Place the wood shavings in a wheelbarrow or dump them into a pile on the lawn. Add 1/4 lb. ammonium nitrate for every 1 bushel wood shavings. Mix the shavings and the ammonium nitrate well with a shovel
Spread the wood shavings over the area under plants until the shavings are between 2 and 5 inches deep. Smooth the top surface out as evenly as possible, but do not pack it down. Pull the wood shavings back 6 inches from the base of each plant to prevent disease from developing.
Water the wood shavings with a garden hose until they are damp. The moisture will begin dissolving the ammonium nitrate into wood.
Add 3 to 4 inches of new wood chips every two to three years to replace decomposed shavings.