Angle-Disc Openers Best on Dry Brown Soil

REGINA- Apr 14/04 - SNS -- Researchers in Saskatchewan say there is no question angle-disc openers do the best job of lowering weed populations, resulting in better yield trends, says Eric Oliver, president of Wheatland Conservation Inc., the producer organization that carried out the project Opener/Rotation Study: The Effect of Opener Disturbance and Crop Rotation on Weed Populations in the Dry Brown Soil.

The project was undertaken because research has shown that the many benefits of a diverse rotation and low-disturbance direct seeding include the reduction of certain annual weed populations, such as wild oats and wild millet. But in the dry brown soils, particularly the light-textured soils south of Swift Current, this weed reduction had not been readily observed, says Oliver, who is also the regional soil conservationist with the Saskatchewan Soil Conservation Association.

"And weed control is critical for alternative crops such as oilseeds and pulses, especially in the early developmental stages. Since the margin for profit is much narrower for farmers in the dry brown soil zone due to lower potential yields, any reduction of the weed populations as a result of a low-disturbance disc will reduce input costs and make the option of including non-cereal crops more viable," says Oliver.

The objective of the study, therefore, was to evaluate the effect of soil and seedbed disturbance on weed populations and crop establishment in the Dry Brown Soil Zone. It also evaluated the agronomic performance of a diverse, extended rotation with different levels of soil disturbance. The project was carried out 100 km southeast of Swift Current on sandy loam soil. Four single shoot openers - ranging from low soil disturbance to high: angle disc, knife, spoon and sweep - were used on four crops: Kyle durum, Delta field pea, Harrington barley and Myles desi chickpea.

"The advantages of the angle disc opener - lower weed densities, and higher yields - occurred immediately, which surprised us. We expected differences in dry years, but not in wet, and they were evident even in the wet years," says Oliver. "Although the knife opener eventually produced lower weed densities and higher yields than the spoon or sweep, these improvements didn't occur until the third year of the study. The advantages of the spoon and sweep tend to be relatively short-lived and consistently produced significantly higher weed densities and lower yields on all crops, especially in the last two years of the study."

A longer study would have more accurately shown long-term potential of the knife in comparison to the much lower soil disturbance of the angle disc, he adds. A longer study would also more accurately reflect the effects of high-disturbance openers such as the sweep.

Overall, Oliver says, the angle disc or any similar very low-disturbance disc opener has a tremendous potential for the Dry Brown, Brown and the drier parts of the Dark Brown Soil Zones. At the same time, however, he acknowledges that the angle disc is not perfect; personal experience has shown that the use of the angle disc can be troublesome on stony dry soil, especially when a consistent seed depth is needed for peas and chickpea.

Nevertheless, Oliver urges farmers to consider the findings of this study of openers when planning for seeding this spring.

"High disturbance openers are often the first choice of producers who switch from conventional farming practices and move into a single pass seeding system. The choice of the sweep is often based on familiarity, ease of retrofitting, and the premise they will obtain good weed control without any negative yield consequences. As this study indicates, however, any advantage of the high disturbance opener is generally short-lived and, after two years, much higher weed densities and lower yields are the result. Furthermore, crop establishment under dry conditions is significantly reduced due to drying down of the seedbed," says Oliver.

The project Opener/Rotation Study: The Effect of Opener Disturbance and Crop Rotation on Weed Populations in the Dry Brown Soil, ##035;19980148, was supported by the Canada-Saskatchewan Agri-Food Innovation Fund. A copy of the final results may be obtained by phoning 306-787-5929 in Regina. It is also available on the Saskatchewan Agriculture, Food and Rural Revitalization Web site.

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