FORAGES IN A ZERO-TILL CROP SYSTEM
By Robert Stevenson, Kenton, MB
I first started zero-till about 10 years ago and since then have included alfalfa in our rotations. My brother and I have seeded about 500 acres of alfalfa over the last 8 years and brought most of it back into crop production without using tillage.
I see no problems establishing alfalfa with zero-till, and some definite advantages. We usually start alfalfa with a flax crop, but we also seeded 100 acres by itself one year. Shallow, early seeding is the big advantage we get with zero-till. Weed control options in the flax crop are limited. As a rule we use Poast and MCPA. We have spot sprayed thistles with Tropotox which worked very well, however it is not registered on either crop.
The flax crop was cut as high as possible to catch snow. Straw and chaff are well spread.
The bigger challenge is moving back into crop production without tillage. I would like to describe our experience on two different fields.
The first field was in alfalfa for 4 years from 1986 to 1989. 1989 was quite a dry year. We took one cut in early July. By mid August there were only 6 or 8 inches of regrowth. 35 acres of the field were sprayed with a tank mix of 1 liter/acre Roundup plus ½ liter/acre 2,4-D. The rest of the field, about 40 acres, was cultivated and disced in a conventional manner as a comparison.
The winter and spring of 1990 were fairly dry but the sprayed part of the field had enough moisture to get a crop of oats growing. The oats were sprayed with Banvel + 2,4-D after the alfalfa regrew to 4-6" tall with good results. It was a cool summer with adequate rainfall. The oats yielded 115 bushels per acre. In 1991 the oat stubble was seeded to canola. It was an excellent stand which yielded very well. After the canola, there was very little alfalfa left.
In the meantime, the tilled side of the field was too dry to seed early. A growth of quackgrass further dried out the field. After a ¾ liter/acre of Roundup was applied, wheat was seeded. The wheat yielded a disappointing 25 bu./acre.
The second field I want to mention was a ¼ section in alfalfa for 2 years, 1990 and ’91. In early September of ’91 I sprayed a lush growth of alfalfa with 5 treatments:
The winter of ’91 – ’92 saw early, heavy snowfall and temperatures above normal. The alfalfa survived very well. I seeded Biggar Prairie Spring Wheat. This was my first mistake. A more competitive cereal crop would have been better. By fall, trial #1 (.75 liter/acre Roundup) and #3 (Roundup + Banvel) had the most alfalfa regrowth.
After harvest the field was sprayed with .5 liter/acre of 2,4-D. Results looked promising, but last spring it recovered to the point where we ought to have left it for hay. We sprayed the field with Roundup and seeded half to Express peas, and the other half to Canola. By last fall the alfalfa had disappeared under the thick canola stand, but the pea side was a different story. They were very un-competitive, and had a lot of disease. I believe the excessive disease was linked to the strong competition afforded by the alfalfa, which in turn was still well established in the fall.
In conclusion, after 6 years of effort, we find it difficult to predict the effect of herbicides on established alfalfa. My suggestion would be: