Home » General (Page 2)

Category Archives: General

ABOUT ME

osunpk

osunpk

Since 2008 I have served as the Precision Nutrient Management Extension Specialist for Oklahoma State University. I work in Wheat, Corn, Sorghum, Cotton, Soybean, Canola, Sweet Sorghum, Sesame, Pasture/Hay. My work focuses on providing information and tools to producers that will lead to improved nutrient management practices and increased profitability of Oklahoma production agriculture

View Full Profile →

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 3,502 other followers

Check Canola for Aphids

Tom A. Royer, Extension Entomologist

I have received scattered reports of cabbage aphids infesting canola racemes and low levels of green peach aphids feeding on canola leaves. Cabbage aphids are small, 2.0-2.5 mm (1/12 inches) blue-gray aphids with short cornicles.  They are usually covered with a powdery wax coating.  They are often found clustering on the developing panicle (Figure 1).  They can cause plant stunting, distortion of growth, and flower abortion.

File written with CompuPic(R) - Photodex Corporation (http://www.photodex.com)

Cabbage Aphids

Green peach aphids are pale green to yellow (and sometimes pink) with long cornicles and antennae and measure 1/8 inch.  They are found in winter and spring on leaves (Figure 2). Their feeding can cause stunting and defoliation. They can also transmit plant disease-causing viruses such as cauliflower mosaic and turnip mosaic viruses.

 

Green Peach Aphid OK 2013 (2)

Green Peach Aphids

Scout for aphids by looking on the underside of the leaves, and racemes. For cabbage aphids, research conducted in Australia suggests that an insecticide application is justified if 20% of the racemes are infested with cabbage aphids.

For green peach aphids, research conducted by Dr. Kris Giles at OSU found that and average of one green peach aphid per plant can reduce seed yield by about 0.5 lb per acre. Thus, if the cost of an application is $10 per acre, and canola is bringing $0.2 per pound (quote from ADM Farmer Services 04/08/2016 www.adm.com), an infestation of 100 aphids per plant would cause yield loss of $10.00 (50 lb, x $0.2/pound) which is equal to the cost of the application. This is known as the ECONOMIC INJURY LEVEL (EIL).  We typically set the ECONOMIC THRESHOLD (ET) below the EIL, in this case at 80% of the EIL (80 aphids per plant) to give time to schedule an application before the EIL is reached.  Below is a set of suggested ECONOMIC THRESHOLDS, based on the cost of the application.

Application Cost                     Economic Injury Level           Economic Threshold                                                                                     (Application cost/
0.5 lb/aphid x $0.2/lb              (0.8 x EIL)

$8.00/acre                                80 aphids/plant                        64 aphids/plant\
$10.00/acre                              100 aphids/plant                      80 aphids/plant
$12.00/acre                              120 aphids/plant                      98 aphids/plant
$14.00/acre                              140 aphids/plant                      112 aphids/plant

 

Current recommendations for control of aphids in canola are listed in CR-7667, Management of Insect and Mite Pests in Canola which can be obtained online at http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-3045/CR-7667web2009.pdf.

Transform® insecticide is no longer registered for use in canola as of November 11, 2015. Only existing stocks that have already been purchased and delivered to the grower before the cancellation can be applied according to the label.

Remember, green peach aphids have a history of developing resistance to pyrethroids, which are the primary registered insecticides for use in canola. Thorough coverage of an insecticide application is necessary to obtain optimal control.

If you notice natural enemy activity, especially lady beetles, and want to preserve their activity, keep several things in mind. Our research shows that Beleaf® insecticide is particularly benign to natural enemies because of its slow acting efficacy on aphids, which allows aphid-feeding beneficials to continue to eat them with little to no consequence on their biology.  That being said, cabbage aphid may contain toxins that they acquire through their feeding which make them less palatable to some predators, and reduces their effectiveness as natural controls.

With all pesticides, review label restrictions for applications during bloom, as honeybees can be killed if exposed to several of the registered products.  One registered product, Beleaf® (FMC Corporation) does not have any restrictions for application during bloom.

Wrong Then Wrong Now

This article is written by Dr. George Rehm, University Minnesota, Soil Fertility Specialist (retired).
See more of Dr. Rehm’s blogs at www.agwaterexchange.com

Various products and/or concepts that pertain to crop production seem to cycle with time.  I’m never surprised.  There are foo-foo juice products that have disappeared only to appear sometime later under a different name.  Likewise, there are concepts that have been proven by research to be bogus.  Yet, they don’t die.  There appear again.  It seems that there are always some who attempt to make money from farmers by selling revived foo-foo juice products or bogus concepts.  To paraphrase a line from a once-popular song: “everything old is new again”.

Recently, there has been a revived promotion of CATION EXCHANGE CAPACITY (CEC) and CATION RATIOS.  The CATION RATIO concept has sometimes been referred to as “BALANCED SOIL FERTILITY”.  So, some review of what we know about CEC and balanced cations is probably appropriate at this time.

The concept of CEC and it’s relationship to crop production was first researched in New Jersey in the mid-1940’s.  At that time, researchers measured the CEC of soils as well as the exchangeable cations (Ca++, Mg++, K+).    The CEC is a nearly constant property of soils that is directly related to soil texture.  Sandy soils have relatively low CEC values.  BY contrast, fine textured soils have high CEC values.  The exchangeable cation values (Ca++, Mg++, K+) vary with other soil properties — mainly soil pH.

In the New Jersey soils, the researchers measured the exchangeable cations in a “productive soil” and a “non-productive” soil.  They calculated the ratios of one cation to another.  For example, the ratio of Ca++ to Mg++ was 6.5 to 1.  Alfalfa was the test crop.  So, it was thought that a “productive” soil should have a Ca to Mg ratio of this value.  These researchers neglected one important piece of information.  This was that lime had been used on the “productive” soil but not on the “non-productive” soil and the sandy soil had an acid pH.  The lime supplied Ca++.  Do you suspect that productivity of the alfalfa crop was a consequence of the use of lime rather the magic ratios?  In the years that followed, numerous research projects were conducted through the Midwest for the purpose of investigating the effect of cation ratios on crop production.

There were the comparisons of fertilizer recommendations provided by various Soil Testing Laboratories.  Some followed the cation ratio concept.  Others Used the sufficiency approach based on the response of crops to measured levels of available nutrients by standardized, routine analytical procedures.  Although costs of fertilizer recommended by these approaches varied considerably each year for extended periods of time (14 years in Nebraska), crop yield was not affected.  Fertilizer recommendations based on the cation ratio concept were much higher than those that were based on the sufficiency approach.

The results of the Midwest research led to the conclusion that the ratio of one cation to another in soils had no effect on crop production.  Crop response to fertilizer was the result of the nutrient supply in the soil — not ratios.  Nutrient supply is measured by the standard analytical procedures.  The crop has no interest in ratios.  Given the uniformity of the conclusions of these research projects, it appeared that the “ideal ratio” or “balanced nutrient” concept was dead and had disappeared from our knowledge base that pertained to soil fertility and fertilizer use.

Land Grant universities in the northern and western Corn Belt have published reports that document the bogus nature of the ideal cation ratio concept.  Staff at Agvise Laboratories have worked hard and listed the links to these reports on the Laboratory web site.  The web address is: agvise.com if anyone is interested in the detailed reports.

The concept of IDEAL CATION RATIOS has been thoroughly research for several crops.  There is consistency in the results of this research.  This concept is not in any way related to effective and economical fertilizer recommendations.  In fact, use of this concept has a high probability of producing less than optimum recommendations for use of potash fertilizers on sandy soils.

The concept of IDEAL CATION RATIOS as a basis for fertilizer recommendations is truly bogus and has no place in agriculture.  Please use this ratio concept if you want to waste money on fertilizer purchases in 2015.  Those who advocate the use of this concept are not up to date in their understanding of modern principles of soil fertility.  They’re still working in the 1940’s.  It was WRONG THEN and it’s WRONG NOW.

Dr. George Rehm,
University of Minnesota
Nutrient Management Specialist (retired)
rehmx001@umn.edu

Recent Weather Causing Corn (and Sorghum) Injury From Pre-emerge Herbicides

While this is not about fertility in the southern Great Plains I feel it is a very important topic.  I will not be surprised if we don’t start seeing this in some of the corn and sorghum that was just planted before the rains. I would also add the over the years I often see bleaching in sorghum, that looks similar to zinc and/or iron deficiency, caused by atrazine injury.  This typically occurs when atrazine is applied prior to a heavy rain. The atrazine is washed down slope and into the rows, the injury is almost always seen in low lying areas.  The crop usually grows out of it.

Atrazine injury in sorghum. Heavy rains followed application.  Pic via Rick Kochenower.

Atrazine injury in sorghum. Heavy rains followed application. Pic via Rick Kochenower.

Brian A.

This article is written by Mr. Cody Daft, Field Agronomist Western Business Unit, Pioneer Hi-Bred

Have you noticed any corn leafing out underground prior to emergence? Have you seen tightly rolled leaves or plants that can’t seem to unfurl leaves and look buggy whipped? Almost all of the fields I have looked at recently have shown these symptoms in at least a portion of the field, and some fields this has been very widespread. The common denominator in all the fields I have viewed has been the herbicides applied were a metolachlor (Dual/Cinch type products) and the weather (cooler than normal, wetter than normal). Similar issues can be noted in grain sorghum to some extent.

The recent wet weather and water-logged soils have increased the possibility of corn injury from many popular soil applied herbicides. Corn growing in wet soils is not able to metabolize (degrade) herbicides as rapidly as corn growing in drier conditions. Plant absorption of herbicides occurs by diffusion. What this means is that the herbicide diffuses from locations of high concentration (application site on the soil) to low concentration (plant roots). The diffusion process continues regardless of how rapidly the corn is growing. In corn that is not growing rapidly (cool, wet conditions) corn plants can take up doses of herbicide high enough to show damage and a few differences in symptomology.

The unfortunate aspect of wet soil conditions is that additional stress is put on the plant not only to metabolize herbicide residues, but also to ward off diseases and insects. These additional stresses can impact a corn plant’s ability to metabolize herbicide.

The most common type of herbicide injury observed under these conditions is associated with chloroacetamide herbicides. These herbicides are used for control of grass and small seeded broadleaf weeds, and are seedling root and shoot inhibitors.

These products include the soil-applied grass herbicides such as:

  • Dual/Cinch/Medal II
  • Degree/Harness
  • Microtech/Lasso
  • Frontier/Outlook
  • Define/Axiom
  • And other atrazine premixes like Lumax (a premix of mesotrione (Callisto), s-metolachlor (Dual II Magnum), atrazine and a safener benoxacor).

What About The Injury Symptoms?

Before corn emergence:

  • Stunting of shoots that result in abnormal seedlings that do not emerge from soil.
  • Corkscrewing symptoms similar to cold/chilling injury.
  • Corn plants and grassy weeds may leaf out underground and leaves may not properly unfurl.

After corn emergence:

  • Buggy whipping – leaves may not unfurl properly.
buggy-whipping syndrom

Figure . Buggy-whipping symptom from carryover of PPO herbicides to corn.via https://www.pioneer.com/home/site/us/agronomy/library/herbicide-carryover/

 

 

What About Safeners?
Products like DUAL II Magnum herbicide contain the safener benoxacor which has been shown to enhance S- Metolachlor metabolism in corn. This enhanced metabolism can reduce the potential of S- Metolachlor injury to corn seedlings when grown under unfavorable weather conditions such as cool temperature or water stress. However, a safener is not the silver bullet, and slow plant growth may still have trouble metabolizing the herbicide even with a safener…but it does help the severity of damage/symptoms.

Will The Plants Recover?
Plants that have leafed out underground or show corkscrewed mesocotyl symptoms are likely to not recover or even emerge from below the soil. Larger plants that are already emerged that show tightly rolled leaves and are buggy whipped will most likely recover once the field sees drier conditions and we have warm weather and sun light to assist in better plant growth.

More Information Discussing Corn Injury From Pre-emerge Herbicides Here:

http://ipm.missouri.edu/IPCM/2009/4/Cool-Wet-Soils-Can-result-in-More-Corn-Injury-from-Preemergence-Residual-Herbicides/

 

Cody Daft
Pioneer Hi-Bred
cody.daft@pioneer.com

I am in Extension and I am just borrowing your idea

This blog is a bit of a self-serving advertisement while at the same time telling an important story about a successful extension program. I am still a newbie in terms of service years as I just finished my sixth year as a state specialist. Over this time I have learned an important fact, an idea or concept does not have to be your own to be applicable. Case in point, ever since grad school I’ve had a tent card, 4”x 3.5” card folded in half to equal the size of a business card, from Potash and Phosphate Institute (PPI), now the International Plant Nutrition Institute (IPNI) pinned to my wall. The Plant Food Uptake card has the nutrient concentrations of the primary grain crops grown in the Great Plains. During my research, it was a handy piece of information. Today, it still hangs on my board today with a series of out-dated photos and thank you cards from former students.

Plant Food Uptake (PPI)

Plant Food Uptake (PPI)

It is from the Plant Food Uptake card that I developed the concept of the first Pete’s Sheets Do’s and Don’ts of using N-Rich Strips and N-Ramps in 2008. I personally thought this was a great idea but did not know if it would be well received by my audience. The results have been more than I could have ever imaged. Since 2009, I have developed 10 additional Pete’s Sheets with the latest out for print. I keep close tabs on how many I have ordered, and the latest order brings to total 38500 Pete’s Sheets. I currently have 8000 Pete’s Sheets on hand, which means there is approximately 30,000 cards in circulation. I doubt any fact sheet I have ever written has that level of distribution.

Cover of the first Pete's Sheets produced.

Cover of the first Pete’s Sheets produced.

Pete Sheets for business card size tent cards Fact-Sheet/Research based information.  The Nutrient Management Field Guide is a spiral bound compilation.

Pete Sheets for business card size tent cards Fact-Sheet/Research based information.
The Nutrient Management Field Guide is a spiral bound compilation.

I am able to travel to meetings and speaking engagements with relevant Pete’s Sheets easily in tow, and I also provide bulk quantities for free via request. Another enjoyable aspect of the Pete’s Sheets is I am able to place them in a tray on my office door. It is always a good day when I have the need to refill card holders, and this happens surprisingly often.

The spin-off from the PS has also been quite impressive. One of the best complaints I have ever received was from a producer who quipped he could no longer carry all of the Pete’s Sheets in his wallet. I took that as a major complement and went to work at compiling the cards immediately. The outcome was the 5″x 8″ spiral bound Nutrient Management Field Guide which has been equally successful. Not only did I “borrow” the tent card concept from PPI/IPNI, but I have also “borrowed” the idea of providing a customized logo just as Purdue has with its fields guides. The most famous is probably the Purdue Corn and Soybean Field Guide. While the custom logo has not been widely utilized, the times it has the revenue has been used to purchase more standard cards.

Office door with the Pete's Sheets tray.  Always free to a good home.

Office door with the Pete’s Sheets tray. Always free to a good home.

My take home from this experience is in extension old ideas can easily be incorporated into new educational tools. Often, it takes just a little time and imagination to be successful. Pete’s Sheets now greatly aid both my extension and teaching programs.

Now to the self-serving portion of the blog an announcement for the newest card titled Nitrogen Cycle. Within the Pete’s Sheet is a visual representation of the N-cycle, which every student enrolled in my Soil Nutrient Management course must learn, and the back of has a list of important N-cycle terms with definitions. I will mail Pete’s Sheets to anyone requesting a set, with a maximum of 100 per style. I continuously look for new ideas and topics and welcome any suggestions. View pdfs of the cards and booklets or download the custom order form on my NPK website at http://npk.okstate.edu/petesheets. To receive sets of the standard Pete’s Sheets, simply email me your request and provide a mailing address.

Nitrogen Cycle Pete's Sheet

Nitrogen Cycle Pete’s Sheet

Time to start topdressing wheat

Great write up by Dr. Edwards.

World of Wheat

There are few crop inputs that deliver as much return on investment as nitrogen fertilizer. It takes approximately two pounds of nitrogen, costing approximately $1.00, to produce one bushel of grain worth about $6.00. Of course, nitrogen is not the only yield determining factor in a wheat crop. Also, the law of diminishing marginal returns eventually kicks in, but nitrogen fertilizer is still one of the safest bets in the house.

Top dress nitrogen fertilizer is especially important because it is applied and utilized at a time when the plant is transitioning from vegetative to reproductive growth. Several things, including the number of potential grain sites, are determined just prior to jointing and it is imperative that the plant has the fuel it needs to complete these tasks. Jointing also marks the beginning of rapid nitrogen uptake by the plant which is used to build new leaves, stem, and the…

View original post 659 more words

Ag Apps Updated

Since my Ag App post in July I have presented on the topic an additional five times and have two more on the books for 2014.  A good thing about doing talks is that you have to update the information to remain current.  Which in all honesty, when it comes to technology of any kind this is quite challenging and even more so for Smart Phone Apps.   In July when I first blogged on the subject I had 76 apps on my iPad.  Today (1.3.14) I have 111 apps on my iPad, for both the iPhone and iPad, that I deem to be Ag related. Since the summer I have found new favorites, changed some, and added categories but for the most part I still maintain my 2 minute rule stated in the first blog.  I have allowed a bit more leniency in that I now say “If I cannot figure it out in 3 minutes it’s GONE.  An app should be intuitive, easy to use and have a purpose.  They only exception to the 3 minute rule is the Scouting and Mapping Apps. Because of their complexity I allow them 5 minutes, and then I am done.  Any app with GIS in its name gets much more time”  I guess I am just getting soft.

Again I must make the obligatory statement; I am not a developer, designer, or expert.  I am just a user who has had a chance to look at a few apps. Almost all of the apps I have are free and I am sure I have missed a few.   Please share those with me.  I am also not discussing Mobi’s, this is another large group of quality decision aid tools.  I am also not discussing none apples apps.  This is not because they are not relevant or important, it is because I do not have that technology.

I now have nine Ag folders on my iPad:
Ag News/Weather/Markets, Scouting/Mapping, Record Keeping, ID Tools, Crop Tools, Calculators, Sprayer/Chemicals, Fertilizer, Seed Select.

Apps are nice because the majority are stand alone and do not need internet or cell connection.  This means they can be used when you are in the middle of nowhere, which is a great deal of Oklahoma, and have no service.  This will exclude many of the Ag News/Weather/Markets, Scouting/Mapping, and Record Keeping apps that need positioning or location information.

Now let’s discuss some of the new and old apps.

Ag News/Weather/Markets

news11 news2 news3

Not much change in this group however I have added one or two.

Scouting/Mapping

Scout2 Scout 1 Scout 3

This category has changed the most.  Record keeping apps have been removed and several new apps added.  The only free apps which can create boundaries are still Scout and Sirrus.  To date Scout remains to be my favorite app for in field scouting notes.  Pictures tagged with Lat Long and a note is very useful.  My knock on is app is its boundary creation.  It is a challenge every time as it is hard to remember the steps and not make a mistake.  That is where Sirrus comes to play, by far the best boundary creation app.  Sirrus has easy to use tools for both point and pivot boundaries.  I like the edit vertex zoom in tool that resembles a rifle scope.   I was able to add 12 fields in a matter of 20 minutes.  Being able to create grid soil sampling scheme and record samples is also a very nice tool.  My favorite part of the app, the UNDO button, and all apps should include this.  The drawback to Sirrus is that it has no ability to take notes such as Scout.  An additional nice scouting tool is South Dakota States NPIPM (North Plains IPM) app.  This app provides not only a pest id tool with morphological drop down, I will discuss this in the ID Tools cat, but also management recommendation for the identified insect.

Record Keeping,

records

The majority of the apps in this category are “Pay to Play”, which makes since as they deal with data management and storage.   Many would also fit the Scouting/Mapping category.  As I do not pay for many apps I do not have experience with any of these.  However this is the category that I would recommend any group to look at as they should be the all-inclusive app.  However, PeRK by the University of Nebraska is a free app designed for field records of pesticide applicators.

ID Tools,

id1 id2

I have added a few apps to this category but my favorites have not changed.  I regularly use Plant Images, ID Weeds, and the Pestbook as references.  I will add more discuss to app ID tools.  The importance of being able to ID weeds and Pest via morphological drop down menus (ID Weeds and NPIPM) is extremely important.  Many of the ID tools just have pictures and names.  Well is I am using an ID Tool I likely do not know what I am looking at or what it is called.

Crop Tools,

Crop

Crop Tools includes my second “Paid in Full” app.  And this one hurt a bit more.  Not because it cost money but because I have multiple versions of the hard copy.  However Field Guide by Purdue is one of my most recommended apps.  Field Guide is the electronic version of the Purdue Corn and Soybean Field Guide, which the majority of consultants in the Corn Belt likely have this sitting in their truck.   The Stoller apps also have nice very nice image bank of plant developmental phases.  FieldGuide and CornAdvisor, another good app, are great examples of what I expect to be coming out of the majority of the Land Grant Universities very soon.   Cooperative Extension has hundreds if not thousands of quality hard copy publications just waiting to be turned in to handy dandy apps.  To be honest I am working on turning my Nutrient Management Field Guide into an app right now.

 Calculators,

calc1 clac2

Only two apps has been added to this category.  I am still using Fert.Removal, HarvestLoss and Growing Degrees on a regular basis.

 Sprayer/Chemicals,

spray1 spray2

Many apps have been added to this group but none of them have been good enough to kick TankMixCalc and SpraySelect of my favorites list.

 Fertilizer,

fert1 fert2

Similar to the Sprayer/Chemicals category several apps have been added to this group, including several from Ok State.  For me the Fert Cost Calc is still very useful.  I do not get to use the Manure Calc I am very impressed by its layout and user friendliness.  This app allows for applicator calibration, nutrient recs and manure value estimator.

Seed Select,

 seed

It is no surprise the apps in this category are company created.  I will say for the central Great Plains Pioneer’s Canola Calc is very useful tool for selecting canola planting rate providing input for row spacing live plants, seed weight, Germ percent, and survival percent.

To wrap up this blog I want to share with you may new Favorite none ag app.  Bump is a huge time saver for anyone who takes pics with your iPhone or iPad.  Bump allows easy transfer between mobile devices but more importantly between your mobile device and desktop by a simple tap of the space bar.  This file share will go both directions.  This means no more emailing pictures from your phone so that you can have them on your desktop.  Bump is a iPhone app that can work on the iPad.

When searching with an IPad, remember to switch the search to include IPhone apps, there are some good ones out there that are IPhone only.  Check out www.npk.osktate.edu/presentations  to see screen shots from many of my favorite apps.

Nitrogen Rich Strips

The Nitrogen Rich Strip, or N-Rich Strip, is a technique/tool/process that I spend a great deal of time working with and talking about.  It is one of the most simplistic forms of precision agriculture a producer can adopt.  The concept of the N-Rich strip is to have an area in the field that has more nitrogen (N) than the rest.  Due to our fertilizer applicators this is typically a strip.  The approach maybe somewhat new but at one point most producers have had N-Rich Strips in their fields, albeit accidentally.  Before the days of auto-steer it was not uncommon, and honestly still is not, to see a area in the field that the fertilizer applicator either doubled up on or skipped.  In our pastures and dual purpose/graze out wheat every spring we can see the tell-tale signs of livestock deposits.  When over laps or “Cow Pox” become visible we can assume the rest of the field is behind in nitrogen.  I like to tell producers that the goal of the N-Rich strip is to make a really big cow pie.

Cow Pox, Image courtesy Kaitlyn Nelson
Cow Pox, Image courtesy Kaitlyn Nelson

What I like most about the N-Rich Strip approach is its Simplicity.  The N-Rich Strip is applied and; Scenario 1. The N-Rich Strip becomes visible (Greener) you APPLY NITROGEN, Scenario 2.  The strip is not visible you Option A. DON’T APPLY NITROGEN Option B. Apply Nitrogen Anyways.  The conclusion to apply N or not is based on the reasoning that the only difference between the N-Rich Strip and the area 10 ft from it is nitrogen, so if the strip is greener the rest of the field needs nitrogen.  If there is no difference N is not limiting and our research shows N does not have to be applied.  However producers who decide to be risk adverse (in terms of yield) can apply N but it would be advised to do so at a reduce the rate.  Now is a good time to note that the N-Rich Strip alone provides a Yes or No, not rate recommendation.  At OSU we use the GreenSeeker optical sensor and Sensor Based Nitrogen Rate Calculator (SBNRC) to determine the rate, but that discussion will come later.  I equate the change from using yield goal N rate recs to the N-Rich Strip as to going from foam markers to light bars on a sprayer.   Not 100% accurate but a great improvement.

N-Rich Strip in no-till wheat near Hobart OK.

N-Rich Strip in no-till wheat near Hobart OK.

Now that we have covered the WHY, lets get down to the nuts and bolts HOW, WHEN, WHERE.

How the strip is applied has more to do with convenience and availability than anything else but there are a few criteria I suggest be met. The strip should be at least 10 ft wide and 300 ft long.  The rate should be no less than 50 lbs N (above the rest of the field) for grain only wheat and canola, 80 lbs N for dual purpose wheat.  The normal recommendation is that when applying pre-plant either have a second, higher rate programmed into the applicator or make a second pass over an area already fertilized. Many will choose to rent a pull type spreader with urea for a day, hitting each field.
Becoming more popular are applicators made or adapted for use.  ATV sprayers are the most common as they can be multi-purpose.   In most cases a 20-25 gallon tank with a 1 gpm pump is placed on the ATV with an 8-10ft breakover boom.  The third applicator is a ride away sprayer with a boom running along the rear of the trailer.  In all cases when liquid is the source I recommend some form of streamer nozzle.  In most cases there is not a great deal of thought put into what source.  I recommend whichever source is the easiest, cheapest, and most convenient to apply.

Vincent N-Rich Strip Applicator, Ponca City OK

Vincent N-Rich Strip Applicator, Ponca City OK

Ok State N-Rich Applicator

Oklahoma State Univ. N-Rich Strip Applicator

Gard N-Rich Strip Applicator, Fairview Ok

Gard N-Rich Strip Applicator, Fairview Ok

When the strip is applied in winter crops proper timing is regionally dependent. For the Central Great Plains, ideally the fertilizer should be applied pre-plant or soon after.  However,  in most cases as long as the fertilizer is down by the first of November everything works.  This does not say a strip applied after this time doesn’t work but it leaves more room for error.  There is a chance the crop could already be stressed or the nitrogen tied up and not release in time.  However when the N-Rich Strip approach is used on the Eastern Shore in Virginia and Maryland the strips have to be applied at green up.  The soils in that region are very deep sands and nitrogen applied in the fall may not make it to the spring.  Also most wheat producers in the area make three or more applications of nitrogen unlike the two (pre and top) of the Great Plains.  It is always important to make the tools fit your specific regional needs and practices and not the other way around.

Where is actually the biggest unknown.  The basic answer is to place the N-Rich Strip in the area that best represents the field.  Many people question this as it doesn’t account for spacial variability in the field, and they are correct.  But my response is that in this case spatial variability is not the goal, temporal variability is.  Keeping in mind the goal is to take a field which has been receiving a flat yield goal recommendation for the last 30+ years and make a better flat rate recommendation.  My typically request is that on a field with significant variability either apply a strip long enough to cross the zones or apply smaller strips in each significant area.  This allows for in-season decisions.  I have seen some make the choice to ignore the variability in the field, made evident by the strip, and apply one rate and others choose the address the variability by applying two or more rates.  One key to the placement of N-Rich Strips is record keeping.  Either via notes or GPS, record the location of every strip.  This allows for the strips to be easily located at non-response sites.  It is also recommended to move the strip each year to avoid overloading the area with N.  

I hear a great deal of talk about how it would take to much time to put out the N-Rich Strip.  However the majority of producers that do it once on one field, end up doing it every year on every field. There is very likely someone in your area who is using the N-Rich Strips.   As top-dress grows closer keep an eye out for a blog “Using the GreenSeeker Sensor and Sensor Based Nitrogen Rate Calculator”.

For more information on N-Rich Strips check out the YouTube video below, visit http://www.npk.okstate.edu or contact me directly at b.arnall@okstate.edu.  I have lots of material I am happy to share and distribute.

See the YouTube Video  http://www.youtube.com/watch?v=kJ3DSwWYgE8