Progress 09/01/23 to 08/31/24

Outputs
Target Audience:The target audience has not changed. It remains organic growers and those considering a transition to organic managementand professionalsin Florida and the Southeast US - this audience will be reached mainly via extension and outreach activities.Students are another target audience of this project, as graduate students will be a key part in conducting the research - this audience will be reached primarily during research activities, group meetings, and lab meetings. Students attending classes are the third main audience for this project - they will beexposed to the research outcomes via educational materials (e.g., lectures, problem-based learning activities) used to teach at the University of Florida. Changes/Problems:As with the previous reporting period, maintaining the organic certification has been a challenge, given the close proximity of the two fields at both locations. Thanks to good support and attention to detail by farm crews, we have remained compliant with the certification. For both the carrot and peanut trials, weed management has been a challenge for organic plots, and a hand-weeding event had to be included. This is not ideal, as commercial producers may not have the capacity to perform a weeding event of that kind. Nevertheless, we recorded the labor required and will factor this in our economic analyses. The carrot trial at Live Oak was damaged by deer browsing, resulting in crop damage, low yields, and lower-quality data. Luckily, a new fence was installed at the station, and hopefully this will prevent future crop damage at Live Oak; carrot production was also very good at Citra, providing robust data for one of two sites. The termination of millet was not complete at both locations, most likely due to its immaturity, and weed pressure was high for peanuts at both locations, even in the conventional systems. As a result, data for peanut might be less representative of farmer practices than for other crops, with lower yields in the conventional systems compared to nearby commercial farms. In the case of Citra, this was exacerbated by sandhill crane damage to the crop after germination, which reduced plant densities in both organic and conventional plots. Finally, reduced tillage in the organic system has been harder to implement than expected, due to very high weed pressure, and the two systems are more similar than originally thought. They are still differentiated by other practices, but the difference between traditional vs. regenerative management has been clearer for the conventional plots. We hope that cover crop biomass production will be sufficient prior to the next corn crop, allowing to separate the two organic systems more clearly based on cover crop termination and tillage methods (e.g., rolling-crimping vs. mowing and disking). What opportunities for training and professional development has the project provided?Field and lab activities provided training for several graduate students (three PhD students have at least one dissertation chapter focusing on this work), while undergraduate students were also involved in field and/or lab activities, receiving training in how to collect data and obtain robust results in the lab. Several research technicians were also involved in the project, helping to train students and perform other activities (e.g., develop spray programs). Two postdoctoral associates are also participating in this project (part-time) and provided several mentoring opportunities, as they were instrumental in helping students and technicians during the collection and processing of samples. Similarly, graduate students gained mentoring experience, as they worked with undergraduate students during sample collection and processing. The PD and all co-PDs provided mentoring to students and staff, whether formally or informally, on key research aspects of the proposal, while mentoring for extension and outreach activities will become more important as those activities ramp up. How have the results been disseminated to communities of interest?As the 3-year field experiment is less than halfway done, with sample processing and data analysis ongoing for all cropping phases completed so far, results and outcomes have not been disseminated to a large extent. As results and outcomes become clearer in the next reporting period, and outreach/extension activities become more important, we will increase the dissemination of key results and outcomes. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will complete peanut harvest, then we will plant and harvest a fall brassica cash crop. After the cash crop harvest, we will plant and terminate a winter-spring cover crop in all systems but the conventional traditional, which will be followed by planting and harvesting the second corn cash crop. Once we plant the corn, we will enter the final year of the field experiment, and the most critical phase of data collection. Plant and soil sample collection will continue, using a similar sampling approach as for previous cropping phases, and samples will be processed using the same methods. As we accumulate more data, data analysis beyond preliminary analyses will take place, and data dissemination will become more important. The dissemination of key results and outcomes will take place through presentations at scientific conferences and extension/outreach activities.

Impacts
What was accomplished under these goals? In the last reporting period, the field experiment continued, several plant and soil samples were collected, and sample processing followed. Preliminary data analysis was also conducted for some variables. Objective 1 The four systems (organic traditional, organic regenerative, conventional traditional, conventional organic) established during the last reporting period were maintained at two locations in Florida (Live Oak and Citra). This reporting period started after corn was harvested, and before carrots were planted. Carrots were planted in October 2023 (same variety, no seed treatment in all plots) and harvested in March 2024 at both locations. Multiple management events were conducted during the carrot growing season: fertilization, herbicide sprays or cultivation, fungicide sprays. After carrots were harvested, cover crops were planted in three systems (all but conventional traditional), with a difference in mixture: pure pearl millet in organic traditional and conventional regenerative, and a mixture of millet, sunn hemp and buckwheat in organic regenerative. Cover crops were planted in late March 2024 and terminated in mid-April 2024, resulting in a short cover cropping season. Peanut were seeded in all plots (late April in Citra, early May in Live Oak), using the same variety in organic and conventional, but with fungicide coating for the latter. The peanut growing season is ongoing, with a planned harvest in September 2024. It involved several fertilization events (including gypsum application), in addition to herbicide sprays or cultivation, and fungicide sprays. Eight capacitance soil probes (measuring soil moisture at 9 depths up to 86 cm deep) were installed during the carrot and peanut growing seasons, i.e., one soil moisture sensor per system at each location. For each cash crop, plant growth variables were collected during the growing season, and yield was sampled at harvest, via manual and mechanical harvest. Crop quality was measured for carrots (e.g., Brix). For cover crops, biomass was sampled at termination, using quadrats. Tissue samples weredried and ground, and they will be analyzed for nutrient concentrations by an external lab. At the harvest of each cash crop, we collected soil samples from the surface (0-15 cm) for nutrients and soil microbes. Soil samples were air-dried and sent to an external lab for soil fertility measurements, using Mehlich 3 extractions and ICP. Subsamples for soil microbes were frozen (-80 C), then extracted for DNA; these samples will be analyzed for amplicon sequencing at an external facility in the next reporting period. These samples were also analyzed for qPCR, to establish the dominant soil microbial taxa and the abundance of functional genes related to C, N, and P cycling. A subsample of frozen soils will be analyzed for soil enzyme activity subsequently, using fluorometric assays. Additional soil surface samples were collected during the growing season to measure nitrogen cycling, using short-term incubations; samples were also collected at cover crop termination for the same purpose. At cover crop termination, deep cores (0-15 cm, 15-30 cm, 30-60 cm) were collected in each plot, to measure soil health indicators on air-dried soils (i.e., POXC, ACE protein, mineralizable C, SOM, total C and N). We used a recordkeeping system to track material costs, labor hours, use of equipment and durable supplies, and marketable yields for all systems, for use in future economic work. Objective 2 During the growing season, weed counts were performed at a regular interval, and weeds were classified by main group. Weed counts and biomass measurements were also conducted for the cover cropping phase. Alternaria leaf blight (ALB) was scouted weekly during the carrot season and it was diagnosed with traditional microscopy or via pure culturing in media plates, with diagnostic validated by PCR. Disease severity was evaluated weekly using the Horsfall-Barratt scale, mid-point averages, and the calculation of Area Under Disease Progress Curve (AUDPC). Multi-spectral mapping was performed with a drone to evaluate crop health during the carrot growing season. The same surface soil samples collected for soil microbes (i.e., after each cash crop) were also used to extract nematodes, and all nematode samples have been counted and identified. Data analysis will be conducted once more data points are available. Objective 3 There were few extension activities planned for this reporting period, as the project is still in its early stages, but we have started planningthe first carrot round table. Activities (e.g., round tables with stakeholders, participating in field days and other activities) will continue to ramp up in the next reporting cycle.

Publications

Progress 09/01/22 to 08/31/23

Outputs
Target Audience:The target audience has not changed. It remains organic growers (and those considering the conversion to organic management) and professionals (e.g., crop consultants, extension agents) in Florida and the Southeast US. The research results obtained during this project will help quantify the effects of regenerative management during the transition period on several indicators of agroecosystem sustainability. Regardless of the outcome (i.e., if regenerative management helps, worsens or is neutral regarding challenges experienced during transition), results from this project will help inform growers and other stakeholders. Extension and outreach activities (e.g., field days, extension fact sheets) will be critical to disseminate key results to this audience. Students are another target audience of this proposal, as graduate students will be a key part in conducting the research. These students will also be exposed to the research via lab meetings and other similar activities where they will learn about other disciplines involved in the project. In addition, key research results will be integrated in educational materials (e.g., lectures, problem-based learning activities) used to teach at the University of Florida. Changes/Problems:The main change conducted to the experimental design was to add a regenerative management sub-system to the conventional systems, to have a balanced design that will be more useful for statistical analyses. Stakeholders will likely be interested in that comparison as well. This made the number of plots increase by a third, so we reduced the size of plots slightly to maintain expenses at a similar level. Maintaining organic certification was also a challenge, given the very close proximity of our organic and conventional plots, and the use of GM varieties on the conventional side. Luckily, our certification agency has been open to this work, and we have implemented several practices to ensure compliance with the organic certification. Finally, a postdoc was supposed to be recruited part-time for this project, but immigration delays made that impossible. Luckily, other personnel stepped up to the task, and the recruitment of PhD students on the project will help. What opportunities for training and professional development has the project provided?Two undergraduate students and a postdoc have been trained on field and lab protocols for this project so far. Two graduate students are joining the project as of August 2023, and they will be trained extensively during the project's duration. How have the results been disseminated to communities of interest?As the project just got underway, with one cropping cycle barely finished (and data not thoroughly validated and analyzed), information has not been disseminated extensively yet. That should start to change in the next reporting cycle. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will move to the second crop (carrots) that will be grown from October until following spring, followed by a peanut crop (which will be planted but not harvested in the next reporting cycle). For both crops, we will manage them according to differences in systems; conduct pre-season, in-season, and post-season sampling for crops and soils; conduct harvesting operations and measurements; and collect data for economic analyses. As more data get collected and analyzed, we will ramp up the rhythm of extension activities in the next reporting cycle.

Impacts
What was accomplished under these goals? The field experiment started in March 2023, and this last year was focused on refining the experimental design, implementing the first crop cycle, and collecting data for the first crop. Several PIs have also assigned personnel, although this is still ongoing. Objectives 1 and 2 We established a systems comparison that will be used for 3 years for objectives 1 and 2. In March 2023, we established four systems (organic traditional, organic regenerative, conventional traditional, conventional organic) at two Florida locations: North Florida Research and Education Center-Suwanee Valley in Live Oak and the Plant Science Research and Education Unit in Citra. We established long-term plots at each of these locations, with all conventional plots located on non-certified fields adjacent to organic plots. Maintaining organic certification has been very important given the close proximity between the conventional and organic. This has been mitigated with multiple standard operating procedures to ensure unallowed substances do not enter the certified organic plots. PI Treadwell has been the main responsible for maintaining organic certification compliance. For each long-term plot, we took initial surface soil samples (0-15cm) for nutrients, soil health indicators, nematodes, and microbes. Deep cores (0-15 cm, 15-30 cm, 30-50 cm) were also collected in each plot for future analyses. Soil were either extracted fresh for N cycling, air-dried and sieved prior to analyses of other nutrients and soil health indicators, extracted fresh and counted for nematodes, or stored at -80?C until further analyses for soil microbes. Basal fertilization was applied in mid-March to each plot, according to system: a high rate of heat-treated manure for organic traditional, an intermediate rate of heat-treated manure for organic regenerative, a liquid fertilization at planting for conventional traditional, and a blend of liquid fertilization and low rate of heat-treated manure in conventional regenerative. Corn was planted in both locations in late March, using the same hybrid in both organic and conventional systems, but with additional GM traits (and nematicide applied in furrow) in the conventional system. A pre-emergence herbicide was added to all conventional plots. Eight capacitance soil probes (measuring soil moisture at 9 depths up to 86 cm deep) were added in total, i.e., one soil moisture sensor per system at each location. In-season fertilization consisted in granular applications followed by fertigation in the pivot for conventional systems (with a lower rate of granular fertilizer for the regenerative to account for manure inputs) or a one-time side-dressing with NatureSafe fertilizer (a mixture of feather meal, blood meal, etc.) in the organic regenerative. Glyphosate was applied for weed control in the conventional side (the grain variety was glyphosate-resistant) whereas cultivation was used on the organic side. Applications of insecticides and fungicides were made on the conventional and organic side. Irrigation was applied as needed based on experience of the farm crew and the soil sensor data. In-season data collection included soil sampling after side-dressing to quantify nutrient cycling, weed counts, in addition to measurements of crop growth and health. For the latter, measurements were started two weeks after planting and continued until harvest, focusing on plant stage/number, stem diameter below cob, number of tassels/green leaves, cob fresh weight/length/damage (herbivory, mold), and cob drooping. We established a recordkeeping system to track material costs, labor hours, use of equipment and durable supplies, and marketable yields for all systems, for use in future economic work. Before corn harvest, a subsample of corn was sampled for biomass allocation and nutrient concentrations, using one linear meter to remove all plants, measure fresh weights of different plant parts, and dry the material (grinding will follow). Surface soil samples were also collected for soil nematodes (extracted but not counted), microbes, and nutrients. Soil moisture sensors were removed before harvest. Corn was then mechanically harvested from each plot using a two-row small plot combine (2 rows of 50 ft per plot), to get a yield estimate and moisture concentration that would match what growers might obtain with their equipment. A sub-sample from each plot was collected to confirm test weight, moisture, and grading according to US standards for corn. Following corn harvest, fields were mowed and/or disked (depending on system) and field preparation will continue until carrots are planted in October 2023, in the next reporting cycle. Sampling occurring at that time will also be reported in the next cycle. Objective 3 As the project just got underway, limited progress has been made for extension objectives, but activities (e.g., round tables with stakeholders, participating in field days and other activities) will ramp up in the next reporting cycle.

Publications