Agronomics101

Smart Fertility — Speaking About N&P

Happy June to all who visits and reads our blog!  Mike Petersen here for just a brief bit of Introduction of our new Agronomist Mick Goedeken.  Mick is jumping in where angels fear to tread these days; that is right alongside of me the  Soils Guy for Orthman.  He is learning real quick that soil jammed under the fingernails is a common occurrence around here and digging to look at plant root systems as deep as need be is the modus operandii.  I have asked Mick if being down on his hands and knees is a bad thing for his posture and back, he has not complained yet.  Mick hails originally from up near Columbus, Nebraska and has a rich background in the Ag World which both of us find extremely helpful and aids our speaking with growers all across the globe for Orthman Manufacturing.  Before Orthman (he started in April 2021) he worked as the research agronomist for Central Valley Ag out of the Waco, Nebraska site.  His contact information is under the Contact Us tab or right here:  Mick Goedeken, 402-860-2489, or email: mgoedeken@orthman.com.

So please welcome Mick and read his first sashay into the Precision Tillage blog realm of writing and offering up-to-date material that fits the scope of Orthman Manufacturing, how we address fertility and important concepts of fertility management in today’s Agriculture.  I am pleased that he is working with me as we communicate how Agronomics affect the Top company of Strip Tillage, very likely Worldwide.
Mick Goedeken, Precision Tillage Agronomist – Out Standing in His Field

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

Many outside the Ag industry complain about nitrogen use efficiency(NUE) for corn being poor and not good enough.  They also point fingers and blame the American farmer for Phosphate pollution.  This blog article will examine smart soil fertility and how we can improve NUE and phosphorus use efficiency (PUE).  Is it possible to improve NUE and PUE on American farms?  Is it possible to improve efficiencies and maintain yield and profitability?

Let’s look at NUE first.  Throughout time the NUE of corn production has seen continual improvement.  Figure 1 from the USDA compares average N rates to average US corn yield.  From this graph we can calculate NUE by dividing the average N rate by the average yield.  If we look at 1970 and 1980 both years averaged 1.35 lbs N/bu of corn.  When we look at 1990 the US average was 1.15 lbs N/bu then improved to 1.0 in 2000 and by 2010 had improved to 0.89 lbs N/bu of corn.  Over the 40 year period we have seen an improvement of 0.46 lbs N per bu or about 0.11 improvements every ten years.  I would say that improvements in genetics, farming practices, a better understanding of soil microbiology, and N management have helped us improve NUE.  Corn grain removes 0.67 lbs N per bushel of corn therefore, it is the opinion of this agronomist that NUE cannot dip below 0.67 lbs N/bu without robbing N from soil organic matter.  Realistically I feel that an NUE between 0.70 and 0.75 is both attainable and sustainable.

Figure 1: USDA Data Comparing Nitrogen Use from 1965-2010

How can we improve NUE? Understandably every operation is different and each individual field within an operation can be managed differently.  When N is applied quite simply there are four things that can happen it can go up, down, in the plant or into organic matter.  N goes up through gaseous losses to the atmosphere and can be volatized ammonia, N2, NO or N2O from denitrification or plant loss as NH3 due to excessive uptake.  Figure 2 has a Nitrogen cycle from Oklahoma State University where yellow indicates N losses and green indicates N additions. When nitrogen goes down it is in the form of leaching or moving below the rooting profile in the form of NO3-N.   Nitrogen can move into the plant as ammonium NH4-N or nitrate NO3-N.  Most N moves into the plant in the nitrate form through mass flow.  Finally N can be immobilized into the organic matter pool.  Some agronomists and scientists consider the immobilization to organic matter as a loss but others such as myself consider it as a storage that can be used later.  Many have tried to manipulate the nitrogen cycle over the years but Mother Nature will only allow attempts to be short lived.  For example, nitrogen stabilizers can help prevent volatilization for a short time (usually 7- 10 days) by preventing the urease enzyme from interacting with urea containing fertilizers.  Likewise, nitrification inhibitors can slow or stop nitrification for a short term (usually 10 days to 2 weeks) by slowing or stopping the nitrification pathway typically by disturbing the bacteria nitrosomonas and nitrobactor that are responsible for converting ammonium to nitrate in the soil.  Utilization of urease inhibitors and nitrification inhibitors are one step to improving NUE.  The most dramatic changes to NUE can be gained by gaining an understanding of when the corn crop needs or uses N.

 

Figure 3 is adapted from How a Corn Plant Develops (see graphic to your left) and will help us better understand when N is needed for corn production.  If we look at the corn crop over 120 days then split that into 40 day increments it helps us understand when N is used.  During the first 40 days corn only uses 15% of its N needs while during the 2nd 40 days it uses 65% of its needs leaving the final 20% being used in the last 40 days.  This is why I find front loading N baffling and especially 100% fall anhydrous programs that can lead to yield loss, financial loss and cause pollution of ground and surface waters.  For example NH3 applied November 15th for corn planted April 15th must be available 5.5 months after application. This is a lot to ask of any product but even more by a product that is vulnerable to loss.  Loss of N is minimized in systems where N is spoon-fed through irrigation applications where 45 to 75% of the N is applied through fertigation.   Understandably, this is not always an option but split applications can still be utilized. For example 25% of N with Strip Till followed by 25% with the planter and 50% sidedress would spread the N loss risk out a lot and insure that N was available during the peak need during the plants second 40 days. Decreasing risk leads to less loss and more available N and can lead to more yield therefore increasing NUE.  Take a look at your NUE and think about spreading your risk is there any option to add another N application to your system that could help you improve NUE on your farm.  Is there room in your system for 1 more application with 20% of the uptake occurring in the last 40 days if we can find a way to apply N later our NUE will improve.

Figure 2: Nitrogen Cycle  Courtesy of Oklahoma State Univ.

 

 

 

Phosphorus use efficiency (PUE) is more difficult to calculate and evaluate than NUE.  The reason for the difficulty is because of the multitude of forms in the soil along with the number of reactions that can occur to each form.   There are differing opinions on how to measure and calculate PUE.  Crop recovery efficiency is calculated by knowing uptake from where P was added and where no P was added calculating the difference and dividing by the amount of P applied.  This always requires a check and can’t be calculated after the fact if a check was not left for comparison.  Another method known as the partial nutrient balance (PNB) is calculated as P uptake by the plant divided by P fertilizer applied.  PNB can be expressed as P removal-to-input ratio or as a percent.  If the PNB is greater than 100% then the plants are removing more P than is being applied resulting in mining of P from the soil.  Conversely if PNB values are extremely low then the P is being used inefficiently.  Typically values for PNB range from 50-70% but can also be higher.  I prefer PNB because I can calculate this post-harvest just by knowing the yield and the P application rate.

Because there is legitimate concern for rock phosphate reserves and how long they will last we must utilize our P as efficiently as possible.  Agronomists, growers and researchers need to explore other P sources that are available, look into new technologies; recycle waste products and most of all utilize P with good agronomics.  In order to improve P efficiency we need to make sure we are managing P in a good agronomic fashion by applying the P with the four R’s (Source, Time, Rate, Place), also make sure that we lime acid soils to help keep P available while managing P with some form of site specific technology at a density that can be managed on your farm. In either liquid or dry forms banding P is more efficient than broadcasting either no-till or incorporated because there is less soil and fertilizer interaction therefore limiting the amount of P tied up by the soil.  In short we can calculate a PUE and from that look at our own operations to find ways to improve PUE and make adjustments to our farms to improve our stewardship and demonstrate to the general public that we are doing a great job with what tools we have.

 

In a world where food production is so vital and yet so ridiculed we have to promote ourselves.  Share with a stranger today how you are improving NUE or PUE on your farm.  Let them know that you are trying hard to be a good steward every day.  Show everyone that by improving nutrient use efficiencies the American farmer is producing more with less in order to feed the growing population. At the Orthman research farm and trials with partners across the globe we are studying different forms of fertilizers and comparing placement of fertilizers to improve both NUE and PUE.  Our Orthman team is committed to demonstrating and recommending the most efficient practices for crop production.

Some recent Canadian Strip Till Research — Two year study to Answer Questions on Fertilizer Placement

The questions asked by corn and soybean growers in Canada relate to many of the farmers in the Great Lakes Region and Northern Tier States.  This was published in Field Crop News, Ben Rosser author.  I shortened up some of the questions and comments including findings of our own with our own (Orthman Mfg) studies.  Field Crop News Story was written April 28, 2021.

                           Those Questions:       All of the trials were planted to corn.
1.  How does broadcast P&K compare to Strip Tilled more precise placed fertilizer methods?
2.  Is there a preferred time to strip till, spring or fall?
3.  If a grower applies P&K in the fall with a strip till implement is there any response when splitting part of the load to the planter?
4.  How does yield performance of strip till compare to full width tillage?

The two years of study were carried out in 2019 and 2020.  Mr. Rosser reported that 60lb/ac both of P and K were applied on ten trials with low soil fertility numbers.  The region where the trials were from west of Kitchner, ON to north of Hampton and one site SE of Ottawa.  Soils were sandy loam. loam, silt loam and clay loams.

Example of an Orthman 1tRIPr following Corn

The treatments:
1.  Full width tillage, no P&K added – control
2.  Full width tillage, spring broadcasting of P&K
3.  Full width tillage, 50% spring broadcast and 50% applied with the planter in a 2×2 band
4.  Fall strip till, , shank placement of P&K
5.  Fall strip till, 50% shank placment, 50% spring placed with planter 2×2
6.  Spring strip till, shank placed P&K
Note: Broadcast applications were broadcast between the tillage passes for incorporation.  All treatments received 30lb/ac N as Urea in a 2×2 band on the planter, then later a sidedress operation was carried out to apply the balance of N.

Some of the findings after two years……….

So over the two years of this three year study the yield responses of broadcast P&K compared to no P&K in the full width tillage systems depicted a 15.6 bu/ac yield bump, one site had a very significant jump of 36bu/ac improvement.  Then as they broke it down further with the comparison of spring strip till and placement to broadcast/full width tillage in the spring, the spring strip till yielded 6.7 bu/ac better with three of the ten sites dropping 1 to 2.5 bu/ac.  One site the strip till spring application site yielded just under 20 bu/ac better than the full width tillage.  Attempting to answer the question of fall vs spring applied with a strip till implement; the study shows an overall 5 bu/ac improvement in yields with spring strip till compared to fall strip till.  One site of the ten had a near 9 bu/ac fall off in yield and one site had a near 17 bu/ac bounce.  Last idea covered, if a grower fall applies P&K in the strip, is there a yield response for moving a portion of his/her fertilizer to starter P&K on the planter in the spring?  The ten sites indicated that there was little difference between 50% of the P&K applied with a fall strip till pass and 50% as planter starter relative to all the P&K applied in the fall and no starter in the spring.  Average was a 1.7bu/ac advantage with two sites near 7 bu/ac and 6 sites hovering zero to 5 bu/ac drop off.

What we have observed in the lower 48………

At our Orthman Farm near Lexington Nebraska for two years we set up trials with center pivot irrigated corn, with strip tilling in the fall and applying dry 11-52-0 and 50 lbs K2O in 2009 and 2010 comparing to strip tilled in the spring a liquid program fir both seasons.  The harvest of 2009 crop yielded in the spring strip tilled liquid fertility 17 bu/ac advantage over the fall dry fertility strip till, then in 2010 the spring strip till fertility program out yielded the fall applied in the strip dry program 11.5 bu/acre.  The soils we were dealing with at Lexington were clay loams and moderate to high fertility.  Orthman no longer has access to carry out trials at that site since 2015.

This year at the McNaught farm near Polk, Nebraska under furrow irrigation we have put together numerous studies but one is a fall strip till application of P applied at 75 lbs/ac actual using 11-52-0 compared to a liquid applied program in the spring strip till pass, same hybrid of corn with the same amount of P.  We also have a replicated site of 3 different starter fertilizer blends compared to no starter but all had a liquid blend of N-P-K-S-Zn with the strip till.  This is a study similar to last year (2020) to determine the effectiveness and advantages of starters.  You can review in the Agronomy blog articles by scrolling down to late last fall on this PrecisionTillage website and see those comparisons.

Closing Comments from me the Soils Guy:

What I have observed with our Orthman studies across a span of years (2006-present) and overall 1986 to present, spring strip till with fertilizers applied with the shank of a strip till tool will and has provided yield improvements dry broadcast and full width tillage 98% of the time in that span of 35 years.  In the early years (1986-1999) I observed big jumps especially in first time strip till under irrigation use with compaction alleviation and fertility in the roots pathway up to 50 bu/ac.  All of those observations came from the Western Corn Belt.  During those years of 2000 to 2006 I did see corn yields continue to rise from 190-220bu/ac to 280 bu/ac steadily with shank strip till tools in the Western Corn Belt.  There was three years in Western Nebraska 01, 02 and 03 that drought was a killer to yields but strip till out yielded full width tillage corn 25 to 80bu/acre.  N, P, K placement was all part of the nutrient strategy in those years but heat and lack of help from the sky just toasted corn those three years.  More recently, 2007 to 2020 irrigated corn yields in the Western Corn Belt due to even better fertility management programs, improved varieties, better managed irrigation water corn yields under strip till out shines broad acre tillage systems greater than 75% of the time.  Top notch farmers in both tillage systems can tap and exceed the 300 bu/ac mark.

With the Orthman 1tRIPr system across the United States where corn is being grown for grain and ethanol production as well as feedstuffs, growers are excelling with the use of precision placed fertility in the root pathway.  It is my observation and continuing urging, growers do annual soil testing.  Know what you have in the soil profile to at least 12 inches (30cm), even better look to 24 inches (60cm) and gain from that data for you can grow great crops with less applied N-P-K than the broadcast methods.  How much?  All depends upon using the right products, right time, right placement and the right amount to furnish the crops physiological needs.  It is not a program to dump loads of fertility with the strip till before planting and think it’s all there and ready to go.  Incremental feeding has proven best hands down year after year.  We at Orthman are continuing to study fertilizer placement, why the 1tRIPr is an excellent tool to prepare the soil for a bumper crop (when the Good Lord smiles upon us all) and we work to improve the tools and methodologies.

I am grateful that a group of people in Ontario; Grain Farmers of Ontario and the Canadian Agricultural Partnership funded this three year project to further the information and method of Smart Strip Till Practices and we will see what Field Crop News writes this fall.

Deep soil profile bacteria – recent findings affected by Strip Till.

Science of soils, a pursuit I have engaged in for over 50 years has been rewarding and yet quite challenging to consider the wide spectrum of physical, chemical and biological factors that affect plant growth.  From the very start of a seed placed into the surface horizons of the soil profile to the time the plant transcends to senility and is ready for harvest or the completion of the flowering stage and dies – the soil is intricately stitched into the plants life cycle.  Considering all of the physiology of the plant, it’s chemistry of what goes on via photosynthesis, the association of microbes on the roots, those microbes that live on the outside plant tissues, heat and cold responses of the above ground parts to the roots in the soil, what a complex and intricate system.

The graphic to the right depicts when soils dry out what happens to the soil bacteria populations in the upper reaches of the soil profile in many cropland soils.  This information I read twice to absorb all the terms from “Frontiers in Plant Science” by Naylor and Coleman-Derr.

Conceptual diagram of drought stress changing biology in soils. Courtesy: Naylor & Coleman-Derr, Frontiers in Plant Science, 2018

For the grower of foodstuffs we far too often take for granted this all happens with very few glitches.  Oh sure the rain does not come as we like or prefer, wind blows like the nasty derecho of 2020, frozen water in the form of hail stomps and rips plants to pieces and we take our lumps even shed tears.  We at Orthman consider how we engage with growers to minimize tillage, help with you managing your soils to minimize any and all erosion by wind and water, offer you good options to place nutrients in the pathway of the crops root system and a systematic approach of growing your row crops.  Strip tillage ever since the concept arrived back in the 1980’s and hesitantly has been adopted, we offer the Orthman 1tRIPr originating out of southwestern Nebraska by a good friend of mine to be a tool in a farmers crop management toolbox.   A useful and good tool is known beneficial by the worn paint, replaced parts at the right times, placed under a roof, known exactly where to be found, talked about how handy it is and how long it has been in use.  Much like my grandfathers 12 ounce hammer he passed on to me with the original handle of ash, handle is worn where gripped since the early 1920’s, few chips and has tapped in thousands of nails.

 

 

 

 

 

 

Proteobacteria – very mobile with flagella to push them around in soil solution

IMPORTANCE OF SOIL MICROBIAL FAMILIES:

What does that you say, have to do with roots, green leaves and here soon planting seeds for much of the U.S. to grow green crops across the summer months?  For you strip tillers, knowing that your strip till unit will till the narrow strip right where you want to place seed, at a specific depth you can apply and place nutrients, accomplish this at a best thought out rate and the right time with the right material.  Following this you are doing the best to protect the soils resources from erosion keeping last years crop residues (which some growers have dubbed as hay – why hay, because one man told me it is hay/feed for the microbes) to maintain the cycle of life in the soil.  I find what this grower in North Texas told me that I knew he has the right attitude and concept of soils in order to grow sustainable top yielding crops.  The science of how soils churn and turn in situ (right in it’s rightful place) and give up water or take it in, make nutrients available in a correct form, exchange gases, cool and heat up, and continue as a medium for plants to live and thrive continues to fascinate me.  From all this love affair with “Dirt” I want to bring items I learn about to you all, get to experience and yes fill your heads to a breaking point of slow down Petersen.

For those of you who are paying attention to soil health and what all that means to being successful and continuing to grow crops that are high producing and economically steady for your budget; I am learning more and more about microbial families that inhabit soils at depths all the way to 😯 inches deep.  Unfortunately the talking heads about soil health usually don’t discuss the one celled critters down below 40 inches, we are reading about and finding certain species are more prevalent below than in the upper 1 foot of the soil profile.  Several of the deep to very deep living bacteria of the Proteobacteria are known to fix nitrogen for spruce and Lodgepole pine trees. Others will use organic acids from root secretions and in turn deposit elemental sulfur potentially available for uptake.  Alcaligenes are found deep in soils where nitrates or nitrites are present and will digest raw minerals in the soil making it available to plant root uptake.  Proteobacteria are the largest group of bacteria below 45 inches in many of agricultural soils.

TILLAGE PLAYS A ROLE IN MICROBIAL LIFE OF THE NEAR SURFACE AS WELL AS DEEPER PARTS OF THE SOIL PROFILE

Another important find, conventional tillage will enhance different species at depths compared to Conservation till such as Strip tillage or No-Till.  Specific bacteria  thrive in the upper 30cm (12 inches) and others like the cooler less range in temperature of the depths below 39 inches.  Quite interestingly with depth and higher bulk densities, the richness of soil bacteria may be under 280 different species down to as low as 11 different species in over 700 hundred soil thin sections analyzed.  This suggests that within a neighborhood of bacteria in deeper sections of a soil profile (>36 inches deep) the diversity of bacteria is low and tells us something about how they interact with cultural events such as tillage above them in the upper reaches of the soil profile. Also microbiologists are accounting for the lack of variability in bacteria species at deeper depths due to the organic substrates from plant/root tissues.   As I consider this it makes sense unless the management of soils includes several crops in rotation and deep rooted crops versus less prolific rooted crops.

A conclusion made from several scientists that deep soils are a critical zone for carbon sequestration and too often today the issue of what goes on below 30cm (12 inches) is not considered and those bacteria down deeper (Proteobacteria) are aiding in storage of carbon. This begs the question for students of soil health, who is doing what and how do they interact with one another to store carbon and if less tillage accentuates the potential to store carbon and nutrients deeper – this needs studied more.

We can say to these findings; great stuff, we already knew strip tillage was beneficial to healthier soils, now this may indicate it is making a difference down deep.  At Orthman Manufacturing we are wanting to know more about the entire soil profile, not just the upper 12 inches.  As we learn what Strip Tillage accomplishes by our own research and what others across the globe learn, it is our intent to make it available to you.

 

REFERENCES:

Naylor, D., and Coleman-Derr, D. 2018, Drought stress and root associated bacterial communities. Frontiers in Plant Science, January 2018 | https://doi.org/10.3389/fpls.2017.02223

Recently an Ole Friend spoke of 4 Supporting Principles that Boosts Soil Health

Long time friend in the business of we who are called “dirt daubers”, “badgers of soil survey”, “two legged moles” – Frank Gibbs was interviewed (recently) by folks with Strip Till Strategies to give his thoughts on what he saw were driving factors from the strip till world and those growers that practice strip till to improve soil health.  Frank and I have known each other for sometime now and when we get together we enjoy talking how soil science stained our hands and thinking over the years, all in a way that is good folks.  Frank numbered off four specific thoughts; 1) Limiting your soil disturbance in a consistent manner, 2) Find and fight soil compaction, 3) Keep fields green whenever you can, and 4) Support soil biological diversity.

I am not going to repeat or totally focus on what Frank said in his interview and then words on paper.  You ever watch the YouTube videos of Frank smoking the soils, oh you gotta folks.  Frank maybe a 1970’s throw back when long hair was in but man he does have some things to enlighten you regarding earthworms and their incredible importance to the soil profile.  I will touch on that here in a couple inches down on this page.  As a soil scientist essentially since I was 4 when my father gave me a small shovel and allowed me to play in our garden on the farm.  I would bring pockets full in my bib overalls to my mother of worms, and other creepy crawlies that were in the soil to tell her all about what was going on in the garden.  Later in my teen years I got involved in Vo-Ag with Land Judging and told myself I was going to be a soil chemist and study all about worms in college.  Land Judging and later at the University I was on the collegiate soils judging team for all four years – pursuing the perspective of the earthworm so to speak and why soils are so intertwined into the web of life for all who engage in Agriculture and working with soils to grow foodstuffs, fiber products and feed.

Allow me to walk through the same four ideas he presented but from a bit of a different slant.  (Image of Frank Gibbs doing his thing showing the extent of earthworms by sending smoke thru their tunnels)

  1. Limiting your soil disturbance in a consistent manner — As I have learned, used, set and reset our top notch Strip Till implement the Orthman 1tRIPr in the field(s) for our research efforts and farmers all over this globe to grow row crops I see with what we aim to accomplish in the soil is extremely important to crop development.  Minimizing hurricane force disruptance of the soil biological realm but we aim to concentrate action to accelerate root growth, place nutrients in front of the root growth pattern since roots are blind to seeking out nutrients, warm the cold soils uniformly where the early root system will go downward by gravity and following a warming front.  This operation with a strip till tool is once and you have done the tillage, unlike a moldboard plow system integrates multiple passes before the seeder or planter comes to start the incredible plants journey from seed to seed.  We know that pulling the 1tRIPr whether three point mounted or pull type we are keep the tractor from installing nasty compaction.  Subsequent passes of spray equipment, cultivators for those that use that method for weed control or preparing the furrows for gravity flow irrigation, and then harvest we encourage folks to be smart how they follow through the field.  However all of the over-the-soil surface passes and/or hoof action from the previous year we can take care of in a zone approach with the Strip Till tool.
    As Frank Gibbs stated jumping in and out of trafficked patterns and using disks one year, then vertical tillage or even heaven-forbid a moldboard plow – you will never get anywhere in obtaining a healthy and vibrant soil.  I am in agreement with his statement.  Stay consistent even for the guy that raises corn and soybeans which is a limited crop rotation methodology when you consider how biological processes should work in the soil.  Now if there is a real wet fall and you created ruts because the crop still needs to come off and a vertical till tool is used to smooth those ruts (only where they exist) out then so be it.  But folks do not go out and disk the entire field for 6 or 7 rutted spots or just the ends of the field.  As Frank noted, it takes it overtilled soils up to five years before the earthworm population comes back to where they are really doing their jobs.

    Use the strip till tool each year and you will see soil intake rates improve, biological activity can increase, soil permeability improve also, and soil tilth will get better.

  2. Find and fight soil compaction — I have had a focus on soil compaction in my soils career since 1981 and the detrimental effects to roots, water uptake, nutrient uptake, crop health, irrigation water management, soil erosion (wind and water), pollution from soil runoff both in solution and what adheres to soil particles as well as siltation.  I have observed cattail marshes where they should have never been in the arid west but over irrigation, runoff, erosion, siltation has created these marshes in draws and low lying areas once only inhabited by native grasses and shrubs.  Why do I see compaction as a causal agent of such marshy areas?  Where I have lived now for forty years in the semi-arid western United States growers have been blessed with adequate amounts of surface water from snowmelt into ditches and pipelines to water crops of all kinds since the 1870’s and earlier.  First it was garden sized plots that were maximum tilled and prepared to grow potatoes, grain, vegetables then sugar beets came along, corn, dry beans, tomatoes, carrots, turnips, lettuce crops of all kinds, cabbages, snap beans and a dozen more types of crops.  All grown out of the mindset of full blown tillage, raking, smoothing and so on to place the tuber piece or seed in the ground for see-to-soil contact and a harvest in a few months.  Left over crop residue – oh that has been called TRASH, stuff to throw away or bury – nasty stuff.  Yet all through this process the tillage was done with a plow to turn, scrape and smear soils upside down, cross ways and be ready for seed and water.  Unfortunately we did not know enough about the resilience of soils, its biology, loss of organic matter until the 1930’s when soil erosion became a monumental issue for this nation.  I digress, but the damage was done by too much tillage and underneath where the tillage tool stopped it’s penetration – a smear zone was created  and year upon year a thin layer stacked on top of another created a layer of soil compaction.  In the world of soil vernacular we call that platy structure and yes it is nearly always man-made.

    It is vital for all growers to know whether they have compacted layers in their field, if they are at the ends or turn rows, where the harvest machinery parked and multiple passes of heavy trucks and wagons placed huge weights upon the soil and compressed it down.  Now dry soils have some resilient features about resisting compaction but not after multiple times of 30-40 tons of grain and cart go over the same spot.  As they say in Minnesota, Uffda!”  With all of that said we strongly urge growers to see where the compaction is in their fields.  At the ends, in specific rows as where you are controlling traffic, parking areas, wet soil spots, etc.  Then to know where the compacted lens or spot is in the soil profile will determine what is the course of action needed to remedy such a restricting layer.  Using a soil penetrometer offers a great perspective where such a zone can be in the upper section of your soils profiles.  A penetrometer uses a 1/2 or 3/4 inch cone shaped tip to offer a good idea the start and end of compacted layers.  There are other small pocket penetrometers which can do much of the same utilizing a set spring tension to force the 1/4 inch shaft into the soil at different depths.  They are quite accurate and I am a big proponent of using these instruments.  You still have to do some digging of a hole or small trench in the ground to expose a vertical face then push this small tool in the soil face.  They usually measure soil resistance in foot pounds per square foot.  That can be converted to pounds per square inch much like hydraulic pressure of soil resistance.  Now doing this when soils are dry will tell you very little due to soil resistance is always high when dry.  Best time of the year is now in the spring after soils have had some winter moisture and thawed.

    Examing fields for compaction after harvest offers a great look at what not to do and what to do.

    Once you have determined the depth, the thickness, if it is consistent in a lot of your field and how dense the compacted zones may be, then a course of action comes into play.  A yellow flag I pull out is – do not get crazy and think a huge 24 inch ripper needs to come out and rip, snort and tear the dickens out of stuff and pulled to a depth of 20-26 inches.  That is costly, fuel foolish, time wasting and loads of more details besides not good for soil health.  Ask a soil scientist, connect with your agronomy Extension agent, call me, email me or any of my cohorts you can find on this Website under our Contact Us tab.  We are more than happy to visit or even stop in and help guide and visit about such an endeavor.

  3. Keep fields green whenever you can — This usually entails cover crops or just plain focused planting of a small grain right after harvest and before freeze-up in the late part of fall.  Many are looking at early in the growth cycle of you target commodity crop of seeding a mix of grassy crops or broadleaf plants to grow at a reduced seeding rate to put more carbohydrates in the soil via the different roots and sugars, proteins, lipids, hormones and attractants to other fungi and microbes.  Covers are good for erosion protection but mainly to add to the organic matter foodstuffs to microbes, fungi and other miniature microorthopods as well as earthworms.

    Cover crops in furrow irrigated fields is quite tricky but can be done, takes some real deliberate actions and thinking to make all that work.   Frank was upfront about this concept of keeping something green on the field as long as one can in a season.  “You should have a legume to create nitrogen and break down residue,” he says. “Then you need a carbon source — like the grasses. You should also have a reservoir to store the nitrogen over the winter and release it in the spring. Brassicas like radishes and turnips are best for that purpose. Having those three plant types in a cocktail can make a huge difference.”  It is a systems approach folks, do not just slap oats in a spinner and drive out over the field in late June and expect this seeding to be the answer.  Consider the natural balance of nitrogen to carbon ratio of what your doing, will the cover aid my mycorrhizal fungi or set it back?  Will it take too much water away from my intended crop, ie: corn?  The cost factor is always part of this.

  4. Supporting and promoting soil biologic diversity — this thought process is not all that clearly understood until you as a farmer know for certain who lives out there in my soils and have I done some damage to their population in the past with insecticides, herbicides and tillage operations.   Grasses, legumes, fat root growing crops/plants, they all release different hormones, acids, sweetners, carbohydrates, proteins, fats and thusly attract different families of microbes to live on their epidermis and accomplish different facets of the soil ecological system.  There are those that fight off diseases, and there are good guys that infect nematodes and kill the parasitic nematodes.  There are specific fungi that excrete and secrete complex proteins that are a gluing agent to hold soil particles together – a significant factor in stable soil aggregates, a feature of soil health I cannot emphasize enough.  This is a recent advancement and find in the last 15 years of soil biologic and microbiology research.

    The importance of those one celled microbes living on the root epidermis and maintaining life off the sugars and fats the root cells leak into the soil rhizosphere is amazing.  They exist off those by-products from the root leaking but convert carbon materials, then they die and release those nutrients directly to the root and feed the plant.  Millions of these microscopic critters are grazing off the plant stuff, eating carbon materials every hour of the day when the soils have warmed up enough to fully sustain life.  The soil ecosystem is an amazing self perpetuating engine that you as a farmer are harnessing to use to grow a corn, soybean, lettuce, potatoe or sugar beet crop.

    A suggestion I have for all growers is to not only find out if your soils are active and to a degree healthy, but to find out who lives in your soils/fields.  There is nothing cheap about getting soils tested to find out who lives in the upper 12 inches of your soil profiles.  But in your regards to making your fields the healthiest you can – see who lives there, why or why not and how you can improve that population.

    As we gain a more informed concept of what soil health is and what it is not, the discussion will always have a facet of tillage.  Strip Tillage can be a key in changing the soil health condition of your fields to a more positive and improving side of how you grow crops.  Please feel free to contact us at Orthman Manufacturing.  Our contact information is available on this website and we are more than happy to be a resource to your questions.  I personally am right there.  Phone: 1.970.302.1442 or at mpetersen@orthman.com.

Carbon banking or sequestration has positive effects for you.

Well the March 2021 snowstorm did lay down some great moisture here in parts of Colorado and then further east into Nebraska, South Dakota and Kansas was great areas covered with much rain.  What all that did beside give me a tired back from snow removal and handling my big snowblower – inside I go to stay for a few days and work on efforts for this website and writing of a forthcoming bokklet on “Root Dynamics and Tillage” [watch for it this fall].  I have written a bit on corn rootworm, compaction, nutrient uptake and moisture… as some of you I hope are paying attention to the idea of companies outside of the world you live in – Agriculture who want to participate in the carbon (C) trading/buying of C credits through government programs or programs initiated by companies like Indio Ag.  Do pay attention folks, there is some value in what they may offer to you in the form of fewer tillage passes down to one-pass as what we offer with the Orthman 1tRIPr implement approach.

Strip till and planter in one pass

Strip tilling and minimizing soil disturbance for residues on the soil and old roots and carbon in the soil organic matter complex to not be released into the atmosphere

In my continuing desire to learn, grow and stay current in soil science research I have been diligent to pay attention to the on-going conversations of carbon and carbon trading.   How do we do it?  How much can be stored in the rootzone?  Do annual crops like corn, soybeans, wheat, dry edible beans, oats and many more store enough to offset what man is purporting to be changing the atmospherical CO2 amount?  Then we read that CO2 at elevated percentages aids the C3 crops (wheat, soybeans, oats) we grow store carbon and can enhance yields some.  With C4 crops (maize, grain sorghum) not as much.

So for this entry of the Precision Tillage blog I am going to offer some  data I found interesting in my text references.  I have come across a long list of resources and the deep dive into C sequestration on the internet is staggering.  Let me tell you all that can be a very deep dive with so many studies and research projects getting published in the last 5 years.

First, researchers Gregory and Barraclough note that for annual crops in the lifespan of those crops (from 90 to 130 days) the early segment of the crop life is when C is stored at some rapid rates.  Then after flowering the C storage drops way back.  Scientists accomplished the actual percentage by using 13C and 14C to ascertain the amounts stored.  In the table below for instance with wheat please observe the amount of C across the growing spectrum.

In this table the scientists observed with wheat that a distribution of the labelled C by percentage of the total measured, ie: 39.6% was found in the roots then later at grain ripening only 10.9%.  Evidence that as the plant life matures less and less of the C allocated and produced goes to the roots.  Reasoning why this happens due to the sink (kernels of grain in the wheat head) is the dominant transfer of carbon in the plant in the way of carbohydrates.  An interesting fact of the soil organic C with wheat later in the crops life is above 41% and root respiration is over 47%.

 

Where does this kind of information go and what does it mean to me?  As you look at what we help you accomplish with a Strip Till System… we are affording you a less than 30% disturbance of the soil surface in a 30 inch row cropping pattern.  We are also helping you the farmer be about minimizing the disturbance below the soil surface to break up residue fragments, old roots, root crowns, buried organic materials, left over root exudates from the previous crop to move into the soil organic complex which is food for microbes, worms and other invertebrates of the soil biome.  In a full width tillage system the ground is rolled, tumbled and exposed to the surface to release CO2, CO, and then oxidation of fiber-type organics, and organic acids and/or sugars up into the atmosphere.  Soil organic matter is the food for the soil microbial engine you rely upon each growing season to also hold water, keep soil aggregates stable, hold onto nutrients and keep soil from eroding away.

This entire subject is growing each day with newly exposed research all to do with carbon being sequestered from trees to ornamentals to rangeland and annual crops.  I thought passing along a portion of what is out there would lead some of you to check out closely the Carbon Credit programs and how dollars may be available in your county. Stay tuned.

Researchers Referenced:

Barraclough, P.B., and Leigh, R.A. 1984 Journ. Agric. Science, Camb. 103, 59-74
Gregory, P.J., et al., 1996, Plant Soil 187, 221-228
Swinnen, J., 1994a. Soil Biol. Biochem 26, 171-182

As you prepare to get the planters ready – Is CRW on your radar?

I know that most of us are still shivering just a little after the cold that swept 2/3rds of the Nation and here I am offering some clues to CRW and what our industry sees as aid in getting farmers back on tops to control if not really suppress these pesky worms.  Some of you may have caught this information, if so it is a repeat but for others as we look to readying the field to plant corn into whether we are planting into 2020 Soybean ground of 2020 corn, corn root worm (CRW) stares us in the face:  “Managing CRW populations is complex, as there is just not one thing that can lead to increased larvae pressure.  Weather can play a role.  Mild winters and springs can create prime conditions for CRW egg survival due to warmer soil temperatures.  Soil moisture can also influence egg survival and hatch later.”  The article in AgriMarketing went on…

“Like many pests, CRW are very adaptable.  Populations are one of CRW species in some regions have begun to lay eggs in soybean fields to get around crop rotations.  If the soybean field is planting with corn the next year, when thos eggs hatch, the insects will again feed on corn roots.  Another species has figured out how to keep their eggs dormant in soils for an entire year – a tactic called ‘extended diapause’.  This allows them to remain in the soil, even through crop rotation, and then emerge when corn is planted again.”

Several CRW larvae doing their root munching. Courtesy Kansas State University

CRW pressure is additionally fueled when growers rely upon Bt corn hybrids that employ just one mode of action.  As CRW has evolved over the last 22+ years, the insect has developed resistance to certain traits in these hybrids and the farmer sees the detrimental effects.  Pioneer, part of the DuPont-Pioneer organization has moved their product lines to employ multiple modes with their Qrome technology.  Bayer Crop Sciences are doing much the same as is Syngenta.

We at Orthman do not want to gloss over the real threats that CRW and ECB (European Corn Borer) or WBC (Western Bean Cutworm) are never very far away from checking out your fields either.  A good Pest Management program of seed coatings like Poncho or Cruiser or even incorporating insecticides during the planting step if the pressures are great is very smart.  The tilled zone we offer with the 1tRIPr Strip Till tool is very important and allows you as a grower to make the incorporation of insecticides an easy step.

Does Western Corn Rootworm Cause More Damage in Strip Till?

Last week in a somewhat surprising question or statement while discussing opportunities to carry out field research; “Is it true that Western Corn Rootworm (WCR) have more of a heyday in strip till outside the strip under the residue in continuous corn?”  My co-worker and I were a bit flummoxed, we have never heard of such.  The claim is that strip tilled corn when the roots go outside the till-zone they are more susceptible to WCR larvae chew and damage.  In all my years of working with, studying, promoting strip tillage since 1986 I have heard of many things.  Now the man telling me this was wanting answers so I went home and began a fairly exhaustive research on-line and have sent messages to seed dealers I know and trust if they know of such.  Still awaiting replies.

After numerous hours going through Google Scholar, Pioneer, Bayer Crop Sciences, ResearchGate websites and several more, asking several different questions to inquire and get a response to the question – nothing that indicates that WCR are more active, more prevalent in Strip Tilled fields and cause more damage outside the till-zone.

Western Corn Rootworm – adult

Western Corn rootworm larvae

 

I did discover that WCR do like later planted corn (in northern hemisphere) late May into June plantings that they thrive and populate heavily in those planting scenarios. I also read that the beetles will lay eggs in soybean fields and continue their lifecycle into next years corn crop for those who rotate with soybeans with very little overwintering effects without corn residues.  A interesting tidbit; For many years it was simply an obscure species until it started damaging corn in north central Colorado in 1909, so this dang bug has been a pest for sometime in corn production. Once the soil temperatures reach 52 deg. F (11.5 deg C.) the larvae can start moving and eating. First-stage larvae are attracted to the CO2 released by corn roots.  Larvae will crawl from 4 to 24inches to reach actively growing roots.  Something akin to one of my wife’s arch enemies – the mosquito.  Those bloodsucking female insects are attracted to humans who exude CO2.

With the advent of the multi-stack of traits and Bt with the Herculex™ materials and SmartStax™ changes, the efficacy of setting back the eating and lifespans of either European or Western Corn Rootworm larvae to adults is very good.  For those of you who also use Poncho Votivo or just Poncho 250, control is in the realm of what you desire.  There are still viable insecticides available to growers that do not want to plant traited hybrids.   Keeping plants from heat or moisture stress is very important for the control of this pest.

Back to the growers question if these pests chew/damage/and populate more in Strip Tilled fields – I came up with nothing in print.  To get a better lowdown on these insects, life cycles, statistics of and more here is a great website:   https://masters.agron.iastate.edu/files/mitchellsteven-cc.pdf.

I will keep looking, listening and asking questions folks.  This pest has been a nemesis to many of you and have had to “bomb” them, use other measures to eradicate/control the cutworm.  At Orthman Manufacturing, yes tillage is our game as well as specialty John Deere planters on our 7×7 toolbars, but farming is a big enough challenge for us all even as we see the corn prices doing better these last few months.  Dealing with this insect is always a presence and in continuous corn like hundreds if not thousands of fields in the Corn Belt of the United States we have to deal with it as well as its cousins the Northern Corn Rootworm, the Mexican relative and the Southern corn rootworm.  In Iowa and Eastern Nebraska I have seen all of these guys in one field – yikes!

Health of the Soil and Root Architecture that Adapts to Aid Soil Tilth

Lots of talk in the Soil Health world lately about all the benefits of generating more living tissue in the upper portion of the soil profile with cover crops, intercropping of companion-type cropping and more.  Within all these conversations, written articles and blogs are we forgetting something?  I do think so.  As a soil scientist who enjoys digging, discovering, observing for some time now I realize soils do have secrets yet to come to light.  How we look at the natural fabric of soils compared to looking at how over the years we have altered soils with tillage, applied heavy forces upon the soils, feeling we have to accomplish a tillage pass or planting or harvesting way before the soil has physically drained?  A good number of us know about compacting soils, especially clayey soils, wet soil conditions and the consequences.  But do we really?

As sure as we know a day is 24 hours in duration, once we as agriculturists manipulate soils wet and often we change dynamics dramatically.  That is not even the half of it folks, roots and root architecture take a back seat in a rough riding Jeep of the WWII vintage, not many like that ride and do not want to go again due to the work holding on or in this case – digging.  Jake Mowrer, Assistant Professor at Texas A&M wrote in a blog not too long ago (first of February) that plants and plant roots have to exert extra energy to modify soil conditions to improve their chances of survival and obtaining nutrients and water.  He said, “The soil is not a very welcoming environment for plant growth.  It does not provide everything a plant needs freely and without reservation,”  he went on, “In fact, left as is, the soil probably would not produce very many plants at all.  Proof of this is found in the tremendous amount of soil modification plants engage in just to improve their chances of survival.”

A lot of what he wrote makes sense.  Draw your attention to soils that are wet like those of locales in Central Iowa, or Northern Ohio near Lake Erie, or the Prairie Pothole region of South Dakota and Western Minnesota where surface drainage and internal drainage are problematic to raising consistent good crops of both crops with fibrous root systems and/or tap rooted crops – soybean and corn.  Old methods of tilling, planting, cultivation since the first pioneers rode oxen or walked wagons west have not gone away.  Growers of foodstuffs and feed crops still till too much or with inversion implements but expecting better results year after year – Albert Einstein made a comment about that which I will let you remember it.  Anyway – Dr. Mowrer says in his blog [https://soilsmatter.wordpress.com/2021/02/01/how-do-different-root-structures-affect-soil/ ] that plants modify the soil; I rather believe plants and plant roots adapt and develop roots to fit the conditions and exert energy to expand to achieve the normal functions of water attainment and accessing nutrients necessary for photosynthesis and reproduction. Maybe that is semantics but I suggest you read his words for he has good points. Carrying this further to

Fig. 1: Diagram of roots, Courtesy: Nature

my 40 years of looking at roots, I have had all those opportunities to offer folks a view of the their soil profile by encountering over 1700 root pits and enough dirt in my pockets that have nearly clogged my wife’s washing machine once or twice.

From the crops we grow around the world there are two dominant root types of root systems, the taproot and then fibrous root system. Mowrer writes in his February blog post that tap rooted crops represent one specific strategy to access water and nutrients held deeper in the soil profile than the fibrous rooted crop strategy.  Roots of grassy crops emphasize growth of laterals and secondary laterals closer to the surface to extract nutrients and water.  A fibrous rooted grass can acquire even small rain events that fall and survive much quicker than a tap rooted plant.  So as an example of adapting; with some grassy vegetation in wet soils they have developed means to keep from drowning in long periods of saturation, for instance cattails, sedges and rushes.  In the instance of the wetland tree – the species Salix, willow is interesting.  Willow’s preference for water means that many of roots will be growing in waterlogged soils or even directly into water. This poses the problem of how to get oxygen in to the root cells. Many plants respond to water-logging by developing air-spaces within the root cortex (the cortex is the parenchyma tissue between the epidermis and the vascular cylinder) which are continuous with the normal air spaces in the shoots above ground. This allows the aerial shoots to supply the roots with air. This spongy, aerated parenchyma tissue is called aerenchyma.  I know, big 5 syllable words.  These soft tissues for holding oxygen is vital to survival in wet oxygen starved soils for trees and wetland grass-like plants.  For maize, the roots do not like wet feet, in fact I have seen maize roots turn back upward when in wet conditions for a period of time, then they stop growing downward and develop more secondary lateral roots above in the more aerated portion of the soil.  Another type of adaptation that works well.

In the cross section to the right in a recent article in Nature (Fig. 1) you can see both micropores and macropores inhabited by roots of primary and secondary lateral roots. The purple color surrounding the depiction of the roots is where the soils are being changed or modified as Dr. Mowrer explains in his blog.  In all my observations this is “the fitting” of the plants root system and architecture.

The interactions of plant roots and soil structure are two-way, i.e. there is also an effect of plant roots on soil structure. During soil exploration, roots push through the soil and alter physical, chemical and biological properties in their vicinity, the rhizosphere. These alterations may persist after roots are degraded, leaving behind a dense system of connected biopores.  These biopores, now become an  integral part of soil structure, in turn feedback on root growth providing pathways of low mechanical resistivity with wall properties reflecting former root activity and in part activity of soil fauna (Lucas et. al, 2019 In Nature).  In the upper portions of the soil profile that are more aerated the soil biology (both fauna and flora) interact with the roots and rhizosphere to supply nutrients and water, ward off diseases and parasitic invaders and live in harmony with the life root tissues.

I as well as Dr. Mowrer look at the distribution of the root architecture depends upon how the plant interacts with macro and micro channels, voids and aggregates forming from decomposing tissues and root exudates.  All of this affect water movement and retention properties of the soil.  The voids (including recent and old root channels) hold oxygen and other gases that sustain microbial and fungal life.  These voids, old root channels with carbonaceous material take on water and during the winter months (where soils do freeze up) will freeze and the ice crystals will radiate outward expanding the voids modifying the soil even more.  All of this aids in soil tilth** and helps roots and plant growth both annual and perennial crops.

**Soil tilth can be described in some general terms; soil physical, chemical and biological properties that promote plant growth, especially that below the soil surface. A soil with proper tilth will be friable (flexible) normally has well developed aggregates and macroporosity and provides the proliferation of roots.

Here at Orthman we see and advise that proper primary tillage management be timed correctly by moisture content, maintaining crop aftermath as much as possible on the soil surface, not rolling or total inversion of the soil.  We are much about how Strip Tillage works with our 1tRIPr tool to develop a proper seedbed, place nutrients when desired by the grower, and develop a root zone for a strong and healthy crop outcome.

All of what we communicate via this website is to offer up-to-date information to promote smart stewardship of your soil resources, conserve and protect soils from erosion, improve your farming practices and help you make profit at farming row crops.

References:

Lucas, M., Schlüter, S., Vogel, HJ. et al. Roots compact the surrounding soil depending on the structures they encounter. Sci Rep 9, 16236 (2019). https://doi.org/10.1038/s41598-019-52665-w
Dr. Jake Mowrer’s article is in the hyperlink, highlighted in blue in paragraph 3 above

Even though for North America we are Frozen!

May I bring some recent concepts of soil temperature and early plant development in the row crops we plant that Strip Tillage has direct influence upon to you to consider?  I have addressed some of this subject in the past in a blog.

Is the Weather outside frightful and the fire inside (in the fireplace) delightful?

As we prepare the seedbed and root zone for the 2021 (yes for those of you that accomplished such in the fall of 2020 too) season we know by research done in the first 12-14 years of this century that a Strip Till System approach warms up quicker and deeper into the soil profile than a Direct Seeding (Zero Till, No-Till).  Strip Till has shown improvements to soil warm up against broad acre conventional tillage most likely 1 degree F or so.  The how much does depend upon the latitude you are.  As those who live in Minnesota, Central Wisconsin, North Dakota, parts of Montana – planting times are bereft with cold soils and for many the older ways usually turned the soils black so they would warm and have what was thought as good seed-to-soil contact.  In those climes, Strip Till (in the till zone has measure 3 to 7 deg. F. warmer than under the residue or in a No-Till environment).  In Central Iowa the strip till in 2 year studies measured 1 to 3 degrees warmer compared to under the residue or No-Till.  In studies in far eastern Colorado over a ten year study we saw 2 to 5 degrees warmer tilled zones each year measured at the 4 inch depth.  During that longer study we had cool springs, warm springs and dry springtime conditions.  A two year study only gives you a short term picture.

What other than warmer conditions which we as growers want to plant our corn or soybeans or other crop as soon as possible to reach our yield goals?  When nutrients have been placed with a strip till implement down between 5 and 10 inches below the surface, none of us want that plant to wait long for the nutrients to be available and spur the plant to grow and take on that “hungry teenage personality”.  So much of the nutrient uptake into a corn or bean crop is dependent upon the roots and microbial population being in sync.  Those little one celled critters to the tune of billions per tablespoon are not really active until for the most part when soil temps reach 63 degrees F.  Not until mid-June do we see soil temperatures below 8-12 inches stay at the 63 degree mark on the thermometer night and day.

Environmental concepts within tillage systems, Courtesy Dr. Wick, NDSU

Watt et al. 2006, determined in a Grains Research and Development Corp research project in Australia that maize roots extended 2.6X more when soils were reaching 84 deg. F than 60 deg F.  What does that have to do withy cool soil conditions earlier and strip till?  To reach the soil potential and what the soil environment is optimal for above and below ground — we at Orthman see the big value in starting off right each seed that germinates and goes on it’s life path.

In a North Dakota study, Dr. Abbey Wick (2019) shows that looking at tillage systems at one of their SHARE field sites, we can see temperature numbers that show differences that Strip Till is a package to give considerable thought to, especially as we look to spring time and wanting to have a great environment for that newly plant crop to thrive in.  What I am saying is, we have to consider how we till soils and how we can positively or negatively impact the soils drives the gears from pre-plant all the way to mid-season folks.  We all appreciate Dr. Wicks work in studying systems to optimize the soil conditions for soil protection from erosion, water management, nutrient management and Soil Health.

Annals of Botany. 2006; Vol.97(5): pp839–855.
Rates of Root and Organism Growth, Soil Conditions, and Temporal and Spatial Development of the Rhizosphere
authors: MICHELLE WATT, WENDY K. SILK, and JOHN B. PASSIOURA

Continuation of the factors that can influence Nutrient Uptake – here we address soil structure

When it comes to the health of the soil, the general consensus is all about the upper 10cm or 4inches.  Haney Tests, the usual  20cm (8inch) soil tests from those who offer nutritional analyses of your soil in a grid fashion or shot gun scatter approach which is not very meaningful, all focus on the surface layer of your soils.  Do your roots remain in the upper 4 inches the entire lifespan of your crop? Well you hope not because the plant would fall over and yield something ugly. For example, roots of a corn plant will reach 48 inches (122cm) quite regularly.  That is over 10 times deeper than 4 inches and there are a good deal of items the soil profile has for you in those next 44 inches.  So I would like to provide you some extra clues on the Soil Structure concept of the latest three blogs I have posted.

FIG. 1:  Image of different soil types, examples from New Zealand. Courtesy NZ Soils

  Soil structure has been just a little of the conversation when it comes to health and soil quality of soils, in fact woefully not thought of in the Soil Health topic and that is a shame.  Structure of soils adds so much to complete the topic of Soil Health.  The conversation circles around soil organic matter and biology – tool little is brought to the forefront with soil structure.  Soils that have a structureless form have all kinds of negative connotations for water movement, root development, gas exchange, soil erosivity, and the biggie – soil compaction.

In the image to your left, the upper right side depicts massive or structureless form.  Soil porosity is usually horrible to non existent. When soil horizons below the soil surface exhibit massive conditions we have to assume soils have been abused, crushed, beaten, sliced, mashed and overall in tough shape.  Some soils that were under glacial ice for so long at a great thickness we can find this kind of form. A tough and serious issue.  There are remedies but all of them take a good deal of time to help.

Soil Structure refers to the arrangement of soil separates into units called soil aggregates. An aggregate possesses solids and pore space. Aggregates are separated by planes of weakness and are dominated by clay particles. Silt and fine sand particles may also be part of an aggregate. The aggregate acts like a larger silt or sand particle depending upon its size.

The arrangement of soil aggregates into different forms gives a soil its structure. The natural processes that aid in forming aggregates are:

1) wetting and drying,

2) freezing and thawing,

3) microbial activity that aids in the decay of organic matter,

4) activity of roots and soil animals, and

5) adsorbed cations.

As aggregates congregate together they take shape into Apedal to Crumb to Blocky and so on.  Soils that have structural types below the surface layer that are blocky or prismatic or columnar are extremely strong and supportive to loading from above.  The more vertical axis of the soil structural type the better water movement and root development deep into the soil profile.  The soils that depict prismatic structure that can part down into blocky structure are fairly mature in age and have been subject to all the 5 items mentioned above.  Gravity is a main factor in all structural unit formation.  Along the vertical faces roots will adhere to the walls, soil organic matter will adhere deep into the subsoil horizons and provide carbon products and also nutrients which the roots and lateral root hairs will access.

When you read a soil profile description of a Marna silty clay loam in Iowa, or a Miami silt loam in Ohio, or a Holdrege silt loam in Nebraska as a few to name off – one will see the horizon designations as Ap, Bw1, Bw2, Bt and so on then words like ‘weak moderate subangular blocky structure’ follow behind that which informs the reader what the soil structure is in a Bw horizon.  Soil scientists that mapped and classified soils for the United States Soil Survey program of the USDA-SCS/NRCS do this in the field all the time.  I know, I mapped soils in three states in my first career with the USDA.

Soil structure of a decently managed conservation tillage program, sound residue covers left on the surface for as much of the entire year as possible and within the cropping portion of the year will provide for good soil structure.  Start moldboard plowing, deep subsoiling (>38cm) 15 inches and deeper and structure takes a beating and takes quite some time to reform, usually in terms of tens to hundreds of years.  Soils in humid, warm all year along have very mature structure types like in Central America.

FIG. 2. Definitions of soil structural types

What does this have to do with me and my soils on my farm or parents place?

A great deal I say.  Having some idea of the horizons in your fields per soil mapping unit in field 11 or field 3 and this can provide you knowledge how they respond differently is partly due to the soil structural types and how well water is absorbed then released to the plants we grow.  I have already written about soil pores and porosity in a previous blog which you can revert to.  The more moderate to strong soil structural units the better movement of water and gases in and out of the soil profile.  When soils are platy which you may have noticed in Figure 2 near the bottom, roots, water movement is all tortuous and slowed dramatically.  Usually in overly tilled soils, it is there due to tillage tools scraping, sliding, smearing on a plane creating layers like separate pages stacked on top of one another.  I am sure many of you know this already, I applaud you for understanding these features of the soil profile.  To further breakdown the idea of soil structure: when the horizons are indicated that it is weak in definition the trend is either the soil is quite young in age or the structure type of subangular blocky is being degraded by abiotic conditions usually.  What does that mean – man is messing with wrong kinds and timing of over-tillage practices.  As I mentioned earlier, when soils are described as massive or structureless – we soils guys or gals have observed degradation at its finest or it is a very immature soil profile.  Do not assume soils with these types of structureless conditions are young and may get better with time.

The soil survey of the county or parrish you live in has all this information as you turn from page to page.  If you have the opportunity to gain access to a day with a soil scientist to explain what you have is good stuff for you to improve upon your soil management techniques, understand the Soil Health or Soil Quality issues and provide you a service soils people love to talk about.