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HYDROCOMPOST EVALUATION PROJECT FINAL REPORTDisclaimer CWC disclaims all warranties to this report, including mechanics, data contained within and all other aspects, whether expressed or implied, without limitation on warranties of merchantability, fitness for a particular purpose, functionality, data integrity, or accuracy of results. This report was designed for a wide range of commercial, industrial and institutional facilities and a range of complexity and levels of data input. Carefully review the results of this report prior to using them as the basis for decisions or investments. ACKNOWLEDGMENTS TechHelp provided oversight management on this project, and is Idaho's Manufacturing Extension Center under NIST. Idaho's public universities are partnered with TechHelp to provide additional resources. Hamilton Manufacturing, Inc. is a manufacturer of various recycled content products, including cellulose fiber used in the home and commercial insulation industries. Another one of their products is paper mulch used in Hydro-seeding of residential and commercial lawns. . Hamilton initiated this project with CWC to evaluate the use of compost with traditional hydroseeding formulations.
TABLE OF CONTENTS1.0 INTRODUCTION.......................................................................................................... 1 2.0 METHODS, RESULTS, AND DISCUSSION.............................................................. 3 2.1 Formulation and Application Procedures................................................................. 3 2.2 Field Application and Evaluation.................................................................................... 4 2.3 Rainfall Simulation Testing at Utah State University (USU).............................................. 5 3.0 DISCUSSION OF RESULTS FOR RAINFALL SIMULATION TESTING........... 12 3.1 Compost Analysis....................................................................................................... 16 3.2 Cost Comparison ....................................................................................................... 21 TABLES Table 1: Application Sites....................................................................................................... 4 Table 2: Water Runoff and Soil Erosion Data....................................................................... 7 Table 3: Plant Quality and Height.......................................................................................... 8 Table 4: Dry Weight of Plant Matter................................................................................... 10 Table 5: Percentage of Germinated Seed............................................................................ 11 Table 6: Chemical Analysis of Comost................................................................................. 19 Table 7: Heavy Metal Content............................................................................................. 21 Table 8: Erosion Control Performance and Cost Comparison............................................ 22
1.0 INTRODUCTION This report reviews the application of traditional recycled materials, such as newsprint and mixed waste paper, combined with compost, to provide a base media for hydroseeding applications. Primary uses of hydroseeding include landscaping, soil erosion control, forest reseeding, and reclamation of disturbed land (e.g., road beds, mine lands, overgrazed lands, excavation sites, and other disturbed land). The hydroseeding mulch or base material protects the seed and retains moisture in the soil to promote good germination. The conventional practice in hydroseeding is to prepare the surface and then make a single application of material consisting of mulch and seed. The mulch base material in conventional hydroseed products varies, but typically consists of wood fibers, wood excelsior, virgin or low-grade recycled paper mulch or straw waddles. Compost has not been widely used or tested as a supplemental mulch media in the hydroseeding industry, partly due to inconsistencies in particle size and density which affects operation of the spray hydro-machines. Hydroseeding application methods vary depending on the base material. The spray application process mixes the seed, mulch, and water (and other additives) at the site of application. Materials are mixed in a large tank, then pumped through a hose and sprayed onto the ground. A glue or tackifier may be added to improve the stability or holding capacity on sloped surfaces. Fertilizers may be added during application or later to assist in plant establishment and growth. Alternatively, some of these materials may be manufactured into blankets or mats which are placed directly on the ground. Two weeks is generally required for initial germination of hydorseeded residential grasses that are irrigated. Most residential sites have irrigation or sprinkler systems, and if the hydroseeded area is watered regularly, the germination is usually much better than on arid highway and mine reclamation sites that typically do not receive consistent moisture during germination. The germination period and success rate of highway and mine site recovery is dependent upon weather conditions, as well as other factors such as slope, soil condition and contaminant levels, terrain, etc. The hypothesis for this project is that by adding compost to a paper-based hydromulch (heretofore termed hydrocompost), the product can be successfully applied with a spray hydro-machine, and the hydrocompost will improve seed germination, require less chemical fertilizer, have better water holding capacity, and provide better soil erosion control. This project will evaluate the potential for and challenges of mixing and applying hydrocompost in hydroseeding applications. The project was carried out in the following steps: 1. Develop hydrocompost product formulations and application procedures that will be compatible with current equipment and application methods. 2. Evaluate and field test the various formulations using industry standard application equipment. 3. Conduct lab tests on the hydrocompost and conventional hydroseed products for erosion control capabilities. 4. Conduct lab tests for water holding capacity, compost maturity, organic and heavy metal content, and chemical analysis of hydrocompost. 5. Develop cost comparisons between various products available on the market. 2.0 METHODS, RESULTS AND DISCUSSION 2.1 Formulation and Application ProceduresThe optimum product formulation was determined to be a mixture of three parts (by weight) compost and one part recycled-paper mulch, plus tackifier and water. The amount of tackifier used varies, depending upon the application site, slope, anticipated weather conditions, and soil type. The constituents are described below: · Recycled newsprint mulch, containing up to 20% mixed waste paper, which is a difficult recycled commodity to market; · Compost, in a 3:1 weight ratio of compost to paper mulch. The compost used for this project was derived from dairy manure feedstocks. Straw-based compost is not preferred for this application due to the abrasiveness of straw which affects the pump in the hydroseeding machine; and · Tackifier, added at 7.5 pounds per acre. For the rainfall simulation experiment, Formulation 1 used liquid acrylic polymer as a tackifier, and Formulation 2 used dry powder called “Hold & GrowTM” as the tackifier. As a result of this initial work, Hamilton Manufacturing proved that existing mechanically-agitated hydroseeding machines with an impeller, are capable of mixing and applying a mulch plus compost hydroseeding mixture. Jet-agitated machines do not readily mix the heavy solutions that have been developed for hydrocompost. However, working with dry mixtures of mulch and compost, the materials can separate due to density differences, which may require addition of ingredients in smaller batches. The hydrocompost formulations for these applications were mixed in hydro-machines with fairly small tank sizes. This initial formulation development and testing provided baseline information for Hamilton Manufacturing to develop and publish a matrix of hydrocompost formulations for a range of tank sizes, from 300 gallons up to 3,000 gallons. 2.2 Field Application and EvaluationThe field site applications originally intended for this project included residential sites, Department of Transportation (DOT) highway roadside, and mine reclamation sites, although only three residential sites and one highway site were actually evaluated. Only one highway site, Horseshoe Bend, was seeded with hydrocompost in April 1997 and was monitored throughout the course of the project. The other DOT site could not be completed because hot summer temperatures prohibit seeding on DOT jobs. Due to climatic and project time limitations, the field applications were limited to three residential sites and one highway site. The three residential plots seeded in this project were rolling to flat conditions normally found in residential locations. Each plot was sprinkler irrigated and thus received adequate moisture for proper germination and growth during the summer months. The highway site was exposed to available ground moisture and normal weather conditions with no additional water application. The application sites and results are detailed in Table 1. No direct comparison or control plots were planted, therefore these results are only qualitative.
2.3 Rainfall Simulation Testing at Utah State University (USU) Two separate lab tests were performed in the Rainfall Simulation unit at USU’s Water Research Laboratory, to compare the hydrocompost product to a conventional mat product (MFP) for erosion control, water run-off, and plant growth. Laboratory tests allowed comparison of the performance of each product under relatively controlled environmental conditions that are virtually impossible to duplicate in the field. The first test was conducted in June 1998 and the second in December 1998. Rainfall can be varied from a mist up to 30 inches per hour. The USU rainfall simulator is a drip-type device that produces drops simulating rainfall at different rates. Five separate inlet orifices are used in each plot chamber. The rainfall rate can be varied at between approximately 2 to 25 inches per hour. Raindrop sizes are representative of typical high intensity storms. The spatial distribution of rain is essentially uniform, and the control of application rates is within the accuracy requirement of most experimental protocols. The USU equipment allows a controlled slope of anywhere from horizontal to a slope (rise to run) of 2.5:1. The test flume is a 20 feet square, divided into six 2’ x 19.5’ test plots that are separated by 2’ wide walkways. The total growing area per single plot is 39 square feet. Two separate tests on the test flume (six plots per test) were conducted; one in June 1998 and one in December 1998. The June test applied four plots with hydrocompost (two with hydrocompost formulation 1 and two with hydrocompost formulation 2), one plot with Mat Fiber Plus (MFP) at 1800 pounds/acre (lb/acre), and one plot with MFP at 2200 lb/acre. The MFP product is 100% virgin wood mulch with 3% guar tackifier. The December test applied one plot with hydrocompost formulation 1, one plot with hydrocompost formulation 2, two plots with Mat Fiber Plus at 1800 lb/acre, and two plots with MFP at 2200 lb/acre, as illustrated in Figure 1. Prior to application of the hydroseeding product, all plots were prepared at one-foot soil depth with a sandy-loam soil consisting of 56% sand, 29% silt, and 15% clay. The soil was cultivated with a tiller to a depth of approximately 6 inches, then raked smooth and uniformly compacted with a roller.
June 1998 December 1998 Barley seed was added to the hydrocompost formulation at a rate of 200 lb/acre. All ingredients were mixed in a laboratory-size hydromulcher and applied directly to the prepared plots per Figure 1. The sunlight simulator was then stationed overhead for three days to dry the plots. For the rainfall simulation, the slope was set at 2.5:1 run to rise, and rainfall was applied at five inches per hour for a duration of 30 minutes (which equates to 60.8 gallons per plot). The conditions were replicated in both the June and December tests as closely as possible, therefore, the average values shown in Table 2 and Figure2 correspond to the average of three repetitions of the test for each material. The sediment and water runoff from each plot were collected and weighed together. After the sediment settled, the clean water was filtered, weighed, and converted to a value in gallons. The sediment was dried and weighed. Table 1 and Figure 2 show runoff and soil erosion results.
Table 2. Water Runoff and Soil Erosion Data
Following the rain treatment and measurement of the soil erosion and runoff, a sunlight simulator was positioned continuously above the plots for seven days. Samples were then collected, consisting of all plant material from distinct areas in three different locations from each plot; the upper third, center third, and lower third. This material was combined into a composite sample for each plot (see Table 3 *). The number of plants from each sampling location were counted, measured, dried, and weighed. Germinating, non- germinating, and lost seeds were counted. The results are presented in Tables 3, 4 and 5, as well as Figures 3, 4, and 5. Table 3. Plant Quantity and Height
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