Agronomy Library > Soil Conservation

Unseeded Spring Acres and Chem-fallow are Ideal for Winter Wheat
Author: Ron Heller, RTL and Dale Soetaert, DUC
Date Created: July 21, 2006
Last Reviewed: June 05, 2007

 Many farms in Alberta have faced unfamiliar circumstances this spring with fields too wet to seed. Special attention to these “idle” acres will be required this summer. Reduced Tillage LINKAGES (RTL) together with Ducks Unlimited Canada  (DUC) recognize both the challenge and opportunity this situation presents.

Fallow – now what?
Experience with unseeded acres may vary amongst growers, soil zone and with farm size. Generally, weeds will pose the greatest threat. Previously disturbed soil (intensive tillage) may already be subject to erosion and further prone to degradation. Ideally, avoid tillage where possible. Custom spraying arrangements are often your best bet. Once the rush for spring crops has passed, spraying can be more easily engaged and likely more cost effective and timely compared to using the field cultivator. Alternatively, most farms have a field sprayer on hand and the current pricing for chem-fallow herbicides is at an all-time low. Well-managed crop residue will not become a barrier for direct seeding. Bare summer fallow will mean more work all season, including next spring.

Residue Friendly Fallow
To fully exploit the benefits of chem.-fallow, planned or otherwise as may be the case with unseeded acres, crop residue must be managed. Ideally, straw and chaff were well chopped or spread previously at harvest. The longer windrows are left abandoned, the more difficult a field will be to manage for chem-fallow and ultimately for re-seeding. Adequate harrowing may be required but also compromises the desirable goal of minimizing stubble knock-down. The degree of residue decomposition to anticipate with chem-fallow depends on weather, soil conditions, and the crop residue type and/or quantity. Typically, canola and pea stubble break down quicker than cereals (the effect of carbon to nitrogen ratios and harvest management).

Fallow Follow-up Options
Ideally, farmers wouldn’t have to worry about unseeded acres; however, it does happen. Here is a list of actions that farmers can plan and prepare for as they attempt to salvage an unexpected turn of events (i.e. forced fallow):
• Relax - you actually have an unexpected head start on next year’s crop (smile).
• Nutrient needs for the crop following chem-fallow may be different than cropped acres. Soil sampling and professional analysis is advised.
• Know your operational costs per acre. A pass with the field sprayer might be less expensive than recreational tillage. Equipment capitalization can be tricky!
• CAUTION: herbicide resistance and/or subsequent cropping restrictions may apply for some herbicide/weed combinations. Glyphosate® is the favoured active ingredient for chem-fallow in Alberta; however, it does not control all weeds equally. Always refer to product labels.
• Consider fall-seeding a crop, such as winter wheat.

Why Winter Wheat?
When land is too wet to be seeded in spring it leaves an ideal opportunity to seed winter wheat in the fall. Having acres available for winter wheat production in a continuous cropping system is almost always a challenge, but having chem-fallow available is almost ideal for northeast Alberta. There are three main reasons why a producer would consider growing winter wheat:

• Higher yields and profits - Winter wheat has higher yield potential than spring wheat. The price tends to be a bit lower, but with potentially lower input costs gross revenue is very comparable.

• Early maturity - Winter wheat matures approximately three weeks earlier than spring wheat and provides premiums through early market availability, disease avoidance and workload efficiencies.
• Weed competition - Fall emergence combines with active spring growth for early competition against spring germinating weeds, creating an opportunity to not spray for wild oats, as an example.

Basic Rules for Winter Wheat
• Seed shallow - Winter wheat has a short coleoptile that is not able to come through much more than one inch of soil, but takes very little moisture to germinate and emerge. Research indicates it is better to seed winter wheat shallow into warm dry soil, than to seed deeper into moist, cool soil. This situation confuses novice growers who may seed deeper looking for soil moisture, or wait for fall rains.

• Seed early - If the goal is high yields, good weed competition and early maturity, then seeding early is the key. By seeding later than September 15th (the traditional cut off date), the more likely these goals will not be achieved. It is possible to seed on the late side and get a viable stand, but chances of achieving winter wheat’s full potential are reduced.

• Seed into standing stubble - In this case, chem-fallow may not be ideal stubble, but rather land that hopefully has some dead growth residue or stubble still standing from the previous crop. This standing material is essential for trapping snow and protecting the crown of the winter wheat plant from cold air temperatures throughout the winter. Without snow cover, there is no insulating layer to protect the plants over the cold winter months.It is unfortunate when wet conditions hamper spring seeding plans, but perhaps the opportunity for direct seeders to try winter wheat on those idle acres of chem.-fallow will create the success and desire to permanently incorporate winter wheat into the rotation.