Published March 26, 2021 | By Mike Petersen

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)

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.

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.

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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.

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.
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.

Published March 15, 2021 | By Mike Petersen

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 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

Published March 1, 2021 | By Mike Petersen

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.

Published February 16, 2021 | By Mike Petersen

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!

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 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 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.

Fig. 1: Diagram of roots, Courtesy: Nature

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

Published January 28, 2021 | By Mike Petersen

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

Published January 20, 2021 | By Mike Petersen

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.

Published January 5, 2021 | By Mike Petersen

Couple three weeks ago I laid out some items that may provide clarification to a developing root system, first I shared about the fertility placement and then wrote to you how soil porosity (abundance, size and continuity) is so important. Soils that are massive or compacted will inhibit root development and depth of penetration for so may crops, perennials can adapt and push through over the years. For an annual plant such as corn, soybeans, dry edible beans, canola – oh we have problems.
So let us consider the water content of soils, where the water is in a soil profile, if there may be a dry sandwich layer (more moisture above a dry zone and wetter below), how much suction power (or not) does a plant exert to draw moisture into the roots, that ‘zone’ around the physical root diameter for water uptake, how far can a root dehydrate or drink water from the root itself, how much that is and briefly what mycorrhizae hyphae does in aiding water uptake. All of the above are factors along with climatic conditions; humidity of the atmosphere, heat of the day, wind and then crop stage.

Fig. 1: On the left is very young plant at V4, the right is a plant at VT

As a plant ages the amount of biomass that is alive has a certain demand for water; for instance, a V4 corn plant is only 13 grams but a fully mature plant with a developing ear may be 2450 grams – 190X more grams and surely a bigger demand to keep hydrated and functioning.

Images to your left represent what we might be looking at….
Facts of water holding capacity:

When the soil matrix is near field capacity for a medium textured soil (silt loam or loam) it can hold nearly 0.34-0.40 inch/cubic inch – what is available tho is 0.21 to 0.22 inch per cubic inch. So in a root zone of the V4 plant the root zone is fairly small, potentially in 144 cubic inches of root zone it could have 16 oz of water available to the root system. When a plant has reached maximum height, maximum root volume in the soil (VT-R1) we are seeing 5000 to 6500 cu. inches of soil volume that can hold water and make it available to the roots. If soil profile is at field capacity when plant is mature we are looking at 21.6 to 28.2 gallons of water available. Compare that to 1 cubic yard then we would have a field capacity 202 gallons available in a silt loam soil profile. Great potential, however those numbers at that stage of growth in a corn field are extremely rare.

Facts of Dryness:

Consider how a soil will be refilled by rain events or irrigation in a medium textured soil (bear with me), the profile has to over fill the upper horizons first to help push water downward through cracks, crevices and pores as well as gravity pulling it. A soil that may be very dry, down to near the hygroscopic range, the soil fills somewhat slow then seems to catch up and water moves into the soil profile. There are times when the soil is so dry a condition called “hydrophobicity” sets up and water will be shed and runoff (not infiltrate). This happens during long drought spells and when a fire has swept across the surface at temperatures up above 500 degrees F. Waxes, lipids, fats and resins in the soil organic matter are the usual culprits that cause such an effect. A 25mm or 1 inch rain when the soil surface is real dry will rarely fill the upper portion of the soil profile evenly. In a strip till environment we find that a 25mm or 1 inch rain may penetrate 30-35cm (12-14 inches) in the strip tilled area but only 10 to 15cm (4-6 inches) between the strips when it is very dry. Part of the reasoning, we have observed over the last 20 years in strip tilled fields the residue between the strips may shed water towards the strip zone, and the porosity and shallow roots under the residue absorb water very quickly. So I am telling you this to say the soil profile will have dry spots, shallow depth in parts and in strips deeper penetration – this gives the plants an advantage in strip till. The existing pores under the residue where the soil surface has not been disturbed in most cases will have contiguous pores under where last years crop stood and aid in water penetration unless as I said it is super dry like the 2020 late summer into fall and winter.

Fig. 2: Courtesy Gary Naylor – Intense rain on soils that puddled bad then soils flow and erosion is severe.

Compacted Soils – And Potential Soil Erosion

I have observed and also measured water movement when soils have a compacted layer within the upper 6 inches (15cm). Ugly effects. What happens? Because of what we call an “abrupt discontinuity” at the top of the compacted layer there is a smear zone. Pores, cracks, crevices, even some of the vertical ped faces can be cut off or truncated, as with a rapid rain events or large doses of irrigation (flood) the soil above the compacted layer has to fill to 130% of field capacity before gravitational water starts to pull water in and down. What does all that have to do with soil water? A bunch, when water is not able to penetrate the soil profile and refill pores so a growing plant can survive – we have problems; the results may well be runoff carrying away soil for a period of time unless the rain slows to a infiltration rate below the normal soil textural rate (ie: loam soils have a standard infiltration rate of 0.6 to 1.0 inch/hour, silty clay loam soils standard rate is 0.2 to 0.6inch/hour). When soils become that saturated and the rain continues to pelt down at a high rate (>1.5-2 inches per hour), the soil above the compaction usually turns into a gel like substance and then flow – water erosion becomes horrendous. Image to your left is a perfect example – losses may exceed 50 to 160 tons/acre.

The amount of water that we hoped to penetrate and go into the soil and replenish what the plants have absorbed or evaporated will be way short of what could and should have refilled the soil. Now please do not think that moldboard plowing is the answer. Strip tillage shanks or coulter units follow the normal vertical structural units of the soil and disturb the soil without inverting, smearing, rolling and smashing soil structural units. All of those disturbances damage soil structure which can and will alter soils to become massive, reducing porosity and that results in less water content for root access.

Water is the essence of plant life. Without water and at the right times plant desiccate, wither and die. Water obtained and drawn into the plants by the root system move sugars, proteins, carbohydrates and basic nutrients into the xylem and phloem tubes to continue the cycle of photosynthesis. It is said and studied by plant scientists that 98%+ of the water in and used by plants come from the soil profile. I can hear several of you say – That is an understatement or in one word, DUH! My writing such is to note we are farmers of water and the soil profile is the bank account we manage with certain tillage practices. This discussion is to emphasize with what we promote with Strip Tillage we are helping you with water infiltration, where it gets banked, making a root system as big as necessary to grow a crop whether it is forage, grains, fruits, tubers, bulbs or nuts.

Effective zone around the root and root hairs can obtain water:

Fig. 3: Diagrams of zone where root of 1mm size pulls water. The red line indicates the distance water can be sucked into the plant (1cm to 2.5cm) on the left.

Roots have to compete against the tension water is held by organic matter and clay particles in the soil to pull water into the epidermis and then Xylem transports it up to the above ground portions of the plant for cooling, hydration and photosynthesis processes. The suction can be measured in atmospheres, pounds of force, or dynes.

In the diagram to the left there is a cross section of a root and then a red line around it giving you an idea of how far the root can pull or suck water when the soil pores are full of water, the tension soils hold water at that phase is 1/3rd of an atmosphere. That is easily obtainable water and the plant exerts little effort. For ease of reference to remember, that is 1 to 2.3 cm or approximately 1/4 to near 1 inch around the root. Finer root size can squeeze into smaller pores, the larger roots when growing fast and down deep do not send as many roots radially outward and may grow past drier zones for cooler and more moist environments.

FIG. 4: Depiction of an Orthman root dig with very fast vertical root development (red circled area) shows where very, very few lateral roots developed

With this drawing [Figure 4] of a root dig we at Orthman completed in 2012 with fast growing conditions of the hot summer, roots show little to no lateral root expression within the 18-32 inch depth. At the time of this root dig it was late August, the plants were mature and had finished pollinating. We returned near to the same site after harvest, dug new holes and discovered the zone 18-32 inches still had moisture and the rest of the soil profile was bone dry.

My intention is to illustrate that both lateral roots and root hairs can make a significant difference in water uptake. Then with the later soil-root dig we observed the remaining mosit soils.

Lastly, Mycorrhizae hyphae contribute to water uptake:
The ever emerging and broader knowledge of mycorrhiza is fascinating and a study in itself with how and what they contribute to crop production. I have written about this fungi before and will just briefly identify in this article what they contribute to plants in water uptake.

The hyphae are small filaments microns in size that grow out from the hosts root into the soils in the upper 4 to 12 inch depth of the soil profile. Aerobic in nature they do not live too much deeper into the soil. These hyphae can extend outward from the host plant up to 10cm (4in). As they do they can absorb water and nutrients to feed its host to continue growing more hyphae. Brassicas – plants of the mustard family do not have a symbiotic relationship with mycorrhiza. Nearly all other terrestrial plants do.

A very interesting feature of these symbionts that they aid the plant handle droughty conditions. Even cactii have a solid relationship with mycorrhizal fungi and thrive due to their interaction. Offering another quick fact about mycorrhizal hyphae – Glomalin is a glycoprotein produced abundantly on hyphae and spores of arbuscular mycorrhizal fungi in soil and in roots. Glomalin was discovered in 1996 by Sara F. Wright, a scientist at the USDA Agricultural Research Service. I had the honor of meeting Dr. Wright when she came to the Great Plains USDA-ARS Experiment Station near Akron, Colorado and she taught a field course about her discovery, identifying the microscopic filaments, the importance of glomalin as a “soil glue” and soil aggregate stability. Since that date the science of soil fungi has exploded and brought so much more to the science of soils.

FIG. 5: Computer image of a soybean root (in yellow) and the hyphae near the surface are very fine in size.

As I said water is absolutely essential and provides life or without soil waster most plant life does not exists. Offering you a small window into the realm of soil science that incorporates physics, biology, chemistry, and specific root relationships that are of recent findings.

Stay tuned as we explore more.

Published December 22, 2020 | By Mike Petersen

Fig 1. Example of compacted root system of canola visualized by X-ray tomography Courtesy Univ. of Adelaide, Australia, 2004 Lateral root expression at 12 to 15cm depth due to compaction. Root volume is then 80% of the root mass is in the upper 20cm (8in).

As I wrote last week that I would update you the reader of the PrecisionTillage blog on more facets of rooting, tillage, nutrient uptake and also water uptake. As I peel a softball sized onion of how soils are so important to every nuance of crop growth, I find more research I need to read, digest and cover to provide you important clues on how to raise a profitable yield. Over the course of a few days working here at my office I have read some interesting material.

Han, Kautz & Köpke (2015) observed in a study of crops following chicory (a taprooted plant) and a planting of tall fescue which produce quite different root systems. In their research growing barley after the taprooted crop vs fibrous fescue, the roots sampled after the tap rooted chicory resulted in a higher Root Length Density (RLD) of two upper root diameter classes (medium and coarse roots; 0.38 cm cm−3) in comparison to tall fescue (0.23 cm cm−3). Roots come in four root diameter classes, very fine (<0.1 mm), fine (0.1–0.2 mm), medium (0.2–0.5 mm), and coarse roots (>0.5 mm). Their data suggest the root architecture of precrops resulted first in different patterns of soil biopores, second in a different morphology of the root system of the subsequent crop and third in amount of soil explored by subsequent crop root systems. Their work detailed that roots of the fine and medium diameter size increased the RLD overall.

In research efforts we carried out at the Irrigation Research Foundation (2004-2007), we determined that with a Strip Till then plant approach in irrigated corn the medium and fine roots increased 4.4X in number under strip till compared to a chisel/disk/springtooth harrow then plant system. Consequently the water infiltration rates improved from 0.6in/hr to 2.9in/hr and more in the 3 year study.

Modeling with X-ray tomography methods in Germany researchers have determined that soils that are compacted (in the upper 25cm-10inches) rely upon the biopores throughout the soil profile in small grains to take up water, nutrients, exchange gases (O2,NO, CO, CO2, etc) and to penetrate greater depths [M. Landl, A. Schnepf et. al, 2019]. Using some modeling processes the researchers simulations suggest that the influence of biopores on root water uptake differs for different soil densities as well as soil types. Due to the larger increase in rooting depth, vertical biopores had a more beneficial effect on root water uptake in more compact soil. Furthermore, the effect of biopores was more evident in a sandy loam than in silt loam due to the sandy loam’s higher soil hydraulic resistivity when the soil was nearer to hygroscopic water conditions. Landl and her fellow researchers went on to say, the positive influence of biopores persisted even under the assumption of reduced root water uptake in biopores due to limited root–soil contact within the pores and was larger for dense soil than for loose soil, again this was specific to sandy loam textures over that of silt loam soils. Improvements of 9-24% more. In Figure 1, the canola plant root (a taprooted crop) followed an old biopore until it hit the compacted zone then turned lateral.

Fig. 2 X-ray tomography images of canola root at 60-112 days growth entering the subsoil. The yellowish root enters surface tilled soils in B, and encounters more dense (compacted zone)as plant matures from left to right in C, D and E. Image courtesy Univ. of Adelaide, Australia

The images to the left depict a series of the X-ray tomographs from 60 days after emergence to approximately 112 days after and what transpired with root development as it encountered the compacted subsoil. The red letter “a” points out across B-C-D-E where the roots enter biopores to penetrate the compacted zone.

Comments and Suggested Conclusions:
Both sets of authors I have referenced here have quantified to a degree that roots from subsequent crops are influenced significantly by size of biopores from previous years and tillage. Our work at the IRF verify that old biopores that are still in tact and continuous into the subsoil influence root development and water uptake. We determined in the IRF study that strip till played a significant role in larger biopores being developed in corn and accentuating roots to penetrate further into the soil profile.

These kinds of data for me say that a crop rotation of crops that leave larger pores (medium and large as described above) have a role in water management, potential drought survival, more potential for the crop to develop a robust root system and possibly yield improvements. It is a goal of ours (Orthman) this coming summer with aid from an intern and the Vo-Ag students carryout some root length density observations where we will be 2 years corn on corn compared to last years soybean crop. Keep tuned in.

References I used for this blog:
Eusun Han,Timo Kautz & Ulrich Köpke, 2016; Precrop root system determines root diameter of subsequent crop, Biology and Fertility of Soils volume 52, pages 113–118
Landl, M. et.al; 2019, Modeling the impact of biopores on root growth and root water uptake., Vadose Zone Journal, Vol.18, Issue 1, pp.1-20.