Agronomist Notes

Who turned the season switch? It’s finally starting to feel like spring out there with water running off the fields and overnight temperatures above zero. I’d guess we’re three weeks away from seeding which brings us to May 1st.

The only real change to seeding plans so far has been for some producers to back off pea acres and seed wheat or malt barley instead. I think it may bode well for pea growers this year if the trend continues. It’s hard to ignore $8.00 wheat and $6.25 malt barley but it’s also another thing to achieve malt barley and produce No.1 13.5 HRS wheat.

This week we’ll look into the controversial issue of micronutrient deficiencies caused by glyphosate use. Next, we’ll look at a study from North Dakota on compaction and yield loss between tracked verses wheeled tractors. Also, I’ve included a number of papers on nozzle selection from Dr. Tom Wolf with Ag Canada and we’ll look at how nitrogen recommendations are developed in canola overseas. We’ll finish with fundamental and technical grain market news.   

Don’t forget the application deadline for the Nuffield Scholarship www.nuffield.ca is April 30th so send yours in soon.

Agronomy

Does glyphosate cause micronutrient deficiencies?

There have been numerous discussions about the effect of glyphosate applications on micronutrient availability. It all started with Dr. Don Huber from Perdue University who did a study on glyphosate interactions with crop nutrients. His research found a reduction in drought and disease tolerance with plants grown after glyphosate applications. The reduction in drought and disease tolerance was a function of glyphosate tying up manganese making it unavailable for plant uptake. 

To give you some background, glyphosate was originally patented as a strong metal chelator. Meaning, glyphosate has the ability to immobilize or chelate specific metals like Cu, Fe, Mn, Ni, Zn as well as other cations like Ca and Mg. It’s Huber’s position that the increase in RoundUp Ready crops has lead to an increase in glyphosate residues and subsequently a reduction in manganese availability.

On the flip side, Darren and Brian Hefty from AgPhD http://www.agphd.com in South Dakota have found different results. Darren and Brian have a weekly telecast and farm in South Dakota and in 2010 they ran a trial comparing nutrient uptake in corn and soybeans on a soil with very little history of glyphosate use. They applied a 100X rate of glyphosate on cultivated soil prior to seeding then ran tissue tests at three growth stages in both crops. The same research was conducted at South Dakota State University and both independently run trials found no difference in nutrient uptake. In fact, Darren and Brian found a small increase in manganese uptake in the 100X rate of glyphosate trial.

Bottom line: be sure to run your own trials to see if the $4.00 “insurance” manganese you’re buying is worth the investment. A small trial with a 100X glyphosate rate compared to no glyphosate and a few tissue samples might point you in the right direction, all for less than $200.00. SL

Watch the YouTube video http://youtu.be/tQEVtHLhU2w of Darren and Brian explaining the results of their farm trial.

To view Dr. Huber’s paper on Glyphosate and nutrient interactions go to:

North Dakota study compares yield loss and compaction on wheeled vs. tracked tractors

A Beyond Agronomy News subscriber from Manitoba kindly passed along a research paper comparing the level of compaction and yield loss that occurred during seeding in wheeled versus tracked tractors. The study compared stem height, number of heads and yield in winter wheat using a Caterpillar MT865, John Deere 9620, and John Deere 9520. 

In the un-compacted treatments, the results showed a 31 bushel increase using the John Deere 9620, a 55 bushel increase using the John Deere 9520 and a 12 bushel decrease using the CAT MT865. Wheel slippage was 1-3% with the CAT MT865, 4-8% with the JD 9620 and 10-12% with the JD 9520. The biggest amount of compaction, slippage and yield loss occurred with the JD 9520 wheeled tractor unit. The lowest compaction, slippage and an actual yield increase came from the CAT MT 865. The reduction in slippage along with proper ballast and overall footprint gave the CAT the advantage in this study.

Study after study shows how tracked tractors outperform wheeled units when it comes to slippage and compaction reduction. The additional yield from the studies I’ve seen will more than pay for the added cost of the tracks. Keep that under consideration the next time you upgrade your 4WD. SL

All you wanted to know about nozzle selection

I’ve been answering several questions about nozzle selection lately and I thought I would pass along some great information from Dr. Tom Wolf, leading nozzle technology specialist at the Ag Canada office in Saskatoon. Tom sent me a spreadsheet that helps calculate droplet size based on speed, pressure and nozzle type. He also provided me with info on frequently asked questions, selecting a new sprayer, spray pressures and a nozzle update. I encourage you to down load and print off these documents for your records, its great information.

Four Rules for Nozzle Selection: http://www.agcanada.com/Article.aspx?ID=33527

If you have a question for Tom, you can email him at Tom.Wolf@agr.gc.ca

Canadian Nuffield Farming Scholarship applications due by April 30, 2011

Nuffield Farming Scholarships are awarded to enthusiastic individuals, with a passion for agriculture and a desire to expand your knowledge, pursue new ideas and to share your findings with others. Applicants should be in mid-career, between the ages of 30 and 45 (although exceptions are made) and must have a minimum of five years agricultural business or farming experience plus the management ability to step away from their current duties. The Scholar must travel for a minimum of ten weeks, with a minimum leg of six consecutive weeks. 

Three scholarships of $15,000 each are available for 2012.

To apply: http://nuffield.ca/
 
Here’s my response to someone who asked me about Nuffield: “I've been around the world three times, been connected to and befriended by some of the finest, most passionate and innovative farmers anywhere. As a direct outcome of my studies, I am the first to bring home and implement one of the most revolutionary farming practices since direct seeding. I’ve become a greater ag advocate, a better businessman, and a better father. I regularly converse with people from around the world, an ag resource base 1,200 people strong and get to live vicariously through fellow Scholars each year when I'm not traveling. When I do travel, I have hundreds of places to stay anywhere in the world that include great conversation and amazing hospitality. Is it worth it to apply? I think yes. Steve Larocque”

A look into nitrogen applications using Green Area Index in canola

I always find it interesting to see how growers around the world approach agronomy. Today, I thought I would give you an idea of how nitrogen applications are made in the UK on winter canola, a crop that typically yields into the 70-80 bu/ac range. The following recipe is from Nick Ward who farms near Lincolnshire. I’ve translated the measurements the best I could to Imperial. (Love our Commonwealth country but that’s another rant.) Here’s Nick’s method:

To begin, everything starts with a target of 8 to 10 plants per square foot for conventional winter varieties. We estimate that 60-70% of these will not survive by harvest and adjust our seeding rate accordingly. We start sowing around the middle of August, immediately following the removal of the previous wheat crop. Due to high levels of crop residue in these situations up to 35 lbs/N/ac will be applied to the seedbed as either diammonium phosphate, monoammonium phosphate (11-52-0-0) or straight ammonium nitrate. This is to avoid the residues locking up most of the available N and leaving the crop deficient. It also gets the crop off to a quick start and will hopefully allow it to reach the 6-leaf stage by early November when growth stops for winter.

In the spring during early February, we will take soil nitrogen cores from three depths, 0-12”, 12-24” and 24-36”. From here we can establish how much nitrogen will be available to the crop from soil mineral nitrogen (SMN) and calculate how much will become available in the growing season through mineralization, which is approximately another 35%.

The second step is to measure how much nitrogen the crop has already taken up. The theory is that the bigger the crop pre stem extension, the more N it contains, reducing the amount that needs to be applied. To quantify this, a 1M square quadrant is placed in the field on a representative area of crop. The green mass on this area is then cut off at ground level and weighed (including dead leaves). Alternatively you could use the BASF website GAI tool: http://www.agricentre.basf.co.uk/uk/common/tiles/static.jsp?page=crops/osr/gai_tool/GAI_tool.html&pageId=795380

This weight of the green mass in grams/M2 is multiplied by 0.8 to give a GAI (Green area index). Each GAI of 1 assumes 50kg/ha or 45 lb/ac of N within the crop. For example 1,000gms of green mass from 1 square metre would equate to a GAI of 0.8.  This in turn equates to 40 kg of N within the crop, (0.8 x 50 kg/ha).

The next step assumes that an optimum sized canopy at full growth has a GAI of 3.5. In this example we need to build a further 2.7 GAIs, (3.5-0.8). The total N requirement from this point is therefore 135kg/N/ha (2.7 x 50 kg/N/ha), which works out to 120 lbs/N/ac.

The next step is to subtract the nitrogen found in the soil analysis plus the N mineralized during the growing season from the total N requirement. For example, if the soil mineral nitrogen showed 50kg/ha of N, this would be removed from the total N requirement, (135 kg/N/ha – 50 kg/N/ha) giving a balance of 80kg/N/ha or 71 lbs/N/ac.

Nearly there! Applied N is subject to field losses and an average crop will recover applied N at around 60% efficiency. Therefore to get our 80kg N/ha available to the crop, you must divide the 80 kg/N/ha by 60% to get the total applied N required. In this case, 80 kg/N/ha ÷ 0.60 = 133kg/N/ha must be applied to reach our target.

In higher yielding situations it may be necessary to add a further 30 kg/N/ha per 0.5 T/ha of yield forecast or 1.2 lbs/N/bu. Spring nitrogen will be applied in 2-3 applications. The first will be an ammonium sulphate/ ammonium nitrate fertilizer to deliver 30-40 kg/ha of SO4 or 25-35 lbs/SO4/ac. We are looking for a sulphur to nitrogen ratio of 1:7 within the plant. The remaining nitrogen applications will be straight ammonium nitrate 34.5% or granular urea 46-0-0.

So there you have it, a new approach to top dressing nitrogen in canola. Perhaps we should take a closer look at measuring Green Area Index’s in our canola here in Western Canada to see if a second nitrogen application is necessary in late June or early July. By this time we’ll know what kind of yield potential we have and whether a top up of nitrogen is required. How many times have you seen canola bolting when you can still see between the rows? The plants are telling us they need nitrogen, but unfortunately we don’t have a way to measure nitrogen requirements and very few of us are set up to apply nitrogen in crop. Thanks, Nick, for the food for thought. SL

Reader comment: Comparing tow between and tow behinds to big tow behind air tanks

Good article on the dual air carts. I'm still torn on the capacity issue as I have clients with multiple combos all with pros & cons. I have two clients that pull dual air carts (JD and FC 430s) and a couple that have the 700 Bourgault and a couple with one pass NH3. I'm not sold on the 700 as that is a lot of weight back there and tank 3 is so small that it is almost a hassle filling it for anything other than canola or inoculants. On the other hand the dual carts definitely spread out the weight but the filling time is definitely longer unless you have another truck and man out there filling both carts at the same time. The other downside to dual carts is that you need a tractor with big hydraulic output which is easy to do but you hit a snag with John Deere and CNH as the high HP tractors don’t allow for high output hydraulics and PTO. It's one or the other which sucks if they want to run the grain cart with that tractor.

I'm leaning towards liquid as you can set up a 3,500 gal caddy with section control for about $70K and depending on how you plan to nurse it you might need to add another $70K for that. I have one client with a JD 430 that runs liquid with a 3,500 gal set up as a 3,000 gal for N and 500 gal for P, both set up on sectional control. He nurses it with a custom built tender that has a 300bu seed tank and matching liquid tanks to the caddy which allows him to fill the cart and pump fluid at the same time. With this set up, he can do about 100-120 ac/fill with fert being the limiting factor but still better than the 40ac/fill he was doing prior. My other liquid clients aren't set up quite as tricked out but the capacity is definitely there for a lot less cost than pulling another air cart. The only downside to liquid is the extra cost of nutrient and access to supply.

Colin Bergstrom P.Ag, CCA
Precision Agriculture Consultant