Tips For The Perfect Seedbed – for Jul. 23, 2010

No till, put simply, is a clear and persistent focus on seeding — with a singl pass — into undisturbed soil. No till and direct seeding have dramatically changed the way we farm our Prairie landscape. No more bare-fallow or seedbed cultivation! Farmers now reap immediate benefits in saved time, labour and fuel costs while the soil stays moist and cycles nutrients for future productive seedbeds; promoting renewal rather than depletion of precious soil organic matter.

My top three agronomic goals for direct seeding cereal, oilseed or pulse crops are to seed early (No. 1) into a moist (No. 2) and firm (No. 3) seedbed. The first two (early and moist) may be qualified depending on climate and crop, but there should be no quibble about the third — which you get from seeding into an untouched seedbed.

Beyond those three goals, individual growers are constantly tinkering to improve their systems. Direct seeding is not a recipe you can follow year after year without change and always expect top results. What worked well last year will always need twigging, especially since we can’t predict the weather. In the delayed spring my area experienced in 2009, there was much talk of re-seeding — mainly canola due to frequent late frosts. This gave us an opportunity to poke and dig around in fields. We confirmed many direct-seeding strengths and flagged a few weak links, giving rise to the following conclusions and tips:

Best seed germination occurred quite shallow — about an inch or less — in standing stubble, even under wheel tracking. See Photo 1. Best crop emergence was in thin surface mulch. To avoid compromising a vigorous start, always minimize chaff rows and reduce residue loading of the seed row. (For more on that, read Part 2, which follows this article.)

Ever looked at soil beneath a seed furrow after displacement by the opener? What should it be like? Look for a firm, moist texture that can be scooped out by fingertip. See Photo 2. If the lower seedbed is hard and dry or glazed — scraping or digging with a knife is required to move the soil — it is likely limiting emergence. I found a lot of these symptoms in high-disturbance fields, and at various shovel depths.

Similarly, densely packed surface dirt above the seed is another telltale sign that something’s not right. Weighttransfer from heavy drill packer wheels was obviously troublesome for cold, wet soils last spring, especially under low organic matter levels or on fine-textured soil. Seedbeds with sufficient levels of surface residue remained crumbly and pliable compared to lumpy conditions often encountered in tilled fields.

The terms firm and moist can be misinterpreted, therefore these points are a guide for checking no-till seed placement more or less where “moist and firm below” joins “dry and loose above.”

COMMON QUESTIONS

Here are no-till agronomy questions I get all the time. After the question is my answer.

1. How much seed-placed fertilizer do I need for crop emergence? None, no matter how “balanced.” For a crop to effectively access and use the nutrient package, seeds must first germinate in order to commence their inherent biological potential to get out of bed (emergence). On the Prairies in May, it can take three weeks for adequate roots and shoots to form, and even more if air temperatures stay below 10 C. It may never happen if soil moisture or rainfall is scarce. In fact, so-called starter fertilizer is often detrimental if seminal roots and shoots are otherwise impaired by the improper seedbed conditions described previously. For example, growers need to study the implications of single versus. double-shoot for the right no-till product, rate, placement and timing in each crop.

2. How much soil disturbance is necessary for planting? Very little, with the right equipment. Conversely, extra is required to counter the biological destruction as a result of seedbed alterations by tillage. In practical terms, no till with seedbed utilization (SBU) below 10 per cent has been performing for decades as well or better than tillage- based cropping systems.

3. With row spacing, how wide is too wide? Depends. The era of airseeders (modified tillage) at least doubled common row spacing, while most no-till leaders followed with multi-function narrow openers for seed and fertilizer (double-shoot). That’s amazing, since very little adjustment for seeding rates was made along the way. Plant science and good agronomy suggest there is a fickle balance between root staging, growth response, seeding rate, nutrient uptake, maturity, yield, and climate. This spatial relationship or plant population factor is more about nutrient access and growing season than simply seed-row distribution.

4. What opener is best for no till? One that presents the best opportunity to profit from no till. The machinery for a progressive cropping system respects the soil and provides the least amount of time in a field, with a degree of flexibility for efficient use of applied nutrients and critical weed control strategies. Opener choice is just one part of your system. I might caution that appropriate opener selection may be “joined at the hip” with the harvest system. (Read Part 2, which follows.)

5. What about crop rotation? After exactly 20 years of direct seeding crops on my own half section, I have some opinions yet not quite enough experience to get all the answers I am looking for. Simply said, most crops are wisely planted into stubble from a different crop for basic agronomic reasons such as weeds, disease and insects. There are external reasons, too, including cash flow and profit.

Even when you do everything right and improve a little every year, weather is a key factor.

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