Location: Soil, Water & Air Resources ResearchTitle: Application of a formulated humic product can increase soybean yield
Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2019
Publication Date: 8/29/2019
Citation: Lenssen, A.W., Olk, D.C., Dinnes, D.L. 2019. Application of a formulated humic product can increase soybean yield. Crop, Forage & Turfgrass Management. 5(1):1-6. https://doi.org/10.2134/cftm2018.07.0053.
Interpretive Summary: Humic products are liquid or solid materials that are made from young coal deposits. They are sold for the purpose of increasing plant growth. Little scientific evidence exists for their ability to increase soybean grain yield on the fertile soils of Iowa. We found that application of a humic product increased soybean yield in two of four situations in Iowa, and these two situations were drier than the two situations where there was no plant response. These results support the belief that humic products most clearly benefit crop growth when the crop is encountering stressful growing conditions. This finding will benefit users and vendors of humic products, agronomic researchers who are searching for opportunities to increase crop yield, and researchers of humic products who are seeking to explain inconsistent performances of humic products in crop production.
Technical Abstract: Application of humic products to crops remains controversial. We conducted a field study in Iowa over four environments from 2012 to 2014 examining productivity of soybean [Glycine max (L.) Merr.] receiving a foliar application of a humic product at four application times based on plant development. Humic product application never influenced soybean height at harvest. Soybean yield increased following application of the humic product in two of four environments, but application timing was not completely consistent between these two environments. In one 2012 environment, humic product application at V2, V6, and R2 resulted in greater yield than the untreated control. In the other 2012 environment, application of the humic product at V2 resulted in improved yield over the untreated control. Application of the humic product never influenced seed oil concentration, however, seed protein concentration was decreased following application of humic product at V2 and R2 in a single 2012 environment. The environments where humic product application influenced yield and seed quality had greater rainfall deficits and above long-term air temperatures, suggesting the humic product was most effective in stressed growing conditions.