All Things Organic - Direct seeding has a place in organic rotations

By Ian Cushon
March 27,2003

Organic farming in Western Canada is often criticized for using excessive tillage because of the potential for increased soil erosion. While organic farmers use tillage more than non-organic farmers to control weeds and to incorporate green manure, there is also evidence that organic farmers do not use as much tillage as expected.

In a University of Manitoba study, cropping data showed that about 40 percent of land on organic farms was dedicated to soil-building crops and only six percent of cropland was in summerfallow. In a 1991 Saskatchewan study, organic farms had about the same provincial average of summerfallow as did conventional farms - about 22 percent. About one-third of this summerfallow was in soil-building green manure legume crops. Most organic farmers are trying to reduce summerfallow tillage. Green manure summerfallow reduces tillage passes by 30 to 50 percent. Organic farmers use perennial forage crops and extended rotations to reduce tillage. They also use direct seeding methods.

In 2000 we rented a John Deere air drill with paired row openers on 12-inch spacings. We seeded Grande peas at three bushels per acre into standing wheat stubble and the peas yielded 35 bu. per acre in a relatively clean field. The paired-row wing-type opener disturbed more soil than we wanted, but the results were promising. That year we also sowed peas with conventional methods on an adjacent field with a different cropping history. It was not a fair comparison, but yield was approximately 25 bu. per acre. I have found that other organic farmers are also using direct seeding. It especially fits well with organic pulse crops.

Pleased with results Clem Perrault of Zenon Park, Sask., has used direct seeding with impressive results for the last four years. Some of his direct seeded peas have yielded up to 50 bu. per acre.He prefers a Dutch opener on his Concord air drill that has a higher level of disturbance to help warm the soil in his more northerly location. Perhaps lower disturbance openers would be better choices in warmer and drier areas. Perrault also collects chaff for livestock feed. The primary advantages of direct seeding for organic farmers are potentially reduced weed populations, better moisture conservation and improved soil quality. Many weeds are stimulated by tillage and exposure to light. Direct seeding can reduce their emergence. Many conventional zero-tillage farmers who can use herbicides report that direct seeding peas often results in fields that do not need in-crop herbicides.

Wild mustard is the most troublesome weed on our farm. With our conventional air seeder and coil packers, we are seeing increasing levels of wild mustard. Too much higher-disturbance tillage and packing is creating an environment ideal for encouraging wild mustard. Direct seeding, on the other hand, disturbs much less soil, packs only on the row, leaves a residue mulch and leaves weed seeds on the surface. All these factors are to our advantage in managing weeds under organic conditions. Direct seeding requires relatively weed-free stubble fields with good residue management. Winter annuals and perennials weeds can cause concern. Spot treatment of Canada thistle and quackgrass with tillage after harvest and before seeding should help.The development of biological herbicides could increase the use of direct seeding on organic farms.

Preliminary research at the University of Saskatchewan shows that vinegar has potential as a herbicide. Household vinegar is about five percent acetic acid. Experiments with varying levels of acetic acid up to 20 percent are under way. Vinegar is a natural product of fermentation and would qualify as organic if made from organic materials. Perhaps vinegar can be used as a spring burnoff before direct seeding. Because of high costs, vinegar could also be used only as spot treatment. Sprayers that only spray the weeds in a stubble field would also reduce costs.

It's unlikely direct seeding will prompt organic farmers to give up tillage and conventional seeding. Tillage is an essential and cost- effective tool on organic farms. Direct seeding has a place in many organic rotations. Accessing the equipment to direct seed is one of the challenges. Mostdirect seeders are busy on non-organic farms. Few organic farmers have wanted to invest in both conventional and zero-tillage seeders. However, lower-cost direct seeding options are available if you are willing to modify or use older and smaller equipment.

Ian Cushon
Moose Creek Organic Farm Inc.
P.O. Box 85
Oxbow, Saskatchewan
Canada, S0C 2B0

Tel. 306-483-5034
FAX 306-483-2799
Cell 306-483-8257
E-mail: coldridge@sasktel.net