This Small Business Innovation Research Phase I project will study the feasibility of developing a novel weed control and moisture conservation (WCMC) mat from recycled diapers for tree protection. Disposable diapers are the most disposed household products in United States and contribute more than 2% to municipal solid waste. The majority of disposed diapers are currently accumulated in landfill fields. By capitalizing on many of the unique features of disposable diapers, the WCMC tree mat product will promote the growth of young trees, protects against drought stress, and allows reforestation/afforestation in arid or semiarid areas, on degraded soils, and on wastelands. It can also reduce water usage and maintenance costs for urban forests. The WCMC product will permit maximum usage of limited water resources by its strong water retention capability and by its suppression of weed growth. Investigations will be carried out on the effectiveness of this product in protecting young trees against drought conditions, the feasibility of using low-cost and environmentally benign manufacturing technologies, and the potential environmental impacts.
The broader impact/commercial potential of this project will be threefold. If successful, it will enable 1) reduction in solid waste accumulation, 2) faster, easier, and cheaper afforestation / reforestation processes; and 3) reduced environmental impacts. The commercial potential of the WCMC products will be global, and will focus on usage in arid/semiarid as well as urban areas. The WCMC products can serve markets including weed barrier, garden mulch, fruit and nuts tree care, and urban forestation and landscaping. The estimated market size is about $1.2-1.9 billion. This product will help trees survive through drought stresses with less water consumption and less after-planting care. It will naturally lead to a reduction in greenhouse gas emissions and increased carbon sequestration, and to a reduction in the carbon, nitrogen and water footprints.
Newly planted trees have restricted root placement, low root system permeability and/or poor root–soil contact, which can limit water uptake from the soil. As a result, young trees are exposed to stress just after planting (i.e., planting stress) because they are not fully coupled into the hydrologic cycle whereby water flows from the soil to plant roots, then to air from leaves. This lack of coupling (i.e. due to a restricted rooting volume limiting access to soil water) increases the possibility of excessive water stress in newly planted trees. It can result in either carbon starvation or hydraulic failure, and subsequently death. Thus, tree survival is related not only to their inherent growth potential, but also to the degree to which field site environmental conditions. The condition may limit or enhance the potential for trees to become established or coupled into the ecosystem. This SBIR Phase I project successfully demonstrated the feasibility for producing weed control and moisture conservation (WCMC) plant mat from recycled baby diapers using an economically viable and environmentally benign method. The WCMC mats developed in this Phase I project are based on the concept of using super absorbent polymers (SAP) recovered from disposable diapers to store and release rain water to tree roots, while the plastic shells of the mats also function as weed barriers. Zynnovation is marketing the WCMC mats under the trade name of TreeDiaperTM. "TreeDiaper" and "WCMC" are used interchangeably in this report. Zynnovation has collaborated with VCU Child Development Center to collect baby diapers for this project. The 600 soiled baby diapers were collected from childcare centers and stored in a lab refrigerator before being processed. The cleaning and sanitation process follows a standard operating procedure (SOP) that was developed previously under NSF award # IIP 1045780.The SAP material and shell plastics were obtained after recycling. Then the SAP materials were used as the core materials for our mat prototype development. Separated and dried plastics shell was shredded and processed into plastic sheets, which are intended for making WCMC mat cover. This part of study was accomplished with collaboration with USDA Forest Product lab in Madison, WI. WCMC prototype mats were fabricated and evaluated for performances under various conditions. Controlled environment trials and field tests, on multiple sites, were carried out in greenhouses and in road medians, parks, landscaping grounds, vineyards, orchards, nursery farms and nursery retail stores. All these field tests are still underway in central Virginia. The results show that the prototype WCMC mats can suppress weed control and alleviate planting stress of trees, especially in drought conditions. The performance of WCMC mats and the test results are shown in attached figures. Zynnovation’s field test results in urban orchard of Chesterfiled County, Virginia was also reported in a feature article of Richmond Time Dispatch on March 3, 2014, where it was stated "The application of Zynnovation treemats has resulted in saving 60 gallons of water per tree last summer and fall". This was for a year with much more than average rainfalls. It would have saved much more water for a typical year we have in central Virginia. With WCMC mat, urban foresters can reduce cost and expand tree canopy coverage while staying under the shrinking budgets in many local governments. The WCMC mats are proven to increase the survival rates of trees during severe droughts with less or no irrigations. Costs for tree planting and after-planting care can be dramatically lower (see attached figures for comparison). It will also significantly increase the possibility of tree survival by increased moisture level in the soil near root systems. It will benefit the U.S. agriculture and reforestation programs, as well as help conserve global forest and water resources. Owners of land, household, orchards, vineyards, and nurseries can benefit from increased survival and growth rate and reduced irrigation / weed control cost. The new recycling technology can significantly reduce the amount of diapers sent to landfill and their subsequent pollution of surrounding water resources. In short, this project will provide solutions to two serious problems: rising costs of plant protection against drought and weed and diapers accumulating in landfill.
