Planting soybeans… forget last year

As soybean producers get ready for the 2010 crop season, Mississippi Extension soybean specialist Trey Koger is offering these words of advice — forget what happened in 2009.

Koger, speaking at Mississippi Crop College at the Delta Research and Extension Center in Stoneville, Miss., said 2009 “was an asterisk, a blip on the radar. We had an extremely wet spring in April and May, followed by the driest June on record, followed by the wettest fall we’ve ever endured, with rainfall at 600 percent of normal in September and October, alone.”

As a result of wet spring weather, 30 percent of the state’s soybean crop was planted in April last season, compared to an average of 85 percent. “In 2009, we were planting soybeans as late as Aug. 4.”

But in a year in which a lot of things were turned upside down by weather, many late-planted soybeans performed well. In fact, those Aug. 4 soybeans Koger referred to, which were planted in Natchez, Miss., cut about 32 bushels per acre.

Meanwhile, losses mounted in the early crop, to the tune of about $335 million in 2009, according to Koger. “I know of one case where around a million bushels of soybeans were sold for under $3 a bushel and placed in storage sheds. A little over 100,000 acres were never harvested because the quality was so poor.”

The season created such disruption in conventional thinking “that some growers want to go back to planting Group 6s and Group 7s, and planting in June.”

But Koger urged growers to stick with long-term data “which says that early- to mid-April is our sweet spot. We still need to be planting our soybeans early, even though we have gone through two very challenging years.”

The wacky season provided Koger and other researchers with some interesting data, including exposing some strengths and weaknesses of particular varieties. “We took some varieties off our short list because they didn’t weather very well. We took a few others off the short list because they didn’t like water early.”

For the short list, see Soybean variety – 2010 best bets.

The bad weather of 2009 underscored the need to spread risk, Koger says. “We can’t always spread out our planting dates. When the weather is dry, we’re going to get out there and plant. But we can spread our risk out by planting Group 4s and Group 5s. Four years ago, we planted about 75 percent of our varieties in Group 4s and 25 percent in Group Vs and few in Group 3s. Today, we’re about 50/50.”

Drainage also proved to be a key to soybean success, particularly in 2009, when producers had to focus so much on getting water off fields. “We’ve seen consistent yield increases in soybeans on beds.” Koger said. “In the last couple of years, drainage has been the difference between making a crop and not making a crop.”

Koger said changes in the crop mix in Mississippi, primarily a shift to soybeans from cotton, mean that researchers are shifting focus to identifying new soybean varieties that perform well on a range of soil types, including cotton soils, and new production systems such as twin-row planting.

“In the Mid-South alone, we grow about 7 million acres of soybeans, and up until the last three years about 85 percent of them were grown on mixed to heavy clays. We haven’t done a lot of research on growing soybeans on silt loam soils. Many of the varieties we plant today were bred for mixed to heavy clays.

“But if you take a variety suited for a mixed to heavy clay and put it in a single, 40-inch row on super strong cotton ground, there is a good chance it’s going to lodge.”

To avoid lodging in varieties suited for heavy clay, researchers recommend planting in a twin-row or a narrow row system. Koger and other researchers are taking a closer look “to see if we can get the same yield returns out of a twin-row system as we see in the heavy clay environment. The last few years, we’ve switched over about 30 percent of our Mid-South soybean acres to twin-row production.”

Recent research in Stoneville on heavy clays indicated an 8 percent to 15 percent yield increase for twin-row soybeans compared to a single 38- or 40-inch row.

Research on silt loam showed much the same result, an 8 percent to 12 percent yield increase for twin-row soybeans over single rows. “What is interesting is that unlike the heavy clays, we’re seeing a little bit of a response to increasing our seeding rates on silt loam soils, up to about 120,000 plants per acre.”

However, researchers found that twin-row soybeans in clay soils achieved the yield bump in a different way than twin-row soybeans on silt loam soils.

“In the heavy clays we found that the plants in a twin-row system put on about 5 more pods per plant. When you extrapolate that out, it’s about 500,000 more pods per acre.

In the silt loam soils, researchers found that plants in the twin-row system did produce slightly more pods per plant, but the yield advantage came primarily from the production of more 2-, 3- and 4-bean pods than those in single rows.”

Research on heavy clay soils comparing soybeans in 10-, 20-, twin-row, and 40-inch rows indicated that “if you have a 30-inch row or less, there is no advantage to planting in twin-rows.”

Another factor to consider is drainage, according to Koger. “We see consistent yield increases that pay for themselves time and time again using bedding system. If you have a 20-inch row, there’s no need to go to a twin-row. You need to get it up on a bed. That’s where you’re going to make your money.”

Koger also discussed a year of research at Raymond, Miss., on the effect of fungicide applications on seed quality. The location had consistent stink bug pressure all season long and soybeans went through about two weeks of wet weather after they were mature enough to cut. “We did get them out before all the rain hit.”

The research indicated that R3-R4 fungicide applications “did not help us with respect to seed quality. We did find that fungicide and insecticide applications at the R5 window can result in significant impacts in preserving seed quality.”

Koger stressed that at a Starkville, Miss., location, “we did the same treatments, and our net losses were consistent across all treatments because any benefit from a late fungicide application was negated by six weeks of rain.

“The R5 application is a complex issue,” Koger said. “If you have a good crop at R5, and you need to spray bugs, there’s nothing wrong with using a fungicide to preserve seed quality. You may get some benefit, but you may not.”

e-mail: [email protected]

TAGS: Soybeans
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