With the recent rise in soybean prices, many producers are considering a number of new and unique marketing opportunities, especially August and early-September delivery premiums.

Mid-South soybean producers have long recognized the benefits of the Early Soybean Production System (ESPS). In addition to the usual yield, irrigation, and pest management benefits, producers can now take advantage of increased prices for August and September delivery.

One of the most popular questions these days is “What soybean variety can I plant and expect to harvest by Aug. 15?” I have even had some producers asking “Which Maturity Group 2s would you recommend for Arkansas production systems?”

Fortunately, we do have data available to aid producers with this decision.

Average days to maturity for different maturity groups utilizing early soybean production system: early- to mid-April planted (three-year average)
MG 3s
(3.6-3.9)
EarlyMG 4s
(4.0-4.7)
Late MG 4s
(4.8-4.9)
Early MG 5s
(5.0-5.3)
Northeast Arkansas1 127 135 145 157
Expected harvest date* Aug. 11 Aug. 19 Aug. 29 Sept. 11
Southeast Arkansas2 122 134 141 147
Expected harvest date* Aug. 6 Aug. 18 Aug. 25 Aug. 31
1Latitude 35.6°N 2Latitude 33.1°N to 33.7°N *If planted by April 7

Each year the Arkansas soybean performance trials are conducted across numerous production systems throughout Arkansas. These include testing soybeans on silt-loam and clay soils, utilizing both wide and narrow row spacings.

In addition to yield, plant height, lodging, and shattering data, maturity dates are also collected. The maturity date for a particular variety is recorded when approximately 80 percent of the plants within the plot are ready to harvest. This is a visual estimate, but when combined with information on planting dates, it can give us a pretty good estimate of the number of days a particular variety or maturity group takes to mature.

The accompanying table compares the average number of days it takes for different maturity groups to reach maturity in northeast and southeast Arkansas for early- to mid-April planting.

This winter, I have cautioned many Arkansas producers about the potential harvest conflicts with rice, corn, and other crops. I have also observed yield variability with late Group 3s compared to Group 4s we have been testing. Three-year averages indicate that the early-Group 4s tend to yield better than the Group 3s. Group 4s also appear to have better disease and nematode packages.

Group 4s may take an additional seven to 12 days to mature, but the increase in yield may outweigh the premium received.

Soybean maturity is highly influenced by environmental conditions (soil and air temperature, available soil moisture, etc.). Cool and wet conditions soon after planting could delay maturity as much as two weeks. Based on this, using a broad-spectrum seed treatment (Vitavax + Allegiance, ApronMaxx, or Stiletto) is highly recommended.

In addition to environmental stresses, soybean maturity can also be impacted by inadequate fertility levels, disease and insect damage, and herbicide injury. Producers should manage early-planted soybeans more intensively to prevent any delays in maturity and to maximize economic returns.

Remember the harvest of 2002. If we have a round of hurricanes in August, as we did in 2002, delays in harvesting are probable.

When possible, narrow row spacings should be utilized with early-planted systems. This will enable the plants to reach the needed height for canopy coverage while preventing harvest losses associated with shorter plants.

Previous research has indicated that a final plant stand of 130,000 plants per acre (approximately 60 pounds of seed per acre based on 3,000 seed per pound) is needed to maximize yields for early-planted production systems.

On a final note, days-to-maturity averages should be used as estimates. Many factors can influence the rate of soybean maturity and who knows what Mother Nature will throw at us in 2004.


Chris Tingle is the Extension agronomist for soybeans with the University of Arkansas Cooperative Extension Service.