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United States Department of Agriculture

Agricultural Research Service

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Location: Soil, Water & Air Resources Research

2013 Annual Report

1a. Objectives (from AD-416):
Determine the effects of a humic product on corn crop growth and soil properties in on-farm production.

1b. Approach (from AD-416):
Sales of humic products have increased in recent years. These products claim to promote plant growth and increase economic yield in production agriculture, although little published research has evaluated such claims. Underlying mechanisms for improved plant growth remain unidentified: it is unknown whether they would involve improved nutrient supply or other traits of soil performance or instead whether the product would directly stimulate the plant. No information exists on whether soil type alters the field efficacy of humic products. The objectives of the proposed research are to first acquire publishable agronomic information that will demonstrate whether a micronized (i.e., super-finely ground) humic product can significantly improve corn growth in field conditions, and on two different soil types. Second, the proposed research will begin testing the hypothesis that a humic product directly alters plant growth through a hormonal-like stimulation and not indirectly through changes in soil properties. This second objective would expand on our existing collaboration with another company, which determines the field efficacy of their humic product made through the conventional alkaline extraction of lignite ore. In a farmer's field, the efficacy of the micronized product in promoting corn growth will be evaluated at two application times in replicated treatments. Crop measurements during the growing season will include leaf area, chlorophyll meter determination of nitrogen status, nutrient status in young leaves at three growth stages, plant height, total biomass and nutrient uptake at harvest, and grain yield as mapped by combine yield monitor. Measurements of plant hormones and other growth stimulant compounds will be taken at selected growth stages. Visual observations of early ear development and root growth will be collected. Post-harvest measurements of hand-picked corn plants will include 100-grain weight, cob length and mass, and stover concentrations of phenols, carbohydrates, and amino acids. All plant measurements will be repeated in two zones of the field that differ in soil properties. Soil samples will be collected at harvest and analyzed to determine basic soil properties and any beneficial or deleterious effects of the humic product.

3. Progress Report:
In a second field season, nearly the same field treatments as in the first season were conducted in a different corn field, and plant measurements were identical to the first year: leaf area, leaf nutrient concentration, leaf hormones, and total plant nutrient uptake shortly before harvest. A field map of grain yield developed during mechanical combining was compared to the map of different soils in the field to prove that the benefit of the humic product to corn growth depended on the type of soil. In addition, root length was measured at four sampling times. Some measurements were also begun in a new soybean field experiment involving the humic product, including total plant weight, nodule count on the main root, root length, and pod count and seed weight near harvest. These measurements were also conducted in the soybean crop that rotated into the corn field of the previous season.

4. Accomplishments

Last Modified: 06/21/2017
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