Quick facts

To maximize profitability, the last plant populace should selection from about 32,000 come 34,000 plants every acre. The economically optimum plant populace varies v seed costs and corn prices. Also high that a planting rate usually does not reduce corn yield, but it does minimize net return.

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Optimum plant population does not adjust if corn is planted through mid-May. However, when planting is delayed until late May, a greater plant population is essential to maximize yield.

Optimum plant population is usually not affected by row width. However, small rows can carry out a usually yield increase for early-maturity hybrids.

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

With boosting corn manufacturing costs and fluctuating grain prices, it’s an essential that corn growers make sound decisions around planting come maximize profits. Decisions pertained to planting price are particularly important, due to the fact that seed represents about 15 percent that the complete cost that corn manufacturing according to an Iowa State college report.

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

Maximizing profit

To maximize profit, research reflects Minnesota growers require a final stand of 32,000 to 34,000 plants every acre (Figure 1), although this varies with the price of seed and also corn price. Corn returns were maximized near a final stand that 33,000 plants every acre and were not lessened as plant population increased come 44,000 plants per acre.


Figure 1: Corn an answer to plant populace in Lamberton, Morris, Rochester and Waseca indigenous 2009 come 2010. Each period in the typical of 228 plots.

Planting rates

Planting rates need to be higher than the optimum plant populace to compensate for beforehand season was standing losses. Based upon Figure 1, planting prices of 34,000 come 36,000 seed per acre maximize network return in most fields.

Like the last stand needed to maximize profit, economically optimum seeding prices vary v corn price and seed costs. We calculated seeding prices (seeds per acre) to get within $1 the the maximum network return in Table 1. These seeding prices are 5 percent over the targeted populace to compensate for beforehand season losses.


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

factors affecting optimum plant population
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Planting date


Figure 2: exactly how corn responds come planting date and plant populace in Lamberton, Morris and also Waseca, from 2009 come 2010.Research conducted in Lamberton and also Waseca uncovered that the optimum plant populations were not affected if corn was planted through mid-May (Figure 2). However, when planting to be delayed till late May, a higher plant populace was needed to maximize yield.

Timely planting in an excellent soil conditions is the structure for successful corn production. Studies display that tiny yield reduction occurs if corn is planted by mid-May. However, productivity drops off easily when planting was delayed past mid-May (Figure 3).


Figure 3: response of corn grain productivity to planting day in Lamberton, Morris and Waseca native 2009 to 2011. Each period is the typical of six hybrids.

Guide: as soon as to plant corn in Minnesota

Late-planted corn in Minnesota: What come consider

Researchers evaluated how corn productivity responds come 20- and 30-inch row spacings over a variety of tree populations. They discovered that narrow rows walk not significantly increase productivity at any plant populace level and also that the financially optimum plant population of both row widths was similar (Figure 4).


Figure 4: Corn response to row width and also plant population in Lamberton and Waseca, native 2009 come 2010. Each dot is the average of 3 hybrids.

Guide come narrow-row corn planting in Minnesota

Row width and also relative maturity

Researchers additionally evaluated just how hybrids in different maturity groups responded to the 20- and also 30-inch heat spacings at different population levels. The early-, mid-, and late-maturity hybrids studied in southern Minnesota were 95-, 101- and 105-day loved one maturities (RM). In west central Minnesota, the hybrid RMs to be 91-, 94- and also 99-day.

Optimum planting rates and also corn grain yields were generally not influenced by row width for mid- come late-maturity corn hybrids.

However, early-maturity hybrids (less than 90-day loved one maturity) planted in northwestern Minnesota developed 4 come 5 percent greater grain yield when planted in rows narrower than 30 inches. This early-maturity hybrids additionally had optimum planting rates that were 3,500 seed per acre better when planted in narrow rows.

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


Figure 5: Corn yield response to hybrid maturity and plant population in Lamberton, Morris, Rochester and Waseca, indigenous 2009 come 2010.

Optimum planting rates differed only slightly for the different maturity team hybrids. For early on maturity hybrids, the optimum planting prices tended to be near or over the high finish of the recommended 34,000 come 36,000 seeds per acre selection (96-day RM or earlier). This is specifically true because that 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 feasible they require greater plant populaces to optimize light interception.

While optimum planting price differs somewhat amongst hybrids, hybrid choice generally impacts yield much more than fine-tuning planting prices by hybrid.


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

An Illinois examine reported that as yield potential raised from 135 to 225 bushels per acre, the financially optimum plant populace increased from about 25,000 to 32,000 plants per acre. For every yield boost of 10 bushels per acre, the optimum plant populace increased by around 800 plants every acre.

While a too-high plant populace generally will certainly not reduce yield, the will minimize net return. In recent trials in northwestern Minnesota where growing season rainfall was just 10 to 15 inches, grain yield ranged from 100 come 130 bushels per acre and also was not decreased with last stands up to 44,000 plants every acre.

Estimating productivity loss

To determine how a lower plant population will influence yield loss, refer to Table 2. This visual reflects averages across experiments, and is a useful tool because that estimating productivity loss resulted in by unexpected weather or floor conditions.

last 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 led to by crop canopies intercepting an ext light during grain-fill.

In a 2008 planting day trial in Lamberton and also Waseca, researcher measured light interception by the crop canopy just after silking (Figure 6). Each data point in figure 6 to represent canopy irradiate interception and also the equivalent grain yield because that each level of tree population, averaged across three planting dates and two locations.

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

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

Figure 6: how canopy light interception throughout grain-fill influence corn grain yield. Points room for six plant populations ranging indigenous 15,500-45,600 plants/acre.Optimizing light interception

Research says growers manage plant population with the goal of optimizing irradiate interception. Fields with optimum plant population have very little sunlight hitting the soil surface, and also very few plants without ears.

To evaluate light interception during grain-fill, watch under the crop canopy close to solar noon ~ above a calm, sunny day.

Jeff Coulter, centregalilee.com agronomist


Thanks to the Minnesota Corn Growers Association, the Minnesota Corn Research and also Promotion Council, National crop Insurance Services and also Monsanto because that generously supporting the bulk of the study 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, plant 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 of corn to planting date and also plant density. Agronomy Journal, 103(5), 1414-1422. Agronomic Responses of Corn come Planting Date and Plant Density.

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