Research conducted at Virginia Tech and the University of Maryland in conjunction with partners such as the Maryland State Highway Authority has demonstrated Bloom’s efficacy in establishing turf, crops and more in a variety of settings, from roadside soil conditions to newly established wetlands. Read more below about the research findings on Bloom’s benefits.

Other Field Experiments

Scientific Field Research

Establishing Turfgrass in Poor Soil Conditions using Bloom

Chenglin Zhu and Dr. Gary Felton, University of Maryland in collaboration with Maryland State Highway Administration.

Few studies have been done on the effects of biosolids products like Bloom on poor nutrient soils, particularly roadside soil. Highway roadside soils often suffer from compaction, erosion, and poor vegetation, making it difficult to establish and maintain turfgrass.

This study, conducted by University of Maryland researchers in conjunction with Maryland State Highway Administration, aimed to assess the effects of Bloom and Bloom mixes on soil conditions and turfgrass growth. The research compared Bloom and derivative products to inorganic fertilizer applied to turfgrass in till and no-till plots designed to simulate roadside soils. Bloom resulted in significantly higher hydraulic conductivity (a measure of soil permeability) than inorganic fertilizer. A mixture of Bloom, sand and sawdust, a registered Bloom blend developed by DC Water, was deemed the most effective treatment for improving soil physical conditions and soil fertility (increasing both carbon and nitrogen).

Click here for presentation deck summarizing findings.

Impact of Biosolids on Plant Drought Resistance and Hormone Metabolism

Virginia Tech, Department of Crop and Soil Environmental Sciences, Xunzhong Zhang, Erik Ervin, Greg Evanylo, and Katie Haering

Biosolids applied at agronomic rates have been shown to improve hormone metabolism and drought tolerance in greenhouse trials; this research sought to test the effects in the field. This study looked at the effects of anaerobically digested biosolids* on hormone and antioxidant metabolism and grain yields in a corn-soybean rotation.

The biosolids product increased leaf photochemical efficiency; key plant hormones (indole-3-acetic acid and trans-zeatin riboside); proline, an important amino acid; and superoxide dismutase (SOD) activity (fighting oxidative stress) in corn and soybeans compared to controls. It increased grain yield by 77% in corn and 18% in soybean compared with the controls. “The research demonstrated that biosolids application improves leaf anti-senescence hormones, osmoprotectant, and antioxidant metabolism to increase grain yields, especially under drought stress,” conclude the researchers.

Click here for full manuscript published in Crop Science.

*Research conducted prior to anaerobic digesters being installed at Blue Plains; AD biosolids material in question was from another plant but of a similar composition to Bloom today.

Tracking pH and EC Changes in Soil

Organic (carbon-rich) amendments have been used with great success in the greater DC area to improve soil quality before landscape planting and turf establishment. Research has been conducted by the University of Maryland, Virginia Tech and other local institutions to test the efficacy and optimal use of compost and biosolids-based products, including DC Water’s Bloom product, to this effect. Bloom has also been successfully utilized in regional topsoil manufacturing projects. In this application, lower quality mineral soils (or sand, reclaimed materials, etc.) are blended with soil conditioners, rich in organic matter and slowly releasing plant nutrients. This technique has been employed using other recycled organic products in the past, but the use of biosolids processed through thermal hydrolysis in this application is relatively new. It should be noted that other ingredients (e.g., sand, bark) are sometimes used as a component to these soil mixes, and blending can be done in-situ (on-site) or ex-situ (off site).

In 2020, Bloom engaged horticulturalist and recycled organics expert Ron Alexander of R Alexander Associates, Inc. to design and conduct research to track changes in the pH and soluble salt content of Bloom amended soil over time. These parameters can not only impact plant selection and soil modification procedures, but also affect whether a soil amendment will meet standard specifications. The key finding: the slightly elevated pH and EC of Bloom has been shown to drop quickly as ammonia in the product is converted to other forms of nitrogen or bound to soil particles, while organic matter, another important parameter of most soil specs, increases.

Read full research summary here.

Biosolids improve urban soil properties and vegetable production in urban agriculture

Odiney Alvarez-Campos and Greg Evanylo, Virginia Tech.

Exceptional Quality biosolids like Bloom may be developed into products to rehabilitate disturbed urban soils for vegetable production in urban gardens. This study sought to investigate the effects of various EQ biosolids products on urban soil properties and vegetable yield. Field research was conducted at Blacksburg, Virginia in an urban subsoil fill from a nearby construction site to simulate degraded urban soil properties. Three EQ biosolids products, including Bloom, were applied bi-annually at agronomic nitrogen (N) rates, and annually at land reclamation rates (5x agronomic N rate). A heat-dried and pelletized EQ biosolids product and inorganic fertilizer were applied bi-annually at agronomic N rate only.

Soil carbon accumulation two years after biosolids applications ranged between 37 to 84%, highlighting the potential benefit of these products to sequester carbon in degraded urban soils. Soil N availability was less than expected based on previous greenhouse research, even after cumulative biosolids rates, likely due to low organic matter and high clay concentrations that reduced organic N mineralization. Cabbage (~3.1 kg m-2) and kale (~1.1 kg m-2) yields were greater with reclamation rates than with inorganic fertilizer (1.0 kg m-2 and 0.4 kg m-2, respectively). Thus, despite limiting physicochemical soil conditions, the addition of biosolids at reclamation rates showed greater potential to increase vegetable yields after two years of application.

These findings were excerpted from a publication under review in Urban Agriculture & Regional Food Systems.

Using Bloom for Wetlands Restoration

Brian Scott, PhD Candidate, University of Maryland, in conjunction with the Maryland State Highway Authority

Wetlands are important ecosystems, cleaning and maintaining our water supplies. Whenever a wetland is removed to build new roads or neighborhoods, new ones are built. The secret to cleaning our water is a soil chemistry that is unique to wetlands. So, to condition the soil, new wetland projects often include some type of soil conditioner, and organic amendment. Recent research conducted by Brian Scott, a PhD candidate at the University of Maryland, compared different amendments.

Bloom performed better than other organic amendments in several areas. First, the research showed that most organic amendments produce excess amounts of methane. Methane is a strong greenhouse gas and contributes 25 times as much to global warming as carbon dioxide. Only recently have scientists realized that methane generated from wetlands is a global concern. When compared with equal amounts of other organic amendments, Bloom produced the least amount of methane and only slightly more than natural soils with no amendment.

Another obvious benefit of Bloom is lush and robust plant growth.  Bloom was more likely to stimulate plant growth, but not the growth of less desirable species. Learn more in this factsheet or this recorded presentation.

Other Field Experiments and Observations

Flowering Plant Trials

Dr. Frank Gouin, Professor Emeritus of Horticulture, University of Maryland

The late Dr. Gouin, a renowned horticulture and compost expert, conducted various trials of Bloom, including leafy vegetables and flowering plants. According Dr. Gouin, “Bloom is rich in iron and essential trace elements. Available iron means that plants fertilized with Bloom will develop deep, dark-green foliage. Growers at Homestead Gardens compared begonia plants grown in Bloom-amended potting medium with begonia plants growing in the same medium amended with Osmocote 18-6-12. The plants grown with the Bloom were nearly twice as large, contained many more flowers and had foliage black-green in color as compared to grassy-green for plants grown with Osmocote.” Click here for photos and more information on his findings. Dr. Gouin discusses his observations on Bloom’s benefits in this video.

Vegetable Growth Trials

Nadia Mercer, Program Director Washington Youth Garden at the National Arboretum

As reported in The Washington Post, Mercer’s team tested Bloom by comparing two beds containing cabbage and celery, one with the garden’s usual compost-amended soil and the other with Bloom incorporated. With Bloom, “they grew a lot more rapidly, they were bigger and healthier in general,” Mercer said. “I was really surprised with the difference.” It clearly drove leaf growth but not so much the development of fruits such as eggplants and tomatoes, or in root vegetables such as carrots, according to Mercer, concluding that “it’s great for leafy things.”

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