Ammonium sulfamate

Ammonium sulfamate, also known as ammonium sulphamate, is a white/colourless crystalline inorganic chemical compound that is easily dissolved in water. It is a salt formed from ammonia and sulfamic acid. Perhaps its best known use is as a safe, broad spectrum herbicide that is particularly useful in controlling tough woody weeds, tree stumps and brambles. Its extremely low toxicity to humans and animals makes it ideal for both amateur home garden, professional and forestry uses. It is considered the most environmentallly friendly and one of the safest weedkillers to use on plots of land that will be used for growing fruit and vegetables intended for consumption. Once applied it is slowly converted in the soil to the useful fertilizer ammonium sulfate (ammonium sulphate). Several years ago the Henry Doubleday organisation, a group devoted to organic gardening, published an article on ammonium sulfamate after a successful set of herbicide trials. Though not approved for use by organic growers it does provide an option when alternatives have failed.

Ammonium sulfamate is used to control the following problem weeds / plants:- Japanese Knotweed(see below), Marestail, Horsetail (Equisetum), Ground Elder, Rhododendron, Brambles, Brushwood, Ivy, Ragwort, felled Tree Stumps and most other tough woody specimens. (Japanese Knotweed is subject to legal controls in the UK and ammonium sulfamate is one of the few products that will provide effective treatment.) A typical treatment would be as a foliar spray of 1 kilogram in 5 litres of water over 10 square metres ( 2lbs in 1 gallon over 100 square feet). The addition of a small amount of washing up liquid to the spray solution helps cut though the natural oils on the foliage. Children and animals need not be excluded from treated areas.

Ammonium sulfamate has been successfully used in several major projects by organisations like the British Trust for Conservation Volunteers, English Heritage, National Trust, and various railway, canal and waterways authorities. However, the UK's Royal Horticultural Society says, "The active ingredient ammonium sulphamate and all products containing it are being withdrawn. It can continue to be sold until 22 November 2007, but can be stored and used until 22 May 2008."

Henry Doubleday also gives advice about Armillaria and the use of ammonium sulfamate. Once honey fungus has been confirmed, first dig up and destroy all dead/ dying woody plants, removing the stump and as much of the root system as possible. Then, if removal of a stump is impossible, the stump can ground, or chipped, up by a contractor. The resulting woodchips should be burned or disposed of outside the garden, not used as a mulch. As a last resort, a stump can be treated with ammonium sulfamate (a stump killer sold as Root Out) which will kill it and hasten its decay.

Within industry ammonium sulfamate is used as a flame retardant, a plasticiser and in electro-plating. Within the laboratory it is used as a reagent.