Agronomics101

More Information regarding Soil Health than just keeping some kind of plant living in the soil

Do not get me wrong I am a advocate of all roots; living or deceased doing good for a healthy soil.  But the big emphasis of being Cover Crops as the answer to soil health misses the many decks of a naval carrier like the USS Abraham Lincoln.  What do you mean Mike?  For a truly healthy soil a wider perspective of top soil health I suggest we look at soil structure, soil porosity (the importance of the varying soil pore sizes in the surface soil as well as subsurface and subsoil), pH, and what are the majority of the species of microbes (anaerobes, facultative anaerobes, aerobes).  Not all are represented in your soil surface horizons to be of benefit to you.  Firmacuties for instance when out of balance with other microbes in your soils can be of detriment to your soils be biologically in balance.

How do we find out what we have in my soils?  That maybe your question.  One can run the simpler soil tests that indicate respiration, fine when the soils are active and above 62-63 degrees Fahrenheit, but that does not give much indication who lives there and who is related to who.  Yes I am partly having you consider an more expensive test at a speciality lab.  Now not everyone is into such due to cost and then who knows what the dickens comes from the test, when to do it and where does one collect the sample(s) in the field.  Mike, what other soil tests that you mentioned in the first paragraph for soil health will aid me in determining if my soils are healthy or so-so?  Soil structure whether or not the soil aggregates are stable in a slaking tests which the NRCS can test with and for you.  A true soil scientist can give you an indication of the soil structure if your soils from the surface or subsurface is moderate medium granular or subangular blocky.  Having a soil test for bulk density can be done by some soil testing labs across the country.  Or a look at the soil with a 10X to 15X hand lens on a 4″X4″ block of soil carefully pulled from the 1 to 5 inch area of the soil profile or 2 to 6″ zone.  This kind of sample should be done in the spring or late winter before all the tillage is done.  Besides, the soils should be moist not dry.  Testing for pH is a standard tests from all soil testing labs whether private or University.  The Haney test and other soil respiration tests can be done but they require some handling, and timing issues along with storage and shipping.  Another suggestion; call your friendly NRCS office, speak to them about having an evaluation of your soil health by one of your states Soil Health guys or gals.  Most are very apt and willing to do that for you.

Couple different ways to test for part of the soil health of your soils

Three different tests that will expand your knowledge about your soils on your farms.  The Haney Test is one way as is the PLFA Microbial Community test.  Many more dollars because they are looking at the DNA signatures of the bacteria in the soil sample at the time of the sampling.  The Solvita tests is a one-time sample when the soils are warm (May into late August) to inform you if according to a standard how much CO2 is given off in a 24 hour period.  All of these tests are usually from your surface 4 inches of the soil profile.  If you would sample from 0-4 then 4-8 inches the numbers will be quite different but very informative.  Then there is the ole grab a handful of the soil from the surface 4 inches and smell it with the nose.  If there is that rich, earthy smell that is a little pungent – that is an aroma from the azotobacter and nitrosommonas little critters, a good thing but only broad brush look and smell.  Do not get me wrong, these are qualitative but can be of some good news.

The PLFA tests require as I said some special handling and shipping steps.  Those of you that want to really know will consider these tests.  May I suggest go on-line and search out who does and gives a sound report of what is happening.

When I do Soil-Root Pit digs and evaluations I have done many of the physical tests at that time to inform you of all what I know from my 45 years of soils experience and learning.  I can offer at the same time sampling for the other tests with a pit opened up.

Look into it folks.  The Soils World is an amazing place to learn more about your farming practices and what you are dealing with each year.

 

 

From Germany – The LARGEST Agricultural Exhibition on the Planet

Today is the last day of this  seven day event (maybe it feels a touch longer November 10–November 16), to show our technology and equipment to the all the European geography, Mid-East, Mid-Asia, Australia and some African nations.  Challenges to work to communicate in five and six language barriers  everyday but farming crosses many boundaries and we get the job done.  Our team from the home office in Lexington, Nebraska USA have met with numerous folks from associated companies to extend our technology and solid iron products to other markets that are quite different than the Corn Belt from Colorado to New York.  Twenty-seven of the thirty plus building complex are filled with every imaginable piece of machinery or component you can think of is here, might be in building 17  but it is here folks.

Orthman Mfg, Inc stand with the USA Pavillion

A very active time when a group of German farmers were speaking/asking 101 questions that would handle liquid slurry manure with the Orthman 1tRIPr before a crop of maize.  Questions of why manure is beneficial, why mineral dry fertilizer may have other attributes that applying manure misses.  Manure in Germany has to be incorporated via rules of the government within 1 hour of taking it from the manure pit.  It has to be tested for all the chemical components as well as for pathogens on the biological side.  Then there is a enormous quantity of swine, bovine and chicken waste that has to be taken care of in much of Europe.  Timber handling, to bearings and then to plastics – folks it is here.

We at Orthman Mfg. have shared our Precision Tillage story to growers, dealers, specialists, salesmen of the Strip-Tillage System that are coming to the realization that too much tillage in many countries has greatly diminished soil quality and it’s health.  Compaction is a world-wide concern that effects growers with nutrient uptake, water use, crop yield, fuel consumption and impacts the bottom line — generally quite negatively.  I have had interesting conversations about the lack of understanding of the microbiologic concerns so many have and that Orthman has a part to play in helping growers do a better job of growing crops in their soil system.

The numbers of folks that attend this show/exhibit nears 500,000 this year.  Spanish, English, German, Kazak, Uzbeki, Russian, Ukranian, Dutch, German, French, Spanish, Portuguese, Afrikaan, Chinese, Japanese and Oklahoman has been languages we have encountered. Those are the ones I can remember.

We will get back with everyone stateside next week.  We have learned a great deal and will have gained good information that will take the business and technology of Strip-Tillage and cultivation far into the future.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

News of the Mycorrhizal Front – The Yet to be Further Unlocked Frontier of Soils

I have been reading some very interesting documents (so many of you do not have to put hip waders on to read the Journals) involved with rhizosphere interactions between fungi, microbes, roots and plant benefits.  This is stuff directly from the electron microscope level of detail ladies and gentlemen, but fascinating all the same and eye opening to what transpires on the surface of the rooted crops we all try to grow.  It is my wish to help many of you garner an understanding that the aerobic fungi are sincerely vital to nutrient uptake, root health, water uptake and carbohydrate (which includes sugars) flow within the plants.  I offer a few real nuggets (8) to store in a net of neurons inside your head…

VAM spores and hyphae — Spores are attracted to specific exudates from the host roots. Spores then will infect the host and live symbiotically and aid in propagating the fungus to live again and again.                       Courtesy: Researchgate.net

Fungal hyphae Courtesy: Western Sydney.edu, Australia

  1.  Of the thousands (over 4500 species have been identified by rRNA gene identification processes) of bacteria that grow in soils, scientists have had much difficulty to grow on laboratory media; much due to the mutualistic relationships with one species to another, age of the plant root, soil temperatures changing throughout the season and the differing plant species that extend roots (weeds versus target crop).
  2. Early on in a crops life, specific bacterial communities excel and then as the life of the plant-root grows, temperatures increase the bacteria can degrade and consume more complex substrates such as complex proteins, and sugars
  3. Mycorrhizal fungi are great protectors of bacterial pathogens that cause root and subsequent above ground shoot diseases – they develop antibiotics, can out-compete infection sites by providing barrier protection to the root
  4. The mycelial or hyphae network can link plants of the same and yes, different species and transfer C compounds back and forth – sharing and donating the goods so to speak
  5. Mycorrhizae attract certain bacteria to the root/host and join forces to benefit the plant – invasive species (weeds) can and do negatively effect symbiotic fungal relationships to the target crop being grown
  6. Mycorrhizal fungi aid in maintaining a barrier/network around the root in highly saline and alkali soils, protecting from desiccation and injury due to salts
  7. Fungal species that are symbiotic to maize for instance are truly due to the composition and release of certain exudates from those maize roots, which attract and aid in multiplying the fungi infection and spore production for future plant-roots.
  8. Root exudates are estimated to be 2 to 10 percent of the total fixed carbon for an individual plant – mycologists say this is not a negative loss of carbon for the plant/crop                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         I could add at least 15 other facts to store in your heads, but for now these may suffice.This last image below is how a network of fungal hyphae can aid, protect and share goodies as I mentioned in items 1 &  4 (above) to facilitate nutrient uptake between a forage sorghum and flax.  Intercropping does work and this provides factual concepts why it does make differences in crop growth, the secrets of the soil biome is just fantastic folks.
  9.   Blog written by:  Michael Petersen, Orthman Lead Agronomist   November 2019
    Intercropping with sorghum drastically enhanced flax’s growth (+46% increase). Nutrient uptake was facilitated via the common
    mycorrhizal network (CMN) Flax. Mixed. Sorghum. Walder, F., Niemann, H., Natarajan, M., Lehmann, M.F., Boller, T. and
    Wiemken, A. (2012). Mycorrhizal networks: common goods of plants shared under unequal terms of trade. Plant Physiol. 159:

2019 Corn Harvest – Was Crop Health in Late Season as You Liked?

Good folks all across the Central part of the United States up into the Great Lakes region and out west are getting into the fields,  Just these past few days tho, the ugly winds swept down out of Canada and have blown down corn and twisted up soybeans that were not harvested making for a large number of growers cranky and in a fashion slapped again by Mother Nature.  I sympathize guys and gals, boy do I ever.

That matter brings me to a fact of late season fertility when your corn for instance was near or at R2 stage.  The plant has just gone through the most intensive period of its lifespan and called for extensive amounts through the roots and leaves for potassium (K), phosphorus (P), nitrogen (N), and sulfur (S) to be translocated into those embryos of the ear.  The stalk being the conduit to get those materials in the form of complex sugars, proteins, fats and fatty acids moved to meet all the genetic demands to fill those kernels.  As that happened a great deal of products were translocated at times at the expense of some other metabolic processes.  What a busy time, much akin to some of the complex busy fly-overs and turns on and off I20 and I10 in the Dallas-Ft. Worth corridors at 7:45am on a Monday morning. Cars going every different direction.

Corn at R2 stage
Courtesy Kansas State Univ.

Where am I going with this?  Consider in that busy traffic of sugars moving, water, nutrients demanded to develop proteins and sugars as well as other carbohydrates developed and going up and down the phloem and xylem tissue highways, from the roots way up to the ear and other fluids from the leaves to the ear – now and then there is some slowed or up against the guard rail with the hood up and steam coming out and a flat tire. Whoa! Something went wrong or petered out. A car with the right amount of K just went flat to a stop.  This all might be an over simplistic representation of the right ions zipping around and hung up or lost in the system of reproduction of a corn plant.  But as the saying goes, “Stuff Happens”.  When this occurs we may observe later a plant lose stalk strength or the top of the plant cracks and blows out or the ear shank drops a full ear out of the shucks and plop – on the ground sits an ear of 650 kernels.  Hmmmm!  Did a miss of maybe a late application or even a miss up in the earlier part of the crops lifespan not get a dose of proper nutrients to feed the plant for the super busy Monday morning on the I10/I20 roadways?  Yes wind is a bugger at 50mph for a long period.  Dried down stalks, maybe some stalk rot crept in or a long dry period and the plant just did not have enough moisture to remain healthy and your plant health was compromised.  My point is, did we look back at the R1-R2 stage and consider a booster shot of the right materials to take the plant all the way to harvest.

For at times I know this is late to be talking about nutrient adequacy.  But harvest shows anyone of us some details we may have overlooked or forgot about until the snout of the combine is running through the field and you are seeing down corn and ears on the ground.  Yes wind is wind, I acknowledge that folks and when the winds are fierce, well we can do nothing about it.

We at Orthman believe a well managed fertility system not only starts with pre-plant nutrient sources and materials, placed at the best depths to be intercepted by the roots but the mid and late season nutrient applications will help your crop perform near your expectations.  Yes Mother Nature as we call it must be right.  Please do not hesitate to talk with our guys that wear the Orthman hats and shirts, contact me Orthman’s soils man if you like and let us discuss some of thos questions you may have.  Your Extension Specialists, Seed Company’s agronomists; they all can discuss what late nutrient applications may mean in the corn crops life all the way to harvest.

May harvest go better and get it into the bins for you all.

Interim Soil Characteristics of Tillage for Today.

Orthman 1tRIPr soil resistance studies tell a story of what Strip-Till is all about

In my last report on September 30th, I offered some more of our observations how this spring (2019) affected soils, with strip tillage, plant root growth and some of the parameters of what the root does to compensate for compacted soils.  We looked at three different row sites in the study; in the present years row where corn is growing, in the mid section of a row where the tractor tires rode and last the guess row.  Those spots are sites in the field for row crop farmer they understand where the soils should be the toughest [wheel traffic rows], where the soil should be the most mellow and what is happening right where the plant lives.  It is our aim for you the reader to gain a better  perspective of what the soil gives or resists to the newly planted crop baby root system, will any of the plants have to put out more or less energy to gain access to water and soil-solution nutrients for growth?

Before I dive in, I want to ask you a question – how many of your implement dealerships, fertility providers, agronomic scout/consultants, seed dealers even; offer you the kind of information we at Orthman Manufacturing are sharing?  Yup, thought so.  Does not surprise me.  Excuse my chasing you with a loaded question, however we in the wide-wide world of tillage, folks assume too much that certain tillage events are necessary when they truly may or may not be to grow your crops.  We have assumed since man started using an ox to pull a rudimentary plow that turning the soil over and over was the way to prepare a seedbed.  Well not quite so.  Nor should we always assume that the Direct Seeding method offers the “perfect” answer to solving the farmers past soil woes of erosion, runoff, lack of the soil breathing or intake of water, loss of carbonaceous materials, declining soil health, and a poor response to commercial fertilizers.  So where do we situate ourselves you may ask?  Moldboard plowing and four or more subsequent passes before a planter or drill inserts seeds is most usually detrimental to soil physical properties, biological life and response. Okay what works best on your fields Mister?  As a soil scientist now for 45+ years, one who came out of the era of acute awareness of soil quality/health, when Conservation Tillage was getting its roots established and defining what it was and what was not in the USDA-Soil Conservation Service — I can tell you this has been much of a journey of change and for some growers even confusion.  I can tell you it was infused into our daily lives to understand and articulate the principles, the modes of action, the good practices versus those that harm soils all across North America.  I excavated soils on level soil landscapes to mountain sides as a public servant to better understand whether soils were resilient, conducive to erosion by water and wind, whether soils are of a prime farmland designation or wildlands and a whole lot more.  I digress – whether in my travels for work I believe in taking care of the finite soil resource.  I have seen and dug in soils in the lands of Queensland, Australia and New South Wales, the Saucony of France, the rich valley of the Volga River, the amazing soils of the Danube in Serbia and Hungary, the High Feldt of South Africa, western Plains of Kansas, the loessal soils of Nebraska, and the lake bed areas of northern Ohio.  Most farmers want their soils to be the most productive.  I throw in a BUT here.  The old ways still pursue, haunt, follow or guide them to achieving what they hope will be produced.  So what works Mike Petersen?

Less inversion tillage for sure.  Slicing, dicing, rolling, tumbling, and crushing soil aggregates are not the way for sure.  With all the soils I have tipped a spade into, now in 5 continents, I have come to a critical point that we agriculturists have flagellated the soil resource far too much, expected big response from those soils and have been disappointed whether the climatic conditions were primo or not.  My observations, digging, studying over the 45+ years have shown me that strip tillage in a concentrated band that does not shear soil and roll it like a plow or disk works extremely well.  Is it the next best operation/practice to accomplish?  Closer than anything else.

With certain tillage that tumble, smear and crash soil these events have a detrimental cause and effect?

SEM micrograph of a soil microaggregate Courtesy: Researchgate.net, Spain

Soil aggregates and microaggregates are thrashed around, microscopic pores, channels and cracks between aggregates are crushed, squeezed, smeared when too moist, organic components are dislodged from the silt and clay particles and when exposed to the sun and warmer air they volatilize and waft away.  So as you see with the image to the left (the 11 dots in lower right corner give you an idea of the size of this microaggregate at 1 micron in size).  Itty bitty creatures, amoeba, bacteria are mashed, rolled, crushed and exposed to the atmosphere and the soil-water films are dried to extinction.  Earthworms are dislodged from their burrows and then either rolled, crushed or cut in two – some make it and others die.  Sounds like a battle zone – yes?  I paint a pretty bad scene I know.  Can we avoid such?  I do not mean to be a scolding momma, but to point out these little particles of the soil form into larger ones to make aggregates and soil structural units such as crumb, granules, tiny little blocks or prisms which are the foundation of good, healthy soils.  It takes these tiny pieces to make the soil come together in specific forms/shapes, provide a good medium for water to penetrate as well as roots, as well as mycorrhizae hyphae and organic compounds to adhere to the soil and the roots to supply nutrients from the microbes and in the soil solution between and on the microaggregates.  It all all must work and stick together in a fashion.  What a marvelous world below our feet where roots grow and thrive or work hard to penetrate that I have had the privilege to study, work with and get paid doing it.

Maybe one or two of you may understand a touch more why I have had my head looking in holes in the ground for over 40 years to see the marvels and mystery of the soil.  Often I have wished to have a scanning electron microscope at my disposal, but I am not capable of dropping 3-5M dollars on such an instrument – whewie!  The intricacies of the soil, how they glue together to form into a cohesive angular blocky structure for instance is vital to soils having resiliency and high value to a growing root.

The chart to the left and below is from a field that has been in strip tillage since 2002 under overhead sprinkler irrigation.  The rotation of crops has been continuous corn for 7 years, soybeans for 1 year, irrigated grain sorghum then back to irrigated corn for 8 years.  The grower has alternated the depth of strip till knife between 6 to 10 inches.  Six inches when soybeans and ten inches when in corn or sorghum.  The values you read are from May 2019 when the soil moisture condition was 85% of field capacity.  The soil organic matter (SOM) level is 2.4% in the upper 3 inches and 1.95% in the 3 to 6 inch zone.

This soil has been measured for intake rate at the surface for four years in a row during a research study for the Colorado Corn Growers.  Prior to strip-tillage we measured intake rates of 0.90 in/hour, then in the fourth year of strip till the intake rate in the guess row was 4.4 inches/hour and in the wheel row (trafficked row) it still had improved to 2.4 in/hr.  That is a 4.9 times improvement.  We also measured SOM during the same study; the SOM improved from o.75 to 2.0% in 9 years which covered the span of the intake study also.  In the last years of the entire study sponsored by Colorado Corn Growers we measured soil aggregate stability of this same soil, the soil aggregate values are measured with a “slaking test” that USDA-NRCS still encourage people to do and their Soil Health Specialists in each state are eager to work with people on.  I ran these analyses with one of the progenitors of the soil slake test for aggregate stability, Dr. Robert Grossman, USDA-NRCS Soil Survey Laboratory-Lincoln, Nebraska before this became “a thing” within the USDA.  I still run these tests and find amazing results from Strip-Till and No-Tilled soils all across the states I get to dig holes in.   The soil aggregates rated a 0 to 1 the first year on a scale of 1 to 5 with 5 being the most stable soil aggregates.  In the last year of the study the aggregate stability improved to a 5 demonstrating the aggregates were more stable to water melting the micro and macro-aggregates.  All of that to say this field in Eastern Colorado has had many studies and I have had a constant eye (year to year since 2000) on to offer what strip till has done and can do.

As you can see in the chart of penetration resistance, there is a jump in vertical resistance at 8-9 inches.  This field was strip tilled at the 9 inch depth this spring.  Even in the row where traffic is the jump in resistance is significant.  The corn that was growing at the time was at V2 stage and the seedling root had not grown beyond the 5 inch depth so it was not impacted by the soil resistance that would have been felt by the 9 inch depth in the middle of the strip tilled zone column.  As has been noted in previous articles on this Precision Tillage website, very young plants will encounter root penetration and elongation at the tip when soil resistance exceeds 60 psi.

I will continue to bring more about our spring soil resistance studies as the next couple weeks come.  Stay tuned.

2019 report of early season soil resistance in irrigated sandy loam soils and pertinent recent root tip research

In my last article I posted (9/23/19) regarding what can happen even in moist soils like what happened this spring of 2019 – I shared data of soil resistance from the perspective of vertical and horizontal compaction in silt loam and silty clay loam soils.

With today’s segment of the large amount of data I will draw your attention to sampled sites of sandy loam soils (approx. 14% clay, 68% sand and the remaining 18% silt).  I was allowed to look and dig in conditions that are normally plowed with a moldboard plow and 4 operations after the pass of the plow, overhead sprinkler strip-till systems approach and then strip-till furrow irrigated.  This ground has been farmed since the early 1900’s by the same family and irrigated.  In the last ten years they switched to part of the entire farm to strip-till for their corn acres.  The family has grown corn, malting barley, sugar beets, and bulk onions as their rotation for more than 30 years.

Fig. 1 Strip-Till beneath overhead center pivot sprinklers. Crop is corn. Has been strip tilled now for 6 years.

 

 

First chart of Strip-Till under Pivot Irrigation

The soils when I sampled back in the first days of June were very moist after the frequent spring rains which were wonderful except for getting crops planted when the calendar seemed to point to NOW!  Take a look at the first graphic of depicting vertical compaction in the row where the current crop resides, the guess row and then the wheel row.  The grower strip tills with an 8 row-30 inch Orthman 1tRIPr at 8-9 inch depth and then plants with a 12 row planter all operations done with RTK-GPS guidance.  My positioning of where I sampled for the guess row (see the blue line in the graph to your left) got in the row where the wheels of the planter rode.  The green line depicts the amount of down-force the grower applied with his planter.  The red line exhibits what occurred in the wheel row which I did find quite easily.  Just below the depth the shank and point ran vertical compaction jumps up to 300+ pounds per square inch (psi).  This soil is low in soil organic matter but the grower informed me that they have risen in the last 6 years with the advent of his using strip-till to right at 1.5% from under 1.0%.  They do not graze stalks overwinter.

Second chart of Strip-Till surface furrow irrigation

In this chart the grower still follows the previous years row on a shallow bed and strip-tills corn.  The lay of the ground is very flat.  As in Figure 1, this chart Figure 2. to your left; red line is the wheel row, blue line is the guess row and green line is in-crop row where corn is growing.  The curved line in red depicts that lateral compaction rises to 27 psi then falls off with depth with a small rise at 9 inches as where the depth of the strip-till shank and point was set during the spring strip till operation.  With the green line where the corn was planted at 3 inch depth there is some lateral resistance to a point of 22 psi.  As stated in the previous blog article last wrote (9/22), root growth at the tip is negatively influenced above the 60 psi range from extending in the soil medium.  So we are seeing any problem due to impedance.  As I was digging, probing and looking the roots, above the 6 inch depth, were not kinked, blunted or swollen at the tip as the seedling roots were growing out and down at the normal 25 degrees of the soil surface.

It is concerning that these soils become hard with drying below that 6 inch depth and a strong 20X hand lens I saw a blunting, helical  and twisted appearance to the root tip and back some 25mm ( 1 inch).  For me I am now curious as a cat.  I got back to my office and looked into my quiver of research papers from Plant Physiology regarding root growth.  Colombi et al. wrote a striking paper in 2017 about shape of roots that encounter increased soil strength (compacted soils).  The premise of their efforts in crops early development that roots have differing shapes some being more elliptical, thickening and larger intercellular spaces behind the root tips.  Researchers at Penn State in 2013 corroborate these kind of findings in corn.  Postma and Lynch, 2011 & 2013 published findings that support this for us to understand how a corn plant deals with physical stresses of water, low nutrient availability and soil impedance.

Fig. 2: Lateral view of compaction in Pivot irrigated field with Strip-Till.

What am I saying here?  When roots attempt to grow in and through more dense, compacted soils they are able to develop cellular structures that have stronger cell walls and larger cavities to hold air behind the root tip to aid in forcing the root deeper and further into the soil.  Anne Ju at Cornell University suggests that roots will form helices to then like a spring force the root tip to push off and extend further when the environment of the soil (Cornell Chronicle, Sept. 2012).  Some scientists call this a root buckling effect. When the spring release the root pushed forward and through.  See the images directly below and to the left..

Also some other Cornell University scientists have revealed with micrographs that very fine root hairs will extend right behind this coil-like structure to anchor the root and the spring-like action is even stronger to push the root forward.  Wow!  There is a point where the root in it’s abilility to overcome soil resistance is around 2MPa or about 300 psi and root tip growth may cease all together. This was observed with Barrelclover in a lab.

This material I read in the Itai Cohen Groups website, cohengroup.lassp.cornell.edu   authored by, Silverberg, et al.

Concluding Remarks:

Whether we are observing corn, wheat, Barrelclover from the Mediterranean area, peas, soybeans or barley – plant roots exert a certain amount of push force to grow down and out from the plant into the soil to gain water and nutrients for growth and maintaining life until senescence.  Our purpose to carry out these early soil resistance studies to offer what is happening with three common tillage systems of the corn growing regions we at Orthman work in.

In this article I wanted to give you an indication of what we observed in irrigated sandy loam soils.  In the fields where I was looking (sandy loam soils) the roots had not extended down below the 9 inch depth.  The penetrometer encountered pressures of 200 to over 300 psi of resistance.  In the next rendition I will compare the resistance values we observed in sandy loam soils that were furrow irrigated with strip till and with the moldboard plow tillage systems approach.  Some striking differences.  Until then….

Cornell Univ. images of twisting of roots in response to longitudinal forces of soil resistance.

References of research:

Root tip shape governs root elongation under increased soil strength, Colombi et al., 2017, Plant Physiology, Vol 174, pp. 2289-2301
Root cortical aerenchyma enhances growth of Zea mays on soils with suboptimal availability of Nitrogen, Phosphorus and Potassium., Postma J. and Lynch, J.P., 2011, Plant Physiology, pp. 1104-1111
Theoretical evidence of the functional benefit of root cortical aerenchyma in soils with low phosphorus availability. Postma,J and Lynch, J.P. 2010, Annals of Botany, Vol 107, pp.829-841
3D Imaging and mechanical modeling of helical buckling in Medicago trunccatula plant roots. Silberberg, J. et al., 2012, Proceedings of the National Academy of Sciences, Vol 109(42) pp.16794-16799

 

 

 

Orthman Manufacturing 2019 Root-Soil Compaction Study Is Very Revealing

Last post (Sept. 12, 2019) I posted to this site a tidbit about compacted soils in very moist environments as what we saw and dealt with this spring.  I would like to delve into this some further to share with all of you what we observed by digging around eight different soil textures this spring in Colorado and Nebraska.  It has been asked of our customers, Orthman dealers, folks at training events we carry out throughout the year, emails and phone calls “what may be limiting my row crops from getting a good start even with starter or popup fertilizers and top-of-the-line hybrids?”

Orthman 1tRIPr comparison studies

Soil compaction also called soil impedance, is quite visible when soils dry down and we can in a soil-root pit see blocked, stunted, and zig-zag roots or no roots at all below a certain depth in the upper two feet of the soil profile.  Well how much soil resistance is too much for young roots in row crops to continue to extend out and away from the plant and grow downward by the pull of gravity as well as follow the moisture/warming front?  It is fairly well documented in soils literature over the past 50 years (Passioura, 1991, da Silva et al., 1994, Bengough et al. 2006, Taylor and Ratcliffe, 1969) that spoil resistance above 2MPa or 290-300 pounds per square inch (psi) will essentially stop root tip extension.  That is when plants are nearly mature, how about when they are young?  When corn, and/or soybeans are V4 or  younger?  The amount of force to exert enough pressure to push roots down and into soil pores, cracks differs by crop but for simplicity, corn at 60psi, roots have a great deal of difficulty to grow.  Even some of you have heard or read that roots at the root tip exude a mucous-like substance as a lubricant to alleviate some of the resistance forces to root elongation (growth).  This slimy material almost like what comes from our nose only can do so much to aid root tip growth.  Early in the plants life the roots are amassing length and absorptive capacity by growth down and out into the soil profile.  An old mode of thought that roots were growing at the pace of the plant growing up towards the sun.  Well that is not much like what really happens below the soil surface.  Soil temperature, soil moisture, crop genetics have much more say in how expansive the root system will be.  Gravity is a constant to help pull roots downward, that is something we can all count on.  In very moist soils like what nearly every state here in USA experienced; roots were slowed by the cold soil temperatures, saturated conditions in the upper 18 inches which caused anaerobic conditions and yes, by soil density or compaction.

At Husker Harvest Days (September 10-12, 2019) we exposed to our farmers a study we did as I mentioned before.  The amount of data we exposed would crowd this blog piece with columns of numbers and figures to many pages and most likely make your eyes and brain reel a bit.  Others may be very intrigued.  Allow me to give you a couple examples and then a summary of what we saw in 2019.  We are going to study this again to capture more sites and other conditions between No-Till, Strip-Till and Broad Acre Tillage in 2020.  What we did to travel between willing customers/clients across the two states, limited manpower and daylight – we saw and measured a sizable amount.  So in this report I will address two very common soil textures, silty clay loam and silt loam. We will compare No-Till to Strip-Till in the silty clay loam and Conventional broad acre tillage in a silt loam soil against strip-till.

Before I move on, why did Orthman carry out such a study?  Our company prides itself in having a premium Strip-Till implement to make three major strides in setting up a row crop to reach it’s potential in growth and yield: 1)  A job of a top-notch seedbed, 2) alleviate compaction in the till zone for optimum root development and lastly, 3)  Precision Nutrient Placement.  All three of these principles demand a high quality and effective  till-zone for roots to extend out and down in the soil.  Water comes into the plant via roots almost wholly via the root hair surfaces (>98%).  Scientists have estimated in a corn plant for instance is replacing new root hairs to the tune of 100 million per day from V9-V10 up until silking period.  That is even mind boggling to me as I have looked at root systems for over 38 years having my head below ground a lot.  Sorry I digressed for a moment.

Fig. 1 StripTill -NoTill Comparison of 2019 spring conditions of silty clay loam soils. Soil resistance values right in the zone where the plant is growing after tillage/planting.

Take a look in the chart off to the left of a comparison of Strip Till (ST) and No-Till (NT).  These values are from a spring strip till operation then planted and a single pass of direct seeding in silty clay loam soils.  Values have been converted to psi for the Torvane shear test which reflects lateral soil resistance (left to right at specific depths) and then vertical resistance with a penetrometer as well the values are in pounds per square inch.  The strip till unit (it was the Orthman 1tRIPr in this case) had positive effect to a depth of  5 to 7 inches vertically.  The lateral or horizontal soil resistance shows the disturbance by the shank and wavy coulters of the 1tRIPr mellowed the soil to 7 inches.  As mentioned above the 60psi level early corn roots will encounter resistance to slow or even retard root elongation and penetration.  In the No Till field that was right at the 7 inch depth.  Speaking with the grower he said grain cart traffic was all over the place the previous fall which most likely contributed to the density.  That is apparent from the NT penetrometer readings also in Figure 1.

It is not our intention to cast stones at the No-Till system, we are reporting what we observed in a wet year and what was happening in this field.  We observed in another soil texture some similar results that vertical compaction was evident below the 3 to 5 inch depth.

Next figure we show soil resistance values both lateral and vertically in the crop row what spring strip till with the standard point accomplishes in silt loam soils. In the conventionally full width tillage it was a pass of a disk ripper tool followed by a field cultivator then plant.

Fig.2: Silt loam soils with a comparison of conventionally tilled multiple passes to spring strip-till.

In this chart, the left two columns after the depth column are the values from the conventionally tilled field, the right two columns are the values from the Strip Tilled silt loam soils.  The first 1-2 inches in the disk-rip field do have less resistance laterally.  These values again are in the crop row where the corn was growing this year.  Wet spring soil moisture conditions depict that the soils melt together and structural integrity is very low and the soil even when moist becomes dense.  The strip till depicts lower values of 20, 48, 48, 34 psi in the first 8 inches measured by the Torvane shear testing device compared to the conventional till of 16, 57, 76,82 psi in the first 8 inches.  Vertically the strip till density is approximately 60% less from the surface to 4 inches in the vertical dimension.  At 7 inches where the strip till implement was pulled through the field, the soil density in 2019 is less than half of the conventionally tilled field.

Our observations depict what is happening with multiple pass tillage which has the tendency to break down soil structure, drag it, smear it and allow for oxidation of organic matter, destruction of earthworm channels and vertical root channels in the upper 8 to 10 inches.  So by this kind of tillage soil structural units are damaged if not demolished.  With the Orthman strip-till unit we vertically break apart the soil after a full season of re-aggregation and mix the soil in a modified U fashion on 30 or 36 inch centers in the fields we looked at and measured with the Torvane instrument and a penetrometer.  We know we are tilling and mixing soil in a vertical sense about 10 inches wide at the soil surface tapered down at an approximate angle of 40-45 degrees to the points insertion depth.  Our point does not create a smear pattern unless the soils are far wetter than 75% of field capacity.  Growers will tell you they were out in fields wetter than that trying to dry the soils out this spring conventionally which very well set in a smear plane that may well have caused a thin barrier and inserted compaction.  For many it was a gamble they said they had to take.

I will put together more charts and facts of the other sites we looked at in my next writing for you to see what other soil textures reveal with 2019’s wet soil conditions in strip till, conventional and some direct seeded corn.  Now we also looked to gain more facts of where the wheel traffic was and the guess row zones can show differences.  Please first digest these data sets as a taste of the rest to come.  Next report will be early next week.

References used:

Bengough et al.  Root responses to soil physical conditions: growth dynamics fro field to cell.  Journal of Experimental Botany, 2006, Vol.57 (pg. 437-447)
daSilva et al., Characterization of the least limiting water range of soils, Soil Science Society of America Journal, 1994 vol 58 (pg.1775-1781.)
Passioura, J.B., Soil structure and plant growth., Australian Journal of Soil Research, 1991, vol.29 (pg.717-728)
Taylor HM and Ratcliffe LH, Root elongation rates of cotton and peanuts as a function of soil strength and water content, Soil Science, 1969, vol.108, (pg.113-119)

Soil Pores Still Make News in a Wet Spring and Summer Season

Cover crops, No-Till corn-soy rotations versus corn on corn, Strip-Till corn on corn, Strip-Till corn-soy rotations; how do these differ, how do they effect soil quality changes in the way of improvement.  A group of researchers at South Dakota State University looked into soil porosity in the surface soil horizons under residue removal at three differing rates to better understand soil function.  In one of several articles I have read recently: Vahyala E. Ibrahim, Shannon L. Osborne, Thomas E. Schumacher & Walter E. Riedell (2018): Corn Residue Removal Effects on Hydraulically Effective Macropores, Communications in Soil Science and Plant Analysis

To link to this article: https://doi.org/10.1080/00103624.2018.1464187  

For those of you that may want to read what Ibrahim et.al. wrote I have set the link above.   It is of my summary of the article that harvesting corn residues in the corn years of this multi-year study that certain soil quality measurements were adversely affected.  Water infiltration through microscopic to macropores in the surface soil horizons was diminished significantly.  By that I read and have observed in the studies I personally ran at the Irrigation Research Foundation Farm near Yuma, Colorado 2001-2005 I do agree soil pores both contiguous and non-contiguous are reduced in number, surface area and continuity from surface into the subsurface layers.  I made observations of visible pores 1mm up in size to 5mm in diameter.

The image above offers some visual idea of surface soil condition where soil aggregates are established and dominated with a wide range of pores to allow water infiltration and gaseous flow.

Now what does that have to do with price of tea or coffee at the local diner? Pore space and pore size has everything to do with water infiltration, carbon exchange, oxygen exchange, carbon storage, microbial life as well as micro-invertebrates, soil aggregate stability (to remain resistant to soil erosion and breakdown) and about 5 other details.  The physical attributes of soils that we take for granted too often when folks drone on and on about cover crops.  Cover crops are important, do not get me wrong here, yet I as a soil scientist want you to understand measurable parameters in soil health and quality provide concrete evidence to whether soils are improving, sustaining or declining.

Ibrahim et. al. observed when “the initial reduction in λΔψ following corn residue removal in high residue removal (HRR) followed by soil surface recovery the following year suggests that inclusion of decaying corn residue is critical in the maintenance of hydraulically functional macropores in this fine textured soil.”  Something of an ahh-hah statement.  I am not making fun at all here.  Having the right soil pore sizes for the soil to breathe and allow more free water movement into the soil profile is vital to any crop to grow and go to yield.

I have discussed here in Precision Tillage.com before about pore space and how Strip Tillage creates a great environment for water infiltration.  We observed with loam textured soils, strip tilled and no over-the-winter crop residue removed by grazing at the Irrigation Research Foundation; soil porosity increased in the guess rows 4.5X to 7X over the four year study and water infiltration in near saturated conditions 2.5 to 4.8X.  There are several other facts and conclusions we can make from Ibrahim et.als article.

In a wet year like this one in places of the Great Plains under natural rainfed conditions this kind of information and data has a big impact.  Under irrigated condition maybe even more so.

Down and Dirty Back in the Pits – Again … And Lovin’ It!

So for many of you the year has been a doozy with wet then dry and then wet, then hail for some that makes record size in the state of Colorado as well as fields obliterated and tussle with insurance companies.  During the week of August 13 & 14th we went up north into central Michigan and participated in the AgroExpo.  It was a great opportunity for folks to come and see what is working, what is new, what happens with high quality fertility ideas which all promote better ways to be more soils and water resources conscious and even more efficient.  Two of us from Orthman Manufacturing did our part to commuicate with growers the highly effective method of strip till and pre-plant nutrient placement.

Root pit at AgroExpo, fertility exhibit of five 6 row plots

With today’s population that live in the Great Lakes region, the issue of water quality, algal blooms, toxin waters for man, avian life and fish – part of the root cause has been pointed to the world of Agriculture and application of phosphorus either commercial or animal manures.  This concern has magnified itself a great deal in the last 4 years.  Lake Erie and Lake Michigan, both are in the lime-light of the public eye.  We at Orthman are much aware and can offer a role to play by suggesting the incorporation of strip till into the way farmers apply nutrients and till the soil.  Placing both phosphorus [P] and potassium [K] in the soil to reduce both mobile silt & clay running off the surface with phosphorus bonded to the soil and organic matter and soluble phosphorus that moves in and through the soils.  We had the opportunity at the soil pit-talks and at the Information Center at AgroExpo to address such and the smart move to place P & K in the upper portions of the subsoil or subsurface.

As you noticed from the picture to the right, we had a pit about 4 ft deep to show differences in root proliferation where starters were applied and other 6 row plots where there was no starter and follow-up changes in N-P-K applied in 30 inch row Pioneer 9608 corn.  As a soil scientist, I am a big believer in what the soil tells us in nutrient and water management via the  health, vibrancy and size of the root system.  I have dug in way over a thousand soil sites to reveal the real story below ground.   I thoroughly enjoy getting down at the moles viewpoint to see the morphology of soils, what has gone on since man broke the land, erosion or sustaining of the soil and what are the soils potentials.  The above-ground portion of the plant may appear okay, but dig down to 4 feet and we have a chance to reveal the secrets.  If the soils have far too much tillage I can tell, if the soils are compacted – I can tell, if the soils were not right (like too wet) I can tell.  Roots will always reveal the good, the bad or the absolute ugly.

So at this neatly done root pit we looked at what differences were visible and measurable from no starter and with part of the starter applied before planting with the 1tRIPr (AgroLiquid owns their own 6row-30) and part of the starter on the planter.  Oh significant differences both below ground and then 3 plant characteristics above ground to tell the story why starters have a “front row, center seats” importance to the crop.  First the root system of the no starter, had 80% of all the roots in the upper 11 inches, 11-16 inches was 15% and down to 34 inches was 5% by volume.  In the split applied starter plots, 65% by volume of the roots were in the upper 11 inches, 11-22 inches was 25% and 22 to 36 inches was 10%.  Clean sand and gravel was below the 36 inch depth and roots stopped there.  As you stare a bit closer at the soil pit image, at 29 to 36 inches below the surface was a layer of darker colored clay loam which sat atop the sand and gravel and both held water and slowed the movement of water rushing through and on out the bottom.  Comparing some more plant data; the height to the flag leaf in the split starter plot – 5% taller than that without, the size of the ear leaf on the split applied starter package from AgroLiquids was 11.25% larger both in length and width compared to the plot without.  The node-to-node spacing on the split applied was extremely even from the ground to the ear placement on the stalk in the split applied plot compared tow without.  The distance from the ground surface to the ear placement was somewhat erratic in the no starter, ranged from 91 – 115 cm.  In the plot where the starter is applied in two applications and times, 92 to 95cm above ground.  Very even and I look at 21 plants in a zig-zag fashion down through the plots measuring.  Darn good way to keep bias out of the observations.  Lastly I pulled ears, stripped back the husk and counted rows and length of the kernel set; in the split applied 18 rows around X 42 in length at 35,000 plant population, in the no starter, 16 around X 39 in length.  That is a difference of 132 kernels more on the split applied.  I believe all should say there is some significant differences.  The total amount of nitrogen remained the same across all 5 plots, with sidedressed nitrogen via Y-drops at 70 gpa.  Having the products applied directly with the seed at planting and then at 4 inches down directly below the seed and where the root will run right into more, so the plant incrementally gets a chance to consume good groceries.  Just what the doc ordered.

With this soil above the clay loam layer at 30 inches or so being a loamy sand it is both a concern and a reality that N will move downward and slow and be absorbed onto the clay where the roots can and did feed.  With more roots filling the upper 22 inches and remainder into the clay in the split-applied approach, the corn is showing what it likes.  AgroLiquids utilizes their trademark Pro-Germinator, Sure-K and Micro500 package for starter in these comparisons.

Over the two days my co-worker Adam Souder and I spoke with folks from all over central Michigan, Ontario Canada area, northern Indiana, the thumb region of Michigan, some folks from Utah, Oregon, Minnesota.  Our story stayed the same, managing your fertility in increments during the growing season will meet the crop demands better and does not fertilize the soil per se, feed the plant when it’s higher demand periods are.  Yes that depends upon what the sky throws at you but as close to those critical periods. AND remember it is not just about nitrogen; sulfur, potassium as well as P with micro’s are very important.

We at Orthman Manufacturing want to thank the AgroLiquid staff and field guys for all their efforts and potentials.  The two days were what we hoped they would be.

Recent News – Factoids of Root Growth of Corn Dealing with Soil Compaction

After attending the National Strip Till Conference (NSTC) in Peoria, IL the week of August 1-2, 2019; I got to thinking that more information to you all seems imperative from what we saw as negative impacts with the wet spring.  Growers that tried to do some tillage then planting when it was wet would want some clues of what we and you are noticing across the countryside.  Using the spring coulter system with the 1tRIPr in near saturated soils did induce some shallow compaction this spring at about 3 to 4 inches down as did planters with more than 100-150 lbs of downforce.  One of my co-workers and I measured some of those ill effects in the Platte River Valley of Central Nebraska.  We also measured where sidewall compaction was induced with planters and created the “mohawk” root system, not a good deal for the plants.  Where am I going with this?  See the image on left.

Sidewall compaction due to wet soil conditions Courtesy Anderson’s

In sandy clay loams, silty clay loams and clay loams – in a wet spring like this one the conditions were ripe for compressing the soils both downward and off to the side or laterally.  In the first 3 to 4 weeks of the corn plants life the root system develops out from the seed placement and down at a 25 degree angle parallel of the soil surface.  Squished and pressed wet soils deform out at a 25 to 40 degree angle from the tires or tracks.  When a farmer is running on dual wheeled setups and too high of pressure in the tires this will more than likely cause “pinch compaction” at depths of 3 to 7 inches deep.  With the rotating of the tires and the pinch-squeeze the soil presses out any air and crushed pores, channels, any kind of a gap and tiny early roots just cannot get through or down; ending up with serious concerns for water/nutrient uptake and stand-ability later in the season.

We have seen quite a number of fields across the Corn Belt with those symptoms.  Before the corn got to tassel time it did not seem to be an issue, now if storms come thru with big winds, folks could be in for problems.  University Extension folks have told me that in Minnesota and Northern Iowa they may be looking at 25% reduction in yields with compromised root systems due to compaction.

Another key point that farmers visited with me about at NSTC in Peoria, IL; what kind of information is out in the soils world did I have about root pits, root growth, compaction did I have that was new.  I have been digging (what else does a soil scientist do?) into the research and finding more information that details the amount of force a corn root can exert at its root tip to penetrate either wet compacted soils or soils that are dense and drying out.  Researchers in Scotland back a few years (2011) back wrote after work evaluating early growth in corn that corn feels the negative effects of soil resistance/compaction from 0.8MPa and at ~2.0MPa root extension stops.  At 2.0MPa (megapascals) corn plants at V2-V5 will curl up their toes significantly.  This amount of soil resistance of 2.0MPa is equal to~280 pounds per square inch (psi).  When corn plants get further into the season V8-VT the amount of turgid pressure at the root tip increases to give ‘push’ at the root tips at a force of up to 2.85MPa or 408psi.  A co-worker of mine and I looked at the very moist to nearly saturated conditions this spring when corn was V2-V4 and measured soil resistance in the seed-zone [1-5 inches] in silty clay loam soils in conventional till to be >250psi.  You can guess what we found, yes sir – blunted off roots, trying to make right turns and kinked.  The first two nodal root sets were blunted or just did not come out on the side where the soil was so dense, but the soil was wet to soggy.  Plants were short, first leaves were purple tinged – strong evidence of compaction when we dug around.  Unfortunately in the long term No-Till fields we observed this also and then with follow up field visits the corn is spindly, shortened, fewer leaves and when shaking a plant it is wobbly and not well anchored in the ground.  I am suggesting to folks take a good look at their corn fields and dig up a few of these kinds of plants and see what your root system looks like.  Small root systems with an appearance of being one sided or like the picture above, compaction either by pinch or smearing is an issue.  Freeze-thaw is not going to remedy this over time folks, other measures will have to be considered.

Looking ahead into the next few weeks; come to Husker Harvest Days [September 10-12, 2019] near Grand Island, Nebraska and visit us at the Orthman Manufacturing stand/booth for we are going to be presenting great information about our spring findings of 8 different soil types in Strip-Till fields, Conventional till fields and No-Till fields as to what two forms of soil compaction is happening in wet soil conditions.  Our guys will be happy to explain what we saw, what values are trouble and what is not a problem.  You bet I will be there ready to visit with you all any of the three days.  This data is not being done by University folks which is unfortunate, so we at Orthman want to bring you finding straight from the field and talk about what are options for pre-plant tillage.  After the show we will be publishing the results here on Precision Tillage.com.