Soil conditioners and amendments improve the physical and biological properties of soil and therefore are valuable tools in the erosion control professional’s toolbox. The range of products and materials is immense, however, and it appears that no one technology stands alone. Best use of soil amendments implies an understanding of their additive and synergistic properties.
Armed with these understandings, Erosion Control decided to ask a group of industry leaders to increase our knowledge of some of the basics. Responding to our request are:
Bob Weltzien of Roots Inc., Independence MO
Steven R. Iwinski, environmental scientist with Applied Polymer Systems, Norcross, GA
Bill Middleton, president of Emerald Isle Ltd., Ann Arbor, MI
Tom Kingman, Jonathan Green Turf Products, Farmingdale, NJ
John F. Lown, president of Earthgreen Products Inc., Dallas TX
Gary Custis, turf and ornamental product manager for PBI/Gordon Corporation, Kansas City, MO
Peter McRae, president of Quattro Environmental, Coronado, CA
EC: What is essential to the understanding and use of soil amendments? How can best management practices (BMPs) for their use be determined and implemented?
Bob Weltzien: Soil consists of minerals with a small but critical carbon element. The carbon is often called organic and consists basically of humus and soil microbes. Under ideal conditions, this soil is adequate for all plants, but conditions are seldom ideal, so fertilizer and soil amendments are added for optimum growth.
Fertilizers are the minerals used in photosynthesis to create plant biomass. The primary mineral nutrients are nitrogen, phosphorus (phosphate), and potassium (potash). Other minerals are necessary in smaller quantities. Soil amendments are nutritional supplements, either inorganic-like calcium-or organic. Organic amendments are widely regarded as snake oil because plants are supposed to use inorganic matter to create organic matter. The phrase soil amendment reflects this bias. It is like calling milk a “refrigerator amendment.” Organic biostimulant is a better description of an additive that helps plant growth. The most critical organic (carbon-based) component is mycorrhizae, the fungi that plants need to extend their root system in order to bring in nutrients. It is very hard to grow plants without this fungus. The other carbon-based requirement includes the humic acids (acid radicals in humus), growth hormones, vitamins, aminoacids, and carbohydrates. These are all molecular structures that plants are supposed to produce through photosynthesis, but which often they don’t produce because of a number of stresses. The soil-stress situations are most commonly drought and poor soil. The plant-stress situations are transplants and unnatural environments (such as bent grass in warm climates). For these stress situations, scientists at Yale University developed formulas they called “biostimulants” to carry plants over stress. The objective is not to change the genetic basis or natural-growth processes of plants, but to provide natural supplements to help each plant to survive and achieve its optimum growth.
Gary Custis: Turf biostimulants have generally been regarded as growth enhancers for use on high-dollar, premium turf. In utility turf applications, however, biostimulants can lead to more rapid germination, establishment, and uniform coverage, which are critical to slope stabilization and prevention of washouts. This applies to both seeding and sodding, as well as hydroseeding. Wildflower germination and establishment are similarly enhanced. Golf course superintendents, sports turf managers, and other turf professionals responsible for high-spec, elite, ornamental sites have learned that using a biostimulant can add “grow-in” power to standard fertility programs by enhancing the plant’s ability to utilize available nutrients. These turf managers are frequently are faced with situations where new turf coverage or sod knit-down must be accomplished very quickly, with the turf ready to withstand heavy traffic and stress.
Steven R. Iwinski: Most soil amendments are site-specific, based on the soil type or lithology of the soil to be amended. An example of this is gypsum that is used on various clays to increase porosity but will not be very effective when used on sandy beach soil. BMPs need to rise to the next level by increasing information of each specific amendment by the various vendors. The knowledge is available to vendors from the manufactures but does not seem to get placed with the end products. Many times contractors, constructors, and agricultural workers simply lack the information to correctly apply soil amendments.
Bill Middleton: Essential to the understanding and use of soil amendments is knowing what soil conditioners are and how they differ from other materials with which they are sometimes confused. For example, organic fertilizers and composts are sometimes considered to be soil amendments. One of the distinguishing features of a soil conditioner is that it has a carbon-to-nitrogen ratio of 12:1 or greater. If the ratio is below 12:1, the material should be considered a fertilizer. Within the category of soil amendments, one should consider whether the material is organic or inorganic, natural or synthetic. For example:
- Natural, organic: Sand-Aid granular sea plant meal. You would use this soil conditioner when you need to increase nutrient and moisture-holding capacity and microbial soil activity. In many cases, this is seen as the best general-use, organic soil conditioner because it holds moisture and nutrients in the root zone but does not contribute to layering because it breaks down relatively quickly in the soil. Meanwhile it dramatically contributes to soil microbial life and plant establishment and health. One of the essential keys to healthy soil is its microbial life.
- Highly processed natural materials: fired, calcinated clays such as Profile. The advantage is in moisture-holding capacity and a more moisture- and oxygen-available system. This type of material lasts quite a long time in the soil. Its disadvantage is that it does not enhance microbial life or contribute any minerals to the soil.
- Synthetic soil conditioners: various manmade polymers that function similarly to the processed materials like Profile. These materials are not natural, however, and they are inert; thus they do not contribute to soil life. While they contribute porosity to the soil, they also introduce a non-natural material into the soil. It is important to know what problems you are trying to solve in using soil conditioners. It seems the primary reason why erosion control managers use the soil conditioners would be to improve plant establishment so to better manage erosion. That’s why we favor the natural, organic approach that not only amends the soil but contributes to its life and the robust growth of plants.
Tom Kingman: An understanding of micronutrients and their role in soil amendments is crucial. It is also very important to be able to identify certain mineral deficiencies in soil. This will help to establish vegetation that can hinder erosion. It is essential that an applicator know what kind of soil he is dealing with when trying to slow down the erosion process. It is also very important to identify the type of erosion you are attempting to slow down. Having a thorough soil test done will provide necessary answers. Once these few questions are answered, the applicator can then tailor his strategy to the specific environment. By familiarizing himself with the roles of nutrients in the soil, the applicator can effectively administer the right product as well as the correct dosages to the area.John F. Lown: In using any particular soil amendment, it is very important to match the qualities of that amendment to the particular situation you are trying to amend. In other words, do you need (a) bulk organic material to enhance soil structure, (b) macro- or micronutrients to enhance plant establishment and growth, (c) a carbon source to feed soil microorganisms, etc.? So many times we see contractors simply add a soil amendment because of its special qualities but not match those qualities to the particular situation they are working with.
Gary Custis: Biostimulants have been defined as substances that are not a plant nutrient or pesticide, but which in some manner have a positive impact on plant health. Humic acids, fulvic acids, and plant hormones such as cytokinins and auxins are examples of important biostimulant materials. These growth enhancers have been shown to stimulate metabolism, increase chlorophyll efficiency and production, increase antioxidents, improve nutrient availability, and increase the water-holding capacity of the soil.
Peter McRae: I agree that soil conditioners and amendments are mere tools in one’s toolbox. They are also pitifully inadequate to deal with head on with the limitations of drastically disturbed soils. Consequently, it is important to recognize that one cannot deal with such limitations by simply amending soil (except perhaps by directly importing live topsoil), but must set in motion a process of rebuilding soil via the medium of growing carefully selected plant species on a sustainable basis. We refer to this as “growing soil.”
EC: What opportunities do you see in the use of soil amendments? Is their use going to increase? What will we learn about their uses? What about the opportunities for recycling of materials as potential soil amendments? Are there any new and exciting developments in this sector?
Bob Weltzien: As the role of stress is recognized in plant health (as it is being recognized in animal health), the more biostimulants will be used. They have only been available for 10 years, so the growth in the category is rapid. The supplements that growers, planters, and maintainers are using are basically in two areas: (1) Where there are obvious stresses in soil or plant, biostimulants are used to optimize growth. In certain forestry conditions, this is not practical, but in nurseries, plantings, landscaping, and maintenance, it is very cost-effective. It pays for itself if even one or two plants are saved. (2) Where the soil is depleted or has been mistreated (as in new construction), it is practical to add mycorrhizae. Each of the Yale University biostimulant products is also available with a mycorrhizal inoculant at a modest price uplift. Organic biostimulants will be increasingly used to replace pesticides. Several European countries are severely restricting the use of pesticides, and our biostimulants are being used to create healthier plants that resist disease.
Bill Middleton: Again, the use of organic amendments speaks to the issue most directly, because organics help the soil directly by contributing nutrient and moisture retention, along with boosting the microbial life and contributing to root growth and plant health. We have found that among organics, some are considerably better than others for these purposes. Currently, our materials are used largely in golf course and athletic-field construction. But they are the environmental and agronomic answer to any situation where plants are grown. Particularly in cases where plants or turf is not grown, opportunities for recycling abound. Newspapers are being used for mulch, and recycled tires have been used to relieve compaction.
Peter McRae: I agree that the range of products and materials being offered for sale is immense; however, the range of materials available that have a ghost of a chance in accomplishing the above-mentioned “growing soil” goal is incredibly small. Much of the effort I see being expended on attempts to establish sustainable native plant growth is doomed from the outset because the goal is flawed. In such circumstances, the benefits of even worthy soil amendments are compromised.
Steven R. Iwinski: Opportunities are boundless at this time. The bulk of current technology focus is for the most part on structural applications. One case in point that I observe often is in highway construction where slope stabilization has been applied very well with correctly installed silt fence, slope matting, downdrains, straw, etc. As one observes the downslope drainage ditches, streams, ponds, and lakes, large amounts of colloidal clays and fine sediments clog the riparian waters. This scenario is easily corrected with the correct use of polyacrylamide (PAMs) when used in conjunction with the structural BMPs. More attention should be placed on combinations of amendments. Like all “good” BMPs, usually a combination of several are required to obtain best performance.
Bill Middleton: We see a continual, enlarging place for soil amendments. First, the earth’s supply of good topsoil is limited and continuously being consumed. Inevitably, the quality will decrease and require organic amendments to increase microbial activity that in turn delivers soil and plant health and growth benefits. Second, environmental awareness is increasing regarding surface runoff. The need to prevent erosion and nutrient leaching will eventually be mandated. But even before the laws are written, anyone concerned with erosion control-e.g., professional ground and turf managers-is already aware of the environmental impact of eroding soils and shorelines and the devastating effects of excess nutrients in our lakes and streams.
Steven R. Iwinski: The purpose of a soil amendment is to condition the soil in preparation for vegetation. The better we become at perfecting soil amendments the better we become at establishing vegetation. Whether the vegetation is a food crop or grass for erosion control, prevention of soil loss is the issue. The recycling of plant material (trees, brush, grasses) should be a given. This is cost-effective and environmentally sound. Unfortunately we haul off most of this material during the grubbing and clearing process only to pay dearly to bring it back on-site for erosion control a short time later. The Texas Department of Transportation has shown that a mere 6 lb. of PAM used in conjunction with mulch will nearly prevent erosion of highway slopes. This is not new information or even the best BMP, but it has been published, allowing this information to read by other states. Good conventional soil amendments-such as dolomite, gypsum, carbonates, and sulfates-have been around forever, work well when applied to the correct lithology, but are not well-enough advertised. The yes is in the area of polymers. Even though polymers have been around and used for many years, recent technological advances in this area have increased their performance beyond what many would believe possible.
Tom Kingman: There are many forums in which soil erosion is present. The largest of these is the construction industry. With the recent influx of new construction, soil conservationists are more concerned than ever about soil erosion. Many counties have instituted mandatory measures for conserving soil integrity. For example, it is mandatory that a contractor apply straw or hay and tackifier on any new seeding job, no matter how small. Another large concern in our area is beach erosion. The use of native and reclamation grasses to conserve sand dunes is booming. Increased awareness for the environment has also opened up another door to soil conservationists. Planting reclamation grasses along a watershed is helping to reduce eutrification of the local streams. Many turf managers are also responding to the public’s environmental awareness by instituting integrated pest management programs. Soil amendments and healthy microbial action in the soil are vital to these programs’ success. The recycling of materials as potential soil amendments is an exciting area of conservation. The materials that are available in each locality are primarily predicated by the local industry. Cocoa shells, wood chips, sawdust, coffee grounds, and seaweed are just a few that come to mind.
John F. Lown: Soil amendments are very beneficial because they can amend soil structure and nutrient content to enhance new plant development and growth. Typically in erosion control the site has been damaged in some way as to not provide the optimum environment for new plant growth. Therefore, soil amendments’ use will continue to increase and become a standard part of any erosion control program. Recycling can be a very important element of this program, but great care must be used in what recycled products are used and what these products are actually providing to the site under consideration.
Bill Middleton: It would be useful for erosion control managers to consider what happens to soil after the construction phase. Soil has to be considered as a living system. It can’t be kept alive without organics. Erosion control managers are currently responsible for just getting things established. It would be a step forward if they were responsible for longer-term effects-for building a living system that continues.
Gary Custis: The components and ratios contained in a biostimulant product will determine the benefits to be gained. Humic acids have been shown to increase germination rates and promote greater growth of fibrous roots. Studies at Virginia Polytech have shown greater root development with humic acids applied with low nitrogen than with high nitrogen applied with no humic acid (R.E. Schmidt and Sunshong Zhang, “How Humic Substances Help Turfgrass Grow,” Golf Course Management, July 1998). Humic acid has long been known to have soil-amending properties. Humic aid increases the nutrient-holding capacity of the soil and is capable of loosening heavy clay soils, improving water infiltration, and allowing easier root penetration. Fulvic acids, known to work more in the plant than in the soil, also enhance nutrient, vitamin, coenzyme, auxin, hormone, and natural antibiotic availability, yet are not included in all biostimulant products. Cytokinins are important plant hormones. Kelp is a source of readily available cytokinins. Cytokinins assist seeds in breaking dormancy and promote root development. All plants contain cytokinins, but internal cytokinins are decreased when plants are under stress. Newly germinated plants have an extremely limited source of their own cytokinins as a result of limited root development. The external application of cytokinins is therefore critical to the fast establishment of new plants.Bill Middleton: What’s exciting? State-of-the-art advancements in organic matter in general. Until recently, only a handful of slow-decomposing organics were available (e.g., peat, gypsum, dolomite, rice hulls, wood chips). These materials are useful but limited. Now sea plant meal is available, which quickly decomposes and contributes a much larger range of benefits in terms of cation exchange capacity, moisture management, and soil friability.
EC: Education and information about soil conditioners, amendments, and fertilizers are essential. What do you see as positive contributions to this effort (universities, soil institutes, industry seminars, etc.)? What would you like to see?
Gary Custis: Hydroseeding research conducted at the corporate research center of PBI/Gordon Corporation has shown that the addition of Launch Biostimulant resulted in a 40% greater germination and establishment rate through 35 days than an identical Kentucky bluegrass-/perennial rye grass-hydroseeded plot without the biostimulant. Hydroseeded-field research plots containing Bermuda grass seed treated with Launch Biostimulant germinated in three days; untreated plots required 11 days. Research by a national paper mulch company has prompted it to produce a line of mulch impregnated with Launch Biostimulant. Bermuda grass sprigs treated with Launch also showed enhanced coverage and less loss as a result of desiccation of the sprigs.
John F. Lown: Education to the market is critical to use these soil amendments properly. Input must come from product producers in cooperation with field trials and university research programs. These programs must have real-life situation applications, not merely programs designed to meet particular funding opportunities offered by government agencies. Typically you can see the effect of these soil amendments in 90-120 days.
Tom Kingman: There are many informational resources available to the landscaper. I think the best and most easily accessible is the Internet. The wealth of knowledge available to everyone is phenomenal. The US Department of Agriculture (USDA) also does a fabulous job of presenting information to the public. I would like to see more on the Web in regard to soil erosion, proper soil-testing techniques, and a listing of laboratories that perform full-spectrum soil testing. Also invaluable are universities and magazines, such as Erosion Control.
Bill Middleton: There is currently very little organized effort in educating people about soil conditioners. It would be nice to have an independent body, a soil research institute, or even Erosion Control magazine taking a leadership role in this area. For example, you could sponsor small-scale experiments in real-world projects with test plots containing different materials. You could measure such things as the speed of growth, speed of establishment, root mass and depth, and top-growth density. Measure results with seeded sodded, sprigged, hydroseeded plots. Measure the effectiveness of turf compared to ground covers as erosion control materials.
Steven R. Iwinski: More emphasis needs to be placed on the private sector for information to the constructor/contractor. A serious lack of “how-to” information is missing in this area. The USDA-ARS has done an extraordinary job for the information dissemination of PAMs. This same approach needs to be directed toward other soil amendments and the various combinations of using them with existing structural technologies.
Bob Weltzien: The only way to advance the use of soil amendments is through the work of serious soil scientists and plant physiologists at major universities. There are a number of scientists doing research, which is being presented to the public through seminars and articles in the trade press. It’s a slow process because people are properly skeptical, and there are a number of companies more interested in promises rather than performance.
Peter McRae: The use of soil amendments will increase, but they will be used selectively as essential components in a master plan designed to address a specific site, not as a panacea for all ills. As to recycling of materials as soil amendments: Materials that contain valuable properties can be utilized where feasible; materials that rightfully belong in a landfill should go to the landfill. They should not be miraculously ascribed plant-growth beneficial powers on account of being “composted.”
EC: Tell us about your product-its benefits and uses.
Bob Weltzien: Our products are biostimulants that carry plants over stress with mycorrhiza when needed. We have done over a hundred studies at 11 universities and distributed the reports widely throughout the industry. ROOTS2 is a university-tested biostimulant with a number of siblings: mycorrhizaROOTS, a soluble form with 12 species of mycorrhiza; ironROOTS2 for iron-loving trees and shrubs; ironROOTS with ectomycorrhiza for conifers, oaks, and beeches; granular dryROOTS; Transplant 1 Step, a dry, granular form with water-holding gel and 12 species of mycorrhiza; and M-ROOTS, which is dryROOTS with mycorrhiza (no gels).
Steven R. Iwinski: The products that Applied Polymer Systems provides are basically similar to PAMs that are currently used in agriculture erosion control with a significant difference. Each target soil type is evaluated first to determine the best fit for a specific PAM. As a soil amendment, one form of PAM must not be expected to work on all soil types. As an example, soils from south Florida are completely different from soils from Tennessee, as are soils from Alaska. This characterization process has proved greater than 99% effective for water clarification and erosion control over the last eight years. The results have shown decreased PAM usage, much less erosion, cleaner water, and reduced cost to the end user.
Bill Middleton: Emerald Isle products for erosion control include GroWin Granular Biostimulant to produce rapid and robust leaf growth, improve stress tolerance, and establish turfgrass better and faster; Sand-Aid Granular Sea Plant Meal, which delivers soil conditioning benefits by increasing the organic content; and OptiMil Optimal Soil Conditioner/Fertilizer, which blends Sand-Aid and Milorganite-an excellent organic fertilizer-to produce a fertilizer and soil conditioner in one efficient and cost-effective product.
Tom Kingman: For hydraulic applications we distribute a variety of supplies, such as Jonathan Green Hydro Seeding Fiber mulch, Hydro Seeding Fertilizer 16-32-16, Super-Cal liquid lime substitute, Green Spray Colorant, Hydro-Green tackifier, Super Tackifier with Aqua Source for added moisture retention, and Tackifier 2000 for longer holding power, reduced loading time, and increased lubrication. In addition to a large variety of soil amendments, including our pelletized limestone, granular broadcast limestone, pulverized limestone and pelletized gypsum, Jonathan Green offers Aqua Source, a water-absorbing synthetic polymer whose primary benefit is the dramatic increase in the long-term water-holding capacity of soils. It absorbs 400 times its weight in water. Penn Mulch Seed Establishment Mulch gives similar results to hydroseeding without the need for equipment or cleanup.
John F. Lown: Our products are highly decomposed humic substances (plant material) that provide (a) a high level of available carbon that acts as a food source for both indigenous microorganisms and augmented microorganisms, (b) trace minerals in a coloidal suspension that are readily available for plant uptake and development, and (c) organic acids that enhance nutrient uptake and aid in early root-zone development. These products are in both a granular and water-soluble form for ease of handling and application. They are very concentrated and effective at low application rates. They have been used very effectively in the remediation of hydrocarbon-contaminated soils and high-nitrate-contaminated soils. They have been used as a filter media in both contaminated liquid solutions and for contaminated air filtration. They are totally natural, safe, and easy to handle. There is no special registration or clearance needed for use of these products. These products are currently distributed both in the United States as well as Europe and Southeast Asia. We own the production facility and are thus able to maintain consistent quality in these products.
Gary Custis: Focus and Launch Biostimulants from PBI/Gordon contain high concentrations of humic and fulvic acids with cytokinins and auxins. Additionally, Launch Biostimulant is formulated in a homogenized and deodorized liquid manure base. The addition of cytokinins, auxins, and fulvic and humic acids to this liquid manure base creates a product ideally suited for the establishment of new turf. All of these components work together both in the plant and in the soil to generate a strong root mass and a stand of dense, hard-wearing turf. Recent experiences have important implications in the establishment of hillside plant coverage for erosion control. Slow establishment risks washout from rains. Quick establishment and enhanced root growth greatly improves plant survival on slopes where soils may drain and dry quickly, causing desiccation of young, underestablished plants.Peter McRae: On one front, Quattro Environmental (with assistance from some of our joint-venture partners) has sponsored quite a considerable amount of research effort at explaining why the “growing-soil” approach to reclamation seeding has enjoyed not only success where traditional seeding has failed, but also such consistency of success. On another front, via the efforts of individuals within the Native Plants Trust association, tough revegetation challenges have benefited from both a consolidation of existing but disparate technologies as well as a comprehensive battle plan designed to keep “weak links” (having the capacity to sabotage an otherwise flawlessly designed, supplied, and executed seeding project) at bay. Bottom line: The technologies and materials for sustainable native plant growth on drastically disturbed soils in harsh environments are available. For the immediate future, however, the implementation of such technologies and use of such materials will be the exception, not the rule. We will continue to fire out seed with fertilizers and wood-fiber mulch in an attempt to “grow carrots in the desert” and the short-term growth results will continue to impress and blind us from the long-term disasters we are creating. Ultimately the concept of “growing soil” will gain even greater momentum and will continue to be improved. In the meantime, it is this “improving-upon” effort that is so much fun and rewarding. I hope this can be helpful down the road.