The chaff lining technique is the cheapest harvest weed seed control tool, both in terms of capital cost and overall cost, including nutrient concentration. Chaff lining involves making a simple chute to divert the weed seed-bearing chaff fraction (from the sieves) into a narrow windrow, which is left to rot or mulch while the straw is chopped and spread.

There are four stages of harvest weed seed control (HWSC) and they all apply to chaff lining:

• Getting weed seeds into the front of the harvester.
• Getting weed seeds out of the rotor.
• Keeping weed seeds in the chaff fraction (for HWSC tools that focus only on the chaff).
• Delivering weed seeds into the HWSC tool (chaff line, chaff tramline, seed impact mill, chaff cart, narrow windrow or bale direct).

This booklet will cover these aspects of HWSC, with a focus on the third and fourth points.