Seed Drill Row Spacing – Part Two (Sort of)

In my previous post on cereal row spacing I discussed the many conflicting functions of modern seeding equipment. By conflicting I am suggesting that particular functions performed by a seed drill actually work against each other. For example, optimizing the function of seed bed utilization (row spacing) conflicts with the function of minimizing seed bed disturbance. Both functions are important but designs to optimize for one function would tend to work antagonistically on the other.

These types of conflicts put rigid limitations and constraints on machine design. It narrows the range of conceptual design options available to perform the many needed functions of seeding equipment. One way to illustrate the way in which this type of conflict plays out with seeding equipment design is through the use of a Venn diagram. With a Venn diagram, we let a circle define the “space” of design options to impart a specified function in a seed drill. Each function which the drill needs to perform as a condition of commercial acceptability is then represented by a separate circle.

The figure below shows a Venn diagram for seven distinct functions which I believe a modern seed drill needs to carry out in order to succeed in the marketplace. While there are no doubt many more functions not considered here it is sufficient to demonstrate the challenge and complexity involved in equipment design.


The figure shows how these functional conflicts work against each other and severely limits the alternatives for engineers and equipment designers. The small shape which I have outlined in black shows the small overlapping area of “solution space” which can reconcile all of the mostly conflicting and non-overlapping space of design alternatives. Note that the optimal design solution for each individual function does not necessarily lie within the small overlapping “solution space”. However to obtain greatest commercial value – which is in theory the maximized sum of values of the seven functions – the ultimate design must lie within the small space.


Which Agronomy Services Are Most Valued?

Yesterday I was in a meeting with Alice Wheaton (@Alice_Wheaton and ) and I got to chatting with her about social media and specifically blogging. I mentioned to her that I had started a blog and she seemed quite interested. So I handed her my ipad and she browsed my blog for a few minutes. Alice had some good ideas that she suggested for posts. She asked me if I had ever done any questionnaires and I told her that I had played around with the poll feature on WordPress. She suggested a post that asks for feedback on which agronomy services are most valued by farmers. I thought it was a heck of an idea and was kind of wondering why I hadn’t thought of it myself! Alas it was not my idea and therefore I gladly give a hat tip to Alice for giving me the suggestion.

So I am going to end this post with a poll quizzing readers on how they value certain services. I encourage responses from all who farm and not limited to any specific service provider – and certainly not just those who have used services I provide. I would even encourage farmers who do not currently use professional agronomy services to respond as well with their take on how they would perceive the value. I will include a question asking if farmers currently use agronomy services or not for interests sake. I have included a brief description of the services I provide below which readers can consider when pondering the poll response (Hey – it’s my blog and I’ll plug my serviceif I want!  🙂 ).

The services that I provide can be divided up into three general categories: Field Scouting, Crop Fertility Planning (through Western Ag), And Unit Cost Analysis.

Field Scouting is done independently and directly with farmer clients. It involves season long monitoring and reporting data and information on contracted fields as they progress through the growing season. Customers use the information to evaluate the potential risk of loss (on a field by field basis) due to weeds, insects, disease, etc. Reports also help customers to plan and coordinate efficient spraying operations based on priority (loss potential) and optimum timing windows.

Crop Fertility Planning is done through the Western Ag system which is also independent (of fertilizer sales) and therefore a perfect fit for me and how I choose to position myself. Western Ag is a bundled service which includes sampling, PRS probe based soil lab analysis, and PRS CropCaster model “crop fertility planning”.  For anyone who has never used the service before, it is a little difficult to do justice to the concept with a few bullet points in a blog post, however the PRS model allows us to plug in and compare variable scenarios of moisture, fertility, and cropping choices on individual fields that have been sampled. By adding in the projected costs of fertilizer and anticipated prices of various crop choices, the model can give you margin / profit projections over a variety of risk scenarios. This is an interactive process and involves input from the customer. This means that the analysis reflects each customers unique risk tolerance, budgets, logistical constraints, and cropping preferences. The service cycle is rounded out by comparing modelled yield projections (using applied fertility, moisture, etc) with actual yields. We call this exercise “backcasting” and this allows clients to evaluate the success or failure of the service.

Unit Cost Analysis is technically not really agronomy I suppose. However being so close to the operations of my customers I can bring an agronomy perspective to this type of analysis. That enables me to be able to consider things like how equipment operating capacity (and therefore unit cost) can fluctuate based on the unique circumstances of the growing season – and other similar nuances which should be considered whenever possible in doing this type of analysis. I find real synergy also with this service and Crop Fertility planning through Western Ag. Our crop fertility optimization can be viewed as a partial budget analysis which, when coupled with full unit cost analysis, can offer valuable insights into potential profitability and sound margin projections of different cropping options.

Now for the poll. Multiple answers are allowed so I suggest if you value two services equally that the appropriate two answers be indicated:



Conflicting Literature on The Effect of Row Spacing on Yield and Yield Components of Hard Red Spring Wheat

A couple of months ago or so I got involved in a discussion on twitter about the effect of ten inch vs twelve inch row spacing on cereal crop yields and decided to make it the topic of a blog post. No one should argue the fact that row spacing which is *too* wide will result in inefficient utilization of space, sunlight, etc. within a field and yields would be less than optimal.  Wider rows leave crops more vulnerable to losses from weed competition as well. However if the seeding operation was only about maximizing the utilization of the seed bed space, then we would just broadcast seed on the surface then incorporate and be done with it. The operation of seeding has other necessary but somewhat conflicting functions which favours seeding in rows (therefore limiting the utilization of space), such as ensuring uniform depth, good seed to soil contact, and applying fertilizer in way which allows the emerging crop timely access to nutrients.

The movement to direct seeding over the last 10 to 20 years has further increased and complicated the conflicting functions demanded of seeding equipment – now having to deal with getting through heavy surface crop residues, attaining precise seed depth and seed / soil contact, and delivering higher and higher rates of fertilizer in one pass operations. Wider row spacing is a design option for systems which helps deal with these increased challenges. But with the competing  problems  of optimum seed bed utilization on one hand, and proper seeding and fertilizer placement on the other, the inevitable question becomes:  ‘What is the proper balance between optimum seed bed utilization (row spacing) vs crop residue management, quality seeding, and fertilizer placement?’

Over 13 seasons of crop consulting and agronomy I have worked with several different farmers using different (direct seeding) equipment and row spacing (up to 12 inches) in everything from drought to excessive moisture. Up to my twitter discussion a few months ago my view from these experiences had been that row spacing can interact with the unique conditions of each growing season in a manner which favours wider row spacing in one growing season and narrow row spacing in the next but that such differences tend to be offsetting when considered over the wide range of conditions over wider time spans.  In academic literature, I viewed Lafond 1994 (L94) as seminal on the subject for the semi-arid Canadian prairies and consistent with my own experiences. However after the discussion I decided that spending some time revisiting the topic and reviewing some literature would be a worthwhile exercise and a good topic for a blog post.

I like L94 for many reasons. It is widely cited and to my knowledge the conclusions still stand as a strong case that wheat yield potential can be maintained with twelve inch row spacing in direct seeding systems. Direct seeding was an important distinction by Lafond in this and other work. According to Lafond, previous work on row spacing was set against more conventional tillage systems with little surface crop residue. With this distinction Lafond implies that inefficiency of resource utilization commonly attributed to wider rows might be countered by the gains in moisture use efficiency under direct seeding systems. The implication for row spacing is not that row spacing does not matter, but that perhaps the width ‘threshold’ – between where it doesn’t matter and does matter – is wider under a direct seeding system. Lafond also collected data on the recognized yield components of cereal crops as well: plant density, spike density, kernels per spike, and test weight to study the row spacing effects on these specific components. Variable Seeding rates and nitrogen rates were also evaluated separately and, along with row spacing, to check for interactions among these variables.

Guy Lafond, who sadly passed away this past April, published on this topic again, and most recently as lead author along with co-authors Bill May and Chris Holzapfel  (LMH13) with similar conclusions studying oats. A key methodological difference in LMH13 is N placement. In L94 ammonium nitrate was surface broadcasted. In LMH13 N as urea was applied in the seeding operation via side band.

After reading through several papers and other publications on the effect of row spacing in cereal crop yields, I’m focusing on one (referenced by LMH13) as a comparison to L94. The paper is Chen, Neill, Wichman, and Westcott 2008 (C08) based on experiments in central Montana. I chose this paper because it is fairly current, geographically relatively close to Southern Saskatchewan, and allows for direct comparison of HRS wheat yield and yield components. L94 looked at 10, 20 and 30 centimeter row spacing while C08 used 15 and 30 centimeter row spacing. C08 reported a different conclusion then Lafond on the effect of row spacing on cereal crop yields.  Like L94, C08 also reports on yield component data as well.

In reading the literature it seems widely recognized (and confirmed by both of these studies) that as row spacing increases, the plant density and spike density decreases. Lower plant density is attributed to greater concentration of seedlings per row in wider row spacing causing greater inter-seedling competition and therefore greater mortality (Amjad and Anderson, 2006). However, the other yield components can respond in a compensating and offsetting manner such as producing greater kernels per spike (Chen et al, 2008). Therefore it seems that a key questions is: Can lost yield potential in wider row spacing due to lower plant and spike density be recovered through increased kernels per spike and/or increased seed weight? Can direct seeding perhaps contribute to such a recovery?

L94 and C08 both looked at HRS wheat and both reported yield components as well as yield. Therefore, I can plot findings of both studies onto common graphs for a visual comparison. Below are two graphs showing crop density (figure 1) and spike density (figure 2). L94 is shown by the black trace and C08 in red. The y axis (vertical) shows units of density per square meter and the x axis (horizontal) shows row width in centimeters. These two figures confirm what has been seen widely in research into varying row width and mentioned above – that plant and spike density decreases with increasing row width. In L94, spike density decreases by 8% when moving from 20 to 30 cm and is consistent with C08 decreasing by 12% moving from 15 to 30 centimeters.


Figure 1


Figure 2

Next to look at is kernels per spike (figure 3) and the findings of these two studies here are in conflict with each other.  L94 (black) shows increasing kernels per spike with increasing row width while C08 shows a very slight decrease with increasing row width.


Figure 3

Both papers show little change in seed weight over the differing row widths (Figure 4).


Figure 4

Figure 5 shows how the yields compared between the two experiments.

Yield L94 C08

Figure 5

So it comes down to the differences in *one* yield component to account for the conflicting conclusions of L94 and C08 on row width and yield in HRS wheat. By expressing the data on a proportional scale, Figure 6 shows the almost perfect inverse relationship in L94 between spike density and kernels per spike with increasing row width. C08 on the other hand shows no such relationship between the components (Figure 7), with even a slight tendency for kernels per spike to vary in the same, rather than the opposite, direction as spike density. What could account for these conflicting results?


Figure 6


Figure 7

Going back to the introductory discussion in L94, Lafond does not dispute that previous work has found the tendency for yields to decrease as row spacing increases. However he does imply that direct seeding systems perform better by enabling more efficient utilization of moisture – in other words directly opposing (in part) previous explanations offered for declining yields with increased row spacing under conventional tillage. In C08 the Manning wheat was described as being planted into a “sweep tilled” annual cropping field therefore is a key difference in the two experiments as suggested by Lafond.

There was another interesting difference between the two methods which stuck out when I compared them: L94 applied the bulk of the nitrogen requirement by broadcasting ammonium nitrate on the surface. C08 states that liquid N “was dripped between wheat rows using a modified herbicide sprayer with special calibrated openers with attached drop tubes”. I read this to mean dribble band placement of N between rows. Dribble banded N would be progressively further from the seed row with widening row widths. Since efficiency of nutrient uptake (along with moisture and sunlight) is cited as accounting for lower yields with wider rows, one could at least question whether there is an (unaccounted for) effect in C08 of increasing distances from a nitrogen band that might confound with the row spacing effects.

Discussion and critiques of the post and arguments on the topic of row width in cereal production are welcome.  I am interested particularly in discussing literature / data which might contribute to this discussion.


M. Amjad , and W. K. Anderson. 2006. Managing yield reductions from wide row spacing in wheat. Australian Journal of Experimental Agriculture 46: 1313–1321.

C. Chen, K.  Neill, D. Wichman, and M. Westcott. 2008. Hard red spring  wheat response to row spacing, seeding  rate, and nitrogen. Agron. J. 100: 1296 – 1302.

T. Fiez, and W. Shillinger. 1999. Row spacing effects on direct seeded spring wheat and barley in the low-rainfall cropping zone. NW Direct Seed Cropping Systems Conference Procedings.

G. Lafond. 1994. Effects of row spacing, seeding rate and nitrogen on yield of barley and wheat under zero-till management. Can. J. Plant Sci. 74: 703 – 711.

G. Lafond, B. May, and C. Holzapfel. 2013. Row spacing and nitrogen fertilizer effect on no-till oat production. Agron. J. 105: 1-10.

Classic Movie Genre on #MovieTriviaMonday

I love watching movies. It is one of my favorite pastimes. I don’t know if I would go as far as calling myself a movie “buff” or “geek” or not, but I have watched many. Today on twitter Cami Ryan (@DocCamiRyan) posted a picture of Harrison Ford from a movie along with a trivia question asking which movie the picture came from under the hash tag #MovieTriviaMonday . If I needed to answer the question right in order graduate to “geek” status then I guess I still have some work to do 🙂 .

I first became aware of the Internet Movie Database website (IMDB) probably about 10 years ago or so. For those not familiar it is an interactive site which allows movie fans who have registered at the site to rate movies that they have watched. The site then takes the rating and adds it to the data base and uses some sort of algorithm to compute and publish a rating for the movie based on this user data base. Pretty cool really. One of the things I noticed on the website was a list called the “top 250” which is a listing of the top movies according to the website user ratings. The year of release accompanies the movie title on the list. Of course the list contains movies from many eras going right back as far as the earliest times of the industry. I started watching some of the “classical” (for me I’ll define loosely as anytime prior to 1970) movies from the list which I had never seen or even heard of in some cases.

I quickly became a fan of the genre and have worked my way through many of these classic top 250 movies. Still many more to go. For those movie fans who have not taken an interest in older movies please consider the IMDB “top 250” list  and make a point of watching a few. I don’t think you will be disappointed. In fact I think you will agree that these movies stand the test of time and deserve the top list IMDB rating.

For whatever it’s worth, here is my own personal “top ten” list in the classical movie genre as I have defined it:

  1. “Lawrence of Arabia” (an amazing spectacle. I got the official “full geek” version HD DVD as a Christmas present last year)
  2. “The Good, The Bad, and The Ugly” (watch the other two spaghetti westerns – also on this list – first as a build up)
  3. “Rear Window” (My favorite Hitchcock movie)
  4. “Sunset Boulevard” (I had no idea what to expect with this show – blew away my expectations)
  5. “Bridge on the River Kwai” (if you liked “Lawrence of Arabia”, you’ll like this)
  6. “The Treasure of the Sierra Madre” (my favorite movie paraphrase – “we don’t need no stinkin badges” )
  7. “High Noon” (as suspensful as any movie you’ll ever watch)
  8. “North by Northwest”
  9. “Cool Hand Luke”
  10. Tie between “Fistfull of Dollars” and “For a Few Dollars More” (gotta get all the spaghetti westerns on here!)

I would have to say that on any given day, I would probably rank the top 7 on my list interchangeably.

Honorable mentions (in no particular rank): Rope, The Hustler, To Kill a Mockingbird, Vertigo, Casablanca, Once Upon a Time in the West.

And now for another fun poll. For those who have watched any of the movies on my list, please indicate which was your favorite.

PS. For those hoping for agronomy posts I hope to have one up in about a week or so.

Where do your pickup truck loyalties lie?

My old friend Doug Fehr (@JDougFehr) today tweeted up a link to a the Official Ram Trucks Super Bowl Commercial”. Personally I’m not into Dodge (though I hear the new ones are much improved) but weaving a Paul Harvey story into this commercial is a stroke of genius in my mind.

Anyway, I have been itching to try out this poll feature with WordPress and thought this one would be fun. Here goes. Please feel free to add your comments as well.

(Update 8:08 pm: poll closes after one day)

What do Tupperware and Your Sprayer Have in Common?

(Updated January 28th 8:43 pm see below)

The first post to my new blog! It is something I have been thinking about doing for several months now. I have several timely topics that I would like to write about over the next few months before things start to get busy in the field by mid April. Hopefully, I’ll get to all of them.

The topic for my first post came to me unexpectedly January 23rd while attending the Crop Life Canada Sask Council meeting in Saskatoon. Clark Brenzil is the Provincial Weed Specialist for the Saskatchewan Ministry of Agriculture and I have heard him speak many times on technical weed issues such as updates on weed herbicide resistance. However the feature topic of this most recent presentation was a bit different (for me anyway). Clark presented on crop injury arising from herbicide residue contamination in Sprayer systems. I say systems because Clark believes much of puzzling chemical injury of canola crops comes not from contamination of sprayer tanks but sprayer plumbing.

I was interested in this topic immediately because I have seen (unfortunately) this many times with my own customers. I have always been certain that the cause was sprayer contamination because you usually could see a line in the field of differing crop damage between the first and second tank fills. However the puzzle always was that my customers and their hired men are usually very careful about rinsing and cleaning between operations and particularly when changing herbicides.

Clark singled out Invigor canola treated with Liberty as being the most frequent for this type of incident. There are two main reasons for this: canola is a crop which is very sensitive to chemical residues, and Liberty acts much like a detergent and is capable of breaking the bonds which cause chemical contaminants to stick on the plastic surfaces in the plumbing of the sprayer. In the majority of cases it is believed to be group 2 chemistry (and occasionally group 4) involved in the contamination.

While listening to Clark an analogy came to mind of Tupperware type food storage containers when they get covered in a film of oily, fatty substances from margarine, salad dressing, etc. Often (in our dishwasher anyway) these containers need to be pre-washed before going into the dishwasher otherwise the oily film will still cover the surface of the container when it comes out of the machine after being washed. And so to is it with spray solutions / suspensions containing oily adjuvants as sticking agents. The plastic surfaces of the PVC plumbing fixtures in most sprayers are vulnerable to this type of contaminating chemical residue bond – particularly after the sprayer has been sitting parked overnight or longer with no clean out or agitation. According to Clark, this residue can stay bound in the sprayer (even after multiple cleanings and/or several thousand acres sprayed of a different herbicide) until the right circumstances converge with a Liberty operation to strip these bound residues from plumbing fixtures and contaminate the contents of a sprayer tank.

For many (myself included) It seems logical that a sprayer should only need to be cleaned when switching to a different product but Clark offers a compelling case that it is these very situations (not cleaning – allowing sprayers to sit for periods and not doing cleanout) which underlie most residue contamination incidents. He goes even further and suggests that perhaps layers of residue can accumulate with each sprayer stoppage if there is no clean out or agitation.

The circumstances for these incidents seem to fit into 3 predominant scenarios:

  1. Damage occurs on the outside round and area the where the first tank is sprayed out. Damage diminishes with each subsequent tank until eventually it disappears all together. Clark believes the chemical mixing / filling sequence in this scenario is that the Liberty is added to the spray tank very early in the process resulting in highly concentrated Liberty being circulated into the system which is very effective in stripping the contaminant from the plastic surfaces in the plumbing. This process is replicated over subsequent tanks until the residue (and crop injury) eventually disappears.
  2. No damage evident with the first tank but shows up with the second tank onward. The chemical mixing / tank filling process is believed to be slightly different in this scenario from the first. Here Clark believes that the Liberty is being added late in the filling process and that the tank is perhaps not being adjitated. Nothing is going into the plumbing during filling therefore the first tank is not being contaminated ergo there is no crop damage. Once the sprayer and adjitation is stopped to fill the second tank the Liberty in the lines has the opportunity to act on any contaminant hung up in the plumbing. Tank content contamination occurs once the adjitation is started again and is then sprayed out over the second tank and on causing crop injury. There is a diminishing effect over subsequent tanks similar to scenario #1.
  3. A single “catastrophic” tank in mid operation causing all of the damage. Here there may be several tanks prior and several tanks after with no symptoms of crop damage. It is suggested that initially sprayer agitation is continuous through each fill not giving the Liberty a chance to sit idle in the lines and strip the residue out of plumbing and contaminate the tank contents. Then the sprayer is perhaps stopped at the end of a work day (or an interruption) for a significant length of time with no clean out. This is the opportunity for the Liberty in the lines to remove bound up residue and contaminate the content of the next tank.

In late, wet springs like we had in 2013 farmers are under more time pressures and have greater weather related interruptions in spraying operations. If sprayers are not cleaned out in these interruptions because there is no change of chemical, then we have the situations which Clark believes could give rise to both the residue hang up (possibly in multiple layers) and the residue removal with Liberty.

There was no type of cleaning “fix” offered by Clark to resolve this type or problem. As well, when Clark reviewed the article he expressed concern that the issue of plumbing vs tank residues could be a bit of a red herring. The real take home message should be to take preventative steps to avoid the circumstances which cause the problem in the first place – which is sprayers sitting idle without clean out or periodic agitation. Clark related a farmer’s comment: “I guess I should be cleaning my tank as often as I shower” to which Clark suggested was “probably right on as long as the person has socially acceptable personal hygiene habits.”

Update January 28th, 8:43 pm – Twitter exchange involving Grant Laroque, Clark Brenzil and myself on a suggested cleaning strategy if contamination (such as discussed in the post) is suspected:

Jan 27 : One thing I have recommended to my growers is to use Merge as a tank cleaner, especially after SU’s and other Group 2

Jan 27 : if contamination is suspected, I wonder if clean out should involve a “standing time” with something like Merge.

Jan 27 : the reason I ask is because stripping (cleaning) of the residue occurred when unagitated Liberty left in lines

Jan 27 : stripping (therefore contamination) was less likely if Liberty was continuously agitated. What say you Clark?

53m : letting sprayer stand w strong detergent mix should do the same thing. PMRA may not like extra Merge load in Env