Iron deficiency chlorosis (IDC) can be a common problem for soybean producers in the Upper Midwest, Northern Plains, and Canadian Prairies. The best ways to manage soybean IDC involve proactive strategies, so thinking about this problem now will help prevent it becoming a big problem during the growing season.
Soybean IDC is not caused by low soil iron but instead caused by soil conditions that decrease iron uptake by soybean roots. Risk and severity of soybean IDC are primarily related to soil carbonate content (calcium carbonate equivalent, CCE) and worsened by soluble salts (electrical conductivity, EC). Soybean IDC severity is made worse in cool, wet soils and soils with high residual nitrate. Soil pH is not a good indicator of soybean IDC risk because some high pH soils do not have high carbonate or high salinity, which are the two principal risk factors.
Soybean IDC is not correctable with an in-season fertilizer application. Foliar application of iron fertilizers, including FeEDDHA products, may have short-term cosmetic effects, but these foliar Fe applications have not consistently increased yield of soybeans affected by IDC. Chlorosis symptoms often lessen as environmental conditions improve (e.g., drier, warmer weather), but severe cases can persist and cause serious yield loss.
To avoid yield loss from soybean IDC, start planning now:
- Consult soil test results for each field, management zone, or grid for soil carbonate and salinity. This may require soil sampling prior to soybeans (possibly outside of your usual soil sampling rotation) or consulting previous soil sampling records.
- Plant soybeans in fields with low carbonates and soluble salts. See table to estimate soybean IDC risk.
- Choose an IDC tolerant soybean variety for fields with moderate to high carbonates and soluble salts. 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. Please keep in mind that all seed companies do not rate IDC tolerance the same so take the extra time to compare them with university ratings for consistency.
- Plant soybeans in wider rows. Soybean IDC tends to be less severe in wide-row spacings (plants are closer together) than in narrow-row spacings or solid-seeded spacings.
- Apply chelated iron fertilizer (e.g., high quality FeEDDHA) in-furrow at planting. In-furrow FeEDDHA application may not be enough to help an IDC susceptible variety in high IDC risk soils (see points #2 and #3).
- Avoid planting soybean on soils with very high IDC risk.
AGVISE Soybean IDC Risk Categories:
NDSU 2020 Soybean Variety Trial IDC Scores: