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Seed coating explained: what belongs on the seed and why

Two wheat seeds with smooth in shades of red, purple, and yellow, set against a plain light beige background.

Seed coating: all you need to know

The cheapest place to feed a crop is the seed itself. Yet most growers still treat seed coating as a colour and a fungicide. In doing so, they hand away the strongest week of root growth they’ll ever get. Here’s what’s actually on a coated seed, and what should be.

What is seed coating?

Seed coating is the application of a thin layer of material to the seed surface to improve handling, protection, and early performance. A modern coating can carry binders and fillers for flow and plantability, plus active ingredients: fungicides, insecticides, micronutrients, biologicals, or nutrition itself. The seed becomes a delivery vehicle. Every input is placed exactly where the root will be, at gram-per-hectare rates instead of kilogram-per-hectare blankets.

Why does seed coating matter for early root growth?

Because the first days after germination decide the root system the crop lives with all season. A seedling that finds nutrition at the seed builds longer roots, more root hairs, and greater soil contact before stress arrives. Moreover, a systematic review of fertiliser-coated seed found it a promising route to better nutrient use efficiency and crop productivity, precisely because nutrients sit at the point of uptake. In soy, coating with arginine-based nutrition has been shown to support early vigour and nutrient efficiency. It also supports yield stability from the first root out.

What can a seed coating contain?

A seed coating can carry four kinds of payload: protection (fungicides, insecticides), nutrition (micronutrients, amino acids like arginine), biology (inoculants such as Bradyrhizobium for legumes), and physical aids (polymers, binders, colourants for flow and identification). The mix is shifting. Polymers still account for the largest share of coating materials. Yet active ingredients are the fastest-growing segment, and the seed coating market is set to more than double — from USD 2.67 billion in 2025 to USD 5.67 billion by 2035. The industry is moving from paint to payload.

Is seed coating worth it compared to soil-applied fertiliser?

For early-season nutrition, the coated seed is often the more efficient route because placement beats volume. Broadcast fertiliser feeds the whole field; a coating feeds the seedling. Think about the geometry: at drilling, the plant’s entire root system occupies a few cubic centimetres of soil. Meanwhile, a broadcast pass spreads nutrition across ten thousand square metres the seedling can’t yet reach. Whatever sits outside that small zone in the first weeks is either banked for later, taken by weeds, or lost. That precision means less input lost to leaching and less feeding of the weeds between rows. It doesn’t replace a full nutrition programme for high-demand crops. Instead, it front-loads the part that matters most, then the root system it builds captures the rest more efficiently. Arginine has a particular edge here: it’s positively charged, so it binds to soil particles at the seed. As a result, it does not wash away with the first heavy rain.

How is a coating applied, and does it slow drilling?

Coatings are applied industrially by film coating, encrusting, or pelleting — in rising order of material added. Film coating wraps the seed in a thin, even layer that barely changes its size or weight. Encrusting adds enough material to smooth irregular seeds. In contrast, pelleting builds small seeds up into uniform spheres for precision drills. For the grower, a quality coating makes drilling better, not worse. Seeds flow more evenly through the metering unit, dust-off drops, and plant stands come up more uniform. The practical checks are simple — ask for the germination test result on the coated lot, not the raw seed. Also, confirm the coating is rated for your drill type. A coating that costs two percent germination has to earn it back somewhere, and a good one does: trial data across crops consistently shows better emergence under stress from well-formulated coatings than from naked seed.

Seed treatment from Arevo: - Non-microbial - Long shelf-life - Stable on-seed - Rooted in science - Compatible with standard treatment

What should growers ask before buying coated seed?

Ask four blunt questions.

  • What exactly is in the coating — full ingredient list, not a trade name?
  • Is the nutrition in a form the seedling can take up directly, or does it need microbial conversion first?
  • Is the coating compatible with your inoculant if you’re planting legumes?
  • And does the polymer comply with the EU’s microplastics restriction timeline, which is tightening rules on synthetic polymer microparticles in agriculture?

A supplier who can’t answer all four hasn’t earned your seed order.

The bottom line

Seed coating has grown up: from colour-and-fungicide to a precision delivery system for nutrition and biology at the exact point of root emergence. Growers who use it well buy the strongest possible start for the smallest possible input. That’s Root Change at its most literal — change what surrounds the seed, and you change everything that grows from it. Arginex Soy and Corn was built for exactly that first metre.

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