# Soil Fertility, Plant Nutrition & Irrigation Water Quality Seminar



## FAST (Aug 20, 2012)

We'll be conducting a two-day pre-conference seminar in Springfield, Illinois in December as part of the overall AcresUSA 2013 conference. The focus will be on making successful crops in challenging climate conditions.

If you're interested, see: http://www.TexasPlantAndSoilLab,com and click on the Advanced Crop Nutrition banner for details. This will be a sophisticated and very intensive real-world course.

I expect to be able to post some pretty good news with data about Alfalfa in the upper Midwest after the fourth cutting and end of the season, later on...


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## vhaby (Dec 30, 2009)

I am curious about how you determine N recommendations for the various crops?


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## FAST (Aug 20, 2012)

It all has to do with the crop and timing. Nutrient needs change throughout the growing season. Most growers think that N is the solution to all their problems. Accordingly, much of what is applied is wasted. Each crop has specific needs for various combinations of nutrients at critical phases of development during the season. N is no exception.

While N makes a crop grow fast and green, lack of other nutrients in balance and availability will make it stressed and subject to disease and insect pressures. Additionally, it will be low in nutrient, mineral and vitamin content. In forage, the result can also be low protien. University studies have shown that a nutritionally-balanced crop (in this case, forage) can require up to 70% less water than otherwise.

We started off with plant nutritional standards originally published in the early 1950s but have continued to update them over the decades to accommodate later research, changing soils and new varieties. Additionally, new trace elements have been recently discovered to be extremely beneficial (if not essential) to some plants. Other labs still use the original standards.

We use the Daubeny Extraction Method on soils which has been calibrated against actual plant uptake as assayed by plant sap (petiole/leaf) testing. The Daubeny has proven itself to be by far the most accurate method for every soil on the planet, as it duplicates the way plants take up nutrients.

Hope this helps.


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## hay wilson in TX (Jan 28, 2009)

Pardon me but what is T P S L?

I gather it will be an Organic & Sustainable Conference.


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## FAST (Aug 20, 2012)

Texas Plant & Soil Lab - http://TexasPlantAndSoilLab.com


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## vhaby (Dec 30, 2009)

What depth/depths do you recommend sampling and how do you handle soil samples to be tested for nitrogen recommendations?


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## FAST (Aug 20, 2012)

Please see our attached Soil Sample Guide for sampling details. I'm not quite sure what you mean by how we handle samples for Nitrogen analysis...?... All our soil samples are air-dried at ambient temperature - no heat used.

If you would like to contact me directly, here's how to do it:

Frank

[email protected]

214-693-0326


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## vhaby (Dec 30, 2009)

When your lab receives moist soil samples taken several days earlier with the request to analyze these for nitrate nitrogen, how do you handle these samples?

What depths do you want producers to sample for nitrogen analysis in row crops, small grains, hay meadows, etc?


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## FAST (Aug 20, 2012)

The preferred sample depth is from the surface to 12", per the previously attached.

I think what you are actually asking is do we use the recently-touted "moist sample method" for nitrate analysis which purports to avoid changing the chemistry of the sample.

This would be of some value if we used added heat to dry the sample as most every other lab employs. However, we use the Daubeny Extraction Method which is extremely sensitive to low levels of nutrients which is why we use ambient temperature air to dry the samples to avoid any chemistry changes.

Accordingly, any benefits of the the moist sample method do not apply to us.


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## vhaby (Dec 30, 2009)

Regarding my previous question, "When your lab receives moist soil samples taken several days earlier with the request to analyze these for nitrate nitrogen, how do you handle these samples?"

What I'm getting at is this- If you proceed to analyze soil samples, that have taken several days to reach your lab and perhaps were not even mailed immediately after collection, for nitrate nitrogen, you are doing a disservice to the producer/s. Bacteria that convert ammonium nitrogen to nitrate nitrogen and bacteria that convert nitrate nitrogen to N2 gas remain active in moist soil. Over the time it takes for moist samples to reach your lab for analysis, the original nitrate nitrogen content that exists in the field will be changed in the samples sent to the lab in the moist condition. If you want to do a good nitrate nitrogen analysis from which to make correct N fertilizer recommendations for producers, require that they begin air drying these soil samples immediately after collection, using fan forced air to speed the drying process, and send dry soil samples to you for nitrate nitrogen analysis.


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## FAST (Aug 20, 2012)

Herewith the verbatim response to your last comments by our vp-research, Dr. Larry

Zibilske. Google his name for his bona fides. Ours is the Larry Zibilske who is not

dead:

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Well, somebody paid attention in soil microbiology class! That's nice to see.

What the person wrote is correct. Mineralization of organic nitrogen in moist soil

may continue after the soil is collected. If the soil is not dried, ammonium may

increase and, with all the new oxygen present (from pulling the sample and

crumbling it into a bag), oxidation to nitrate may proceed and, as the nitrate

accumulates and if oxygen is then depleted, denitrification to N2O and N2 reduces

the nitrate in the soil again. This can happen fairly quickly.

More than likely, however, the abundance of oxygen introduced as the sample was

taken would not be exhausted over the few days normally needed to send the

sample to the lab.

Drying soil before sending is not usually needed. Wet soils would be an exception

to this. Oxygen depletion is far more likely in that case. The amount of nitrogen

mineralized in transit would normally be small. Because the mineralized nitrogen

comes from organic matter, which is normally low in soil, the absolute amount of

error introduced into a nitrogen recommendation is rather small. Crop needs are

normally an order of magnitude greater than usual amounts of residual and newly

oxidized nitrogen, so we disregard amounts under about twenty pounds per acre.

Note that this has nothing to do with giving a legume credit. That is applied to crop

needs based on the production of a legume immediately preceding the next crop.

A more complete picture of how we generate cropping recommendations may be

helpful. Nitrate nitrogen levels in the soil are commonly a minor factor in crop

nitrogen recommendations. Nitrate is so ephemeral in soil, we believe we're better

off putting greater emphasis on the other factors, such as crop needs, soil physical

and environmental conditions, ancillary nutrients, irrigation and equipment

capabilities, etc. The role of soil nitrate present in the soil when it's analyzed tells us

more about the biological potential of the soil rather than how much of an offset we

can allow for it in terms of nitrogen recommendations.

Our approach to cropping recommendations has several facets and provides for

better conservation of nitrogen and other nutrients in the plant root zone. On a larger

scale, our recommendations result in the most efficient use of nutrients and other

inputs that tally up to a much better margin for growers. This is realized in lower input

costs, better yields, and higher quality.

LZ

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In reviewing this chain, I do not understand what the point is to any of it. I originally posted a simple announcement to which no response was anticipated. The link included all of the details as we know them. You asked the same question about sample depth twice, even though it was clearly addressed in the attachment the first time. Your mention about N was so obscure that it took you three exchanges to finally make the point that you really wanted to say something dogmatic at the onset. Accordingly, I do not suppose Dr. Zibilske's comments are of any value to you and I am sorry to have wasted his time on this.

Your fixation [sic] on N is interesting in that it is only one of a number of essential major/minor/micro/trace nutrients necessary or desirable for a healthy crop. N deficiency is one of the most easily corrected, while the others, some at least as critical, may not be so much so. As Dr. Zibilske (and you, too, by the way) pointed out, compounds of N levels are among the most transient. A few units per acre, one way or the other, simply don't matter.

I do not understand what the value of any of this could be to anyone - especially the participants. The lab does not debate and especially does not argue. We strictly limit ourselves to providing measurable field results and information. It is up to recipient to do with it as he shall. If he does not agree with our recommendations or information, then he can certainly go his own way at his own peril with our best wishes.

We are a very old and public organization and I have provided my direct contact information - which you have chosen to ignore by continuing this exchange on this forum and anonymously. This tells me that your questions were disingenuous at the onset. Accordingly, if you wish to continue this, you will have to contact me directly, as I'll respond to no further communications from you, as some anonymous person - even as I have given full disclosure, on this website.


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## vhaby (Dec 30, 2009)

Fast, you wrote:
"We are a very old and public organization and I have provided my direct contact information - which you have chosen to ignore by continuing this exchange on this forum and anonymously. This tells me that your questions were disingenuous at the onset. Accordingly, if you wish to continue this, you will have to contact me directly, as I'll respond to no further communications from you, as some anonymous person - even as I have given full disclosure, on this website."
__________________________________

I regret that you have taken offense to my concerns regarding sample handling in preparation for NO3-N analysis and have chosen to disregard these concerns. And, I beg to differ with you regarding my being an anonymous person. My "Profile" is posted on HayTalk.com for you and everyone else to view at any time, and I use my name. In contrast, you appear to use a psudoname and your profile does not appear to be available, so who is the anonymous person here? Further, if you wish to post an advertisement concerning a "For Profit" seminar, perhaps you might consider paying to advertise on HayTalk, like others who are selling things do. But since you posted a Thread on this web site, your post is open for blogs from others.

But enough of that and back to my original concern regarding your laboratory's analysis of soil samples received wet, or even moist- not having been dried prior to sending them to your lab for nitrate-N analysis. I refer you to the following: (To convert kg/ha to lb/ac; kg/ha x 0.893 = lb/ac

http://www.tandfonline.com/doi/abs/10.1080/00103627809366797#.UjpwLcbBNgi

Communications in Soil Science and Plant Analysis
Volume 9, Issue 2, 1978
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Translator disclaimer

The effect of soil sample handling between collection and drying on nitrate concentration
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DOI:
10.1080/00103627809366797

D. G. Westfall, M. A. Henson & E. P. Evans
pages 169-185

Abstract

The residual soil NO3‐N concentration is used in determining the N fertilizer recommendation for many crops in the arid United States. Accurate representation of the field levels of residual NO3‐N is complicated by the fact that the NO3 concentration in a soil sample can change significantly if the sample is not handled properly after collection. This will result in erroneous N fertilizer recommendations.

Soil samples were retained in their field moist state after collection and subjected to various conditions that would be encountered under normal soil sample handling situations before they were dried and analyzed. Subsamples were removed periodically to determine the change in NO3‐N as influenced by the various handling conditions. Samples with an original NO3‐N concentration of 26 ppm increased by 30.4, 12.8, 27.5 and 36.4 ppm when incubated (30 C), refrigerated, kept at room temperature or placed in a window where they were exposed to the sun 7 hours/day over a 7 day period, respectively. These changes would result in N fertilizer errors ranging from 52 to 147 kg N/ha (based on a 0-30 cm sample depth). During the first 48 hours after collection the same treatments resulted in changes in NO3‐N concentration that would cause N fertilizer errors in the range of 24.3 to 57.3 kg N/ha. Seven different soils were used in these investigations and only one showed a significant change in NO3‐N concentration upon freezing or air drying for 7 days. Although these changes were statistically significant they were so small that the error in the resultant N fertilizer recommendation would be meaningless.

Based on the results obtained, soil samples should be dried immediately after collection. Since "immediate"; drying is not always logistically possible, samples should be placed in a dryer within 12 hours after collection recognizing that changes in NO3‐N will occur but the magnitudes of these changes will be relatively small when translated to N fertilizer recommendations.

Key words
• Soil testing,
• N fertilizer recommendations,
• Nitrogen,
• Soil nitrogen,
• Soil nitrate changes


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## FAST (Aug 20, 2012)

It appears that we have many mutual interests. It is a pity we cannot communicate. Accordingly, I'm retiring from the forum.


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## hay wilson in TX (Jan 28, 2009)

FAST.

You sparked my curiosity, with all the ducking and dodging some fairly simple questions from vhaby of Tyler, TX.

I looked at the little dots and it appears I could walk to the closest location where TPSL has tested, I presume soil test.

After digging around I probably will not be interested in anything that uses a Universal Soil Extractant. 
I do not like a computed CEC value.
Actually I am comfortable with my on file soil analysis and now depend on plant analysis to monitor fertility.

I am interested in the statement *news with data about Alfalfa in the upper Midwest after the fourth cutting and end of the season, later on. *
I would be interested in knowing if your data would be useful in growing alfalfa in this Calcareous, Vertisol clay & in Central Texas Micro Climate.

Feel free to respond to me at [email protected]


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