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

A thought regarding last years Prevent Plant acres

As we saw in the middle-few days of April, we saw a dump of snow from the Rockies eastward into Iowa dump 6 to 12 inches here and there of the Christmas Joy, many said Bah-Humbug, tho a reminder came to some of us who are weather watchers – another wet spring.  What does that conger up?  Oh we hope not, more Prevent Planting. Then nice days came the last two weeks for a good cross section of the Midwest –  time to get after the 2020 crop year.

It is being brought up here on Precision Tillage to offer some thoughts and comments what happened last year and what ideas may be important for you all that dealt with 2019’s Prevent Planting ground, especially in fertility management.  A question that comes up; I had lots of weed growth – how does that effect my fertility program for 2020?  Great question for our discussion. I am a student of soil testing but not just any ole go out with a bucket, 10 inch probe and poke a few holes 35 ft into the field and co-mingle the samples and send them off and call it good.  Consider what species of weeds were dominant.  Were these weeds in patches such as huge areas of pigweed or Palmer Amaranth?  Did Russian thistle mix or take over the sandier spots?  In the low lying areas, did Johnsongrass, Quackgrass, Crabgrass, Nutsedge, Yellow and Green foxtail become overwhelming?  I am asking because those weedy species all consumed a tidy amount of nutrition some are nitrogen consumers others the full spectrum of nutrients and not only in the upper 12 inches but deep (>24 inches).

Prevent Planting field in the Platte River Valley – Nebraska

 

There is also the issue of an enormous seed bank now in your field that will become very problematic on into the future which can offer challenges.  Another question; were you able to get into that field or fields and manage the weed growth before they went to seed?  I ask this because those fields will suffer from what is called the “Fallow Syndrome”.  No doubt before the weeds canopied the soil surface the surface baked hard and there was oxidation of organic matter, soil biological activity was reduced, mycorrhizal fungal spores did not germinate and do their job with corn or whatever crop we normally plant.  Some of those spores desiccated and others sat and will wait for a symbiotic host’s root to arrive.  All of this is part of the “Fallow Syndrome”.  Sure the soil may have seemed to have rested but, when weeds went wild and grew prolifically – a real detriment was against  you the grower.

A third issue with Prevent Planting and fallowing ground are losses of residual fertility due to certain percolation and losses out the bottom of the profile.  True phosphates do not move very far downward unless they are in the soluble form in soil solution which was the conditions you sustained with wet, wet soils.  Also sulfur components and maybe some micronutrients leached and reached a water course or water table and gone.  Deep soil testing can be a tool to determine how much is gone.

Why is the agronomist with a tillage implement manufacturer visiting this issue?  I assume by now many have done some form of tillage to deal with the impact of those pesky weeds, with a so called cleanup operations.  What to do?  Do not think you have solved the weed bank, changed the surface 4 to 6 inches, root balls from the big broadleaf weeds and un-oxygenated soil conditions?  Please I am not trying to say all is awry, but if soil conditions are amenable the strip till tool with precision placement of this year’s nutrition program can be very wise choice in preparation for the 2020 year.  Yes last year was unfortunately a stinker and a loss of income.  Using a smart and conservation minded system that can go through all the leftovers, minimize disturbance before you plant and broad-acre tillage only encourages more weed species.  So to minimize unnecessary soil compaction which wetter soils are prone to so often Strip tillage can work.  With the benefits also of less fuel consumption with strip till unless you have already disked the field twice and a surface leveling tool after already, strip till can be effective.  That potential weed seed bank does not need to fed again with high priced nutrients, strip till and placing a portion of your total program in the pathway of the crop you are planting has loads of potential you desire after a year of nothing.

We at Orthman empathize problems that occurred with last year’s flooding and wetness just obliterating the farming potential.  Today we would like to team up and help you see this Strip Till System one that hold potential and financial gains.

By:  Mike Petersen, Agronomist/Soil Scientist

What are some important features of Potassium and why we fertilize

What is it when you consider the third macronutrient that we talk about fertilizers from mineral sources that intrigues you? The element K (potassium) is the one I am discussing here today.  Yep for you chemistry buffs; Potassium is a chemical element with the symbol K (from Neo-Latin kalium) and atomic number 19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Its molecular weight is 39.089 and has a positive valence of +1.  It is found in crystalline form of orthoclase, predominantly from granitic origin.  It also is a precipitate of certain salt mines from Australia and China.

Potassium mining in Western Australia, evaporative process for sulfate of potash salts, K2SO4   Designated as:  0-0-51-18.

So?  You ask what are some of K’s dominant functions in a plant whether C3 or C4 metabolism?

Potassium has many different roles in plants:

  • In Photosynthesis, potassium regulates the opening and closing of stomata, and therefore regulates CO2 uptake.
  • Potassium triggers activation of enzymes and is essential for production of Adenosine Triphosphate (ATP). ATP is an important energy source for many chemical processes taking place in plant issues.
  • Potassium plays a major role in the regulation of water in plants (osmo-regulation). Both uptake of water through plant roots and its loss through the stomata are affected by potassium. This nutrient plays a huge role in how the stomata cells open and close throughout each day a plant lives.
  • Known to improve drought resistance.
  • Protein and starch synthesis in plants require potassium as well. Potassium is essential at almost every step of the protein synthesis. In starch synthesis, the enzyme responsible for the process is activated by potassium.
  • Potassium catalyzes chemical reactions by regulating > 60 enzymes associated with plant growth. Furthermore, the amount of K present in the cell determines how many enzyme-driven reactions can be activated at any one time.
  • K is necessary to maintain the function of phloem (the vascular tissue that transports sugars and other metabolic products downward from the leaves) and xylem (the vascular tissue that transports water and nutrients from roots to shoot and leaves) transport systems.

The roles of K in plant health is amazing:
K fertilizer is now known to significantly reduce the disease incidence of stem rot and aggregate sheath spot, and negative correlations were found between the percentage of K in leaf blades and disease severity in rice and wheat. K fertilizer is widely reported to decrease insect infestation and disease incidence in many host plants. A French scientist (Perrenoud, S. Potassium and Plant Health, 2nd ed; International Potash Institute: Bern, Switzerland, 1990; pp. 8–10.) reviewed 2449 references and found that the use of K significantly decreased the incidence of fungal diseases by 70%, bacteria by 69%, insects and mites by 63%, viruses by 41% and nematodes by 33%. Meanwhile, K increased the yield of plants infested with fungal diseases by 42%, bacteria by 57%, insects and mites by 36%, viruses by 78% and nematodes by 19%.  I quickly gather from that information that potassium is vital to crop health and should not be taken for granted that certain soil tests values may depict>300ppm K and all is going to be fine and dandy.

Considering Potassium in Plant Metabolism:

Courtesy of: International Journal of Molecular Science; Weng, et.al. 2013

Some scientists have stated and I am one of those, that K is the “Big Sister” to nitrogen in nearly all crops; nut trees, conifers, small grains, large grains ie: maize, peas, lentils, dry beans, garbanzos, sorghums, forages, root crops, vine crops which include tomatoes and so on and so on.  For those of you who had a big sister, what did she do with you when you were 1 to 4 or so? Drag you here to there, haul you around by the hand or hand to the back and softly push forward was the mode.  For those of you who did not appreciate that you know it was annoying or embarrassing.  With K in the plant cells, it smooths the way for N to move into metabolic pathways and get there quickly (a less scientific way of saying the of the protein transport pathways).  To the left is a flow diagram of what critical roles potassium plays in all grains.

In a future blog article I will bring out the major players in the microbial world of bacteria and fungi who is at work to make potassium available to the root.  For now, chew on this information, I realize there are texts and hundreds of scientific articles covering every side to K in plants and having rudimentary information for today will have to do.  Just getting a different perspective on this important nutrient source is the right start.  I know I learned a few great points of how I should look at potassium.

We will discuss some of the prime important times to fertilize with potassium.  The Fertilizer Institute of Canada retains a great deal of research and data on potassium, you may want to go and look at what they have.  Website: https://www.tfi.org/

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.

What’s all the Hubbaloo with Cover Crops as a Magic Elixer?

Early March 2020, we returned from a high powered, well attended Commodity Classic held in San Antonio, we returned with tired voices from talking and interacting with so many good folks at the Trade Show.  In fact we were informed that the crowd was a record number, made for many conversations going on with two to three sets of growers per Orthman representative and others wanting to ask questions.  Good position to be in.

There were some Win-win sessions going on each morning of the Trade Show and audiences crowded around tables and chairs to hear speakers that spoke to issues marketing, Soil Health, High Yields and Cover Crops.  The latter subject just mentioned was very prevalent with the exhibitors, Soil Microbial mixes were also a topic from many of the exhibitors and then Cover Crop seed sales and mixes they sell.

As a soil scientist I shake my head at the lather that has been rubbed up into suds regarding cover crops, their inevitable roots living longer if planting properly.  In that mantra that is spoken of over and over  (living green matter year around) there seems to be a lack of sense about what

Soil Scientist for Orthman Manufacturing, Mike Petersen [guy in the dark green shirt] explains physical characteristics of Soil Health to Idaho growers.

is happening in the active biological realm of the soil profiles on a growers farms.  There is also a itty-smidgen of material that comes out about the physical characteristics of soil.  I sat in on a breakout session that was to be on Soil Characteristics sponsored by Winfield Ag and the three men on the panel may have talked about characteristics of soils 3 minutes and allowed the Cover Crop person sway the topic to cover crops – not soil characteristics.  As a soil scientist for over 44 years now and would have liked to hear that the audience would get “the rest of the story” promoted.  Remember Paul Harvey on his daily radio broadcast about noon every day when he said with his dramatic pauses, “And now you know the rest of the story.”

Folks living roots, exuding and secreting have a  great effect on the biology and chemistry and yes even the physical.  But with my emphasis for growers is to understand physical characteristics play a very serious part in the orchestra of soil health.  I know No-Tillers bray and proclaim pretty loud that they have the answer for Soil Health, the vertical tillers say they too are strong advocates of Soil Health. Be cautious folks what you read, hear – do investigate the major three components equally when you look into Soil Heath and the selling of the emphasis of Cover Crops being the “Next Best Thing”  I think that was sung by a Country –Western singer.  Weigh the facts with Cover Crops, there are places here in the U.S. and across the planet where Cover Crops may just not have all the bi Wow effects.

I will in the near future, write blogs to go more into each of the three parts to Soil Health.  We here at Orthman Manufacturing want you to have a greater awareness and knowledge level to weigh the cover crops additions to benefit your crop rotations and soil resources where and when they can fit.