Location: Soil, Water & Air Resources ResearchTitle: Maize growth responses to a humic product in Iowa production fields: An extensive approach
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2021
Publication Date: 1/10/2022
Citation: Olk, D.C., Dinnes, D.L., Callaway, C.R. 2022. Maize growth responses to a humic product in Iowa production fields: An extensive approach. Frontiers in Plant Science. 12. Article e778603. https://doi.org/10.3389/fpls.2021.778603.
Interpretive Summary: Humic products are liquid or solid materials that are made from young coal deposits. They are advertised as having the capability to increase plant growth. Little information is available on whether their application increases corn growth on fertile farm lands in Iowa. Here we studied whether corn growth was improved by adding a humic product to a large number of farmers' fields located across Iowa. We found that applying the product led to small or medium increases in corn grain yield in many but not all fields, and also greater amounts of corn straw and larger corn leaves. These results show that humic products can help improve corn growth in farmers' fields, even on fertile soils, and they deserve further study as an option for increasing grain yield. These results will be useful to farmers and other land managers, agronomists who wish to increase corn grain yields, and scientists who study humic products.
Technical Abstract: Field evaluations of commercial humic products have rarely involved replication across location or year. We determined the effects of a humic product on corn (Zea mays L.) growth and grain yield in high-yielding fields of the Western Corn Belt, U.S., through two extensive approaches: (i) replicated strip plots in five site-year combinations of three production fields in 2010-2013; and (ii) demonstration strips in 32-35 production fields annually for 2009 to 2011. Mechanized combine measurements of grain yield for the replicated strip plots found increases with humic product application by 0.2-0.4 Mg ha-1 (1-4%). This difference was positive in all five site-year combinations. The positive response of individual treatments within the fields was significant (P<0.07) in 7 of 10 cases. In the demonstration strips, corn grain weight in hand-collected samples increased significantly (P<0.004) with humic product application in each of the three growing seasons and also by 6.5% (P<0.001) across all three seasons. Grain weight increased numerically for 76 of the 98 demonstration strips. Yield component analysis for both the on-farm survey and the replicated strip plots attributed the yield boosts largely to increased ear length, especially of the shorter ears. Humic product application caused significantly (P<0.10) greater total leaf area in all field treatments at three site-year combinations, and this effect occurred mostly in later leaves. Humic product application did not consistently affect total nutrient concentrations of the grain or stover or any measured soil property. These results represent the broadest evaluation published on field efficacy of a humic product. They demonstrate the capability of a humic product to improve corn growth in rainfed, high-yielding conditions, to extents that can be profitable if modest agronomically.