Recipient Organization
UNIVERSITY OF TENNESSEE
2621 MORGAN CIR
KNOXVILLE,TN 37996-4540
Performing Department
(N/A)
Non Technical Summary
Demand for organicproducts has increased in recent years, especially organic corn (Zea mays L.). This market expansion has been driven by rising consumer demand for products produced with and animals fed by organic grain. However, corn is one of the most challenging crops to grow organically due to the need for high inputs such as fertilizers and herbicides, which are not allowed to be used in these systems. In addition, synthetic seed treatments are normally used in conventional systems to protect the corn seed from seedling diseases and promote adequate emergence. However, these treatments are not allowed in organic cropping systems, which warrants the need to examine natural seed treatments that could benefit organic producers. Therefore, organic corn production requires intensive management to ensure succesful seed emergence and stand establishment, and to achieve a reliable fertilization and weed competition program.There is a rising interest in expanding organic corn production in the Southeast, but many producers are still hesitant to transition their conventional operations due to a lack of management recommendations appropriate to the Southeastern environmental conditions. The development of adequate organic corn management recommendations, such as introduction of living mulch, can encourage producers to adopt this system, and successfully transition from conventional to organic practices.This study will examine several perennial legume species that can also contribute to nitrogen management, weed suppression, corn grain yield, forage yield, and forage nutritive value when used as a living mulch in an organic corn grain system.The University of Tennessee Institute of Agriculture strives to develop methods and approaches to become a leader in sustainable and organic crop production research, dedicating certified organic fields in two research and education centers strategically selected within the state, being one in East Tennessee (Knoxville metropolitan area) and one in Middle Tennessee (Nashville metropolitan area). The Southeastern U.S. has yet to develop organic crop methodologies that can be useful to producers in this area; therefore, the University of Tennessee facilities and locations are ideal for conducting the proposed study.This study will provide important information that can improve the profitability to producers interested in capitalizing on the increasing demand for organic corn grain. Although this study will focus on living mulch in organic systems, results will also be relevant to producers managing conventional corn grain systems who are interested in introducing potentially cost-saving sustainable production practices.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The specific goal of this project is to develop a multi-location study aiming to develop management recommendations to produce organic corn under different living mulch systems. To achieve the overarching goal, the project will look to:expand organic corn production in the Southeastern U.S.,improve organic corn yield,reduce weed competition,reduce the need for N (nitrogen) fertilization, andincrease profitability in the system.Our specific objectives are:Objective 1: To identify alternative seed treatments to be used in organic corn production in the Southeast.Objective 2: To determine how different living mulch species will influence corn yield, fertilization needs, weed competition, while maintaining soil health.Objective 3: To determine the potential economic benefits of introducing living mulch species into organic corn for organic crop producers in the Southeast.Objective 4: To develop an extension program to help educate agents and producers about successful strategies in producing organic corn under living mulch systems.
Project Methods
For Objective 1, the potential efficacy of organic corn seed treatments will be evaluated with artificial inoculum in the greenhouse. The experiment will be implemented in the fall 2022 and set up in a randomized complete block design with four replicates. The treatments will consist of two controls, non-inoculated and inoculated without seed treatment, as well as the following organic seed treatments with and without pathogen inoculation: organic quick roots, AgriCoat Natural II ™, and 1r seed treatment. If any additional organic seed treatments become available for corn they will also be included. Organic corn seed will be treated using a Hege seed treater, as it would be in a commercial setting. Additionally, germination assay will be done on all treatments.Pathogenic Pythium spp. or Rhizoctonia solani isolates will be cultivated on autoclaved milo medium, individually, to use for inoculation in the furrow when planting corn seed in pots. These pathogens represent oomycetes and true fungi that regularly cause seedling disease and death. In conventional seed treatments, compounds that control one does not control the other, hence the importance to evaluate each pathogen individually. Many species of Pythium can cause seedling disease; hence a complex of Pythium species will be used for inoculum, from Tennessee fields. In the trial, each pot will serve as a replicate, with the 3 seeds serving as subsamples. Pots will be watered daily, and greenhouse lighting will be programmed to a 12-hour light/dark cycle. Each plant will be assessed daily to record date of emergence and at 7, 14, 21, and 28 days plant vigor will be assessed and the number of plants surviving. The trial will be repeated. Data (emergence, vigor and survival of plants from each treatment) from the greenhouse trial will be analyzed using PROC MIXED of SAS .For Objective 2, the experimental design will be a randomized complete block design with four replicates (Fig. 1). The treatments will consist of the following: 1) no-living mulch, soil tilled prior to corn planting; 2) hairy vetch as a cover crop, soil tilled prior to corn planting; 3) white clover as living mulch; 4) red clover as living mulch; 5) hairy vetch as living mulch; and 6) sericea lespedeza as living mulch. All treatments (with exception of the no-living mulch treatment) will be established in Fall 2023 using a no-till drill. Plots will be 20 ft by 30 ft at each location. Prior to planting corn, manure will be applied at a rate of 80 lbs. N/ac. In April 2024, corn will be planted using strip tillage on 30-inch row spacing with a target population of 28,000 plants per acre.After establishment, monthly, a 0.1-m2 grid will be randomly placed in two locations within each individual plot to measure living mulch botanical composition (forage grass species, alfalfa, broadleaf weeds, grassy weeds). Once the individual botanical components have been dried at 60oC to constant weight, each component will be weighed to determine its percentage. Samples will then be recombined to determine total living mulch mass. After determination of botanical composition and living mulch mass, samples will be ground through a 1-mm screen in a Wiley milland analyzed for crude protein (CP), neutral detergent fiber (NDF) and NDF digestibility (NDFD) using Near Infrared Reflectance Spectroscopy (NIRS). Data at each location will be analyzed using PROC MIXED of SAS.At the termination date of cover crop or the end of living mulch growing season, a 0.5-m2 cover crop or living mulch biomass sample will be collected from each plot. These biomass samples will be dried at 65ºC until they achieve a constant weight, and final dry weights will be recorded. Samples will then be ground to pass through a 2-mm sieve. Ground biomass samples will be measured for nutrient (N, P, K, S, Ca, Mg, and selected micronutrients) concentrations. The total accumulation of each of these nutrients by each plot will be calculated as the product of dry weight of the cover crop or living mulch multiplied by that specific nutrient concentration in the dry cover crop or mulch.A composite leaf sample will be collected from each corn plot at the following growth stages: V6, V10, R1, physiological maturity. A composite corn stalk and grain sample will also be taken from each plot at corn harvest, respectively. Nutrient (N, P, K, S, Ca, Mg, and selected micronutrients) concentrations in leaf, stalk, and grain samples will be determined. The total uptake of each of these nutrients by corn plants (stalk plus grain) will be calculated. The removal of each of these nutrients due to corn harvest will also be calculated. A composite soil sample of 10 cores (2.5-cm diameter) will be collected at 0-15, 15-30, 30-60, and 60-90 cm depths at each of the aforementioned growth stages and analyzed for available nitrogen (NO3--N + NH4+-N) in the soil profile. At the V4 growth stage of corn, a composite soil sample with 10 cores (2.5-cm diameter) will be collected in 0-15 cm from each plot in Years 2 and 3 for assessing the soil health. Additionally, four cores of a 5-cm diameter and 15-cm depth will be taken from each plot for soil bulk density.The soil physical indicators will include surface and subsurface hardness (PR15 and PR45, respectively) measured using a penetrometer, wet aggregate stability measured using a wet sieving apparatus, and bulk density measured using the core method (Grossman and Reinsch, 2002). Meanwhile, soil moisture content will be determined with a moisture meter at the following growth stages of corn: planting, V6, V10, and R1.The soil chemical indicators will include soil pH measured on a 1:1 soil:water (v/v) suspension, Mehlich-3 extractable macro- and micro-nutrients (P, K, Mg, Fe, Mn, and Zn) analyzed by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), and ammonium N (NH4-N) and nitrate N (NO3-N) using 2-M potassium chloride (KCl) extraction followed by measurement on a Skalar Continuous Flow Analyzer. Available nitrogen, phosphorus, and potassium (lb./acre) for crop will be calculated. Some important soil nutrient ratios [Ca:Mg, (Ca+Mg):Al] will also be calculated.Soil biological indicators will include soil respiration from 4-day incubation (4d CO2) using potassium hydroxide (KOH) trap method , permanganate oxidizable C (POXC), soil organic C measured by dry combustion using a CN analyzer, microbial biomass C (MBC) and N (MBN) using chloroform fumigation method.Analysis of variance will be performed on each measurement under a randomized complete block design using the ANOVA procedure in SAS version 9.4. The treatments will be used as a fixed factor, whereas the replicates being used a random factor. Treatment means will be separated with the Fisher's protected LSD. Probability values less than 0.05 will be considered significant for all analyses. For Objective 3, production records will be kept each year to quantify total costs of production from the establishment of living mulch and corn through the entire project. We will analyze cost of production for each of the six treatments described in Objective 2. We will also take into account costs of successful seed treatments as described in Objective 1. These records will be used to calculate and demonstrate the relative treatment costs. This will allow us to construct enterprise budgets comparing the cost of producing organic corn by including different living mulch species (as well as comparisons with different systems such as conventional corn production and organic corn with cover crops system). A keyway to analyze enterprise budgets is by calculating breakeven yields and prices. We will use these budgets to develop breakeven corn yields for each treatment. This will show the yield a producer would need to achieve to break even for the year.