Palmer Amaranth

We recently attended a Bayer Crop Science field day in Central Indiana about Palmer Amaranth (also known as Palmer Pigweed). Palmer Amaranth is a very agressive weed, can spread very quickly and most populations are resistant to glyphosate and ALS herbicides. Palmer is a highly competetive weed and can grow 2-3 inches per day. A mature plant can produce at least 100,000 seeds.  Until recently, Palmer Amaranth was only found in the southern US, but there have been confirmed reports in Indiana, Ohio and Michigan. Researchers beleive Palmer was introduced to our area in dairy or beef manure from animals that were fed cotton seed hulls that came from the South that were contaminated with Palmer seed.  This weed is in our backyard and it is very important that we take a proactive approach to controlling it.

Palmer can grow at a rate of 2-3 inches per day, making it highly competetive with both corn and soybeans.

Palmer can grow at a rate of 2-3 inches per day, making it highly competetive with both corn and soybeans.

Control of Palmer Amaranth takes a multi faceted approach. If you encounter Palmer, treat it as if the population is ALS and glyphosate resistant – reason being that most populations are ALS and glyphosate resistant. Here are some key techniques that can be used to control this beast:

  • Rotate Crops – While this is obvious, rotation allows the use of herbicides with additional modes of action that will control Palmer.
  • Deep Tillage – Deep tillage may be used to bury seed below its preferred emergence depth. In extreme cases moldboard plowing may be recommneded.
  • Cereal Rye Cover Crop – A cereal rye cover crop managed and crimped to form a mulch will suppress Palmer Amaranth emergence.
  • Hand Weed – Get out your garden hoes! Hopefully it doesn’t come to this, but in some southern cases weeding crews have been hired to remove Palmer Amaranth.
  • Monitor Ditches and Borders – Keep your eyes open, any Palmer plant needs to be addressed. A single plant can create  major problems.
  • Herbicide Control – There are quite a few corn herbicides that can be used to control Palmer. The key is to use multiple modes of action. Soybean herbicides are limited for post emergence control. Therefore, you must look to burndown and residual products to control Palmer in soybeans. Liberty Link soybeans are also a good option when dealing with Palmer infestations. 
  • Timing – Post emergence applications must be made very timely to contrl Palmer. As we stated earlier, this weed can grow 2-3 inches per day. Research shows herbicide control to be effective on small plants, and they obviously do not stay small for long. 

The bottom line here is to stay alert and keep an eye on things. Dairy’s or farms receiving manure need to be on high alert. If you think you see  it, give us a call and we will be happy to come out and take a look and help you develop a plan to eradicate it. We need to take this very seriously as this weed could drastically change agriculture in NW Ohio, NE Indiana and Southern Michigan.


We are seeing corn turn purple in several areas, and it is creating some concern among farmers.  The first thing they think of is phosphorus deficiency from old days, and it had a similar appearance.  That is not the case with the purple corn we are seeing today. 

Closeup of purple corn at V3-4

Closeup of purple corn at V3-4

It is hybrid specific, and those hybrids that have a gene to produce anthocyanin are the hybrids turning various degrees of purple.

This happens when the corn is small, V3 to V6 in growth stage, and brought on by bright sunny days with cool to cold nights.  We also had a cool rain a week ago that dropped soil temps and antagonized the situation.  It is actually an accumulation of sugars in the leaves during the daytime, that are not adequately metabolized by the plant in the cool night time.  Whenever a symptom like this hits entire fields, entire varieties, or very fast, like this did in a couple days, look to environmental conditions rather than nutrient deficiencies, which accumulate over a longer period of time.

Will it cost me money?  Corn will usually come out of these symptoms very fast, depending on the stresses present in the field.  If you had low areas that water stood on, they will be slower to respond.  Insects and herbicide stress can extend the condition also.  If nutrition and soil balance are good, the symptoms should disappear in about a week.  You should be able to see new green leaves emerging, like in the picture attached to this story.  When we encountered these conditions with certain hybrids last year, I was concerned because when we came out of the cold nights, it went right into 95+ degree days.  This purple corn absorbed more heat that the green corn, and I think it extended the stress period in the susceptible hybrids.

We have a plot out this year to compare hybrids that turn purple with those that don’t, but it will be hard to pin down a yield difference due only to the purple leaves, since there are many other differences between the hybrids.

Moral of the story- keep your soils well balanced and strive for optimum soil health and structure conditions, and the likelihood of a yield reduction from purple corn will be minimal. 

This farm has a consistent purple color.

This farm has a consistent purple color.

Side by Side variety comparison.

Side by Side variety comparison.












 March 8, 2013

There has recently been an increased interest in gypsum as a soil amendment. Let’s talk a little about what gypsum is and where it comes from, how gypsum works, and how you can use it on your farm.

Gypsum is not a new product, historical records show that gypsum was used is the early Greek and Roman times and in the US during the Colonial Period. George Washington, Thomas Jefferson and Ben Franklin have all been cited as users of Gypsum. Gypsum is Calcium Sulfate, and while it can be mined where it occurs in nature, most of todays gypsum is synthetic and a byproduct from coal fired power plants. EPA regulations have forced power utilities to remove the Sulfur from their gaseous emissions,  therefore a process was created to mix a high calcium lime slurry with the gas in order to remove the Sulfur. Basically, the double positively charged Calcium cation combines with the double negatively charged Sulfur anion. The slurry is pressed to remove the water and we are left with a powder like material –  FGD Gypsum or Flue Gas Desulfurization. FGD Gyspum is a fine, soluble powder that contains about 20% Calcium, 16% Sulfur and has a moisture of about 10%.

On the heavy clay soil in the Western Lake Erie Basin, Gypsum can be an excellent tool to adjust the physical and biological properties of the soil. We often find elevated Magnesium levels in these soils, which may occur naturally or as a result of a historical Dolomitic lime applications. These elevated levels create a hard, dense and crusting soil that can be a challenge to establish a good stand in and move water and air up and down through the  soil profile. In these conditions, it is key that we address lime needs first and set the stage for a good soil structure and water infiltration. Once your lime needs are addressed, gypsum can be used to leach magnesium from the root zone and improve soil structure, allow  water and air movement and increased biological activity in the soil. Studies have also shown that gypsum applications can dramatically decrease surface erosion and help to tie up microscopic clay particles that may be leaving your field via tile drainage water.

Samples of tile water collected 2/27/13 following 1.3" of rain. The jars on the right had gypsum applied at 1 ton/ac in the Spring of 2012.

Samples of tile water collected 2/27/13 following 1.3″ of rain. The jars on the right had gypsum applied at 1 ton/ac in the Spring of 2012.

We have also seen some results that are showing that gypsum may also help to tie up some of the Dissolved Reactive Phosphorus which has been plaguing Lake Erie and Grand Lake St. Marys. Lastly, Gypsum may be a good product to look at for a Sulfur source. As EPA regulations have removed the Sulfur from acid rain and atmospheric deposition, we have seen our soil test Sulfur levels dropping. Gypsum may be a product that will be applied at relatively low rates (500 lbs/ac or less) every 3 to 5 to cover the crops Sulfur needs.

Gypsum is a good product and is something you should consider taking a look at on your farm. Application can be a bit tricky for some types of spreaders, a box with steep sides and smooth sides is recommended to avoid bridging. Some applicators we have talked with have mentioned that it is difficult for them to spread below a 1 ton/acre rate, I would suggest to talk with your applicator and see if they have any constraints. Application rates are really going to be dependent on your individual soils, the clay content in your soils and the base saturation percentage of Magnesium. Timing of application is going to very similar to lime, spreading after wheat is ideal. If you do not have wheat in the rotation, a fall or spring application will have to work as long as conditions allow you to be in the field. Spreading on frozen ground is not recommended if there is a chance of offsite movement. However, an early spring application when we are getting freezing and thawing may be a good option. We usually figure it will take about 15″ of rainfall to get the gypsum washed in and to allow it to leach down through the soil profile. One thing to note, on low exchange or sandy soils, we need to be a little bit careful with gypsum applications. In these soils we need a given amount of Magnesium for crop production, a Magnesium deficiency can result in a serious yield hit.

In summary, there is a huge upside for gypsum as a tool to help manage magnesium levels and improve soil structure on heavy clay soils. Furthermore it looks to have excellent potential at reducing erosion and keeping your Phosphorus in the field. Remember that we really need to get your lime in order first to set the stage for the gypsum application. Also, watch applications on sandy soils to avoid getting into a situation where you will take a yield hit. Gypsum is not a silver bullet, but a useful tool that you can put in your toolbox for managing soil health. If you have any questions give us a call and we can discuss how gypsum can be used in your operation.



Winter Phosphorus Applications  

Jan. 18, 2012

The tri-state area of Ohio, Indiana, and Michigan has seen the wetest fall ever.  A few crops remain in the field today.  The soils are at 100% field capacity, and any moisture in the next month will run off or through the tiles.  For the most part, no fertilizer for the 2012 crop has been applied.  With Lake Erie and other watersheds in the tri-state area currently in bad shape with Algae blooms (due to phopshorus runoff), you should not make any broadcast applications of Phosphorus this winter. 

MAP and DAP are soluble forms of P, and that is good for crop uptake.  The problem is- saturated soils allow immediate solubility, and the P will leave your field if any water leaves it.  You can not afford this for the health of your bottom line, and we can’t afford the detrimental effects to our water systems.  We have an excellent inventory of your P levels in the soil, and can find a suitable time to replace it.  Your crop will not suffer if you skip a year of application.  It can either be applied in crop, when the soils get drier, or ahead of 2013 soybeans.  If you have new farms or unknown P levels, call me and we will figure out a plan for you. 




Jan. 18, 2012


I recently returned from the National No-Tillage Conference in St. Louis.  This was the 20th  annual, and I think I have made all but 1.  The NNTC is annually one of the top meetings I attend, and this year’s was no exception.  I would rate it as the best so far.


Many general session presentations, classrooms, and roundtables span the 4 day event, but maybe the most valuable information is shared in the hallways, at breakfast and dinner, and after the sessions close at 10 pm.  Agriculture is very complex, and the knowledge you can gain from the innovators that attend the NNTC is unlimited.


This year the topics dug deep into successful farming techniques across the country, and soil quality and health was a major focus.  Opening night of the conference I spoke on VRT fertility and soil tests.  My focus was on the physical and biological properties of the soil, not just the chemical portion.  You can spend a lot of money on fertilizer, but if your recovery system in the soil is poor and inefficient, it will be money wasted.  In a nutshell- a soil that can move water and air into the soil, has decent microbial and biological populations, can produce optimum yields with less nutrients on paper.  Recoverability is the key to profit, as well as environmental stewardship.

Next year’s NNTC will be in Indianapolis- hope to visit with you there!



February 3, 2011     

Nutrient Recovery and Efficiency  

By Joe Nester
Posted on No-Till Farmer Blog

I thought I would follow up on my nutrient management session at the National No-Tillage Conference in Cincinnati a few weeks ago.     

This session had a lot of interest and questions, and the time got short, even though discussion followed for over an hour in the hallway afterwards.     

With commodity prices and input costs, much more emphasis will be on doing the right thing with nutrients and application. This includes applying them in a way where they are not subject to loss and available for crop uptake. These nutrients are part of the “equity” of whoever owns and manages the land, and the grower that manages them properly will not only be more profitable in the short term, but will be building value in the soil they farm.     

All soil is not created equal just because it is the same soil type. The condition of the soil can mean a vast difference in profitability — including not only the chemical, but also the physical and biological components of the soil.     

Many times the chemical properties are managed the most because they’re the easiest to control.     

But as crop values and inputs increase, the actual impact from the chemical (nutrient) side is reduced in proportion to the physical and biological properties of the soil.     

The soil condition is the OPERATING SYSTEM for the crop, and determines the efficiency and recovery of nutrients from the soil. You can have a fantastic inventory of P and K on a soil test, and a poor operating system, and recovery by the crop will be inefficient and expensive.     

On the other hand, if the soil condition is such that roots grow easily, soil microbial life thrives, water and air move freely through the soil, and beneficial chemical reactions occur with ease and frequently. A soil test that shows marginal P and K levels can easily out-yield a similar field with high levels of nutrients, and the profit difference is tremendous.     

We’ve been led to believe that as long as your pH, P and K are within given ranges, and you apply calculated amounts of nitrogen when needed, everything will be fine.
Agronomy for today’s farmer is much more complicated than that. RECOVERY of those nutrients is much more important than the actual levels shown on a soil test, and our research plots prove that.     

A soil that has good structure, ample microbial life, and a decent water infiltration rate (remember that air follows water into the soil as the water moves through it) needs less nutrients on paper than a soil with lesser structure and biological activity. Stress on the crop is much less in the good soil structure; stress from too wet, too dry, heat and cold, herbicides, insects, and disease. These stresses compound upon each other, and methodically reduce the yield potential of the crop.     

You can help create this optimum soil structure condition by paying attention to the calcium/magnesium relationship in the soil, if you have marginal internal drainage and significant clay content in your soil.     

Although both elements have the ability to purge hydrogen from the soil colloid and create an acceptable pH, their reactions with clay are quite different. Calcium has a flocculating property that supports good soil structure.  Magnesium, much smaller than Ca, can “peptize” with clay particles and cause a sealing effect that makes water movement tough in the soil.     

A word of caution: lower-exchange soils that don’t contain a significant amount of clay should not be managed in this way, as Magnesium is not a soil structure component in those soils, and is necessary in levels that support crop uptake without deficiencies.     

Other management techniques that enhance the physical and biological properties in the soil are tillage that improves soil structure, and lack of tillage that reduces soil structure. Tillage usually breeds tillage, so be careful to ensure you are, in fact, improving the soil structure.  Avoidance of compaction, proper planting without sidewall compaction, residue management, efficient nitrogen management, and use of cover crops should all be considered.     

Over the last several years, our nitrogen plots have strongly supported this recovery enhancement in optimum soil-structure conditions. High-yielding zones are requiring much less nitrogen than low-yielding zones, and the difference is soil structure and recoverability.     

Nitrogen is an easy nutrient to evaluate on this basis, because it isn’t stored in the soil to the extent of P and K.     

We can evaluate applied rates to economic return in the year of application. We’ve shown that soils with an optimum calcium/magnesium relationship can produce corn at a rate of near .5 pounds N per bushel, while those soils with adverse Ca/Mg conditions may take as much as 2 pounds of N  per bushel.     

This makes a big difference to the bottom line. We were tipped off on this years ago by our consultant friends in the sports turf industry.     

You also need to pay close attention to the timing of your nutrient application. We ask these crop inputs to be soluble in the soil so the crop has a good chance of recovering them. You can’t ask them to wait until planting time to become soluble, it doesn’t work like that.     

I believe the timing and method of application have much more to do with off-site movement of nutrients than the actual rate applied. When I make a recommendation for nutrients, the only consideration is what the crop will need.  We need to make sure those nutrients are properly applied.     

If there’s a likelihood of off-target movement, don’t do it.  Applying to snow-covered, frozen ground is a recipe for economic loss. You may find yourself replacing those lost nutrients at a price twice their cost. If a soil is well balanced and managed, a grower can skip a year of P and K and apply them at a time when we know they will become part of the soil. This also allows for purchasing nutrients on “down cycles” with the great commodity swings we are seeing.     

Blanket application of nutrients and guessing without a representative soil test are fast becoming a thing of the past.     

The profit potential of VRT applications of lime and fertilizer is greater today than ever, and enhancing your soils’ recovery rates will put much more profit in your operation.     

And fortunately, enhanced recovery of nutrients is the solution to water impairment and environmental stewardship for agriculture.



September 8, 2010           

Nutrient Management Systems for Profitable Farming

By Joe Nester, Owner-Nester Ag, LLC

 I’ve been working with soil tests and correlating them to crop growth and yield for over 30 years now.  First and foremost, you need a soil test that accurately represents the nutrient inventories in various zones within your fields.  This can’t be done with a test that represents 25 acres, and it can’t be done with a test that is 3 or 4 years old.  The soil is much too dynamic to assume things stay the same in that size of sample for that period of time.  I also feel strongly that you can’t be representative with grid sampling that you live off of for several years because you dropped 4 years soil testing budget in one year.  I see grid sampling being tests from a 10’ x 10’ area in the center of a 2.5 acre grid, that magically flow to 2.5 acre grids when the results come back from the lab.  Poor representation for recommending valuable nutrients and lime that have a profound impact on optimum yield.  If you disagree with this, feel free to call me on my cell, 419-769-0926, and I will be happy to listen to your opinions to the contrary.            

 There is, however, a system that I feel gives farmers an excellent opportunity to manage nutrients in the most profitable way available.  That is using a combination of soil type and yield zone management.  Good yield maps can lead the agronomist and farmer to a geo-referenced blue print that will be the starting basis for sound VRT applications in the future.  This system takes information from the crop (who better to ask?), the farmer, and the agronomist with regional experience on thousands of like acres, and fits it into management zones from 8 to 12 acres, depending on the soils.             

These zones need to be sampled by someone that is well versed in what makes soil tests good, and what makes them worthless, at least every other year.  Preferably every year until a decent data base is established, because the soil sampling procedure is NOT perfect.  ( The reason I say sampled by someone who is  well versed in representative sampling,  you can put 2 samples from different zones in the same bag, send it to the lab, and it will spit you out a data sheet.  It will not represent anything you have in your field, but it will be accurate for what was sent in.)   Accurate soils data can be use to decide whether to spend money in an aggressive fertilizer market, or skip a year and catch it up at a more economical time.  Huge dollars are effected here, both on the expense and income side.  How can you spend $400 to $500 per year to put out an acre of corn, and not know for sure what you need in the health system of the crop, the soil?  If you guess, you will be wrong.  And independence from the sale of fertilizer products when making this nutrient plan is important, and that’s where the team at Nester Ag comes in.            

Variable rate fertilizer and lime recommendations made off these yield management zones are working well for our top clients.  Rates of fertilizer can easily vary 150 to 200# per acre within a field, and this can mean savings of $30 to $40 an acre for 1 year.  Don’t be thinking the low yielding areas need more fertilizer, either.  That’s not what we see.  Nutrients have been built in those areas for years by blanket applications and lower removal rates.  They are probably low yielding due to drainage or lime, and if it is lime, that can be fixed in 1 season.             

If optimum yield is your goal, and you have an honest concern for doing the right thing environmentally in your farming operation, give us a call.  Our continued relationship with our clients is based on their profitability and the sound future of their operation, related to nutrient management and guidance. They are using this management system to grow their operations.  If it wasn’t working, we’d be the first to know.  And an additional benefit- we utilize Brookside Laboratories, a major league lab that specializes in analysis for consultants NOT associated with the sale of fertilizer.  They also run a tremendous amount of soils for universities that can no longer afford to run their own analysis, and need top-notch consistency in testing.  With 40 full time employees, you will not find a better full service soils laboratory world-wide.  A long time leader in the North American Soil Proficiency Testing Program, this is a laboratory you need as a partner in your profitability.             

My next article will deal with the size of your nutrient cupboard.  This is something that has been extremely overlooked for years, but is critically important for your profitability and success. 



August 26th, 2010            

With crop fertilizer, there can be too much of a good thing

By Matt Reese, Ohio’s Country Journal             
Nitrogen is a critical nutrient in corn production and farmers, crop consultants, the Joyce Foundation, the Natural Resources Conservation Service and the Environmental Defense Fund (EDF) are teaming up to find out how much a productive corn crop really needs.           

In the past, nitrogen applications have been based on the yield potential of the field. When the N cost was very low, the safe bet was to add a little extra to make sure that it was not the limiting factor in corn production. High N cost and increasing awareness of the potential water quality impacts, however, have made that safe bet of the past not so safe anymore. But determining how much N is needed to maximize corn production while minimizing costs and environmental impact is not easy.           

In the On-Farm Network of N research plots in part of the Lake Erie Watershed in northwest Ohio, crop consultant Joe Nester has been working extensively to target the ideal rate of the nutrient for the specifics of each unique situation in the field.           

“We are getting good data now and we’re getting guys ratcheted into a finer N rate. As tight as the economics are in agriculture, you can’t spend money on N that you do not need,” Nester said. “We’re trying to get a target pretty close to what the crop is going to need for optimal yield. This isn’t something that you can say, ‘We’re going to raise 160 bushel corn and we need this much N.’ That is not the case at all. This can vary by farming operation, practice, soil condition, weather, drainage and a whole bunch of different things that come into play. But with this program, farmers are learning about what affects their N and they are making some adjustments in their application with the rate and the timing of their N.”           

The soil and the plant can only handle so much N, the rest leaves the soil, often in the water. Nester is working to find out how much the N application rate can be reduced without hurting corn yields. The study includes N rate test plots in the fields, soil samples, aerial imagery, corn stalk nitrate tests and yield data. This is a tremendous logistical effort that is time consuming, but it provides a fairly complete picture of how much N is needed.           

Nester is working with 90 farmers in his area and the On-Farm Network is also tied in to identical projects in several other watersheds around the country. The results have been surprising in that the most productive soils are often requiring the least amount of N.           

“We’re finding that the highest yielding areas of the field top out at the lowest N rate and the lowest yielding areas of the field might need more N to reach an optimum yield — exactly opposite of what we thought before,” he said. “The reason is recoverability. In the good areas of the field, I may have three times the root system I have in the poor areas of the field so the plant can recover more N.” While every field is different, there are some trends showing up.           

“We don’t want to be short because we know the penalty, but we want to find that breaking point. By going down to 100 pounds, we usually do. Weather comes into play then. We’re never going to pin this down exactly, but the farmers are learning how much N they need for their different conditions,” Nester said. “In many cases that 100 is our break point. In the first year, we tried 50 pounds and that was always too low. We were always losing money there. In the last couple of years we are finding that N rates were often optimized between 100 and 150 pounds of N.”
These results are allowing farmers to reduce their N rates accordingly, which improves the profitability and environmental sustainability of their farms.           

“We’re finding that farmers who participate in the program are reducing N use by 10% to 20% because they see that they can do this and be more profitable,” said Karen Chapman, Great Lakes regional director for EDF. “This is not an environmental program, this is an economic program. Reducing nitrogen offers an economic value to producers and they are contributing to improving water quality at the same time.”           

For more about the On-Farm Network, visit          


Precision Nutrient Management

by Joe Nester, Owner Nester Ag,LLC

Baseline fertility recommendations have been around for years and have stayed the same over time. Keep a certain pH; 1.2 pounds nitrogen per bushel for corn; ranges of phosphorus and potassium that are considered low, medium or high by looking at the number on a soil test; and “removal rates” based on element levels per bushel.            

Many of these needs were based on “efficiency factors” that may have estimated your crop could find 70% of available nitrogen, 30% of available phosphorus and 40% of available potassium.            

These were decent recommendations for their time, but very general in nature, and led to blanket applications of nutrients that could mean overapplication based on unrealistic yield goals and non-representative soil tests. Over the years, farmers got the impression that more fertilizer equaled more yield potential.            

Fast forward to 2010. Things have changed in a hurry in agriculture. Many of the input costs have increased by two to 10 times. Equipment has gotten much better, especially planters. Hybrids and varieties have many advances, and seed treatments, along with the planter improvements, have made near-perfect stands possible.            

Weed-control options are many, so competition for nutrients should not be a problem. GPS has brought evaluation tools to field level for every farmer that wants to learn. You can now know more about your own performance than ever before and make better decisions for nutrient management.            

Let’s talk a little bit about soil testing. This is an excellent tool with many uses, but widely misunderstood. When grid sampling came out in the 1980’s, it was thought to be state of the art. (This was before invention of the yield monitor.) The good part of grid sampling was it got farmers to soil test. Many were doing very little testing at the time, and what was done was not representative, perhaps one sample for 40 acres.            

One bad point of grid sampling was that it preceded digitized soil surveys, so it ignored soil types. It cost a lot of money to sample on 2.5-acre grids, so most farmers were asked to live off that one test for 5 years, a risky move with fertilizer dollars.            

This system ignores two of the most important elements of a representative soil test: The farmer and the local agronomist or CCA. No one gets asked where to sample except the computer. Give it a boundary and it will tell you where to drive the ATV to for sample No. 1.            

And once the ATV is parked, the sampler takes five or six samples, puts it in a bag and sends it to the lab. The lab runs the analysis and magically, when returned to the software, those results now represent a 2.5-acre grid.            

But, was that grid adequately represented? No! A 10-by-10-foot area was sampled, and there are 1,090 of those in 2.5 acres. And then, besides being non-representative, variable-rate nutrients and lime are applied, creating more variability than was present to begin with — depending on the mathematical equations chosen in the software.            

This type of nutrient management was widely used as a marketing program by fertilizer dealers to differentiate them from their competition, justify variable-rate technology equipment and develop another business enterprise. Could variability be shown? You bet! Could the products be varied? You bet! Could results be analyzed and best management practices that were more economically and environmentally sound be established? No. Another case of “more is considered better.”            

Now, let’s look at the actual soil test. Guidelines assumed all soil tests are created equal, and they are not. Ten different labs can give 10 different results, depending on the methodology used at the laboratory. Not wrong, but different. The challenge for the agronomist and CCA is to correlate consistent lab data, from well-represented samples, to crop growth.  But, it’s extremely difficult to compare one lab’s results to another.            

The most variability probably comes at the field level and the person pulling the sample. Close-core inspection, so the area sampled is representative, is a must. You can mix two soil types together in the same bag and the lab will return an analysis to you, but it may well represent something that is not even present in your field. You make an application based on it, get no results and create variability.            

I’ve also seen samples taken by people that didn’t realize the depth needed to be strictly controlled at 6.67 inches, unless otherwise directed to the laboratory. Analysis equipment only can measure parts per million, and the industry assumes one acre of soil 6.67 inches deep weighs 2 million pounds, thus the “pounds-per-acre” figure on the test.            

Does it really mean pounds per acre? No, it’s just a number to correlate to crop growth. If the sample depth is anything different than 6.67 inches, and not noted to the lab, poor representation results.            

Good representative soil samples on a regular basis — at least every other year — can help you build a good database. This will allow you to verify the accuracy of your tests, and enable good fertility and lime recommendations.            

I’d suggest you use a laboratory that participates in the North American Proficiency Testing Program. These laboratories are checked for accuracy regularly and scored accordingly. If the lab you use doesn’t participate in the independent rating program, ask them why not.            

Huge dollars in the farmer’s budget are riding on sound fertility recommendations every year. Those recommendations are also the key to environmental stewardship.