Residue Management is important to the success of no-till farming. Residue management affects erosion control, moisture conservation, seed and fertilizer placement, crop emergence and weed control. Residue management starts at harvest time when you handle straw and chaff from the combine.

Spread the straw and chaff as evenly as possible. The best way to do this is with good straw and chaff spreaders on the combine. It may be necessary to harrow after harvest in a year with particularly heavy straw. However, a well adjusted straw chopper/spreader can make harrowing unnecessary most years. It is NOT POSSIBLE to spread chaff effectively by harrowing. An efficient chaff spreader will prevent that two or three inch thick blanket behind the combine. If the chaff is not well spread, there will be problems all season long. The first problem is poor performance of the seeder through the chaff row. Plant growth will be weak with spindly plants which are more susceptible to disease. There will be extra growth of weeds and crop volunteers in the chaff row as well as more weed problems because of reduced competition from the crop. Finally, there will be later maturity in the strips which will delay harvest. Another problem is a biochemical interaction called allelopathy where the residue from certain plant species may exude growth inhibitor. Because of this, in poorly spread chaff rows, there is often noticeably less crop growth in a subsequent year.

While harrowing is not an efficient means of spreading the chaff and straw, there is another reason why some zero tillers harrow after harvest. Harrowing can promote fall growth of weeds and crop volunteers and can be a way to make the fall weed control program more effective.

"The first year, we thought we could get away without chaff spreading, so we didn't bother. In the spring, about mid-May it was 8 degrees celsius cooler at the 4-inch depth of the soil under the chaff row. It delayed emergence by three days and maturity by a week. Because of that, we couldn't straight combine most of the crop that year. "

Robert Stevenson Oak Lake, Manitoba