Soil and ballast

Soil is earth or clay mixed into the groundbait. It adds no nutrition to the mix, and that's the whole point: soil is put in precisely to make the mix poorer. Sand sometimes plays that same ballast role.

Two effects at once

It makes the mix heavier: the ball falls faster, lands more accurately, and gets swept away by current less. And it makes it poorer: the same volume ends up with less that's edible. The two effects together are the direct answer to the conflict of groundbait's three jobs.

Why this matters most in summer

In warm water fish are active, move in fast and eat a lot. A mix with no ballast just gets eaten — and the fish leaves. Soil makes it possible to put the same volume of feed in the spot without increasing what the fish can fill up on.

Different soils do different things

Manufacturers tell soils apart by density and colour. Sensas writes directly about its own Terre de Rivière: it's darker and denser than Terre de Somme, holds groundbait in place on the bottom better and doesn't produce a cloud — and so it doesn't spread the fish out where the water is moving. In other words, soil is chosen for whether or not a cloud is wanted.

Soil and the colour of the bottom

Dark soil makes the patch less noticeable on a dark bottom. This matters where fish are wary and where a light-coloured base scares them off on its own.

Where it comes from

From the water itself, or from molehills and clean loam — and either way it's sieved: lumps, roots and stones act as foreign bodies in the mix. Soil from a vegetable patch or flowerbed won't do: it's been treated with fertiliser and plant-protection products, and there's no telling what exactly would go into the water along with it. Sand has none of that problem, but it doesn't darken the patch either, and it doesn't hold moisture the way clay does.

Where less of it is added

Where a spread through the water column is exactly what's wanted — for example, when fish are being gathered above the bottom: ballast pulls the mix down, and it needs to stay up in the water instead. And in the winter mix: falling through an ice hole is already vertical, so the weight of the soil decides nothing there — but it keeps making the mix poorer, and that's why it's still added in winter.