Agronomics101

A product of plant chemistry that dictates what happens in plant root systems

Agronomic sciences have advanced a long ways in the last 5 years which pleases me.  Nigh on 40 years ago this fall I worked in a backhoe pit along side a good friend and Technician for one of the Soil Conservation District field offices (now USDA-NRCS) in eastern Colorado to study and determine why an irrigated corn crop was doing so poorly – we were looking at roots and if compaction was the ugly culprit.  For sure it is not like yesterday but I remember working with this man on several hundred soil-root pits until his retirement and later passing on.  Kudos to you Marv for getting me into this dimension of the soil science profession.  Why do I mention this?  A highly regarded scientist from back in the eastern Corn Belt wrote recently about the importance of cytokinins, roots, root tips and the value of these phytohormones.

The basic molecule rings of a cytokinin. Organic Chemistry comes to light.

John Kempf, writes a daily blog that detailed a few words I would like you to read, “Cytokinins are produced in growing root tips and cobalt is a key enzyme cofactor needed for cytokinin synthesis.  The key is that a growing root tip is needed to produce cytokinins, particularly at the stages of bud initation and pollination.

A healthy disease resistant plant will always be cytokinin dominant, rather than auxin dominant. This means they will always have more growing root tips (producing cytokinins) than they have growing shoot tips or seeds (producing auxins). It also means that these plants will have larger root biomass than vegetative biomass. Cytokinins are produced in growing root tips and cobalt is a key enzyme cofactor needed for cytokinin synthesis. The key is that a growing root tip is needed to produce cytokinins, particularly at the stages of bud initation and pollination. A healthy disease resistant plant will always be cytokinin dominant, rather than auxin dominant. This means they will always have more growing root tips (producing cytokinins) than they have growing shoot tips or seeds (producing auxins). It also means that these plants will have larger root biomass than vegetative biomass.”  He goes on to speak about plants such as edible beans and soybeans are quite dependent upon cytokinins to produce many pods and healthy beans.

Allow me to expand for a moment, having healthy roots, thousands of square inches of soil infiltrated by roots, root hairs and root tips will produce a lot of this phytohormone to stimulate photosynthesis and sugar production, move nutrients up the xylem tissues to the leaves and keep the cycle of plant life going all season until senescence in nearly all if not all crops farmers grow.  To tell you what I have measured in root pits and explored with others the under-the-surface hidden world of roots would be a long conversation – I am saying that Dr. Kempf just tapped the upper part of the iceberg with this and I hope he writes more on the subject.

In my 1700+ root pits since that first one with Marv back in 1981 exposed for a farmer I have measured root lengths, root density, root penetration, counted linear inches of even the smallest roots, photographed roots, invested 8-9 hours in a soil pit to get the facts.  I have read numbers and numbers of scientific journal articles about roots, own texts about roots and so on and so on.  Well that is nice you are weird Mike.  No, it is this part of soil science that resonates with me for me to really know why the plant does what it does in a growing season, it is why I find some corn varieties excel where others flop-fizzle, why knowing that compaction is the number 1 limitation for top root development, cytokinin expression and best yield outcomes.  When we get down to it, knowing how plants move nutrients, absorb and move water, utilize phytohormones that sense details of the soil environment to aid crop development – Wow!

We at Orthman Manufacturing have a good understanding of compaction and soil resistance and what kinds of tools farmers need to combat this problem that plagues growers not only in conventional tillage systems, yes you folks with No-Till are not immune to it and even growers who routinely strip till are aware of the compaction culprit.  We study it, we talk about it and then provide solutions at Orthman.  As we do we are learning more about what goes on in the root system down to the xylem tissues so we can be an informed resource to growers all over the globe.  Folks it is not just selling iron, we are offering tools that are steel but also tools that go into your mental toolbox to give you more in the harvest truck that goes to market.  Get in touch with us today.

Sidedress Fertilization Is it only Nitrogen you should be applying?

Good question for all of you that are getting after the duty of sidedressing or fertigating now that the corn is climbing towards the sky like in the story of “Jack and the Beanstalk”.  The demand from corn plants DNA signals is about to “hit the gas” on N consumption.  You all are aware of that whether you are a rainfed farmer or an irrigated farmer, but what about potassium, zinc, sulfur and even phosphorus?  Have you sampled with plant tissues to get an up-to-date view of how the plant stands with existing soil conditions and what you fed it earlier?  Yes there is a cost to that, yet folks in the days we sit in with low commodity prices a full awareness of your crops nutrition has much value to fall time results.  Sure we want to get by and hope for the best.  I get that, but even though prices look pitiful would you stop feeding that hungry teenager who fades 20 minutes after lunch and looks like he will gnaw on your arm while you haul gated pipe off the trailer and onto the ground and shove them together?  Inside joke I know for the rainfed grower in Iowa, Illinois, Indiana or other states that have not irrigated with 8 inch pipe.  Just the same folks, we do not stop feeding a crop.  Having a good idea where one stands sets the stage for the hybrids of today to do well or just so-so.

We at Orthman have teamed up with some great partners to study what happens to resurrect a farm that was less than optimally treated for some time nutritionally, old traditions of dosing with big amounts of N up front and little or nothing throughout the season was the game plan.  We soil sampled before we strip tilled and placed nutrition and the soils were quite depleted, that literally made me gasp some.  All that is to say now we have tissue sampled and found with the soils just warming into the temperature range in the upper 10 inches for the microbes to assimilate, populate and release nutrients as well as the early root system proliferate the soil profile.  We are still a bit shy of what should be a sufficient to adequate level but we are responding with two sidedress operations.

Applying liquid products with Orthman cultivator during sidedress and ditching process.

Soil temperatures last week (1st week of June) were touching 70 degrees F. at 8-9 inches below the surface.  That says what to you reading this?  A large cross section of the microbial population is getting into the mode of working, eating, populating, dying and cycling.  The nutritional products we laid in at 6.5 inches is right in that zone where we observed the 70°F are poised to and is being utilized and made available in the form most readily taken up by the young root system.  Those old decaying roots are food for the bacteria, earthworms, other microorthopods, spiders, and such to breakdown organic carbonaceous materials, unlocking nutrients.  All that being said, now is the time to supply N to feed the microbes but not over-feed them to take the crop towards its fruiting stage and kernel set.

In the field these last two weeks I have observed yellow striping in the corn at V3-V5.  It is not zinc but sulfur for many plants.  Sulfur as I have written on this blog plays a key role in photosynthesis and protein movement within the plant.  May I suggest you get out and take a close look in your fields and before you finish every field in the sidedressing with 32% or 28% or even anyhydrous – to evaluate for sulfur needs.  From here at the V4-V6 stage to V10 the call for sulfur is not huge but quite apparent to top production.  You purchased >$300 bag corn, please be wise about how sulfur is critical to what the rapidly growing plant needs.

Yes Nitrogen is needed; please take into consideration the important secondary nutrient – S.  We at Orthman also realize that many of you are using cultivators. Truly, a super time to place some of your total N and S fertility program — up-close and personal to the growing crop.  As you do the plant will very likely respond within 2 to 4 days with a color change and growth.  As it does the on-off switches inside the xylem and phloem tissues go on!  Cultivating not only for pesky weeds, the feeding of the hungry teenager makes for a better ending to the last part of the yield game plan.  I don’t know very many of us that walk away from well earned , hard fought and planned victory in the fourth quarter without a big smile.  A story of the fourth quarter success:  A tough quarterback in a post season game behind by six in the last few minutes with the ball on 6 or 7 yard line said “we’ve got ‘em right where we want ‘em”.  He marched the team 94 yards and crossed the goal line for a touchdown and a win, later a Super Bowl ring.  Some may remember that team.

You got ‘em right where you want those plants.

Some of the Latest Field Research on Soil Compaction – 10 Years No-Till to 11 Years Strip Till

It comes to you hot from the fields with growing corn at the V4 stage.  In East Central Nebraska my cohort Pat McNaught and I have been digging up in between corn rows and right in the row where the present crop is growing and taking soil resistance measurements to follow up with the 2019 project and learn even more of what is happening below ground.  This year we were able to get to a long term No-Till field and then same vintage of Strip-Till duration.

In the chart below you can observe in the soft row what the soil condition is like.  Pat and I dug this five days after the 4+ inch rain in late May.  The corn in both fields was V4 to V5 stage and not under any stress, the soil moisture condition was 75-80% of field capacity at 6 inches and 85% at 12 inches.  The lateral (side-to-side) soil resistance values in the soft row is significantly less in the Strip Till ground.  In the upper 5 inches of the soil profile the vertical soil resistance is less dense than the No-Till.  As we observed these two fields within 7 miles of one another, two very dedicated farmers to their systems and very good corn production 250-295 bushels per acre yields (irrigated), we observed the root systems, both were starting the second set of nodal roots. The big difference was the Strip Tilled corn was 23 inches deep and the No-Till was 16 inches.

We are not casting stones here, but you get to look at some differences in how a No-Till field stacks up to a long term Orthman 1tRIPr Strip-Till field.

We will be monitoring these fields as the season progresses.  As of this early part of June all systems are go to hit a top notch yield.

 

Sulfur one of the secondary nutrients in crops carries out some very important functions in the plant growth cycle from early emergence to starch fill in grain.  Even though it is pretty well known that sulfur (S) is mobile in the soil, it is not in a plant’s vascular system – the lower sets of leaves will not show deficiencies of S as much as the upper/newer leaves will depict a yellowing appearance.  Do not misdiagnose that yellowing a lack of nitrogen (N), if that happens folks tend to think more N will solve it – no sir, usually creates more of a sulfur problem especially late in the crop’s life cycle.  Sulfur does not transfer from older growth into the new leaves.  With reason then late applications of S when diagnosed properly can be a great help in yield and plant-grain function.  Usually a foliar and soil feeding will do the trick.

What is the function of S in the plant?

Dan Davidson who I have known for more than 15 years, writing for the Illinois Soybean Growers, reports that sulfur and nitrogen work complimentary to one another. Sulfur is a component of specific amino acids in the photosynthesis processes and seed production: methionine, cysteine and cystine.

He went on to say; “Sulfur is a component of numerous enzymes (proteins) that regulate photosynthesis and nitrogen fixation and assimilation by the plant. It’s a component of ferredoxin, an iron-sulfur protein found in the chloroplasts—the site of photosynthesis. Ferredoxin also plays a metabolic role in both nitrogen fixation and sulfate reduction and the assimilation of nitrogen by rhizobacteria living in the nodules in soybeans”.

Early season sulfur deficiency, V5 stage

One of the important enzymes that drive nitrogen fixation is nitrogenase. This enzyme contains considerable amounts of sulfur and converts atmospheric nitrogen to ammonia. In addition Ferredoxin acts as an electron transfer agent in both nitrogen fixation and nitrogen assimilation into protein found in legume production like soybeans.

When does sulfur become available via the microbial breakdown of the organic sulfur components in soils organic matter (SOM)?

The activation of S is very dependent upon soil temperature and soil moisture.  Both air and soil temperature below 50°F (10°C) is very minimal.  Oxidation of the SOM really kicks in gear between 75-85°F [23-29°C] which says this importance nutrient for photosynthesis production, enzymes, and proteins is not happening in the upper 8 inches of the soil profile until early to mid-June in the Northern hemisphere.  A short list of who in the soil (bacteria) that oxidize S to become Sulfate (SO4) for the plant to utilize it directly: Chlorodium spp., Chlymydiaceae spp., Cytophaga spp., Flavobacterium spp., Porphytomonas spp., Prosthecobacter spp., Rubritaleaceae spp., Bacteriodes spp., Candidatus spp., Chthoniobacteria spp., and Fucophilus spp.  As I indicate with the spp, we are looking at multiple species within the two genuses of Chlymydiaceae and Candidatus for instance.  Please I am not trying to slap a big number of genus and species names to tie your tongue and sound like I am so smart with microbiology.  The number of bacteria in the soils both anaerobically and aerobically is large and their function oxidizes carbon rich compounds in residues and SOM and provides Sulfates available to the plant root.  For example; most obvious to anyone who has dug around in a mucky soil near a cattail mud hole know about the sulfidic odor [hydrogen sulfide] that on a hot summer day can make you nearly gag – those are anaerobic bacteria – some 23 genera, 220 species are known of the Deltaproteobacteria order; the second most is in the facultative-anaerobes of Firmicutes.  All in all these bacteria are important to take SOM and make SO4 available to a plant.

Therefore an important point to make here, sulfur coming available via bacteria in the soil and some mycorrhizae does not start right off the bat.  The need of sulfur within the first 40 days after emergence is high and we can help that hungry growing plant function better and improve yield potential by adding S via the spring pre-plant and in the starter products. Couple of examples: Soybeans remove 1.7-2.0 lbs. per 10 bushels of grain at a 60 bu/ac yield or 10-12 lbs/acre in a season, then corn removes 0.5lb per 10 bushels of grain or requires 30-35lbs/acre in a season.  Of those noted needs sulfur from V10 to hard doe stage R3-R4 in corn is over 60% of the plants total requirement of sulfur.  The soils are at their maximum of temperature extension at V14-R1 into the soil profile.  Soil temperature in the upper 10 inches (25cm) is reaching even under full canopy 85-88°F [29-31°C] and the soil bacteria are turning over nutrients in the SOM every hour of the day.

Sulfur deficiency in soybeans

In continuous corn fields the amount of S in the residues is not that great so a smart/wise nutrient management plan begins in a strip till system right as one strip tills to planting time and then during the rest of the season.  We here at Orthman advocate tissue sampling to best identify what is happening in the growing crop.  From information back in 2017 from a Purdue University Soil Fertility Update, the good folks at Purdue suggested;  In the plant, S is a component of two amino acids and occurs in protein in a ratio of 1 part S to about 15 parts N. Therefore, the N:S ratio of plant tissue as well as the S concentration are used to identify S deficiency. The lower the S concentration and the higher the N:S ratio the more likely S is deficient in the plant. Tissues from corn as you look at sulfur less than 0.15% and N:S ratio greater than 20:1 are most likely S deficient. Sulfur is most likely adequate when corn tissue S is greater than 0.20% and the N:S ratio is less than 12:1. Tissue S and N:S values in between these levels can go either way – deficient or adequate. Critical tissue S levels for soybean have been studied much less than for corn. Typically 0.2-0.3% S is considered adequate.  This kind of information can really be helpful in determining the S health of your plants and what to do about it.

Knowing that a good amount of sulfur prior to 2007 came from atmospheric deposition, mainly from coal-fire generating plants.  Good scrubbing techniques of the exhaust stacks have changed that but our plants have lost that input.  In fact there are power plants that offer the cleanings as a fertility source of sulfur for very little money per ton.  Higher yielding hybrids have shown us the demand for S, so we must watch our all-season nutrient program.  It is our belief to bring this up before your eyes and know that Orthman is capable of helping your deliver nutrients to your crops via the 1tRIPr, cultivators, and in-crop fertilizer soil insertion applicators.

Stay tuned as we keep exploring, offering tools, recent information and knowledge of nutrients, their function, how to get products applied.

Going to Go Into The Weeds with Potassium Made Available by Bacteria and fungi

In preparation for this tidbit of news I went deep into the weeds of scientific articles, journals and musings folks.  I came out of it a changed soil scientist.  What?  I had read and been informed incorrectly in the past about the small number of microbes involved with potassium (K) releasing bacteria.  It was known [to me] that only a handful (<6) bacteria and fungal microbes worked on the K from added K nutrients be they inorganic or organic.  Now my head is opened and knowing that more microbes work on potassim latticed feldspars in many areas where K values in soil tests can be high(>250 ppm), it sure does not mean the K is readily available to a plant root system.  In fact many crops we grow struggle to get K – why? Might it be our soils lack the right families and species of bacteria that make K available in an organic soluble form for the root to absorb I asked myself?  Uhhh, duh!

The lifestream in the root rhizosphere again comes into the light so to speak.  Similar to the flora in our gut and in the gut of lactating four legged critters, incredibly vital to digestion and absorption of key nutrients for all of us to sustain life, bacteria are the front-line soldiers.  So how do they make K available?

The group of P, K & Fe solubilizing bacteria and their activities

An overview of the mechanism used by bacteria and fungi to mobilize nutrients (P, K and Fe) in the soil.  See graphic to the right.  Courtesy: M.I. Rashid et. al, 2016, Microbiological Research, Elsevier Publ.

Legend of the graphic to the right of fungi and bacteria aid in the rhizosphere to make nutrients available.

 Indicates processes carried out by microbial inocula(materials/sources  growers add to the soils) to enhance nutrient
bioavailability.
 Specifies primary intermediary steps.
 Specifies secondary intermediary steps.
 Microbial inoculum.  [You noticed too I suspect that these inoculum are right in the first steps of these processes]

Here is a quote from the authors of one of the research papers that made total sense to me as I consider the complexity of microbial action in soils: “Bacteria release various types of organic acids to solubilize K in the soil through various processes such as acidolysis, chelation, complexolysis and exchange reactions. Rashid et.al.”  Those acids are citrate, malate, oxalic, tartaric, succinic, α-ketogluconic acid and oxalates.  Now the complexity grows exponentially and I am not going to go into that because the weeds entangle your feet and mine way too quickly.  As the microbes live, multiply and die they are making K as a nutrient available for the root hairs and epidermis to absorb, move into the cytoplasm and feed the plant for photosynthesis to keep going.  I know I am throwing out a good deal of organic chemistry terms in this, but these acids break free chemical bonds holding tight the K, P, Fe ions on the clay particles and organo-complexes to become available to the root.

Deeper into the weeds:  An associated group of bacteria first have to work on the mineral fraction, the rock or salt types of potassium. only few microbial strains have been isolated that have an ability to oxidize in the first step Fe2+ from primary phyllosilicates mineral in order that they release iron and K from these minerals.  Bacteria species that split iron and potassium apart (Neutrophillic lithotrophs) utilize structural Fe2+ in biotite (the black felspar we see in granite) as an electron donor for their metabolism in order to produce energy and oxidize biotite.  Who are those guys?  The microbes which oxidized biotite (Fe2+-bearing mica) include Bradyrhizobium japonicum, Cupriavidus necator, Ralstonia solanacearum, Dechloromonas agitate, and Nocardioides sp.  During the process of acidolysis, these rhizospheric microbes can chelate Aluminum and Silicon cations associated with K minerals and by doing so they also enhance the exchangeable K in soil solution.  In a series of steps one group of bacteria work on the clay silicates, then another set who need to be there make the potassium available to the root for absorption.  Some other scientific papers identified a number of species:  Bacillus pseudomycoides, B.mucilaginosus, B. edaphicus, B. circulans, Acidothiobacillus feroxidans, Aspergillus tenens and Paenibacillus spp that were right in the soil matrix, thick as thieves on the organic components from old roots, manures, and  dead/inert cellulosic materials.  An important issue microbiologists have discovered that not all of the species are up and living in the soil complex together to make K available or P or N or S or Fe.  I connected some dots in my head then, oh my no wonder we find in soils that crops need K — not all the players are on the roster.  Wow!

You are reeling maybe some from all the chemistry, it is important to note ladies and gents that the microbiological world is so intricate and intertwined to make the soils medium an environment for the root/crop prosper, take up water and hopefully yield grain or fruit.  So what in the dickens does this happen to do with Strip-Tillage on this website?  When we place mineral fertilizers in the root zone with a tool like the 1tRIPr what happens besides us placing it in the root pathway and just expecting all the work out.  Oh the itty-bitty critters that live in the soil (it is said that billions can be alive in 1 teaspoon) have such a gigantic role in making N,P,K,S,Fe,Zn and so on available.  Every year more great research is discovering or uncovering secrets of the soil world.  We are seeing that innoculating or invigorating soils with bacteria and fungi (which I did not talk much about in this blog article) has great promise to support the soil, supplement the line-up of players who belong in making the soil medium have a full roster (I am thinking of a baseball team analogy).  Just placing the nutrients starts the game like throwing the first pitch.  From there on it is the players swatting at the ball, hitting and catching or running it down in a certain amount of time before the harvest machine rolls in.  For all of you, I played baseball, catcher in my high school years.

This kind of reading tells more of the story folks.  I wrote in a previous article about potassium and its importance within the plants growth cycles, this offers you how the root obtains it.  I am excited to offer this.  The world of soil science is still after 50 years firing me up because of the incredible “digging deeper” gives me and hopefully you better understanding.  Are you ready for more?  How about Sulfur in the coming weeks?

References I read to get this to YOU:

Bacteria and fungi can contribute to nutrients bioavailability and aggregate formation in degraded soils; 2016, M. I. RashidL. H. MujawaraT. S.Talal AlmeelbiI. M.I. IsmailM. Oves; Microbial Research, Vol. 183, pp.26-41

Using Phyllosilicate-Fe(II)-Oxidizing Soil Bacteria to Improve Fe and K Plant Nutrition;  Evgenya Shelobolina,  Eric Roden, Middleton, Jason Benzine, Mai Yia Xiong,  United States
(12) Patent Application Publication; 9/2014

Paving the Way From the Lab to the Field: Using Synthetic Microbial Consortia to Produce High-Quality Crops; Z Kong, M Hart, H Liu – Frontiers in plant science, 2018

Phosphate and potassium solubilizing bacteria effect on mineral uptake, soil availability and growth of eggplant, 2005; Han and Lee, 2005, H. Han, K. Lee, Res. J. Agric. Biol. Sci., 1 (2005), pp. 176-180

Beneficial plant-bacterial interactions; BR Glick – 2015 – Springer, Book

Physiology of Crop Production; 2006, N.K. Fageria, V.C. Baligar and R.B. Clark, Haworth Press, Binghamton, NY; Chapter 8

Research on potassium in agriculture: Needs and prospects; Römheld, V.Kirkby, E.A.,  2010; Plant and Soil, Volume 335, Issue 1,  pp. 155-180

Phosphorus – What do we do with it and what does it do?

 

The index finger is touching the 2nd most important nutrient for many crops we grow. Phosphorus

Last blog I spoke about placement and the wiser way to put it in a band right in the pathway of the row crops root system.

When you as a farmer place P & K and maybe some other elements such as S and Zn with a strip till rig we are putting it in something of a concentrated zone.  A caveat here – you do not have to apply the same amount as one would if broadcasting the material whether dry or liquid.  How much less you ask?  We have seen a reduction as much as 40% (ie: 90lb/ac or 100kg/ha reduction to 54lbs/ac or 60kg/ha) when banded at 6.5 inches deep (160mm). Today’s price at $19.50/cwt {dry 11-52-0} or $390/ton that can be a savings of 40% or a savings of approximately $7.00 per acre.  And that is just for the phosphorus.  Now folks that does not say it is the exact right thing for you if you are new to deep banding with a strip-till tool.  A good approach is to incrementally ratchet this down first year and so forth in the next season and so on.  Hundreds of seasoned Strip-Tillers have told us at Orthman, they can reach that goal of 40% in three years and maintain depending upon replacement or satisfying plant use needs with both tissue and soil tests.

A question for you.  As you hitch up the planter, are you using a Phosphorus component in your starter products? I ask this because the plant usage of P in the first days after the coleoptile erupts through the seed coat to 15-20 days after emergence N,P,K and other elements consumption is not much.  For P, it might be ~2 pounds per acre.

But where it is, is just what the realtor tells any one of us if we a buying a new home; location, location, location!  Nearest to the seedling root and the best products you can give that infant plant the better.  A salt laden fertilizer – bad idea!  I say that because that brand new tissue that erupted out of the seed is a lot like an infant human child’s skin.  Tissue burns, cellular breakdown, toxicity, pain – it all happens to this infant plant if we burn that seedling root.  Cooper and MacDonald back in 1970 published in Crop Science, that the preautotrophic stage in maize is 14 to 26 days after germination, that time frame is dependent upon air and soil temperatures.  After that short period maize becomes autotrophic, that is when photosynthesis plus root absorption do it all in the way of feeding the plants engine.  But during that time maximum number of leaves is determined and a certain number of other genetic switches are flipped on.  Soil temperatures after 20 days are warming along with daytime ambient temps.  Bacteria and fungi growth and activity is so minimal unless you supercharge it with a biostimilant that it is pretty imperative to have some nutrients close at hand.  This is dependent upon soil pH in the upper 10 inches (250mm) for the soil solution with inorganic or organic forms of P to be readily available.  Phosphorus is most available in pH’s of 6 to 7.  There are those that will tell you that starters are too expensive and they do not give a decent return or yield bump.  I like to say and do, “When your baby boy or daughter was fresh from the hospital did your wife quit feeding him or her?”  Didn’t think so, I ask again; does placement of nutrients have value/importance?  You bet your last dollar you bet on your college football team to win by 6 points over its archrival.

So what does P do in the plant?

Phosphorus in even the very first days out of the ground is beginning to start photosynthesizing.  Light energy is being used to split water to produce molecular O2, reduced nicotinamide adenine dinucleotide phosphate and adenosine triphosphate (Yoshida, 1981) which sends these NADP and ATP through the leaf to enlarge the plant, make it grow to a 12 foot (300cm) tall plant with an ear and kernels.  Note phosphate in those molecules – IMPORTANT!  Thus, phosphorus is essential for the general health and vigor of all plants. Some specific growth factors that have been associated with phosphorus are:

  • Stimulated root development

  • Increased stalk and stem strength

  • Improved flower formation and seed production

  • More uniform and earlier crop maturity

  • Increased nitrogen N-fixing capacity of legumes

  • Improvements in crop quality

  • Increased resistance to plant diseases

  • Supports development throughout entire life cycle

Another set of scientists from British Columbia, our neighbors to the north of us in the States, state this; “Phosphorus is important for all photosynthesis, maintenance and transfer of genetic code, development and growth of all new plant cells, and formation of seed.”  To me that is pretty doggone important.

As I reiterated last week in the Precision Tillage blog, early P consumption is minimal but by the time the sixth leaf collar is exposed the plant starts consuming P.   At what kinds of rates, about 0.42lbs/acre/day by the time it reaches tassle or VT.  Then during the VT to R2 stage the plant ramps up again and calls down to the roots or maybe by a foliar application for more phosphorus.  Nearly all of that rushes to the ear and all the kernels, putting on bushels or tonnes.

By R6 when we are near full starch line and drying down the maize plant has used phosphorus to grow cells of stalk, leaves, collars, tassle tissues, pollen, pollen tubes, cob full of kernels and god ole my favorite ROOTS.  Follow us along as I delve into Potassium in the coming weeks.  K is the big sister to nitrogen, remember that.

 

 

Definition of autotropic – An organism, such as a maize plant capable of synthesizing its own food and cellular growth from inorganic substances using light or chemical energy.

References I used in writing this article:

  1. Fageria, N.K., Baligar, V.C., Clark, R.B., 2006;  Physiology of Crop Production., 345pp, Haworth Press, Birmingham, NY
  2. Cooper, C.S., and MacDonald, P.W., 1970; Whole plant physiological and yield responses of maize to plant density., Crop Sci., 10:136-139
  3. Yoshida, S., 1981; Fundamentals of Rice Crop Science. Los Banos, Phillipines: International Rice Research Institute

Second Installment – Phosphorus, 2nd Most Important Nutrient Right Behind Nitrogen

In the last Agronomic blog I here at PrecisionTillage.com, I began a conversation to look into plant use and efficiency of phosphorus in a fertilization scheme in high production Agriculture.  Phosphorus is ‘the’ second most important nutrient to plant growth for nearly every crop we grow behind nitrogen.

Fig. 1. Estimated cumulative P uptake for maize as a function of grow¬ing degree days (GDDc on the Y-axis) for maize growth with vegetative (V) and reproductive (R) stages shown for “modern hybrids” (adapted from Bender et al., 2013a) and “older hybrids” (adapted from Ritchie et al., 1997).

Fig. 1. Estimated cumulative P uptake for maize  which I will explain throughout this article.

What I am aiming to accomplish in this part, is to offer to the Phosphorus discussion is:  smart placement of said P products, and why we scientists see P placement important in affecting plant growth and ultimately yield be it grain, forage or fiber.  Some of you already know my perspective that roots are such an emphasis to me personally in this discussion, which zone of the rooting profile extracts/takes-up the nutrients (in this case P) and how we can enhance that use and uptake efficiency with the methodology of Strip-Till.

As you observe in this graphic (Figure 1.) to your immediate left in maize that older hybrids dropped off in P uptake at the V10 stage to a small degree and the newer, more recent breeding and selectivity of maize characteristics has given rise in thinking when later P fertilization gives desired outcomes are a little later.  As new longer cellular life functions are bred into the maize hybrids, the P uptake curve changes into latter parts of the plants life.  Early on in the life of the maize plant the uptake of P is (<5lb/ac) now known to be slightly less than observed before (prior to somewhere around 1996-2000) just when genetic modifications were really getting off the ground.  With the successes here in the United States of 400, then 500+ and now {2019} >600 bushels per acre (10.9T/hectare to 13.6T/ha to 16.3T/ha) the P needs and P uptake curve has been altered.  Growers should be changing their thinking and what should be their P fertilizer recommendations.  In some instances the step-by-step approach of incrementally fertilizing for P looks daunting compared to the big juggernaut load prior to planting.  Loading up front with P and the propensity of soil systems to tie-up P appears to me an inefficient way to feed this crop, maybe any row crop we grow.  Especially as you look at V10 and then R2 stages (see black solid line in Figure 1).  I try to wrap my agronomic mind around that amount of maize coming from one hectare or one acre when I think of those kinds of yields – Wow!

Figure 3. Early corn root system with 1st nodal roots emerging with banded nutrients with planter and deeper placed with 1tRIP tool (yellow blotches)

Back to considering Figure 1 folks, I ask this age ole question: have we been carrying out our Phosphorus fertilization practices to feed the soil, the organic matter complex in the soil, as well the unfortunate calcium tie up mechanisms in our Western U.S. soils or – are we seeking to best feed the plant?  Okay, you are giving that some thought, which is good.  Let us next consider the earlier root system of the maize plant (seedling root to Nodal system 1 and then extending to the beginning of nodal stage 2 development).  Where one places nutrients via broadcast and using tillage to mix to feed the very limited number of roots and root hairs, the surface area of all roots in the first 15 days after emergence could make an incredible difference in those days of growth and future days ahead.  [See figure 2]   Then as you consider the placing those nutrients including P as a starter mix in the seed trench or along either side of the trench, associate that with pre-plant placing P by 1tRIPr tool is seen in Figure 3.  In this depiction (Figure 3) the roots can run into an initial amount of addition of nutrients and then as the deeper seedling root obtains the deeper placed materials the root can proliferate and take in another dose.  I will chance repeating myself here; roots have to physically run into nutrients whether liquid or dry for osmosis, diffusion and mass flow to gain access to them.  The two dark background images (Figures 2 & 3) are what one observes at 15-18 days after emergence stage as the soils are beginning to warm above 55 degrees F. at 6 inch depth.  As soils warm at the depth of 6 to 9 inches (15 to 23cm), bacteria and mycorrhizae that live on and in roots do rapidly populate and fungi infect roots. Both bacteria and fungi gain activity, access and breakdown for the plant what we add of nutrients and then the plant roots absorb.  Numerous scientific articles from worldwide research studies (Netherlands, UK, India, Pakistan, Australia, United States to name a few) have looked in depth at how hundreds of bacteria species along with mycorrhizae do feed the plant hosts through the root system.  Mycorrhizae are of prime importance in absorbing P and feeding its host plant very efficiently of which maize is dependent upon.

Figure 2.  Early corn root system with 1st nodal roots emerging, colored dots depict nutrient products after surface broadcast & mixing

 

The maize plant may have 85 to 110 square inches of root-to-soil surface area which I have done the measurements (look again at Figures 2 & 3) at this V3-V4 stage for absorbing water and nutrients.  It is very important that the P products are placed right near the root system to efficiently and effectively supply nutrients to the fast growing plant.  I have to remind myself, that plant roots do not grow upwards towards the surface where broadcast fertilization drops N,P,K etc.  Gravity pulls roots downward – you physically place said products in the pathway of the root growth – Violá!

As the soil temperature warms to 63° then up to 75° the bacteria are ramped up to a near frenzy and are working on converting inorganic P source products or taking it off the organic complex right in that zone of 6 to 9 inches  below the surface – back to Figure 1, we are right in the steep up-climb of the maize plants needs.  We see the roots that are in this zone with their symbionts of fungi and billions to trillions of bacteria working in harmony together.  Up near the soil surface the soil temperature is rising into the 90 degree range and bacteria die back and the fungal hyphae shrivel and die.  Why we to think the plant roots will be effective at gaining access to surface applied and lightly mixed to roots that are dying due to heat and desiccation?  It is about placement folks into where an abundant root system will proliferate and using a tool that helps the grower conserve moisture, allow residue to protect and insulate the soil surface, water to infiltrate better, feed the biological life, use less fuel to prepare the seedbed and a host of other benefits.

All of it works together so beautifully folks.  The amounts of N,P,K we place is your choice.  Fertilizing as a pre-loading the soil up with broadcast rates in a strip till system approach is not the most wise, you are becoming more efficient with strategic placement, please be smart about this.  May this article be helpful to you as you get after it this spring and into the future.  I will be getting Potassium info ready and up and running so you will reading that in the coming weeks.

 

References I used for preparation of this article:

  1. Battini, et.al, 2017, Facilitation of phosphorus uptake in maize plants by mycorrhizosphere bacteria. Scientific Reports in Nature Publishing Group, Scientific Report 2017; 7:4686

2. P.S. Bindraban, et.al. 2019, Exploring phosphorus fertilizers and fertilization strategies for improved human and environmental health., Biology and Fertility of Soils 56:299-317

3.  D.P. Schachtman, et.al., 1998, Phosphorus uptake by plants: from soil to cell. Plant Physiology 116:447-453

4.  A.E. Richardson et.al., 2005, Utilization of soil organic phosphorus by higher plants. Organic phosphorus in the Environment. CABI-Wallingford 165-184

5.  Schnepf, et.al., 2008, Impact of growth and uptake patterns of arbuscular mycorrhizal fungi on plant phosphorus uptake – a modelling study. Plant Soil, 312:85-89

6.  M.J. Harrison et.al., 1995, A phosphatic transporter from mycorrhizal fungus Glomus versiforme. Nature 1995; 378:626-629

7.  S.M. Kaeppler, et.al., 2000, Variation among maize inbred lines and detection of quantitative trait loci for growth at low phosphorus and responsiveness to arbuscular mycorrhizal fungi. Crop Science 2000; 40:358-364

8.  G. Hopkins & Niel Hansen,2019, Phosphorus Management in High-Yield Systems., Journal of Environmental Quality, 48:1265-1280

The Second Most Important Nutrient/Ion to Dominate Our Nutrient Management Programs — Phosphorus. Let’s start with some ideas of products.

All over the globe we as Agriculturists are aware of the challenge to provide the nutrient phosphorus to small grains (ie: wheat, rice, oats, barley, rye) larger grain crops being maize and then broadleaf crops (ie: sunflower, soybeans, dry edible beans). The concern stems from the role P plays in photosynthesis for plant growth then the finite supply of rock phosphate around the world which is running low in North America.
Knowing that, how do we use less or somehow obtain access to the material in solution or tied up in polyphosphate forms or in the resident soil organic matter? Adding animal manures is one option. Another is to add bioenhancers or biostimulants that stimulate the resident mycorrhizal fungi and microbiology. It has been determined that more use of fungicides and certain herbicides, that mycorrhizae and some microbial families have been diminished in the soil. To me that is alarming and I have seen such but was not putting the two factors together. Since so much of the biology of our soils is intertwined it all makes sense.
From that said, there can be additions of mycorrhizae spores and specific families of bacteria that work on resident P compounds in the soil. The addition of microbes can be difficult due to these creatures in a water based product for any long period of time may drown since they are predominantly aerobic; do not survive under water very well. There have been efforts with the seed companies to place a coating on the seed which can include Phosphorus specific bacterial spores and to offer an influx of bacterial activity early for the emerging root system. The jury is still out as to the effectiveness of that in the seed bag. But with personal eyes digging the summer of 2018, I was part of a team for Bayer Crop Sciences to examine maize plots in Iowa and NW Missouri as to the effectiveness of said seed coatings, we did see several plots that had definite size, number and root development over hybrids without the microbes.

May I first move this conversation to using certain mineral based P fertilizers? Dry products; mono-ammonium phosphate (MAP, 11-52-0) and Diammonium phosphate (DAP, 18-46-0), Triple superphosphate (0-46-0), MESZ (10-46-0-1Zn), 40Rock (12-40-0-6S-1Zn); have been used and continue to be used for what is touted as ease of handling large quantities, spreading quickly (for the applicator) and lower costs for liquid P products are yes some more cost. Too often to the grower because he/she is adding quantity the cost factor plays a big role in what to use and then the choice of all dry can be fraught with pitfalls and availability to and for the plant. [[I want to insert a question for you all to think on – Are we fertilizing to always to have it easy for us OR are we fertilizing to feed the plant products that will give the desired result?]] We have seen a huge pitfall in the Great Lakes region in the past 5-9 years of enormous algal blooms (eutrophication) in streams, rivers and the Lakes due to growers going ahead and applying in the winter months on frozen ground. Then along comes the shallow winter thaws and rains and off these products run to water courses, my oh my. Now state rulings are being organized to restrict ill-timed applications as well new conservation programs. Let me give a for instance in Ohio; a specific region of the state growers can participate with financial incentives to change their modes of applying P sources in a big 14 county pilot program. This is all happening this spring in Northern and NW Ohio to lessen the soluble P movements of getting P into the lakes. It is called “H2Ohio”. Deep banding, injecting, timing of tillage and that fits perfectly with the practice of Strip Till. Here at Orthman we are responding to be part of the solution.

The index finger is touching the 2nd most important nutrient for many crops we grow. Phosphorus

In the more moist environments east of the Missouri River or the I-29 corridor and east, dry fertilizers will with time become available in soil solution and in moderately acid (pH 5.6 – 6.0) to neutral (pH 6 – 7.3) soils so the ‘fixing’ of Phosphorus is not so ugly. When pH of the soils rise from 7.4 to 9.0 then the calcium and or sodium ions will complex with the P and it is like going into a prison lockdown, phosphorus can take years to become available. It has been observed by this scientist and many others that most polyphosphate products will become tied up and or slowly release into the latter part of the cropping season and not be available at the critical times. Yields can be reduced and that is not good. Saying that folks, using dry products are not a bad choice but one must be aware of the complexities and limitations with timing and product choices with dry. Turn 180 degrees geographically and head west, the growers in Central Nebraska and Kansas out to the Continental Divide where rainfall is less and less, where soils are higher pH, lower cation exchange capacity, lower soil organic matter levels to the subsoil and free calcium carbonate can run as high as 10% — the dry fertilizers are not as widely used. In many geographic areas dry products are not used at all.

So that leads us to change modes of thinking, considering liquid products – there is a big grocery list of liquids available to the grower these days. Orthophosphate and polyphosphate combination products are used to insert the phosphorus right where the roots can gain access quickly. Some of these products are manufacturer specific. Products with more Ortho; breakdown of N-P-K: 9-24-3, 3-18-18, 9-18-9, 10-34-0, 11-37-0, 15-15-15, 15-15-2, 6-24-6, 7-21-7 and the list is longer. These products applied right in the pathway of the roots by deep banding with a Strip-Till implement is ideal.

In the next segment of this topic I started with, I want to cover how the products get engaged then we will turn to the plant needs for Phosphorus, the action of P getting into the soil and available for plant uptake and who in the biological world is assisting the farmer, crop and soils.

More Nitrogen News – Can We Feed Our Crops Better?

In my continual search and self education for all of our customers and potential customers which are the rest of you, I read in one of my texts; “2006, Physiology of Crop Production.” by N.K. Fageria, who has been a scientist studying rice and maize production more evidence to support more than one form of Nitrogen during the season .  He writes about the energy required to convert NO3 to the more usable form in the maize plant as, ammonium (NH4+).  His data states that the amount of energy in ATP/mol is four times higher for the plant to assimilate NO3 than NH4+, that can be a setback in crop production potential.  Then in another text of mine, according to Tisdale et al. (1993, Soil Fertility and Fertilizers), the rate of NO3- uptake is usually high and is favored by low-pH conditions. NH4+ uptake proceeds best at neutral pH values and is depressed by increasing acidity.  That is pH levels of 5.5-6 and under.  Fageria reports that maize and small grains do best in N  uptake efficiency when the nitrogen sources are mixed between nitrate and ammonium throughout the season.  NH4+ is the N source of choice early in the life of a maize plant.

Feeding the corn plant to produce the most grain as possible takes multiple forms of N.

Now all of this absorption and uptake depends upon the amount of carbon in the soil rhizosphere.  If soils are low in available C such as soils in the Sandhills of Kansas, Nebraska, E. Colorado, the efficiency of N uptake and utilization to create grain will depend upon how the grower takes care of the crop aftermath, tills, where possible and available adding a living plants that root down well to supply an addition of carbohydrates, proteins, nucleic acids and lipids in left over tissues.  We also know that nitrate is more available to the maize plant in better aerated soils.  We also know the factor of nitrate is readily available in soil solution and the plants can access it via the roots as well as the number of soil bacteria that work on nitrate are numerous.  But the genetics of upland plants prefer nitrate for a major portion of the plants lifespan so we have thought that we should us nitrate as the source of N to improve yields.  Something of a conundrum.

So where do we go with all of this?  Early on as I have written before in this blog and many other scientists have written in journals and blogs, NH4+ is preferred in the first 25-30 days after emergence (DAE), then NO3 up until 75-85DAE after that time frame it seems that urea and NH4+ has much value.  You as a grower ask what makes all the difference Mike?  I buy nitrogen in the form of NO3 and call it good, all what you are saying is fooling around to me. My response – I want to inform you that depending upon your growing which crop of grassy-types or broadleaf crop; certain forms of N are more efficiently absorbed, taken into the root and uploaded in the xylem tissues and moved up towards the sink, the ear or florets or pod.  Considering which N source fits the plants physiology is important for you to know how to be as effective as you can be feeding the crop for the optimal yield you can gain.  Not everyone can push 600 bu/ac corn, your climatic factors are never perfect or maybe conducive to such.  I am concerned tho if we add more and more nitrates as the N source of choice we can cause harm to the soil and water ecosystems, cause groundwater pollution for drinking supplies which in turn cause infant blue baby syndrome and eutrophication of rivers, streams and lakes.  To repeat myself then, mixing our N sources can change the plants growth and efficiency, feed it properly and we accentuate yield of biomass and grains.

I will keep digging folks, asking questions of other scientist I rely upon, reading and getting material for you to gain a further understanding that we can grow some amazing crops.  This is one thing I have is some time right now with so many venues and events are shut down for me and many others while we work to remain healthy folks.  Stay in touch and come back to Precisiontillage.com.  As noted on the Home page; you can call me or send an email.  Cell number is 1.970.302.1442 or email – mpetersen@orthman.com

Importance of Nutrient Timing for Row Crops – Especially in a Strip-Till System

For the number of decades (4 and some months) I have worked and dug in fields across the globe, I have observed growers apply commercial or natural fertilizers too early or for convenience-sake for the grower but not the target crop they are growing.  There was old ideas that put it in the soil and it will be there for the plant later on.  Too often we see the application of products laid out on the surface during the winter months and losses are substantial.  Other losses come from leaching the mobile products like nitrogen (N) and sulfur (S).  Losses from volatilization out into the atmosphere can and does occur.   The real need for those mobile nutrients may be 75 to 100+ days later.  In parts of the United States for instance, that far in advance there can be 50 to 75% loss – out the field from rain runoff, snowmelt and into a stream or river.  When applied either by deep tillage, banding or Strip-till too early N and S can leach out of the upper reach of the sol profile and move deeper than what the early root system can intercept, losses do occur.  If we just count the cost in nutrients as well as the dislodged soil particles and organic matter – oh my the dollars are flying away.  Some of those numbers can go over $100/acre.  Enough of the gloom and doom words.

All of the images below are tools for growers to aid them in adding micro’s and Nitrogen near the seed for better use and setting of the stage for early vigorous growth and plant health.

Yetter attachments for 2×2 placement
Courtesy Yetter Mfg.

Bandit 2×2 placement – Courtesy 360 Yield Center

Conceal 2×2 placing nutrients         Courtesy Precision Planting

May I start with the crop we grow extremely well in North America – maize or corn.  Corn has what I have studied seven critical physiological periods in its life span that are nutrient demanding.  With today’s blog I will cover up to the 45th day after emergence and in a subsequent blog finish the corn seasons demands/critical periods for nutrient usage/uptake.  Some folks say that the corn plant is like a hungry teenager, from 13 to 20 years of age for a boy as an example.  My gosh there are not many of his waking moments he is not wanting sustenance.  The bottomless pit Mom may say.  I know when I was a teenager my metabolism ran full steam all of my waking moments even there were some midnight ‘fridge’ raids.  And I am still not a man of weight on my frame.  My studies of soybeans depict four critical times the plant has high nutritional demands as does dry edible beans.  Sorghum for grain or forage – five times.  Cotton which is a perennial plant that we attempt to fool into being an annual crop is a little harder to say but I see – five times.  My experience with peanuts (groundnuts) is so limited I cannot say.  Other crops that are grown in rows; safflower, sunflowers, canola, lentils, potatoes, yams and sweet potatoes, sugar beets, sugarcane and even hemp; all these crops do have specific critical periods of requiring nutrients.  Not all nutrients are being demanded equally across their life span.  Let us look specifically at corn; within the first minutes to hours after the seed imbibes water and the emerging plantlet erupts from the seed shell and the root radicle extends out and downward it will take in P, K, Zn, Fe, Mn a touch of N as ammonium.  Now a portion of this is pulled from the endosperm (starches and proteins) of the seed to send the plant upwards to pierce the soil surface and the seedling root to grow.  When the infantile seedling root does access nutrients right away in the seed trench it will not have to exhaust the supply of food source in the seed.  That being said the first critical period is very early.  The next period is 10-12 days after emergence, mainly uptake is P, Zn, Mn, and Fe.  The amounts are low but critical to starting the developing leaf systems.  Then, at 20-25 days after emergence the corn plant undergoes a change in how it absorbs N.  Nitrogen has been consumed in the ammonium form from root eruption till now.  Now the plant can absorb N as proteins directly, Nitrate, ammonium to a lesser degree.  At 40-45 days after emergence, the corn plant is developing the ear size in circumference, rows of kernels.  P, K, N, Ca, Mg, Zn and small, small amounts of other micro’s are called up.

The Orthman 1tRIPr point and shank system can deliver products in 2 locations – this can be liquid and dry or liquid in 2 spots, very versatile for pre-plant fertilization

By the time the plant is genetically requiring nutrients as of the critical times, yes we need products to be in the root rhizospere, that immediate area where the roots are growing and active ready and absorbing.  Where can those nutrients come from?  A certain portion comes from the soil complex and the soil organic matter that can be from 20 to 50% of the total needs depending upon the exchange capacity, amount of organic matter and what is in the soluble fraction then the rest usually is what we tend to add via commercial or natural manures.  There are a number of schools of thoughts that offer [from University testing and USDA-Agricultural Research Service] what are the plant nutrient needs.  You have trust or faith in a reliable source, do keep tract of their recommendations.  It is also a wise approach to do your own testing to  have a baseline as to what, how much of N,P,K,S and so on your soils, fields and crop selections require.  Climate has a great deal to dictate how your 2020 crop will respond, what I know and have observed filling up the tank weeks ahead of the crop even being planted will lead to losses of the mobile ions.  Spreading on wet, frozen ground due to the convenience of having the local big fertilizer company apply – not so good folks.  Having a better concept of when a crop requires N for instance is so extremely valuable for the plant, your soils and water resources can lose big time, the environment, down river neighbors in their water quality issues. Do not get me wrong our neighbors in the cities have a responsibility too, maybe even more than we in Agriculture.  I am suggesting let us be wise to feed our crops for the first 45 days, not all 125 days.

In the coming weeks we will go into the days after the first 45 to describe those critical physiological time markers that can drive nutrient application.  I am watching that spring is right around the corner this week and the bit is chafing some and the calendar calls, but folks the crop cannot go into the soil until the soils dry enough and the temperatures warm.  The days will come, I know.