optimum planting rates tended come be close to or above the high finish of the recommended 34,000 to 36,000 seed per acre range (96-day RM or earlier). This is specifically true for hybrids less than 90-day RM.

Since earlier-maturing hybrids have tendency to be shorter and have less sheet area than full-season hybrids, it’s possible they require greater plant populaces to optimize irradiate interception.

While optimum planting rate differs somewhat among hybrids, hybrid an option generally impacts yield much more than fine-tuning planting rates by hybrid.

 


Research mirrors the financial optimum plant population is greater under higher-yielding environments.

An Illinois research reported that together yield potential increased from 135 to 225 bushels every acre, the economically optimum plant populace increased from around 25,000 to 32,000 plants per acre. Because that every yield increase of 10 bushels every acre, the optimum plant population increased by around 800 plants per acre.

While a too-high plant populace generally will not minimize yield, that will mitigate net return. In current trials in northwestern Minnesota where cultivation season rainfall was just 10 come 15 inches, grain yield ranged indigenous 100 come 130 bushels per acre and was not lessened with final stands approximately 44,000 plants per acre.

Estimating productivity loss

To determine exactly how a lower plant population will affect yield loss, describe Table 2. This visual reflects averages throughout experiments, and is a beneficial tool for estimating yield loss led to by unforeseen weather or soil conditions.


final stand (plants every acre) supposed yield
44,000 100%
41,000 100%
38,000 100%
35,000 100%
32,000 100%
29,000 99%
26,000 96%
23,000 92%
20,000 87%
17,000 81%

Grain yield increases from higher plant populations are primarily brought about by chop canopies intercepting an ext light during grain-fill.

In a 2008 planting date trial in Lamberton and also Waseca, researchers measured irradiate interception by the crop canopy just after silking (Figure 6). Each data allude in figure 6 represents canopy irradiate interception and also the corresponding grain yield for each level of tree population, averaged across three planting dates and also two locations.

Results display that as plant population increased from 15,600 come 32,400 plants per acre, canopy light interception increased from 82 come 92 percent and also grain yield increased from 157 to 190 bushels per acre. However, together plant population increased from 32,400 to 43,600 plants every acre, irradiate interception only boosted from 92 come 95 percent and grain yield boosted by simply 1 bushel every acre.

Figure 6 additionally suggests a relationship between optimum plant populace and the lot of light interception during grain-fill. The financially optimum plant populace is likely near the minimum plant population needed come intercept the majority of light during grain-fill.


Figure 6: exactly how canopy irradiate interception during grain-fill affect corn grain yield. Points room for six plant populaces ranging indigenous 15,500-45,600 plants/acre.Optimizing irradiate interception

Research argues growers regulate plant population with the score of optimizing light interception. Areas with optimum plant populace have very small sunlight hitting the soil surface, and also very few plants there is no ears.

To evaluate irradiate interception during grain-fill, watch under the chop canopy near solar noon top top a calm, clear day.


Jeff Coulter, benidormclubdeportivo.org agronomist

Acknowledgements

Thanks come the Minnesota Corn Growers Association, the Minnesota Corn Research and also Promotion Council, National chop Insurance Services and Monsanto for generously sustaining the majority of the research in this summary, and to Tom Hoverstad and also Steve Quiring because that conducting lot of the research.


Coulter, J. & Shanahan, J. (2012). Corn response to heat width, tree population, and also hybrid maturity in the much northern Corn Belt.

Nafziger, E.D. (1994). Corn planting date and plant population.

Van Roekel, R.J. & Coulter, J.A. (2011). Agronomic responses that corn to planting date and plant density. Agronomy Journal, 103(5), 1414-1422. Agronomic Responses the Corn come Planting Date and also Plant Density.

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Van Roekel, R.J. & Coulter, J.A. (2012). Agronomic responses that corn hybrids to heat width and plant density. Agronomy Journal, 104(3), 612-620. Agronomic Responses the Corn Hybrids to row Width and Plant Density.