Crops Insights

Guide to deciding whether to replant soybeans


The business of farming has always been a gamble, with factors such as markets and weather playing one against the other. And to paraphrase the old Kenny Rogers song, “The Gambler,” every good farmer knows when to replant soybeans, when to walk away, and of course, when to run.

Doing the math is a must when making the decision to replant soybeans — or any crop for that matter. Variables to consider include the cause of the problem, the stand density, the expected yields, and the expected return from either course based on pricing of all associated inputs. Good sources for discussion on the topic include a local extension or farm services office, many of which include calculators and worksheets designed to assist farmers in making this decision.

Variables to consider

The first issue to consider is the cause of the low plant population, which of course would be the cause for considering a replant. If the cause relates to unchanged conditions, then replanting might simply cause a repeat. Planting too early is often a cause in these cases. Germination of soybeans can be very slow, uneven, and sporadic in moist soils below 50 degrees F. Depending on whether seeds are treated with fungicide, a planting problem of this nature could result in disease. Other causes, of course, can involve heavy rains and flooding, or a severe drought. More remediable causes might be as simple as the farmer’s cows getting out of pasture and stomping over a field. Regardless, the cause must first be established, because depending on insect feeding or weather forecasts, replanting might simply not be an option.

The second step a farmer should take is estimate the stand density as it is. Two methods for establishing this estimate include Counting Plants in a Row and the Hula Hoop. To use the Counting Plants in a Row method, one counts the number of plants in a row equal to 1/1,000th of an acre. Purdue University offers a table for this calculation. Using the Hula Hoop Method, involves taking any perfectly round hoop with a known diameter and tossing it into at least five randomly selected locations within a field or where the plant stand is low. Count the plants within each hoop, calculate the average, then multiply it by the factor provided.

Once a plant population estimate can established, growers can estimate yield percentage for the affected area. For help with this, a table has been provided. The decision to replant will be based on expected returns. This requires a number of considerations, including potential crop insurance coverage, date of the replant and fluctuating markets. Another source of advice would be the farmers’ insurance agent handing the crop coverage. For planting dates at May 20th, most mid-season varieties of seeds will yield 100 percent, as will full-season types. However, this drops down to 60 percent by July 10 for mid-season varieties and simply isn’t recommended for full-season types. The location of the replant, season expected weather-wise, and cost of herbicides and other inputs.

The materials, hybrids and various treatments selected will play a large role in this decision. A demonstration trial conducted by Monsanto at its Monsanto Learning Center near Monmouth, Illinois, showed three different treatment options relative to a control, with yields being 98 percent, 93 percent, and 70 percent of the control, depending on the treatment used. The team reported a number of late-planted trials generating higher yields than the controls, but again, a farmer should consult with their seed dealer and local extension agent to determine the best course for their location and particular hybrid used.

Options to weigh

Replanting options do not have to be zero-sum. Depending on the stand involved, farmers can choose between filling in the stand, performing a tillage operation, or completely replanting the entire stand. One study determined that replanting soybean stands below 100,000 plants per acre by filling in the stand increased yields regardless the date, but again, all variables and inputs must be factored in, including price to be expected at market and whether crop insurance would be involved, such as would be the case in the event of hail damage.

Replant worksheets from numerous sources are available to help with the decision and each features a slightly different take on the same decision. As, Kenny Rogers once sang, the secret to survival is knowing what to throw away, and what to keep. But doing a little homework can help tilt the odds in the farmers’ favor and help them do better than just break even in the event of a hail storm, flood, or poor tilling.

Sponsored Content on AGDaily
Any views or opinions expressed in this article are those of the author and do not reflect those of AGDAILY. Comments on this article reflect the sole opinions of their writers.