Switching More Acres to Soybean?

The spike in nitrogen fertilizer prices over the past month has prompted many growers to think about switching more acres to soybean in 2026. The high nitrogen fertilizer prices are squeezing the potential profitability of any crop requiring nitrogen fertilizer, such as corn, dry bean, canola, or wheat. The symbiotic nitrogen fixing behavior of soybean is an impressive feat of nature that helps reduce nitrogen fertilizer expenses in farm budgets.

If you do plan to plant more soybean acres in 2026, remember that soybean still has its own crop nutrient needs and removal, like phosphorus and potassium, that cannot be ignored for the soybean crop or across the crop rotation. In addition, iron deficiency chlorosis (IDC) is a common problem in soybean fields across the region, and soybean cyst nematode (SCN) can debilitate and cripple soybean yield now and into the future.

Before you plant soybean on any acre, it is important to have current soil test information for IDC and SCN. These two problems are best managed with the right soybean variety, and there is a nice window before spring planting to collect soil samples.

Soybean Fertility (Phosphorus and Potassium)

Soybean does not respond to phosphorus as dramatically as grass crops like corn or wheat do. Nevertheless, medium to high soil test P is required to achieve good soybean yields. Soybean responds to broadcast P placement better than seed-placed P or sideband P. In no-till regions where soybean is often planted with air drills, seed-placed P or sideband P is often the only opportunity to apply phosphorus in the system. You must pay special attention to seed-placed fertilizer safety with soybean.

Soybean removes far more potassium in harvested seed than canola or wheat. Soybean yielding 50 bu/acre removes about 60 lb/acre K₂O, while wheat yielding 80 bu/acre removes only 25 lb/acre K₂O. Pay close attention to potassium removal across the crop rotation. After soybean is added to the crop rotation, cumulative crop K removal over numerous years increases greatly, and declining soil test K is observed over time.

Do not place potassium fertilizer with soybean seed; delayed seedling emergence and reduced plant population can occur. Any potassium fertilizer should be broadcasted or banded away from seed.

Soybean Iron Deficiency Chlorosis (IDC)

Soybean is very susceptible to iron deficiency chlorosis (IDC). Soybean IDC is not caused by low soil iron but instead by soil conditions that decrease iron availability and uptake by soybean roots. Soybean IDC risk and severity are primarily related to soil carbonate content (calcium carbonate equivalent, CCE) and worsened by salinity (electrical conductivity, EC). These primary risk factors (carbonate and salinity) can be measured with routine soil testing.

Soybean IDC is common in the upper Midwest, northern Great Plains, and Canadian Prairies, where soils frequently have high carbonate and/or salinity. Within a field, IDC symptoms are usually confined to soybean IDC hotspots with high carbonate and salinity; however, symptoms may appear across a field if high carbonate and salinity are present throughout the field. Soybean IDC severity is made worse in cool, wet soils and soils with high residual nitrate-N. Soil pH alone is not a good indicator of soybean IDC risk because some high pH soils lack high carbonate and salinity, which are the two principal risk factors.

Guidelines for managing soybean IDC

1. Soil test each field, zone, or grid for soil carbonate and salinity. This may require soil sampling prior to soybean (possibly outside of your usual soil sampling rotation), or consult previous soil test records.
2. Plant soybean in fields with low carbonate and salinity (principal soybean IDC risk factors).
3. Choose an IDC tolerant soybean variety on fields with moderate to high carbonate and salinity. This is your most practical option to reduce soybean IDC risk. Consult seed dealers, university soybean IDC ratings, and neighbor experiences when searching for IDC tolerant soybean varieties.
4. Plant soybean in wider rows. Soybean IDC tends to be less severe in wide-row spacings (more plants per row, plants are closer together) than narrow-row spacings or solid-seeded spacings.
5. Apply chelated iron fertilizer (high-quality FeEDDHA or FeHBED) in-furrow at planting. In-furrow iron fertilizer application may not be enough to help an IDC susceptible variety in high IDC risk soils (see points #2 and #3).
6. Avoid planting soybean on soils with very high IDC risk.

Soybean Cyst Nematode (SCN)

Soybean cyst nematode (SCN) is the #1 pathogen causing soybean yield loss in the United States. It is a microscopic parasitic worm that lives in soil and attacks the roots of susceptible soybean and dry bean varieties. Soybean cyst nematode is found across the soybean-growing regions of the United States; it first reached Manitoba in 2019.

Soybean cyst nematode is best managed with crop rotation and SCN-resistant soybean varieties. Soil sampling for SCN is your best tool to learn if you have SCN and also if the SCN resistance traits in your soybean varieties are still working. In recent years, AGVISE Laboratories has documented failing SCN control with PI8878 resistance (most common type) and a continuing increase in SCN egg counts across the region. In some places, the SCN egg counts are so high that no soybean crop (resistant or not) should be planted for multiple years. Once you have it, SCN is nearly impossible to eliminate from fields. A current SCN soil sample will help you choose the right SCN-resistant soybean variety and manage SCN populations now and into the future.