Grey Farming: Cotton

Location and design

This trial is in collaboration with Grey Farming, on their rainfed cotton farm on the Darling Downs west of Brisbane. The climate is humid sub-tropical, and the soil is black cracking clay (Vertosol).

The trial was established in September 2025 and will run until at least March 2028.

The trial has two treatments in factorial combination:

• Basalt (0, 20 or 40 tonnes per hectare in 2025)
• Nutrient source (feedlot manure, biosolids biochar or conventional fertilisers)

each with 4 replicate plots. Each plot is 70 metres long and 12 metres wide.

Monitoring

• Yield of the cotton and wheat crop will be measured.
• Leaching of water and solutes will be measured during the wet season, using ‘drainage flux meters’ installed at 0.6 metre depth.
• Soil properties will be measured once per year, using soil cores.