Answer: When fresh sawdust is used as mulch around garden plants, it may initially use up the available nitrogen in the top layer of the soil. That's because microorganisms use the nitrogen in the soil to break down the sawdust, but generally, as long as it's not incorporated into the soil, it's not a problem. A sure sign of nitrogen deficiency on your plants is older leaves turning light green to bright yellow and eventually dying. When mulching with sawdust, apply only a 1- to 2-inch layer. One small caution, powdery sawdust tends to mat and prevent water and air penetration into the soil. For these reasons, it is better used in paths between beds than around the plants themselves.
Q&A Library Searching Tips