HOW THE MRB SYSTEM OPERATES
Seeding Efficiency & Optimal One-Pass Fertilizer Placement
The MRB® system places nitrogen and sulfur blends at the optimal distance from the seed, creating ideal conditions for root development while preventing seed burn.
The MRB® III System is Bourgault's most advanced and reliable mid-row fertilizer placement system.
HOW THE MRB SYSTEM OPERATES
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Mid-row fertilizer distribution: Fertilizer applied between rows is delivered through an independent distribution line to the MRB coulters, which are mounted along the front rank of the seeding system.
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Coulter & opener layout: MRB disc coulters (indicated by red arrows) are positioned centrally between adjacent seed openers (indicated by green arrows).
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Dual-row feeding: Each MRB coulter applies the designated fertilizer rate for two seed rows, allowing a safe threshold of starter fertilizer to be placed directly in-furrow with the seed.
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Seed safety with high rates: If high fertility rates are required, the balance can be safely banded between the rows through the MRB® coulters, completely eliminating seedling toxicity and fertilizer burn.
This approach ensures the most effective nitrification of the soil and, as a result, an increase in the overall nutritional potential and moisture supply of the entire plant.
NITRIFICATION DYNAMICS & ROOT DEVELOPMENT
All urea-based fertilizers (such as 46-0-0 dry granular and 28-0-0 liquid UAN) are converted into plant-available forms by the urease enzyme, which hydrolyzes urea into ammonium and free ammonia. Soil bacteria then drive the nitrification process, ultimately producing nitrates to fuel vigorous vegetative growth and root development. By banding target fertility rates mid-row with the MRB (Mid-Row Banders) system, high fertilizer concentrations are kept safely away from the seed row, preventing seed burn, root pruning, and stand reduction.
Stage 1 – Ammonia
Immediately after application, ammonia (NH3, shown in red in the figure) begins to be released. Ammonia is highly toxic to germinating seeds and is particularly mobile in dry soil. Only by applying it between rows can the negative effects of ammonia, such as root burn and dieback, be avoided. Fertilizers applied with the MRB® system are typically placed 3-4 cm deeper than the seeding layer. This ensures they are always in a zone with greater moisture availability, which is the key to high efficiency, as they dissolve in soil moisture and are effectively transferred to the plant.
Stage 2 – Ammonium
The ionic transfer of hydrogen from water and clay particles in the soil gradually converts ammonia into ammonium (NH4+, shown in orange in the figure). Ammonium dissolves in soil moisture and is absorbed by the root system. Unlike ammonia, ammonium is not very mobile in the soil, as it readily binds with soil water and organic matter. With the MRB® system, conversion into a plant-available and safe form of nitrogen occurs very quickly—within two days of fertilization.
Stage 3 – Nitrate
Certain bacterial strains in the soil convert ammonium (NH4+) into nitrate (NO3-, shown in green in the figure). Nitrate is highly mobile in the soil and is also susceptible to denitrification (resulting in the release of gaseous nitrous oxide N2O, which is freely released into the atmosphere), leading to soil leaching. Therefore, it is crucial for every farmer to choose a fertilization system that minimizes the time nitrate remains in the soil before developing plants can absorb it.
Nitrate in the soil acts as a "bait" for the root system: plants, upon detecting fertilizer, begin to rapidly form new root hairs, directing them toward the fertilizer source. Numerous studies have shown that when fertilizer is applied between rows, the root system extends to 10-15 cm by the time the plants reach the one- to two-leaf stage.
THE PRECISION-ENGINEERED MRB OPENER DESIGN ENABLES PRODUCERS TO:
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Optimize Nutrient Placement: Band nitrogen and sulfur blends at the ideal distance from the seed row, eliminating toxicity risks while promoting aggressive early root development.
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Conserve Vital Moisture: Preserve seedbed moisture through minimal soil disturbance, maintaining a clean, consolidated furrow profile.
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Drive Uniform Emergence: Accelerate root extension toward deep moisture to ensure vigorous, uniform crop emergence—the critical first step toward maximizing yield potential, particularly in arid conditions.
MRB III system design
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Parallelogram Linkage: The parallel link mounting arms of the MRB® III coulters ensure a constant disc angle of attack and maintain the precise orientation of the fertilizer boot (for dry, liquid, or NH₃ delivery), regardless of working depth.
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Hydraulic Lift & Control: The MRB® III coulters are raised and lowered hydraulically on-the-fly. This system also allows operators to lock the coulters in the raised transport position when mid-row banding is not required.
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Streamlined Depth Adjustment: Depth control is managed via cylinder stroke collars installed on the hydraulic cylinder rods (each ¼" (6 mm) collar provides a ½" (13 mm) working depth increment). Extra depth stop collars are conveniently stored directly on the upper cylinder mounting pin.
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Wear-Resistant Boron Coulter Disc: The heavy-duty 20" (51 cm) Niaux 200 boron steel disc delivers superior toughness and fatigue resistance. Set at an optimal 4.5° compound angle, it cuts a precise furrow for safe fertilizer placement with minimal soil disturbance.
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Double-Row Bearing Hub Assembly: A rugged hub and spindle assembly maximizes operational life. A premium triple-lip seal prevents contamination and allows generous greasing without blowing the seals. The bolt-on hub design enables rapid field servicing or replacement.
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High-Strength Ductile Castings: Precision-engineered cast steel arms and mounts allow the MRB® III system to endure rocky, abrasive field conditions without bending, flexing, or fatigue failure.
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Adjustable Carbide Scraper: Keeps the disc clean and ensures a defined, open furrow in sticky or heavy soils. The wear-resistant tungsten carbide edge provides maximum longevity in abrasive soils.
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Heavy-Duty Needle Bearing Pivot Pins: Main pivot locations utilize 1" (25.4 mm) diameter pins riding in sealed needle bearings, engineered with an extended 250-hour service interval.
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Precision Scraper Adjustment: Scraper placement relative to the disc bevel adjusts in fine ⅛" (3 mm) increments to maintain optimal scouring performance as the disc wears. Scraper tension against the disc can also be tuned quickly for specific soil and residue conditions.
The outer scraper A is designed to direct loose soil back into the furrow for optimal trench closure behind the disc. It also improves residue clearance and prevents wet soil buildup on the disc face. For reduced soil disturbance, an optional retaining / closing wheel B can be installed, featuring spring-loaded downforce adjustment and spacer washers to fine-tune its position relative to the disc.
