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I am a student doing a science fair project relating to nitrogen content in plants. For some trials, I will need nitrogen-poor soil. Can anyone point me in the correct direction?

And if you have used sawdust to remove nitrogen, does it return it to an optimal amount or does it have the ability to remove large amounts of nitrogen?

Brōtsyorfuzthrāx
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Human
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  • Did you try google: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=nitrogen+fixing+plants+list – black thumb Jan 21 '17 at 20:45

2 Answers2

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I see two possibilities:

  • You get poor soil
  • You transform your soil

You can walk around your place, and you will see some places with poor soil. This probably is also poor on nitrogen. Try a dry, stony place, with non-black (and not to dark soil), or sandy soil. Nitrogen (in soil, and humus) is made from plants, so you should look where there will be not much deposit.

An other good place, it is deep soil (just a feet down (30 cm)) should be enough to have a less dark soil, so (usually) less rich. Note: near rivers, it is possible that you need to dig too much to find poor soil.

To transform your soil. Usually adding sand should be enough (50% sand, rest normal dirt).

Note: the soil is not characterized only by nitrogen, so other factors could miss-up your experiment (acidity, other nutrients, ...)

Giacomo Catenazzi
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    Most nitrate and ammonia compounds are very soluble in water. As long as you avoid soil with a high level of organic content (hummus, peat, leaves etc) a good rinse with deionized water, say 4 soil volumes, should eliminate most nitrogen. If you *really* want to go hardcore, you could rinse with 1 to 2 molar salt (NaCl) to drive off any nitrogen bound by ion exchange, and *then* rinse with deionized water. Be aware that washing soil is likely to leach out P, K and micronutrients as well. – Wayfaring Stranger Jan 21 '17 at 16:46
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    @WayfaringStranger: put it as a full answer. – Giacomo Catenazzi Jan 21 '17 at 16:49
  • For short time periods, you can just grow your plants in 5% agar: https://en.wikipedia.org/wiki/Agar That'll give you complete control of nutrient levels. – Wayfaring Stranger Jan 21 '17 at 16:49
  • I would, but that "(hummus, peat, leaves etc)" includes enough space for entire *worlds* of misunderstanding between chemists and non-chemists. – Wayfaring Stranger Jan 21 '17 at 16:54
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    @WayfaringStranger: we are "farmers" in this SE (so we are not Biology, Chemistry, and other SE). So I would not read any text there with high scientific mind (but with Alina and Graham, we are rising the accademic level, but still understandable). A discussion in Meta could help to define the limits, but I usually the tone of the answer helps to read correctly the answer (register/style). – Giacomo Catenazzi Jan 21 '17 at 17:09
  • My goodness Giacomo. Farmers need to know Biology, Chemistry, soils, hydrology, botany...gosh wildlife...the area's key plants or association. Period. Have to know..otherwise disaster is on the horizon. Why try to reinvent the wheel? Every hour spent studying or every cent spent on higher education will more than pay for themselves...it is tough to fail when you really don't have to! These sciences should be like treats to a gardener! They make sense especially when you have a forum to use them on. Not tough at all! Do not be afraid of the verbiage!! Or the science itself! – stormy Jan 22 '17 at 00:48
  • And DO NOT ADD SAND to garden soil!!! ARRRGGHH. Again, when one takes clay soil, gravel, lime, gypsum, water and then ROTATE what does one get? Concrete. Sand is right in there. Does NOTHING for the soil. The ONLY WAY to improve ANY soil is the addition of DECOMPOSED ORGANIC MATTER. Period. Allow me to elucidate!! I love this question and it is so vital to understand. – stormy Jan 22 '17 at 00:52
  • Thanks all. I have one question though: Would I would be able to measure the nitrogen content in agar? @WayfaringStranger – Human Jan 22 '17 at 02:29
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    @stormy: yes, but I mean we are a lot more relaxed about terminology, and we should also not trust that all people, books, etc. uses the correct scientific terminology. I'm not afraid about science (I have a PhD), and I could be very pedantic on right terminology on scientific papers, but I know that we must not make afraid new people with uneccessary complex terms. [BTW I like systematics (taxonology), and about 100% of non-accademic book have errors on systematics (also reading with past codes and knoweledge)] – Giacomo Catenazzi Jan 22 '17 at 11:51
  • @stormy: I'll ask that question (but for this question, I assume the OP will make the experiments on pots). – Giacomo Catenazzi Jan 22 '17 at 11:52
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    @GiacomoCatenazzi Well, I didn't mean to raise the bar, I just developed this time consuming habit after posting an answer on Biology SE without references and being asked to prove my claims. It took me six hours to search for scientific proof for every claim and edit my answer and the habit has stuck with me. BTW, I like your answers a lot at all questions, they give insight to aspects I never think of. – Alina Jan 22 '17 at 12:48
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    @alina: no problem. I like to have different answers, at different levels (and SE encourage also to have multiple answers). And a refresh is always good. Additionally I think we have variours people with biology degree here, but they add much experience to the answers. – Giacomo Catenazzi Jan 22 '17 at 16:52
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Nitrogen poor soil would be SUB SOIL. Dig down at least 2 or 3 feet and you shall find nitrogen poor soil. Get a test! From the Coop Extension Service and while you are there ask them what they think!!

stormy
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