Photo Blog

Why do we see Phosphorus a limited nutrient?

by:  Michael Petersen, Orthman Agronomist

 

We are well aware for the most of us in the Farming world that phosphorus (P) is a limiting nutrient for top yields, stalk health, reproductive health right around flowering, early vigorous growth in corn especially and in western United States calcareous soils gets tied up.

On this site I will be looking into articulating what those limitations are.  Sure we see Universities talk at great lengths about N and some about P and its importance – but with the phosphorus mines across this nation being mined heavily, rapidly diminishing rock phosphate sources hold concerns about what the future brings.

Microbiologically the number of species that work directly on organic sources and the P fertilizers we apply are not that high in number.  They are predominantly aerobic (requiring oxygen to respire/live) creatures. Penicillium, Psuedomonas, and  I want to focus on Bacillus subtilis, member of the Firmicutes phylum.  This strain of bacteria are one of the most common that work on phosphate we fertilize with.

Bacillus subtilis is known to have a symbiotic relationship with the Azotobacter (a nitrogen-fixer affiliated bacteria) only six species of this cyst forming aerobic bacteria exist. These two work together on insoluble phosphorus within soil normally that is material like rock phosphate in dry fertilizers. The phosphorus gets trapped with the clay particles and begins to freeze ionic speaking, because the phosphate ion tightly bonds to the positive cations (calcium, iron, magnesium, silicon, and aluminum) found in the soil. B. subtilis coordinates with Azotobacter vinelandia by helping to release the phosphate bonds and release the phosphate (PO4) throughout the upper 6 to 10 inches of the soil profile. Without the addition of B. subtilis, the phosphorus can’t do its job effectively and further hinders agriculture. The phosphorus can’t move around to the plants and help maintain prosperous growth. Soil microbiologists consider B. subtilis and arbuscular mycorrhizae are  both a good alternative to insoluble phosphate fertilizers.

Scientists out of the microbiology world have discovered that B. subtilis and Azotobacter can be an aid to seed germination which is a big deal in certain seed crops like sorghum, canola, and small seeded vegetables. B. subtilis is able to take up DNA from its environment and creat antibiotics for itself and the host plant root it lives on to protect it from pathogens.  Quite the organism to aid a plant due to the net it makes to help its host.  See the figure below – electron micrograph image of the Bacillus subtillis colony and the net it produces around the colony. The strands you see are actually millions of these microbes swarming and releasing a slime layer which is what you see to the outside of the image, making the colony mobile to move about on root surfaces or on the soil liquid interface.  Probably more than you wanted to know, but think about the lack of mobility of P in the soil; here the microbes distribute what they use and secrete away.

B_subtilis_colony
Color electron micrograph of a colony of Bacillus subtilis on a media plate

Because B. subtilis is mobile with flagella (short string-like tails act as whips to scuttle the bacteria cells around on the root surface and in the soil solution) this bacteria can redistribute PO4 in the upper portions of the soil profile (0-9 inches) and feed roots in that section.

Another biological phenomena in the soil surface horizons is the arbuscular mycorrhizae that can infect roots to live inside the cortex of the roots symbiotically and bring N, P, S and Zn back to its host.  These ultra thin strands or hyphae that extend out of the infected root cells grows outward to access soil organics, humic acids, peptides, polysaccharides (complex sugars), a host of cellulosic materials – all to feed its host which requires simple sugars from the plant.  The plant gets the much better side of this relationship.

Microbes are extremely important to the breakdown of P in soils, can dislodge the tightly bound PO4 ions and make them able to interact with the roots.  Cyanobacteria, specific species of Glomus sp. mycorrhizae are included in the list of phosphorus solubilizing microbes which has Aspergillus sp., Penicillium sp., Trichoderma sp., and Actinomycetes a very robust group of bacteria in cropland soils.  Scientists have determined that the Actinomycetes are able to withstand dramatic temperature fluctuations from hot to cold and remain viable and energetic to solubilize phosphorus in the organic fraction and added phosphate fertilizers.  For those who are small grain farmers in with their row crops; the dryland farmers who have wheat and corn in rotation – you have an added advantage that wheat residues and old wheat roots are occupied by several genus of bacteria that remain to be phosphate solubilizers for the next crop.  For those of you that consider cover crops or companion crops, wheat has this relationship to continue a so-called home for these bacteria.

All great bits of information to provide you with tools and knowledge that the soils can be managed to aid with releasing P naturally and not use so much added phosphate.

 

Sources for this post:
Schaechter, Ingraham, and Neidhardt in Microbe. ASM Press 2006
Todar, K. “Todars OnLine Textbook of Bacteriology
Morikawa, M. Journal of Bioscience and Bioengineering, 2006 Vol 101, #1, 1-8
Sharma et.al., Phosphate solubilizing microbes sustainable approach for managing phosphorus deficiency in agricultural soils. Springer Plus 2013, 2:587

 

Newer Nitrogen Tools for We Strip-Tillers – Options to Consider!

For many of you, and for us at Orthman Research Farm near Lexington, Nebraska we are planning the pre-plant tillage operations of the spring 2013 to be underway very soon. Tillage via strip-till methods will be our way, but how about many of you as you consider the fertilization part of the puzzle? How will that be happening for you?
Just recently we attended a good set of meetings in Reno at the Western Fertility Conference to hear recent findings and interact with industry and research scientists about some gains in fertility management for row crops, small grains, and orchard/fruit crops. The issues of ground water contamination, overland flow issues getting into the major water course of the Mississippi River and major river systems of the West are challenging the way we growers must consider our operations. You all have heard about well waters reaching levels of nitrate in the water that surpass drinking standards not only for human infants but even livestock due to leaching and other contamination processes. Being good stewards now is very wise, but we are coming against issues of the past 65+ years of intensive farming with nitrogen sources.  After WWII and thoughts that “if a little is good than a whole bunch is that much more better.” Yeah bad grammar but it was an addage that numerous growers thought and employed. Now we pay for it and have to be that much more on top of our game.
The good folks I met, listened too and spoke with in Reno, NV are saying there are Nitrogen products on the market that will give better and sustained release to the crops root system over a longer period of time and resist the change from first introduction into the soil profile to convert to Nitrate and leach away before the roots have a chance to access to it in the soil solution. Products such as ESN™ being a granular urea coated with micro thin polymer, yes it is a dry product. This method of release can aid in slowed access to the urea-N product so it does not leach away, gobbled by the microbes or become mineralized so quickly that the plant root starves for N when called for by the growing above ground plant.
ESN™ is an Agrium product which responds to soil temperature and soil water content. Another product out on the market is Nutrisphere-N™ by SFP that works a bit differently than ESN™ but offers another management alternative for growers on how N releases into the soil environment. For the strip-till grower these products offer advanced ways to accomplish higher management of your N-fertility and feed the plant incrementally. Agrotain™ by Koch Industries, then there is Instinct™ by Dow are other products out there that all should be aware of so N management is not a willy-nilly part of how we furnish the corn, wheat, grain sorghum, dry edibles, cotton, peanuts, etc what is needed. As we learn more about these products from trials in each of our regions or even on a neighbors ground – we can better feed the crops we grow with the Nitrogen.
It was in the conference that we learned that especially with veggie crops N is in big demand for a short period and timing is everything. Consider maize/corn, we know it has three major calls if you will when N is in demand. Dump a hugeload prior to planting like 300 pounds per acre 30-90 days ahead of planting, do you really think it is going to sit still and not move deep or get fixed in the organic colloids or onto the clay complex or move off the surface if surface applied? Here is when these slowed release agents/products come into play to offer new solutions to our old loss problem. A little further study can really help you gain when and which product can work in your soils environment whether you have dry, wet, cold or what ever conditions.
In the strip-till system where the soils off to either side of where we strip-till 10 inches deep can be 2 to 8 degrees Fahrenheit colder, more moist if not wet and cause issues of root N-uptake and maybe even yield reductions early because the availability is just not there. You pour on N via anhydrous ammonia and expect because it is cooler that it will be there when the roots get to it, wow that could be an issue. It is a cheaper form of lots of N but is it the right one when any of it volitalizes or gets converted too soon? Cavities in the soil, shanked in and you may see it escaping, warmer than 50 degrees, dry soils – all issues and 20+% is poof, gone and that price differential just evaporated. Placing a charge of 250-300lbs/acre and then a couple-three inches of rain and the stuff will move even in clay loam soils 10-25 inches deeper than where you placed it. In some environments folks, the roots may never reach that and it is lost to never be had. Yes the same can happen to high rates of N via liquid products.

This day and age we are called to be better managers and come out of the shell the old way Daddy did it and move to spending time to educate how we can do better and wiser. Allocate time to have products be within reach of the roots when the demand for N is there will take new skills when we place it with the strip-till tool that we make called the 1tRIPr or another tool is very important. We, Mark and I at Orthman Farms are using some of the above products and getting positive responses that these products yield good results in grain and healthier crops. Check back with us or go to your agronomist or fertilizer dealer and learn about these products.

In California the watchers and monitoring agencies are clamping down on how fertility is managed, in Delaware and Maryland the environmental agencies by law demand fine-toothed control of N-P fertilization. In segments of the Central and Eastern Corn Belt states fall applications of N products are restricted and certain watersheds are being monitored and evaluated to stating growers may only apply 70lbs/acre (as an example) of N for a 200 bushel/acre corn crop. That is quite restrictive – yes? Other environments we can still be applying high amounts of N but to what cost? As a soil scientist and agronomist for Orthman Manufacturing I am going the route of top flight management with better products that will feed the plant incrementally. It has paid off and we encourage the same with the checking into the use of these good products that I named as a few of them to start with.
We will one day maybe feeding the corn we plant only half of what we have conventionally tilled into the soils and still yield 300 bushel/acre corn regularly. It has been done in the past three years in the Western Corn Belt under intensively managed irrigated corn. Instead of 300-350lbs N/acre researchers applied 140-150lbs/acre. Consider the dollars savings alone folks.

All of us who grow crops to reac a production goal know it takes fertilizers, either commercial or with use of manures.  We know our dollars stretch only so far and our water is stretching us to be better about how we grow crops.  We encourage you to place those nutrients in the soil precisely, with the understanding how much will the plant need and when.  Using the Strip-Tillage tools manufactured at Orthman is a great choice to put this all in motion.  Please contact any of us on the Sales, Marketing and/or Agronomy Team here at Orthman.

Strip-Tilling with Liquid Fertilizers for Early to Mid-Season Growth

Moisture Collection vs Moisture Lost

by Mike Petersen, Lead Agronomist

Fall Strip-Tilled into Barley Stubble

Storms are advancing from the Southwest into the Central Corn Belt with blizzard-like conditions at times but are we getting enough moisture to provide replenishment? Further west in Western NE, KS, SD and into Colorado and Wyoming, we have much less snowfall – oh my pitifully dry.
One of the wonderful details about maintaining all last year’s stalks, leaves, shucks in the field is trapping all these snowfall events. Over across the road where the neighbor fall tilled or used his “vertical” tillage or disk tool the residue was sized, chopped and free to blow from here to the Gulf. Also simply put, the taller stalks left in corn to cause movement of lateral snow to drop and stay on the ground compared to the flattened soil surfaces. Many times snow blowing around can accumulate in the standing stalks and give you another 3 to 8 inches of snow, which means harvesting water.
Even if a grower strip-tills in the fall the surface profile of the soil/field is left very rough and allows for catchment areas to have snow stop and store-up in the field. Why all this? Every inch of these snows is priceless. We know that very few of us want to plant into dry soils, irrigate up if irrigation is possible, or just hope for the next rain to be plentiful to start the planted crop.
For the conventional tillage farmer each spring tillage operation has the potential for loss of moisture, and that could be up to 0.75 inch per tillage operation. As dry as it has been that is 8-10 inches of snowfall loss in one pass. Wow, consider that and we have had so little snow since December 1, 2012, I worry about the condition of the soil profile moisture even for the Strip-Tillers. So what growers may want to consider in the Western Corn Belt is waiting until the very last week to strip-till and then follow close behind with the planter. The Orthman 1tRIPr was designed way back in the late, late ‘90’s to be a connected set up of strip-till and planter attached. This year, 2013 there is a great deal of merit to give that a long look.

Caught in action!

Caught red-handed… Mike talks about strip tilling with corn and how important it is the alleviate compaction for early, robust plant development. Video is courtesy YouTube channel “hayspringshawks.”

Watch the video here!

2012 – 1st Season of Strip-Till Results in South Africa

Strip tillage results with fertilizer placement in South Africa

This is the report from South Africa with two short but direct accounts of growers using strip-till to grow corn. Click HERE to download the strip till row crop report from agronomist Mike Petersen.

Orthman agronomist Mike Petersen took part in a ro…

Orthman agronomist Mike Petersen took part in a root study with DEKALB near Gothenburg, NE. Send your autograph… fb.me/1rW0FPKPY

Some more information regarding Soil Organic Carbon – Strip-Till

Over the Christmas and New Year holidays our Lead Agronomist has been digging into research findings, reviewing our Orthman work and writing.  Take a look at the post that Mike wrote in the section of Agronomics 101 articles.  It is a couple of pages that depicts findings from what we have been doing, some from Europe and a bit from Down Under by Dr. Hulugalle.

We think this will give you more clues on the importance of not turning over those residues which farmers have called trash for far too long.  The benefits are far reaching for years to come.

Orthman 1tRIPr maintains residues

Agronomist Dennis Neffendorf shares some research…

Agronomist Dennis Neffendorf shares some research info with the Illinois Soybean Board.
youtube.com/watch?v=_gVTsu…

2012 Research findings

Summary of field test results

Mike Petersen highlights 2012 research

Fresh off the assembly line… a 16-row 30″ Orthma…

Fresh off the assembly line… a 16-row 30″ Orthman 8450 Cultivator! fb.me/CSbaeBP7