Pond Gleying

Gleying seals a leaking pond with material already on hand instead of a bought liner or hauled clay. Manure and leafy plant matter are spread on the pond floor and covered with soil, and bacteria that work without oxygen turn the buried layer into a dense, near-waterproof skin. There are two versions. The lighter is a dressing of cattle manure, at least 2 cubic metres per 100 square metres of floor (about 65 cubic feet per 1,000 square feet), spread before refilling and repeated every eight to twelve months until the leak slows enough - a standing job, not one with an end date. The heavier, for soil too porous for that, lays moist manure about 10 cm (4 in) deep under leaves or straw and a soil cap of the same depth, cures two to three weeks, then fills the pond slowly.

What the floor is made of decides whether it works at all. The seal needs clay to bind to, and sources differ sharply on how much: one gives 15 percent clay for pig or poultry manure and 5 percent for grazing animals, another more than half. Clean sand and gravel will not seal this way and needs a liner. Where it works the gain is large: seepage can fall tenfold within a year. Sound banks matter too: water leaving through the embankment is not a floor problem and sealing the bottom cannot stop it.

The seal holds only while it stays wet and airless; let the pond dry and the layer rots, so a basin emptied every dry season is the wrong one for this. The soil cap is thin beside the 23 cm (9 in) usually asked over a flexible liner, so stock wading in, burrowing animals or a dropped anchor tear it, and the tear is underwater where nobody sees it - which means fencing animals off a pond dug for them. The manure is also a nutrient load, so a freshly sealed pond is not one to stock or swim in that season. And it is manure the garden does not get: buried as a structure, it leaves the fertility cycle for good.