May 14, 2013

Agronomist Notes

Hello Reader

Seeding has progressed rapidly with the warm, dry, windy weather with producers 65% complete in the west and 45% complete in the east. The 14-day forecast calls for temperatures in the high teens, no frost risk but rainfall by the weekend. Soil temperatures are in the high teens and early May planted wheat is already out of the ground. It won’t be long and we’ll be busy with in-crop spraying.

This week we’ll look at the effects of wheel traffic on weed growth after an observation in our tramlines. Next, we’ll look into the damaging effects of castor wheels on soil flow and seed placement. We’ll also look at a seed depth issue brought on by CTF. Then we’ll talk about the best mud scrapers on the market from heavy clay farmer, Adam Gurr, from Manitoba. We’ll finish with technical grain market news.

Have a great week.

Pictured above: Oh, she's a little damp in places. Photo source: S. Larocque

CTF offers a solution to herbicide resistance

Seed to soil contact is not always a good thing!

It’s amazing to see the impact wheel traffic has on today’s random farming systems. It’s only when you remove wheel traffic that you begin to realize the damage it causes unknowingly. For example, take a look at the photo. You’ll see our tramlines that only have last years harvest traffic on them. The only thing growing in this field is volunteer wheat, a few cleavers and dandelion. The interesting part is that 98% of those weeds are growing inside the tramlines.

The way to improve germination of any seed is to give it good seed to soil contact. That is exactly what we’re doing in a random traffic system. If you were to combine, post harvest spraying, pre-burn spraying and in-crop spraying and combine it with last years harvest traffic and this years seeding traffic, you would easily cover 35 to 50% of your acres with wheel traffic. I know you do a great job but that’s a lot of weeds and volunteers caused to germinate.

We may be smug to think we have herbicides to control weeds but resistance is growing rapidly. In fact, research shows that 40% of fields in Alberta have Group 1 resistance to wild oats. Cleavers, annual sow thistle, kochia and chickweed are high on the list for Group 2 resistance as well. The reality is, herbicides aren’t a silver bullet and it’s a matter of time before we run out of chemical options. That is where CTF comes in. Why germinate the weed seeds in the first place?

If you have severe weed issues, perhaps you should look at minimizing wheel traffic or concentrating it to specific areas of the field. I would think every organic grain grower on the planet would latch on to CTF like white on (organic) rice. The day will come where we look for answers to herbicide resistance and CTF is an excellent solution. So, while you’re out spraying weeds, you’re helping more grow at the same time. Kind of like putting out a fire with gasoline? SL

Pictured above: Only the tramlines are "packed" with weeds and volunteers this time of year in our CTF fields. Photo source: S. Larocque

Air drill castor wheels effect seed placement

I was with a client last week checking seed depth and noticed the effect of castor wheels on soil flow and seed placement. The drill was a 70-foot New Holland P2070 precision drill with six sets of castor wheels across the front of the frame. Oddly enough on this heavy clay soil the castor wheels were turning the loose, moist soil into a rock before the shank ran through it.

The result was a lumpy furrow behind each of the twelve castor wheels.

The photo you see here shows two furrows. The one on the right was under a castor wheel while the furrow on the left was not. The castor wheels are causing poor soil flow around the opener and reducing the drills ability to place seed properly. The furrows under the castor wheels are now at risk of drying out faster than the rest from a poor pack or seal over the seed. Not an ideal situation for any drill.

The situation has me questioning the bias-ply tires we use on castors to support the heavy drill frames. Are they enough? Do we need to run radial tires instead to give us strength while running lower air pressure? I have yet to monitor other drills in clay soils to see if it’s a make and model problem or a problem across most drills wider than 50 feet.

I encourage you to monitor the effects of castor wheels to see if it is effecting soil flow, seedbed moisture and seed placement. The castor wheels on the 70-foot P2070 I observed cover 15% of the soil beneath the drill. That is a significant amount soil damage. As air drills get wider and wider, the wheels that carry the heavy frames may have to change. It’s not just about carrying the load. It’s about carrying the load and minimizing the effects of wheel traffic. SL

Pictured above: Lumpy furrows behind each castor wheel account for 15% of the soil under a 70-ft air drill. Photo source: S. Larocque

Fourth-year CTF creates an issue with seed placement

Yet another lesson on proper residue management

The moment we flipped the switch to begin CTF, we knew there would be hurdles along the way. I was told by CTF pioneer and friend, Robert Ruwoldt, from Victoria, Australia that over time the center section on our drill might begin to seed deeper than the wings. I thought it might happen if the castor wheels, which ride on the tramlines hit some ruts or depressed areas. The reality is, our center section is seeding deeper and it’s due to the poor residue management after three years of CTF. There is a buildup of straw and chaff between the tramlines where the soil has risen in height. Couple that with more soil moisture under the residue between the trams compared to the wings and the drill is sinking deeper. Not good!

To rectify the situation, we inflated the castor wheels on the tramlines to 25 psi compared to the wings at 20 psi. This little adjustment has lifted the centre section 15mm out of the ground and evened out the seed placement across the drill. Thank goodness! To avoid this problem in the future we will take every step possible to manage residue properly and spread it evenly across the width of the cut. For those of you transitioning to CTF I suggest you do the same. Residue management is number one on the priority list. Number One. SL

Pictured above: Our modified Concord was riding heavy in the centre section until we changed the castor wheel psi, a neccessary quick-fix measure to account for residue buildup in the centre of the tramlines. Photo: S. Larocque

Finally, a mud scraper that works!

One of the biggest issues with dual shank machines like the SeedHawk and SeedMaster in heavy clay is mud sticking to the packers. The deeper fertilizer shanks bring up moist soil, which then coats the packer tires. The buildup of mud on the packers forces the wheels to skid, openers begin to lift out of the ground and skew seeding depth. The Conservapak, another dual shank machine can set depth independently from the packer but it too can plug up badly with mud and stop turning. The solution, the Devloo roto-mud scraper.

Adam Gurr, who farms heavy clay soil in Manitoba, sent me video on how well the roto-scrapers work on his SeedHawk. The design uses an upside down bowl shaped design that spins on top of the packer wheel to remove mud. I also found a YouTube video, which shows them in slow motion. I’ve now seen them in action on a SeedHawk and a JD Conservapak and they do an amazing job of scraping mud off the packers. The roto-scrapers are a real game changer for producers using dual shank machines in clay soil. Take a look at the video to see how well they work. Kudos to Adam for the heads up on this product. SL

Roto-mud scraper website

Pictured above: Devloo roto-mud scraper on a SeedHawk. Photo source