June 12, 2012

Agronomists Notes

Hello Reader,

Crops are progressing quickly after 1 to 2 inches of rain across my territory last week. Daytime temperatures in the high teens have been ideal for tillering wheat and barley. Wheat and canola spraying are in full force and I’ve complete my first checks on about 28,000 acres.

While out and about I’ve noticed that wheat and barley emergence is low on average with mortality running roughly 20% or higher. I have barley seeding rates at 135 lbs/ac that made just 25 plants/ft2. I can’t imagine what plant stands look like for those seeding at 2 bu/ac.

We’ll begin this issue of Beyond Agronomy News by taking a close look at the air delivery system of a few common air drills. Next, we’ll continue on and look at the results of our precision drill tour focusing on the Case 800, Seedmaster and Conserva Pak drills. I’ll outline how to identify herbicide symptoms so you can make sure your herbicides are working properly. Also, I’ll briefly discuss how to determine whether a half rate of fungicide is warranted at herbicide timing and finish with estimating top dress nitrogen by using green area index. As always, we’ll end with technical grain market news.

Have a great week.

Picture: Clients touring SeedHawk drill during our precision air drill tour.

Crop Staging

(Calgary to Drumheller to Three Hills)

Seeded    Apr 24-30          May 1-7           May 8-15
Wheat      5-leaf 2 tiller     4-leaf 2 tiller      3-leaf 1 tiller
Canola     6-leaf                4-leaf                3-leaf
Barley      5-leaf 2 tiller      4-leaf 2 tiller     2-leaf
Peas        10th node         8th node           6th node

Steve's tips and tricks of the week

Follow me on Twitter for in-season updates @BeyondAgronomy

Monitor disease pressure in cereals. Is disease creeping in already?
Avoid spraying when temperatures will drop below 5oC at night and begin applying when daytime temps climb above 10oC for optimal weed control and crop safety.
Canopy closure will occur shortly under these conditions with moderate disease pressure likely. Book your fungicide today.
You could throw in a half rate of fungicide at herbicide timing but remember that only buys you 7 days worth of protection.
Measure wind speed at each manifold on your drill with at least two seed tubes. This will help you discover possible seed delivery issues.

Improving air delivery systems

I mentioned last week that today’s air carts are built for efficiency and not accuracy. I’ve always struggled with answering why certain rows have higher plant densities and why seed distribution in the furrow is always so random across each drill. Well, a few days ago I took the time to measure the wind speed coming out of two seed tubes on each manifold across three drills. The results are enlightening and point out some serious design flaws in today’s air distribution systems.

I removed two seed tubes from each manifold and placed a wind meter at the bottom of each tube for 10 seconds, which then calculated an average wind speed. All drills happened to have 10-inch row spacing and varied in width from 50, 60 and 70 ft. I did not intentionally choose long hoses versus short hoses but in some cases that did happen.

John Deere 1910, 50-foot 1830 drill on 10-inch row spacing, tow behind tank

The difference in wind speed from highest to lowest is 9.3 km/hr.
You’ll notice the seed tube on Manifold 1 and Manifold 6 show 23.2 and 21.6 km/hr. Both these hoses are longer than the rest and are located on each wing.
Manifolds 2, 3 and 4 are faster than 1, 5 and 6.
The owner said the seed tube with the longest hose typically plugs first.

New Holland P1060, 70-foot 2060 drill on 10-inch row spacing, tow between tank

The difference in wind speed from highest to lowest was 14.7 km/hr and both are located on the same manifold on the outside wing. Checked lines and nothing was plugged.
Manifold 5 had the highest wind speed compared to the other 7 manifolds.

New Holland P1060, 60 ft 2060 drill on 10” row spacing, tow behind tank.

The difference in wind speed from highest to lowest is 11.5 km/hr.
Manifold 4 has the fastest wind speed and is located in the middle of the drill. If we measured primary hoses, I bet they would be the shortest.
The manifolds on the outside wings (1 and 7) have the lowest wind speed coming out of the seed tubes.

I’ve only measured three drills so far but the results are staggering in my mind, considering that I’ve never thought it to be a problem. How can you expect to have consistent seed delivery when you have varying wind speeds down each seed tube? I suspect every drill on the market experiences this type of variance. Initially the results tell me that hose length makes a difference and unfortunately, many drills don’t have the space to move manifolds, which would help equalize hose length.

The second issue wind speed. Each drill owner said there is barely any wind coming out of the opener when they have it baffled down for canola. Well, I had each owner set their wind to where they would seed canola and then measured. The average wind speed for canola was 26 km/hr! Spitting canola into the furrow at this speed while travelling 8 km/hr— is it any wonder that we find seed at 2 inches deep when we’re aiming for half an inch?

The idea of wind brakes and baffles makes sense like the SeedVu air brake I mentioned last week. However, there needs to be a second step past the manifold to equalize the wind speed at each seed tube. As we know, if wind speed is slowed down at the head of the manifold, the seed tubes that are already slower will start to plug off. The air brake system must have two stages that includes an air brake at the manifold to slow wind speed and an air brake at each seed tube to equalize the wind speed at each tube.

This all sounds like a great deal of trouble but you can almost guarantee that you will find more canola at seeding time if you can slow canola seed drop down to something reasonable like 10 to 12 km/hr instead of 26 to 30 km/hr. Also, you’ll see more even seed distribution in each furrow if you can manage wind speed at the manifold so all openers are delivering seed at the same speed. A side benefit of braking air at the manifolds is a reduction in plugging. You can keep your fan speed up in the primaries so you don’t plug up by managing the wind speed at the manifold.

Be sure to pull off some hoses, long and short across your drill and let me know what you find. There are some big issues with air delivery systems and some fine tuning of air speed might be just what your drill needs. SL

Table: Table displaying varying wind speeds at the opener on three drills.

Precision drill tour 2012

Assessing performance outside the tradeshow floor

When it comes to assessing precision air drills, there’s no better place to look than in the field just after emergence. You have to wonder how so many drills are sold on the tradeshow floor by someone who’s never operated the drill they’re selling. Last week, I hosted a precision drill tour for my clients and looked at five precision air drills to see which ones performed the best and to find out first hand the pros and cons of each machine.

DISCLAIMER: All precision seed drills do a good job of placing seed in the ground accurately within reason. Compaction, steep rolling terrain and heavy residue will reduce the performance of these machines. Also, packing pressure and seed depth must be adjusted properly to really make these drills perform. Almost every precision drill we viewed in the field had a consistent seeding depth, unfortunately the canola was accurately placed at 1.25 to 2 inches deep, which is less than ideal. I also viewed some canola fields with too much packing pressure that left ½” cement layers above the canola seed. Packing pressure can be changed as field conditions change and so can seeding depth. All in all, with the right adjustments, these drills do provide better seed placement which translates to better emergence. The question is how does it pencil out in the end?

SeedMaster: 60 ft 300 bu on frame + 800 bushel TBH tank

This machine has the largest depth from front to back at 17 ft. This doesn’t make for the best depth control on hilly ground. Other drills are between 7 ft and 14 ft from front to back.
Height from ground to paralinkage was hard to measure because shanks were in up position but I estimate it at 14 inches. The aluminium residue deflectors are built to offset the short height from ground to hinge point which normally catches residue and balls it up.
Seeding depth is set by packer wheel and so is SeedHawk. Conserva Pak sets seeding depth independently of packer wheel.
300 bu on frame tank with tow behind 800 bu tank offers excellent seeding efficiency.
Load sensors on tanks are an excellent idea to help calibrate machine and calculate leftover fertilizer and seed.
The frame mounted tank is a pain to unload because the auger can’t reach underneath.
Aluminium deflectors on shanks help direct residue to the side.
SeedMaster has a bolt together frame as does SeedHawk. Conserva Pak has welded frames. Bolts and pins can stretch and wear.
Sectional control works well and is a real money saver in odd ball fields.
Packer to seed opener is 4 inches which reduces residue flowing back into the furrow before the packer wheel follows.

Case 800: 70 ft and 430 bu TBT tank and 3500 gal TBH NH3 tank

Depth of frame is 7 ft 6 inches which is the shortest frame on the precision market. This gives it decent ground following capabilities, especially in the hills.
The packer wheel is 11 inches from seed tube which allows a little more residue to flow back into the furrow unlike the dual shank machines which are typically just 4 inches.
Height from the ground to paralinkage is 20 inches which leaves plenty of room for residue to travel up the shank and fall off without balling up.
This drill has the tow between 430 bu tank with twin 1750 NH3 tanks which gives them roughly 100 acres per fill even with 100 to 110 lbs N/ac.
CNH now has the tow behind 580 bu tank to boost seeding efficiency but the Bourgault’s, SeedMaster and SeedHawk’s have much larger capacity tanks.
The single shank design makes residue flow very acceptable compared to dual shank machines like SeedMaster, Seedhawk and Conserva Pak.
The Case opener was good when it first came out because it didn’t have hard surfacing on it. It started to wear on some soils so they decided to put hard surfacing on it last year. The hard surfacing collects soil which builds up and pushes soil instead of letting it flow around the opener.
The Dutch 2-inch sideband opener worked very well on heavy clay soil. The Dutch 2.5-inch precision paired row opener did not fair well on this drill with several plugging issues at the opener.
Mud scrapers on this machine are insufficient in wet clay soils.

John Deere 1870 Conserva Pak— 56 ft 430 bu tow behind tank

Handles residue better than the SeedHawk and much the same as a SeedMaster.
Depth of frame is 10.5 ft front to back which is similar to the Bourgault.
Packer to seed opener is 4 inches. Short distance allows less residue to flow back into furrow before packer wheel follows.
Height from paralinkage to ground is 20 inches which allows residue to flow up and off shank.
Fertilizer shank depth can be set independently of seed shank. Other dual shank machines can only adjust fertilizer shank a couple of inches. Important when clay soils get wet and you want less iron in the soil.
Small 430 bu tank size limits seeding efficiency when everyone else is 550 bu and bigger.
Seed knife and fertilizer knife are very close together, almost one behind the other. This improves residue flow compared to SeedHawk and SeedMaster which have seed and fertilizer knives a few inches apart and to the side.

What I learned most on our tour was that a $2000 pool cue does not make you a pool shark. Meaning, residue issues, seeding depth, packing pressure can all be managed poorly and leave you with an average seeding job no better than a regular hoe drill. It’s the ability to make those subtle but necessary changes that will improve germination and emergence from a precision hoe drill. SL

Picture: SeedMaster (top) Case 800 (middle) and Conserva Pak (bottom) shanks.

It's Time to Check Post- Herbicide Efficacies

The most important role of a farmer or crop advisor during spray season is not only to apply the correct herbicides at the right time but to follow up with post herbicide checks. Follow up efficacy checks should be done 10 to 14 days after application. More wild oat or weed escapes can be corrected if only producers and crop advisors checked how well the herbicides worked after application. Calling the chemical representatives at harvest to tell them the herbicide didn't work is futile and besides, herbicide inquiry cut off dates are usually around the 15th of July.

Below is a list of herbicide injury symptoms for the top six herbicide groups I use to help identify herbicide injury and efficacy.

Group 1: ACCase: Axial, Achieve Liquid, Horizon, Puma Advance, Centurion
Symptoms: The first sign of injury on wild oats or green foxtail may appear as intervenal chlorosis or yellow striping on newer leaves. Older leaves may show red or purple. The growing point turns brown and dies. The newest leaf can be easily pulled from the crown where you will see a "pinching" at the base of the leaf. New growth dies first, such that the plant appears to take considerable time to die after application.

Group 2: ALS: Simplicity, Everest, Frontline XL, Refine SG, Odyssey, Varro
Symptoms: In broadleaf weeds the first visible symptom is the termination of plant growth. A few days after application you may see yellowing, reddening and purpling of the leaves. In grassy weeds like wild oats, you may see a yellow striping and purplish discoloration of the leaves. The youngest leaves die first followed by older leaves. Death of grassy weeds may take 1 to 3 weeks to occur.

Group 4: Auxinic: 2,4-D, MCPA, Attain, Buctril M, Curtail M, Frontline XL, Target
Symptoms: Bending and twisting of stems and petioles, stem swelling, especially at the nodes, elongation, leaf cupping and leaf curling. These signs are followed by yellowing at the growing point, growth inhibition and wilting.

Group 6: Photosynthetic Inhibitors: Buctril M, Infinity, Benchmark, Thumper
Symptoms: Rapid yellowing and whitening begins at the leaf edges. Later symptoms include desiccation and a burned-off appearance of the leaves. Symptoms develop rapidly under full sunlight conditions.

Group 9: EPSPS: Glyphosate: Roundup WeatherMax, Touchdown Total, Vantage PlusMax
Symptoms: Gradual wilting and yellowing at the growing point of the plant that advances into browning of above ground growth. Annuals may show signs within 2-4 days and perennials within 7-10 days.

Group 10: Glutamine Synthetase Inhibitor: Liberty 150
Symptoms: Yellowing and wilting usually occur within one to three days after application, followed by necrosis or bleaching-death of plant tissue. Symptoms develop more rapidly under bright sunlight, high humidity and moist soil.

Group 27: HPPD Inhibitors: Infinity, Tundra, Velocity
Symptoms: Small burnt spots on the broadleaf weeds can appear within hours. The pigment and photosynthesis of the plant shuts down resulting in bleaching symptoms with 6 to 14 days.

Here is a link to the visual symptoms of each herbicide Group:

Reference: How Herbicides Work, Alberta Ag publication

Should I apply a fungicide at herbicide timing?

Should I apply a fungicide at herbicide timing?
The quick and dirty answer is no on most occasions, however, there are times when a fungicide can provide an economic benefit prior to flag leaf emergence or at herbicide timing. An early fungicide application may be warranted if:
1. The crop was planted into infested cereal stubble (ie. wheat on wheat stubble);
2. The crop has a very dense and moist canopy due to tight row spacing (ie. reduced air flow);
3. Lesions are observed on the newest leaf growth;
4. The lesions are caused by stripe or leaf rust;
5. The crop is of high value.
* If you have checked at least 3 of these, then there may be an economic advantage to applying fungicide at the seedling stage

Cereals in the seedling and vegetative stages are most susceptible to leaf spots because they are located close to the ground where conditions are more humid and are closer to disease inoculum from infected stubble. This is why the most early and severe symptoms are seen in cereal crops planted into the same type of cereal stubble.

It is essential to accurately diagnose whether the symptoms observed are caused by disease pathogens. Yellowing, spotting, streaking and leaf death could be the result of other problems including root disease, nitrogen deficiency, insect damage, herbicide injury, heat banding or frost. At first glance, a crop may look unhealthy if the oldest leaves are infected with disease or have other injury. However, it is important to look at the new leaf growth. If the new growth is healthy and the overall crop density is sufficient, the crop should quickly recover.

Source: Penny Pearse, Saskatchewan Agriculture & Food

Optimizing leaf area index is key to achieving high canola yields

One of the key drivers in canola yield is leaf area index or what's commonly known as green area index (GAI). GAI is the ratio of green plant material that covers a square meter of land and has a direct influence on crop vigour, root development, moisture use efficiency, weed suppression, carbohydrate storage and nutrient transport. In a nutshell, obtaining optimum GAI's can build bigger canola yields with less water and nutrients.

Measuring GAI is one way to estimate the nitrogen top dress requirements in canola. Peak nutrient demand begins at bolting which is not long from now. Here are the steps to measure GAI and calculate nitrogen requirements in season. As a side note, BASF has come up with an iPhone app that measures GAI for you.

Measuring Green Area Index

To quantify the amount of nitrogen taken up by the crop prior to bolting, a 1 square metre quadrant is placed in a representative area of crop. The entire green mass (stems and leaves) on this area is cut off at ground level and weighed (including dead leaves). Alternatively you can take a picture of 1 square metre of area standing above the crop and insert it into the online BASF GAI calculator
The weight of the green mass (stems and leaves) is measured in kilograms and multiplied by a factor of 0.8. This will give you a Green Area Index number. For example, 1 kg of green mass from 1 square metre would equate to a GAI of 0.8. (1kg × 0.8 = 0.8 GAI) or (0.750kg × 0.8 = 0.6 GAI)
Pictures of GAI examples.

Calculating nitrogen uptake and N application rate

It is assumed that each GAI of 1 contains 50kg/ha of N within the crop. If you want to convert kg/ha to lb/ac, simply multiply kg/ha by 0.893. For example, 50 kg/ha × 0.893 = 45 lb/ac of N within the crop.
Now, multiply your GAI × 50 kg/ha to calculate the amount of nitrogen in the crop. For example: 0.75 GAI × 50 kg/ha = 37.5 kg/ha N within the crop or 33.5 lb/ac N
Next, the optimum sized canopy at full growth (bolting) has a GAI of 3.5. We need to build the crop canopy up to a target GAI of 3.5. Example: 3.5 - 0.75 = 2.75 GAI
To calculate the nitrogen necessary to build an additional GAI of 2.75 we need to multiply 2.75 GAI × 50 kg/ha. For example: 2.75 GAI × 50 kg/ha = 137.5 kg/ha N or 123 lb/ac N
Therefore, the crop needs 123 lbs/N/ac to reach its optimum canopy size and yield potential.

In Canada, a GAI of 4 is considered optimum for the crop canopy to intercept about 90% of the incoming solar radiation. (The picture above has a GAI of 1.8 to show you an example.) The larger the leaf area the crop can expose to the sun, the more dry matter the crop can produce per day. The more dry matter a crop can produce, the higher the yield potential. I'd like to run some numbers but instead, I'll challenge you to start measuring GAIs in 2012. Start questioning what it would take to produce a GAI of 4 in your cropping system. Is it a change in row spacing, opener width, fertility program, nutrient placement, seeding rate, fungicide or variety? Let this be the beginning of a new way of measuring yield potential in canola.

Photo source: BASF UK showing GAI of 1.8 in winter canola

Source: Nick Ward, Lincolnshire, England