The research behind the Sigma Foundation Program: the evidence, the organisms, soil carbon, how the program is built, black layer and thatch, and practical problem guides.
What the published research shows, what each organism in a biological program does, how biochar holds water and nutrients in the root zone, and practical guides to common turf problems. Agronomy first; product options where they apply.
Reduction in initial dollar spot severity on creeping bentgrass, with disease onset delayed by up to 30 days, in four years of field trials. Trichoderma populations stayed at or above 10⁵ CFU/g through winter.
Lo, Nelson & Harman (1996), Plant Disease 80:736 ↗Phosphorus uptake in plants colonized by arbuscular mycorrhizae under drought, with root length up 37%. Meta-analysis of 106 studies across plant species.
Chandrasekaran (2022), Journal of Fungi 8:660 ↗Time for 1,000 ppm hydrogen sulfide to kill creeping bentgrass. Sulfur combined with high organic matter produced far more sulfide than sulfur alone, so keeping the root zone aerobic is the core of prevention.
Berndt (2016), Golf Course Management ↗
Colonize the rhizoplane and drive nutrient cycling, making bound nutrients plant-available. Several species produce compounds active against soil-borne pathogens.
Arbuscular mycorrhizal fungi extend hyphae beyond the root depletion zone, increasing uptake of water and immobile nutrients, especially P, Cu, Mn and Zn.
Mycoparasites that coil around and degrade pathogenic fungi, compete for root-zone space and nutrients, and can stimulate plant defenses.
Micrographs are illustrations. Species and counts per Sigma Bio product labels.
One strain featured each week, with a published study behind it. Tap any strain to read it now. The studies were run on crops and seedlings, so the test conditions are listed with each result.
The Sigma Biochar Platform is built from premium biochar feedstocks, including virgin pecan shell biochar, and engineered in four forms. Particle size decides where each one works best: fine particles carry the most surface area per pound and move easily through a spray tank or a thin layer of topdressing, while granules stay where they are placed in the profile. All four are compatible with humic acids, biologicals and seaweed extracts.
| Product | Form | Where it fits |
|---|---|---|
| Sigma Biochar EZ Mix | Medium granular | Construction, renovation and grow-in on bare soil; root-zone mixes; placed below the surface with DryJect or WetJect; fertilizer blending. |
| Sigma Biochar Powder Plus | Fine powder | Blended into topdressing sand so every pass adds carbon habitat; greenhouse starter trays and plugs; liquid and specialty formulations. |
| Sigma Biochar 5M | Sprayable liquid, 5-micron | Existing spray programs where moderate rates are needed: tank-mixed with Sigma Bio, Molasses and Seaweed on the 21-day liquid cycle; injection and fertigation. |
| Sigma Biochar Dispersion | High-solids liquid | Growing media, soil and compost manufacturing. |
Water leaving the root zone carries whatever the soil could not hold. Biochar's porous structure and charged surfaces keep more water and nutrients in the zone where roots and microbes can use them, so on average less nitrate moves down toward groundwater.
Average drop in nitrate leaching with biochar across published experiments, with reductions above 26% in experiments that ran longer than 30 days.
Borchard et al. (2019), Science of the Total Environment 651:2354 ↗More water held at field capacity in sand amended with biochar versus straight sand, and nitrate in the leachate fell from 5 ppm to zero as biochar content increased.
Brockhoff (2010), Iowa State University ↗Above about 10% biochar by volume in a sand green, bentgrass rooting depth fell by as much as 46%. Biochar works as a light amendment and a spray, not a bulk replacement for sand.
Brockhoff (2010), Iowa State University ↗Results vary with soil, biochar source and rate. A USDA-ARS field study on a sandy loam in California found no drop in nitrate leaching, which is why Sigma recommends rates from soil tests and pairs biochar with biology and sound irrigation rather than relying on it alone. Gao, USDA-ARS (CDFA FREP report) ↗
A biological fertility program in two layers, designed to run alongside an existing fertilizer and protection program rather than replace it.
Slow-release organic granular (8–12 week feed) carrying humic acids and the Bacillus, endomycorrhizae and Trichoderma consortium. Applied early season, every 6–8 weeks, and at 2X at aerification.
Inoculum (Sigma Bio), microbial food sources (Molasses, Microalgae, Seaweed), carbon habitat (Biochar 5M) and potassium (K-Ferm). Tank-mixed with existing sprays on 21-day intervals.
Core Program: Sigma 4-4-4 Bio with the liquid cycle. Tailored Options: a different granular base chosen for site conditions such as phosphorus limits, Poa pressure or fairway acreage. Both are listed in the product library.
← swipe to see both cores →
What it is. A dark band, usually 2–8 cm deep, that forms when part of the root zone goes anaerobic. Sulfate-reducing bacteria produce hydrogen sulfide, which reacts with iron and manganese to form black metal sulfides. It smells of rotten egg and is toxic to roots.
Contributing factors. Excess organic matter and mat, layering from topdressing or sod, compaction, perched water, overwatering, and high sulfur inputs.
Program role. Aerobic microbial activity and thatch decomposition (g) limit the organic matter that drives oxygen demand. Deeper roots (b, c) also improve water movement through the profile.
Biology complements cultural control; it does not replace it. Core or solid-tine aerification, venting, sand topdressing, irrigation management and reducing sulfur sources remain the primary corrections.
Figure 1. Putting-green soil cores, USGA-type sand root zone, rendered at 1:1 scale. A: thick thatch and mat over an anaerobic black layer that limits rooting. B: thin thatch, an aerobic profile and roots extending past 12 cm. Rendered illustration based on typical field cores; not a photograph of a specific site.
A 68-second animation, with narration, of how the granular base and the liquid cycle build the aerobic, biologically active profile shown in core B.
Core aerification relieves compaction, removes organic matter and opens the profile to air and water. Recovery time depends on growth rate, so most of the work is timing and supporting growth before and after the event.
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A strong El Niño is expected to bring above-average rainfall, more cloud cover and cooler periods across the Southeast this winter. Main risks: root-zone saturation and low oxygen, carbohydrate depletion under low light (notably on ultradwarf bermudagrass greens), large patch, spring dead spot, Pythium and dollar spot, nutrient leaching, and traffic injury on wet soils.
