MSR (Micronised Soft Rock Phosphate)

MSR (Micronised Soft Rock Phosphate)

MSR is micronised soft rock phosphate, a sedimentary rock phosphate ground to a very fine powder so it can be suspended in water and applied as a soil drench, a bloom booster or a foliar spray. It supplies phosphorus and calcium that soil microbes release over time.

At a glance

• Type: amendment (phosphorus and calcium, water suspendable powder)
• Analysis: 21.00% phosphorus as P₂O₅ (9.16% elemental P)
• Use for: phosphorus and calcium in soil, media and foliar programmes
• Rate: 1 to 4 g per 10 square metres, in water with constant agitation
• Particle size: no larger than 10 microns

What it is

Soft rock phosphate is a sedimentary phosphate rock formed from the remains of ancient marine life. Beside phosphorus it carries calcium, magnesium and a range of trace minerals, which is why it is used to rebuild depleted soil rather than just feed one crop.

The process of micronisation refines MSR into particles no larger than 10 microns. They have a relatively large surface area and can be easily suspended in water. Once applied, microbes in the soil can solubilise the phosphate and reach the trace elements that come with it.

What it does

Phosphorus drives energy transfer inside the plant (ATP), early root growth, flowering and seed set. The calcium that comes with it in soft rock phosphate is useful in its own right for cell walls and fruit quality.

Soil phosphorus sits in three pools: dissolved orthophosphate in the soil water, phosphate bound to calcium, iron and aluminium minerals, and organic phosphorus held in soil life and plant residues. Roots take up phosphorus almost entirely as dissolved orthophosphate (H₂PO₄^- and HPO₄^2-), so the bound and organic pools only become available as weathering, root acids and soil microbes release them. Micronising the rock speeds that release because the fine particles give microbes and root acids far more surface to work on.

Used as a soil amendment it supports germination, root growth and flowering through steady phosphorus and calcium supply, with the trace minerals as a bonus.

Analysis

• Phosphorus (P₂O₅) 21.00%
• Phosphorus (P, elemental) 9.16%

How to use

• Foliar application: 1 to 4 g per 10 square metres. Mix with enough water to cover the foliage, and keep the mix agitated so the product stays in suspension.
• As a bloom booster: 0.25 to 0.5 g per 4 L of growing media, or 150 g per cubic metre of soil. Mix with water, apply to the soil surface and keep the mix agitated.
• Soil grown crops: 1 to 4 g per 10 square metres. Mix with water, apply to the soil surface and keep the mix agitated.
• The powder settles fast. Keep it agitated in the tank or sprayer or the last pot gets the whole dose.
• Foliar sprays go on with the lights off or in the cool of the day, both sides of the leaf, with a surfactant.

Learn more in fifteen seconds

• Phosphorus: what it does
• Too much P turns mycorrhizae down
• Foliars: fast fixes, then the soil

Handling and storage

• Wear a mask to avoid inhaling particles and open the bag in a well ventilated area.
• Wear gloves and eye protection, and wash hands after use.
• Once opened, keep sealed and dry.