1a.Objectives (from AD-416):
Evaluate the field efficacy of a humic product in promoting corn growth in Central Iowa.
1b.Approach (from AD-416):
The primary body of work will be a formal field evaluation of a humic product applied to corn in Central Iowa. Replicated treatments will be established at two to four sites. The treatments will compare several modes and timings of product application. The funder has previously observed these treatments to promote corn growth in Central Iowa, although replicated data were not collected. In this first year of a planned multi-year evaluation, we will conduct several plant and soil measurements during the corn season to identify the growth stage(s) at which corn growth and soil properties respond to the humic product. Primary plant measurements include biomass and total nutrient content at both vegetative growth stage and grain harvest, and also nutrient content of ear leaves at initial silk stage. Other plant measurements include stand count, net photosynthesis rate, and disease incidence. Soil samples will be collected and archived while the treatments continue for a few more years. Initial soil measurements include total soil carbon and nitrogen and aggregate stability. In a related side project, we will collaborate with the funder in conducting a broad survey of on-farm use of the humic product. A large number of farmers will devote small strips of their corn fields to application of the product. The funder will measure corn yield by weigh wagon for these strips and adjacent non-amended strips. We will monitor plant growth during the season and collect soil samples for the amended and non-amended strips. We will also compile a database on these farmers, consisting of corn yield response to the product, on-farm management practices, and soil types. Knowledge gained from this first year will support more indepth studies in subsequent years, when we will strive to identify the mechanisms for how the humic product benefits crop growth. Favorable results will strengthen collaborations with other humic product companies; currently there is no understanding of how any humic product benefits plant growth in field conditions.
The humic product was evaluated for a fourth year in several corn fields in Iowa. In-season measurements in one farmer’s field included leaf area and leaf concentrations of hormones and anti-oxidants at two growth stages. In this field and a research station field, leaf nutrient status was measured at two or three growth stages, and crop nutrient uptake was measured at a physiological maturity sampling for total biomass. Another field experiment received the product in designated treatments for a second year, now being the soybean phase. In several farmers’ fields, plant samples were collected shortly before harvest from strips with or without the product and partitioned into leaves, cobs, and grain for measurement of biomass and nutrient uptake. The humic product was also applied for a second year in treatment of a field experiment on alfalfa.