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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #408947
Research Project: Optimizing Carbon Management for Enhancing Soil and Crop Performances

Location: Soil, Water & Air Resources Research

Title: Interactive effects of humic product application with nitrogen fertilizer rates on corn grain yield in a central Iowa field study

Author
item Olk, Daniel - Dan
item Dinnes, Dana

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/22/2023
Publication Date: 10/29/2023
Citation: Olk, D.C., Dinnes, D.L. 2023. Interactive effects of humic product application with nitrogen fertilizer rates on corn grain yield in a central Iowa field study [abstract]. ASA-CSSA-SSSA Annual Meeting. Paper No. 252-4.

Interpretive Summary:

Technical Abstract: Biostimulants such as humic products promise greater nutrient use efficiency by promoting more vigorous crop growth and thus greater demand for nutrient uptake. In this four-year split-plot field study of continuous corn (Zea mays L.) growth in central Iowa, main plot treatments were N fertilizer rates, ranging from 0 to 280 kg N ha-1 by increments of 70 kg ha-1, while subplot treatments were with/without humic product application. In the first three growing seasons of data collection to date, humic product application resulted in greater combine-measured grain yield at the medium to higher N rates, by degrees that varied by the year. However, with only 70 kg ha-1 N application, humic product application resulted in significantly less grain yield compared to the control, and a numeric but nonsignificant decrease occurred at 0 N input. In one year of yield components analysis, vegetative (stover) growth was enhanced by the humic product at all non-zero N fertilizer rates. These results indicate that this humic product promoted early season vegetative growth at all non-zero N rates and also grain yield at the higher N rates. To explain the inhibited grain yield at the second lowest N rate, we hypothesize that the early season stimulation of vegetative growth depleted the soil N supply at the 0 and 70 kg N ha-1 rates, causing late-collapse of the N supply during grain filling and hence diminished grain yield. These results demonstrate that this humic product promoted crop growth through a plant-based biostimulation, not through enhancing the availability of soil N.