Got it! Here’s the revised entry with sulphur instead of sulfur:

Ammonium Polysulphide

Overview

Chemical Name: Ammonium polysulphide (NH₄)₂Sₓ
Common Name: Ammonium polysulphide solution
Type: Inorganic compound
Use in Horticulture: Fertiliser, soil amendment, and pest control

Ammonium polysulphide is a liquid compound formed by dissolving excess sulphur in ammonium sulphide solutions. It has been used in agriculture and industry for soil conditioning, sulphur supplementation, and pest control.

Chemical Properties

• Formula: (NH₄)₂Sₓ
• Appearance: Yellow to reddish liquid with a strong odour of rotten eggs due to hydrogen sulphide release.
• Solubility: Highly soluble in water, decomposing into ammonia (NH₃), hydrogen sulphide (H₂S), and elemental sulphur upon exposure to air.
• pH: Strongly alkaline

Uses in Horticulture

1. Sulphur and Nitrogen Source

Ammonium polysulphide provides essential sulphur and nitrogen, crucial for plant metabolism:

• Sulphur (S) is vital for amino acid synthesis (e.g., cysteine, methionine) and chlorophyll production.
• Nitrogen (N) supports leaf and stem growth, aiding in protein synthesis.

2. Soil pH Adjustment

• Acts as an acidifying agent, beneficial for alkaline soils needing pH reduction.
• Helps with micronutrient availability, especially iron, manganese, and zinc in high-pH soils.

3. Pest and Fungus Control

• Historically used as a fungicide to control rusts and powdery mildew.
• Can act as an insect repellent due to its strong sulphuric odour.

4. Soil Detoxification

• Used to treat saline and sodic soils by helping leach out excess sodium.
• Promotes soil aeration by breaking down compacted clay.

History of Use

Ammonium polysulphide has been used in agriculture for over a century, primarily as a soil amendment and pesticide. It was historically applied in orchards and vineyards to control fungal diseases and sulphur deficiencies. In the early 20th century, it was commonly included in mixtures for pest control before synthetic alternatives became widespread.

In industrial applications, ammonium polysulphide has been used for metal treatment, removing heavy metals from wastewater, and as a flotation agent in mining. These uses have influenced its regulation due to environmental concerns.

Availability and Legal Status in the UK

In the UK, ammonium polysulphide is not commonly available for home gardening. Its use is primarily restricted to industrial and agricultural applications, and it may require professional handling due to its hazardous properties. Regulations on sulphur-based chemicals have tightened due to environmental concerns, particularly regarding air and water pollution.

It is advisable to check with regulatory bodies such as the Health and Safety Executive (HSE) or DEFRA (Department for Environment, Food & Rural Affairs) for up-to-date information on its permitted uses and restrictions in the UK.