Location: Soil, Water & Air Resources Research2013 Annual Report
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.
3. Progress Report:
The humic product was evaluated for a fifth year in several corn fields and also in a few soybean fields. Measurements taken during the growing season in several corn fields included leaf area, leaf nutrient concentrations at three stages of crop growth, and root length at four growth stages. Corn leaf and root concentrations of hormones were measured in one field at two growth stages. Plant content of nutrients and grain weight were measured shortly before harvest in all fields. Another field experiment comparing different rates of nitrogen fertilizer received the product in designated treatments for a third year, now being the second corn phase. In several farmers’ fields, plant samples were collected shortly before harvest from strips with or without the product and partitioned into grain and leaves for measurement of weight and nutrient content.