"The trials aim to find out the commercial benefits of using compost for soil improvement and establishing woodland and biomass crops on brownfield land.
"The results will continue to highlight technical, financial and environmental reasons for specifying good compost and in developing new applications and markets."
The trials will make use of green compost produced from garden waste and food-derived compost made out of household kitchen waste.
One of the new trials, on Dalquhandy opencast site in Lanarkshire, is led by Forestry Commission Scotland and Scottish Coal.
"It will investigate the establishment of sustainable woodland, said Forestry Commission Scotland manager Michael Wall said: "Transforming a completed opencast site back into woodland and helping to reduce carbon dioxide in the atmosphere makes sense."
WRAP director for Scotland Iain Gulland said: "These trials will help landscape and regeneration leaders make cost savings in an environmentally sustainable way."