Performing Department
(N/A)
Non Technical Summary
The marketplace adoption of bioplastics over petroleum-based plastics is gaining pace and popularity, in part from increased regulation, but also as a result of grassroots efforts and emerging corporate sustainability, environmental, and human health concerns. Within this material subset exists bio-based, compostable and biodegradable plastics. These materials are often used in agricultural applications such as plastic mulch film, plant containers, seed trays, and many small items like vine clips and twine. In horticulture, the promise of compostable and biodegradable bioplastics carry a massive benefit for plant health and sustainability, but they are plagued by poor durability and high costs - generally 2-3x the price of their petroleum counterparts. The US alone consumes over 5 billion petroleum-based plastic containers each year (750,000 metric tons of plastic), resulting in $3.8 billion in spending, and scalable solutions are needed to address this plastic waste problem.In this proposal, our goal is to investigate the performance of lignin-polymer-based horticultural containers. We will evaluate container durability during automated filling, transplanting, and irrigation processes. We will also focus on potential benefits to plant health measuring plant size, aesthetics, root structure, and soil microbial population and water nutrient content. To test these variables, we are planning to conduct two greenhouse production trials with three container types and 3-4 short-cycle plant species. When commercialized, lignin-polymer containers could be used in commercial greenhouses around the world. Successful implementation of our lignin-based materials into horticulture is a stepping stone to produce a larger portfolio of products addressing the over $12.5 billion in agricultural plastics. Farms and nurseries across the country are highly interested in new biodegradable plastic solutions in the field that have tunable, switchable biodegradation, strengthening this opportunity for sustainable innovation in the US food and agriculture system.
Animal Health Component
75%
Research Effort Categories
Basic
(N/A)
Applied
75%
Developmental
25%
Goals / Objectives
ProblemToday, nearly 75 years after the adoption of petroleum containers, the horticulture industry is valued at $90 billion in global market size. The US alone consumes over 5 billion petroleum-based plastic containers each year (750,000 metric tons of plastic), resulting in $3.8 billion in spending. While there are several advantages of using petroleum-based containers, like low cost, good durability, and good manufacturability, there is growing awareness of the downsides, from plastic waste pollution and lack of recyclability to negative impacts on root and plant health. In terms of sustainability, using petroleum as a feedstock leads to greenhouse gas emissions from extraction, refining, and material production and the resulting materials are generally not degradable due to the strong carbon-carbon bond structure of many petroleum-based polymers. In contrast to petroleum-based plastics, bioplastics (plastics produced from renewable resources) are being investigated as an alternative material with potential plant health and biodegradability benefits. The most commonly used bioplastics are polylactic acid (PLA), polyhydroxyalkanoates (PHAs), bio-polyethylene (Bio-PE) and bio-polypropylene (Bio-PP). PLA is the most abundant bioplastic and while naturally brittle, can be modified to have reasonable mechanical properties compared to petroleum plastics. PLA is only degradable in industrial composting conditions and the raw material is expensive, limiting applications in horticulture. PHAs also exhibit reasonable mechanical properties and are readily degradable in soil, but limited availability and high cost prevent widespread adoption. Bio-PP and Bio-PE are created using bio-based feedstocks, such as sugarcane, and have mechanical properties identical to petroleum-based polyethylene and polypropylene but lack biodegradability due to their chemical structure. To mitigate these downsides, researchers are investigating the combination of bioplastics with fillers, additives, and colorants to improve the mechanical properties, lower cost, and improve aesthetics; however, the addition of colorants has shown to decrease biodegradability even at low concentrations, and some additives like carbon black have known human health and environmental effects.Availability and cost are two of the most significant drawbacks for bioplastics today. The global production of PLA, PHAs, Bio-PP, and Bio-PE combined is estimated at 690,000 metric tons and is expected to grow to 2,180,000 metric tons by 2020. In theory, this could satisfy the 750,000 metric ton plastic material demand for horticulture but competition with other markets such as consumer goods and packaging will diminish the quantity of plastic available for horticulture. In addition, the price of these bioplastics today is too high to see more widespread adoption compared to commodity prices for polyethylene and polypropylene.There is an opportunity for a new bio-based material platform to produce a family of low-cost and biodegradable containers with a range of mechanical performance, sustainability, and plant health properties. The existing work to identify new bioplastic formulations for containers in horticulture has not found a material that can match the price, availability, and performance of petroleum-based plastics. The work to date has focused on using PLA or PHAs as the primary polymer and adding fillers, colorants, and other additives to improve performance. Even with increases in availability and decreases in price, poor degradability of materials like PLA are difficult to overcome. In contrast, lignin is a biopolymer produced as a waste product from the paper and biofuel industry at a rate of over 100 million tons per year, is widely available for use as a biorenewable material feedstock, and is very low cost. Lignin can be used as the foundation for a new family of bio-based and biodegradable container materials.Major GoalThe Major Goal of this project is to develop a degradable lignin-polymer horticulture container that can be used in commercial greenhouse operations. In Phase I, our goal is to investigate the performance of lignin-polymer-based horticultural containers. We will evaluate container durability during transplanting, irrigation, and automated processes and plant health, measuring plant size, aesthetics, root structure, and soil conditions. To test these variables, we are planning to conduct two greenhouse production trials with three container materials and 3-4 short-cycle plant species. At the end of Phase I, we will make material recommendations for specific crop types and growing conditions.To accomplish our objectives described below, we are proposing a 3-stage research plan to investigate the effectiveness of lignin-polymers as a material feedstock for horticultural containers, looking specifically at the durability and mechanical properties during and after greenhouse production and the impacts on plant and root health. To do this, we will compare two of our material formulations against polypropylene (PP) as a control throughout the greenhouse production cycle, starting with tests to evaluate durability. These durability tests will subject our containers, and the PP controls, to standard automation, irrigation, transportation, and transplanting processes and evaluate the condition of the containers afterwards. We will evaluate Crush Strength and Wet Strength of containers before and after these processes to characterize the effects of watering and handling on mechanical performance. To study the effects of lignin-bioplastic containers on plant health, we will grow short-cycle greenhouse crops in the various containers in a commercial greenhouse. In order to gather sufficient data, we will carry out these tests using 3-4 different plant varieties, including Calibrachoa, Petunia, Vinca, and Penta, in a standard soil mix, based on recommendations from our greenhouse partners. These are crops with a high tolerance to changes in pH and are in high commercial demand for retailers. With the time permitted by the grant, we will be able to perform two production trials, which will allow us to test these plants multiple times throughout the year and/or select new plants for the trials. To characterize plant health, we will measure plant shoot size, root health (evidence or absence of root circling), plant and flower color, presence or absence of chlorosis/necrosis, water nutrient content, soil microbial health (presence or absence of pathogenic microbes) and the dry weight of roots and plant biomass. To address these challenges, we have the following Objectives for this project:Assess lignin-polymer container durability and performance during automation, irrigation, and transplanting trials during regular greenhouse production operation. In this objective, we will test our containers in a commercial greenhouse environment including automated soil filling equipment, automated seeding and transplanting, and regular irrigation to determine material durability. Evaluate lignin-polymer container mechanical properties after a full greenhouse crop cycle. In this objective, we will work with our greenhouse partners to carry out production trials of 3-4 recommended annual crops, evaluate the condition of the bioplastic containers after the trial, and compare them to the condition of petroleum-based container controls.Evaluate plant health of crops grown in lignin-polymer containers, based on root structure, plant size, color, and soil conditions. In this objective, we will evaluate the growth and health of the plants grown in bioplastic containers compared to petroleum-based container controls to determine if there are benefits from a bioplastic container during product.
Project Methods
The following Methods will be used to evaluate the Objectives mentioned above.Objective 1: Assess lignin-polymer container durability and performance during automation, irrigation, and transplanting trials during regular greenhouse production operationIn this objective, we will compare two formulations of our lignin-polymer blends against polypropylene (PP), a common plastic used for horticulture containers, during automation, irrigation and transplanting. To evaluate these materials, groups of 10 containers will be placed on a tray. We will use standard soil filling equipment with our greenhouse partners to evaluate the performance of our materials. In normal operations, trays of containers are conveyed through these machines to fill them with soil. After filling, we will inspect each container to see if any were crushed or cracked. This will provide us with material scores for Crush Strength. Following filling, we will water each tray and inspect the durability of each pot after they are sufficiently wet, providing scores for Wet Strength. After watering, the trays will be moved to the transplanting area prior to Stage 2. During the transportation step, we will evaluate the durability and usability of these containers for simple tasks like handling and moving.Objective 2: Evaluate lignin-polymer container mechanical properties after a full greenhouse crop cycleWe will work with our partners to carry out production trials with 3-4 recommended crops, including Calibrachoa, Petunia, Vinca, and Penta, in a standard soil mix. After a few weeks, the seedlings for these crops will be ready for transplanting into larger 4.5" containers for greenhouse production. At this stage, we will have 3 container types (lignin-polymer blend 1, lignin-polymer blend 2, and petroleum-based control), 3-4 plant varieties, and 20 replicates for each container/species unit. After each crop is grown to a sufficient size and would be ideally ready to be shipped to a retailer, we will conclude the production trial. At the conclusion of the trial, we will evaluate the integrity and aesthetic quality of the containers compared to new containers and control PP containers. Objective 3: Evaluate plant health of crops grown in lignin-polymer containers, based on root structure, plant size, color, and soil conditions.As mentioned above, we will work with our partners to carry out production trials with 3-4 recommended crops, including Calibrachoa, Petunia, Vinca, and Penta, in a standard soil mix. After each crop is grown to a sufficient size, we will conclude the production trial. At this point, we will separate the plants and soil from the container for follow-on analysis. We will be evaluating the presence or absence of root-circling, plant appearance and health, based on leaf color, presence or absence of chlorosis/necrosis, flower color (if applicable), cell counts of soil microbes, water-use efficiency, nutrient content, and soil pH. We will then separate the plants from the roots and dry them in order to quantify the root, plant, and root-to-plant ratio of biomass. These factors are indicative of plant healthObjectives 2 & 3 will be repeated in a second greenhouse trial. Many of the crops have ideal growing conditions and recommended growing times throughout the year that are useful for commercial production. In an R&D context, plants are often grown throughout the year to observe changes in plant growth and evaluate the effects of new growing practices, new material choices, or new plant breeds. By repeating these experiments, we can see if the time of year and variations in greenhouse operations impact container performance, plant growth, and plant health.SBIR Phase II R&D Plan. Our go/no-go metric for pursuing a Phase II grant to continue development of this technology is that "Lignin-polymer containers demonstrate mechanical properties similar to petroleum-based containers and/or show improvements in plant health." Demonstrating material performance is very important for commercial adoption by large-scale greenhouses. Similarly, improvements in plant health would have significant impacts on the economics of plant sales for both greenhouses and retailers. In Phase II, we will continue to investigate the material formulations from Phase I and if necessary, expand the sample size to include new formulations with: soy-protein or distillers' grain additives to improve plant health and other lignin/polymer combinations to evaluate other mechanical properties. A longer Phase II experiment will also expand the scope of greenhouse crops used to include medium and long-cycle crops. We have a particular interest in nursery containers as this product could be beneficial to large paper companies who plant millions of trees each year to support their business models. A Phase II R&D plan would also include an end-of-life study to evaluate the biodegradability of lignin-polymer containers in different soil types.