From Field to Cup: Sustainable Soil Fertility Management for Quality Tea Production

Project Overview

Project Type: On-Farm Research
Funds awarded in 2023: $29,869.00
Projected End Date: 03/31/2025
Grant Recipient: Louisiana State University
Region: Southern
State: Louisiana
Principal Investigator:
Dr. Yan Chen
Louisiana State University


  • Additional Plants: tea


  • Soil Management: soil quality/health

    Proposal abstract:

    In this project, we propose to use a newly established tea field (2-month-old in the field) and an established tea field (5-year-old) at Fleur de Lis Tea Co., a commercial tea farm in Amite, LA, to study the effects of adding a locally available soil amendment composted with horse manure and parish unitality trimmings over a year, in combination with three supplemental N fertilizer types (blood meal, Black-Kaw cow manure, and ammonium sulfate, on soil microbial activity, young plant establishment, and leaf quality (key chemical compounds) of mature plants. Fertilizer treatment rates were determined according to plant age, soil type, soil fertility testing results, and the goal of these fields (Figure 1 Tea fields at the farm).

    Since 2017, PI and a tea research team at LSU AgCenter have received supports from the Specialty Crop Block Grant program in Louisiana to study the suitability of growing tea as a new specialty crop for the state. As researchers conducted germplasm evaluation and field trials with different production systems in southeastern Louisiana, several tea farms and research tea fields have been established, including the Amite tea farm and two plantings in New Iberia, LA. A research tea field with ‘Georgian (the Republic) Tea’ seedlings was established at the LSU AgCenter Hammond Research Station in 2016, and three more fields were added in 2019 and 2020 for the evaluations of cutting propagated ‘Brew-Tea-Ful’ and seedling collected from various sources. All tea fields at the station are under full sun. In addition to variety evaluations, research studies such as weed management using organic mulches and weed barriers, responses of young tea plants (2-year-old) to organic and synthetic N fertilizers, and changes in leaf chemical compounds in response to temporary shading onto mature tea plants have been conducted in these fields.

    Since 2016, project PI and several other LSU AgCenter tea researchers have worked with the Fleur de Lis Tea Co. along every steps of their development, and provided technical support to issues they have encountered through this tea-farming adventure, for example, soil testing result interpretation, field design (with drainage issues), and pest and weed issues. The tea fields at this farm are under loblolly pine trees, an indicator species of acidic soil and low fertility in southeastern LA and representative to several large areas along the Gulf States. So far, the farm has four long rectangular raised beds built on top of native soil with the addition of pine bark, for a total of ~1 acre (Figure 1 Tea fields at the farm). After planting, during the first year (and if needed, in later years), the grower liked to add a compost material made onsite by mixing horse manure (free of charge from neighboring farms) and parish utility trim (free of charge) then composting (rotating once a month) for one year. This composting practice is also representative among orchard growers in the area and can be used by other prospective tea growers because utility trimmings are available free of charge in many Louisiana parishes.

    The long-term relationship PI has built with the farm owner, Mr. David Barron and his farm manager Mr. Hans Marchese, and the field set-ups at this farm present a great opportunity for conducting on-farm research. From this project, we expect to test the hypothesis generated from previous research studies conducted at the research station and collect real-world data. Results from this project will be used to demonstrate the benefits, upon approval, of using locally available materials and composting, and using organic N sources vs. synthetic N for increased root and aboveground biomass and also leaf quality. Because the tea plants at this farm are grown under pine trees, we also expect that data collected from this study will complement those already collected from a N fertilizer type study conducted in 2021 in the tea fields under full sun at the research station, where different rates of blood meal, ammonium sulfate, and their combinations were tested.

    In addition, the tea farm is 28 miles away from the Hammond Research Station and ~ 1 hour drive from Baton Rouge and New Orleans, two metropolitan areas where urban farming and agriculture tourism are very popular. The farm manager, Hans, has conducted many public tours as an important source of income for the farm, especially after the farm began commercially harvest, process and market the “Big Easy Black Tea”, an award-winning black tea debuted in May 2022 ( Four tea workshops have been conducted by LSU AgCenter and an annual meeting of USLTG has been held at the farm and the research station tea fields, and we expect to hold similar workshops in 2023 and 2024, with additional information and experimental results from this project presented at the 2024 workshop.

    Therefore, the objectives of this project are to:

    (1) Evaluate the impact of a local compost material on soil microbial and soil property (organic matter, bulk density, pH, and nutrients availability) in new and established tea fields.

    (2) Measure the effect of the same supplemental N treatments at a moderate rate on leaf quality (health benefiting chemical compounds as indicators) of established plants that are being trained into plucking tables.

    (3) Determine potential benefits of using supplemental N (organic or synthetic) in establishing young tea transplants in a silty upland soil.

    (4) Document and share project progress and results with other tea farmers and specialty crop growers interested in growing tea by presenting at tea workshops, grower association meetings, UC Davis Global Tea Initiative annual colloquium, and field days; and by posting to social media and developing factsheets on tea fertility management.

    We expect to collect preliminary data that will enable us to provide basic information to tea farmers on plant nutrient management at early and more established growing stages, and help us design more complicated experiments in the future to study interactions among fertilization rate, timing, harvest schedule, and other production practices, and compare regional differences in fertility management.

    Project objectives from proposal:

    The soil type at the tea farm is in the category of Subtropical Mississippi Valley Silty Upland soils with organic matter content from 2.5% to 5% (LSU AgCenter Soil and Plant Tissue Testing Lab, April 2021). To support our objectives, we will conduct two experiments each using a long tea field at the farm (Figure 2 Field layout of treatments). We will collect data from both experiments for Objective (1), and collect data from Expt. 1 (using Field #1) for Objective (2), and collect data from Expt. 2 (using Field #4) for Objective (3). All results will be used to support Objective (4).

    Two factors, soil amendment with an aged compost as Factor A at two levels (with or without), and supplemental N sources as Factor B at three levels [blood meal (12-0-0), Black-Kaw cow manure (0.5-0.5-0.5), or ammonium sulfate (21-0-0)]. The soil amendment will be applied as a 4-inch thick layer over the top of existing mulch in Expt. 1 (Field #1) and on top of native soil in Expt. 2 (Field #4). Fertilization rates for Expt.1 will be at 450 pounds of N per acre per year for Expt. 1 with all three N sources, and at 150 pounds of N for Expt. 2. These rates were selected based on a discussion with Hans and David, considering soil type, organic matter contents, plant age, and the goal of these fields. Phosphorus has been high at this farm and will not be added but monitored with soil testing. Potassium will be applied at the same rate to all fields. For both experiments, fertilizers will be applied as four split applications every two months starting from March of each year.  

    A split-plot design is used for both experiments. Each field, running east to west, is divided into 3 sections, with 3 plots nested in each section. Then each plot is divided into two smaller plots, running north to south (Figure 2). The 3 sections serve as whole-plots, and the smaller plots serve as sub-plots. Treatment factor A, with or without compost amendment is randomly applied to sub-plots, and treatment factor B, three N sources will be randomly applied to the nested plots within each section(serving as replications, and blocked along drainage direction from east to west). Treatment units for factor A are the small plots, and treatment units for factor B are the total of 9 larger plots.

    All plants were planted at 3-foot spacing, and there are a total of 72 plants in each of the 9 plots, and a total of 36 plants in each of the smaller plots to receive Factor A. We will use the middle row along the field from east to west, the plants next to the dividing line between the 9 plots, and the plants located at the perimeter (the north and south rows) as “Buffer plants” that, they will be treated but no data will be collected from these plants.

    Data collection and sample analysis. From both fields, we will collect the following data. In addition, temperature, humidity, and PAR sensors will be installed in the middle of the fields to record environmental conditions.

    • Soil samples for microbial activity analysis will be collected by sampling the top 4-inch of the actual soil (remove top composting material when sampling, then putting them back) using a sampling tube. Samples will be stored in Ziploc bags, placed on dry ice, and stored in freezer until sample analysis. Soil microbial activities will be evaluated by FAME in the soil microbial lab. Student working on this project will be trained by lab staff and conduct the analysis. Soil samples for routing soil fertility analysis will be collected from top 6-inch soil using a sampling tube and placed in paper bags and dried for analysis. We will also test soil pH and bulk density with this sample.
    • From the established field (Field #1), we will collect 10 grams of fresh weight as leaf tissue analysis samples for nutrient analysis (total N, P, and agricultural metals). These samples will be collected from three randomly selected plants in the middle area of each sub-plots. The LSU AgCenter Soil and Plant Tissue Testing Lab will perform the analysis. Because this field is being harvested for making black tea, we will also sample the final products at three harvests in the summer between two commercial harvesting, and only use leaves collected from each sub-plot. Although regular harvesting and processing are done by machines for this field, the harvesting for research samples will be hand plucking, and then these leaves will be processed into a black tea following the same method used by the grower to process small batches by hand. A total of 15 grams dry weight of the processed black tea will be used for the analyses of caffeine, EGCG, total polyphenol, and theaflavin. These compounds are key health benefiting compounds that have been studied in a previous research conducted at the Hammond Research Station tea field. Dry black tea samples will be analyzed by a staff at the Chemistry Department with the student assisting sample preparation and loading.
    • A root imaging system, CI-600 In-situ Root Imager (CID BioScience) will be used to obtain 360 degree root scan images from the young transplants in Expt. 2 (Field #4). The system has been used with other plant species before but we expect successful application with establishing tea plants. A total of 18 observation clear tubes will be installed next to 18 selected plants, each from one sub-plot, and used to collect root images. Images will be collected every two months starting from the summer of 2023. Images will then be analyzed by WinRhizo software for presenting root length, diameter, number of internode, etc. Although the set up and use of this technology is not new, these images will provide large number of measurements on root structure, growth, and architecture traits. This will be the first ever collection and analysis of such images for developing tea plants.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.