November 27, 2013

Agronomist Notes

Hello Reader

Today I’m nestled in the Rockies at a Bayer Crop Science meeting until Thursday to discuss herbicide and fungicide technology as well as resistance management. I’m really looking forward to catching up with my peers and bringing home a few good nuggets of information.

This week we’ll look at the sprayer rut dilemma and what to do to reduce our impact on the soil. Next, I’ll show you an interesting phenomena happening with the direction of our stubble after four years of CTF. Last, I'll give you an update on herbicide resistance from some leading researchers in the US, Canada and Germany. We'll finish with technical grain market news.

Have a great week.

Photo: Neufeld Farms loading from the barley pile before the big snow comes this winter. SL

Solving the sprayer rut dilemma

Research says that 90% of compaction occurs in the very first pass. Nothing can be truer than the compaction and soil damage caused by high clearance sprayers. The question is; what do you do? You’re travelling around during the wettest time of year with 25,000 to 35,000 lbs sitting on 320, 380, 450 or 540 mm wide rubber. With 100 ft to 120 ft booms, you’re looking at the potential to damage 2.5% of your field each pass. Couple that with random traffic and poor GPS tracking and you have a recipe for severely damaging up to 10% of your field. There are three solutions that will help reduce the impact of sprayer track damage.

To set the stage I’m going to run a little Steve’s quick math to estimate wheel track covered with various sizes of tires and boom widths.

Area covered
320 mm tire, 100 ft boom = don’t even bother
380 mm tire, 100 ft boom = 2.5%
450 mm tire, 100 ft boom = 3.0%
380 mm tire 120 ft boom = 2.1%
540 mm tire 120 ft boom = 2.9%
620 mm tire 120 ft boom = 3.4%

First, after running RTK guidance for four years, nothing beats the sub-inch repeatable accuracy RTK offers. It seems like an expensive upgrade from WAAS, OmniStar or Starfire2 but the repeatability is paramount to narrowing wheel track damage to one set of tracks year after year.

Second, you have to begin tram lining and using the same AB lines each year to follow the same path with RTK guidance. We’ve used the same AB lines in each field for the last four years and it makes it very simple. This sounds very rigid and there will be years where wet areas force you off your tramlines, but that’s where the last piece of the puzzle comes in: wider tires.

The third and most important piece of the puzzle is to use wider profile tires or what some would call flotation tires. Narrow tires (380 mm or less) create deep ruts in wet soil, wreak havoc on your tramlines and really give your auto steer a workout as it tries to hold the line in. Wider profile tires like 540 mm to 620 mm radials reduce the chance of rutting, provide better floatation and allow you to travel through very wet areas without having to move off your tramlines.

The difference between a tire like a 380 mm to a 540 or 620 mm tire as a percentage of field covered is minimal. As we’ve measured above, a 540 mm on 120 ft boom tracks only 0.8% more than a 380 mm. Instead of purchasing two sets of rims and tires and the hassle of changing them in-season, run one expensive pair for a similar cost.

Revenue loss 120 ft boom

Random traffic 380 mm: 3 passes
2.5% area x 1 pass (fungicide) at 100% yield loss x $350/ac revenue = $8.75/ac
2.5% area x 2 passes (herbicides) at 30% yield loss x $350/ac revenue = $5.25/ac
Total: $14.00/ac

Tramline 540 mm: 3 passes
2.9% x $350/ac revenue x 100% yield loss = $10.15/ac

There is no amount of disking that will repair the damage caused by sprayer ruts. You can cover up the ruts but the damage below remains. You start multiplying that damage over multiple wheel tracks and multiple growing seasons and it begins to add up. In my example, there is almost a $4.00/ac gain by running tramlines, wider 540 mm tires and RTK. If the tires and RTK cost you $25,000 to upgrade, a 6,000 acre farm would pay for it in the first year, a 3,000 acre farm in two years.

Operating in the same tramlines with flotation tires gives you the footing, stability and traction you need while reducing the impact on soil structure and yield loss. As a percentage, you’re increasing your footprint slightly but in reality reducing your impact on yield and ultimately revenue. Time to think outside the circle and throw the skinny tires away for good. SL

Photo credits: top photo; bottom, Steve Larocque

Inter-row seeding inside CTF

Where’s the freeze thaw action?

Mitch and I just finished our fourth year of controlled traffic farming and have started to notice an interesting phenomenon with the stubble. Looking back through photos I noticed how irregular and crooked our stubble was in our first year of CTF. The photo above shows the wavy stubble pattern from our Concord drill in 2010. It appears that it wasn’t tracking very well in the beginning.

Fast-forward to 2013 and I’ve noticed how much our stubble lines have changed since in the span of four years. The stubble rows now track straight as an arrow except for the usual headland turns where the autosteer wasn’t grabbing the wheel yet. The photo below shows the stubble lines in wheat from this fall.

So what has changed? We’ve removed random wheel traffic from the system. The result is the equaling of soil resistance across each drill pass. In the beginning, random wheel traffic created different levels of resistance as the drill came across random wheel tracks. The action of shanks hitting different points of resistance would force the drill to skew side to side and leave a wavy stubble pattern like in the photo above from our first year in CTF.

I keep getting told how much our freeze/thaw cycle does for compaction. If that were the case, why didn’t the freeze/thaw cycle remove the shallow compaction layer and prevent my drill from constantly skewing side to side? The openers are no more than 1.5 inches in the ground. One would think the freeze/thaw cycle occurs many times in that zone and would easily take away the compaction caused by wheel traffic. Looking at our soils today and our stubble rows, I suggest the freeze/thaw cycle is doing very little to repair soils over winter and the proof is in the stubble rows.

At the end of the day, it may look really cool to have arrow-straight stubble rows but the reality is that it offers a new realm of precision opportunities. We can now run implements between the rows all season long. We can side dress nitrogen, inter-row seed, keep tall stubble, inter-row cultivate or inter-row spray with shrouded sprayers and I’m sure there are a dozen more things I haven’t thought of yet. What I do know is that the elimination of random wheel traffic and CTF is opening up more doors than we originally thought. SL

Photo credits: V. Larocque, S. Larocque

Facts on herbicide resistance

Plan your strategy now

Dr Neil Harker – AAFC, Lacombe, AB

In 2013 there are 404 resistant weeds globally
Canada is #3 with 59 resistant weeds
24 weeds in 5 countries with glyphosate resistant weeds
50% of fields in Alberta have Group 1 resistant wild oats
37% of cropped land in W Canada have resistant weeds
Farmers spend $500 million on wild oat control in W Canada
The number 1 resistant weed is ryegrass to 11 modes of action
Top five resistant weeds are grasses. i.e. wild oats, rye grass, green foxtail, barnyard grass
No difference in weed competition from 8-12" row spacing
Use higher seeding rates and rotation with fall and spring crops to combat weeds holistically

Steve Lindell –Bayer CropScience, Germany

No new herbicides have entered the market in 25 years
It will likely be another 10 years before another one enters the market.
Over the last two decades we’ve gone from hundreds of small companies doing herbicide research to just six major players
Everyone thought glyphosate tolerance would reduce the need for new chemicals so research on herbicides was backed off for a time.

Jason Norsworthy - University of Arkansas

49% of surveyed farms in the US have glyphosate resistant weeds
RR resistant Palmer Amaranth moved from 33 to 61 million acres inside of 3 years
Farmers have gone back to hand weeding corn and soybean fields at a tremendous cost because they have no effective herbicides left.
2.5 million acres in Arkansas are resistant to RR Palmer amaranth
Weeds are spreading quickly in the movement of feed around the US and soon Southern Ontario
Focus on resistant prone weeds in your herbicide strategy (wild oats, annual sow thistle, kochia, cleavers)
Make use of residual herbicides because it hits weeds young
The majority of the problem with resistant weeds is applying herbicides too late and not being effective. Next generation of weeds become more tolerant to the herbicide.

What caused RR resistance?
1) Solely planted glyphosate-resistant crops
2) Solely relied on a single herbicide
3) Applied reduced rates to save money
4) Reduced number of applications and applied to large weeds

This sounds a lot like the situation with RoundUp Ready canola. Tight canola rotations, one shot applications, single herbicide and low rates of glyphosate. Western Canada is not immune to herbicide resistance; make it a part of your strategy. Remember, we have 59 of the worlds 404 resistant weeds.