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Soybean Watch: Yield comes down to number of nodes, pods per node, beans per pod and bean size.

Tom J Bechman 1, Editor, Indiana Prairie Farmer

November 6, 2020

3 Min Read
hand holding soybean pods
PODS AT THE TOP: What growers like to see at harvest are soybean plants with pods clear to the top, with multiple pods per node. Tom J. Bechman

Several pods with multiple beans per pod clustered together on the very top node of a soybean plant is an impressive sight. It’s what every soybean grower wants to see just before harvest. If pods at the very top nodes didn’t abort and instead filled with beans, it’s a good sign yields will be average or better for that variety.

In early October, Steve Gauck found “pods to the top” on most plants in the earlier of the two varieties planted in the Soybean Watch ’20 field. Gauck is a regional agronomy manager for Beck’s, based near Greensburg, Ind. Beck’s sponsors the Soybean Watch program, which follows a single field in central Indiana from planting to postharvest each year.

Related: Strange maturity pattern just one more observation in unusual year

“Sometimes pods near the top of a plant, on the very last node or couple of nodes, abort late in the season — especially if it’s dry and plants are under moisture stress,” Gauck says. “That likely happened in some fields this year.”

The bulk of the Soybean Watch ’20 field, however, was irrigated. The field was in a county that received historically low rainfall in September and early October. In fact, it was the lowest amount of total precipitation ever recorded in that county since weather records began in 1895.

“The grower irrigated several times, all the way until most leaves were dropped,” Gauck says. “Finding most plants in that variety with pods near the top is evidence that irrigating paid off.”

Irrigating was especially important in this case, because soybeans were planted June 5 and were still heavy into the reproductive phase when the weather turned dry in late August.

Soybean yield factors

The ability to prevent pod abortion and finish the crop with full pods even on top nodes is important, Gauck says. However, there are other factors that affect yield, he adds. Some of those begin with planting date.

“Evidence is mounting that planting date is important with soybeans,” Gauck says. “Anecdotal evidence from reports so far this season indicates that it may have been especially important this year in some areas.”

Developing enough nodes per plant is critical, Gauck says. Seeding rate can affect number of nodes per plant. While low seeding rates appear to work well with soybeans planted early or on time, most agronomists recommend upping the rate for late-planted beans to increase the odds for more nodes per acre. The theory is that plants are likely to be shorter when planted later and produce fewer nodes per plant.

You also need good growing conditions when plants flower so blooms don’t abort at an excessive rate due to stress, he adds. Blooms lead to pods. Soybeans naturally abort a significant number of flowers even under normal conditions.

“Number of beans per pod and size of beans inside the pod are also critical,” Gauck says. “Bean size can make a huge difference in yield. You need enough moisture and good growing conditions in the late reproductive stages to increase individual bean size and deliver better yields.”

About the Author(s)

Tom J Bechman 1

Editor, Indiana Prairie Farmer

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