HYDROCOMPOST EVALUATION PROJECT

FINAL REPORT

Disclaimer

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 CONTENTS

 1.0    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 Procedures

The 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