[APWG] What caused surprise results in Poppy Project?--Test soil for soil nutrient thresholds

Fri Sep 20 23:34:41 CDT 2013

APWG:

EXACTLY! Beyfuss is right again! My education was my biggest problem in developing a viable program for ecosystem restoration here in CA; it took me fifteen years to un-learn my agronomy and horticulture. Ecosystems are the opposite of culture. 

Undisturbed ecosytems tend to sequester (tie-up) the available nutrients as soon as they are made available by a root-death or a bit of leaf or animal dropping. Agronomic soil tests will ALWAYS show a "deficiency" in dynamically stable ecosystems. Even the amounts of P and K, not to mention trace elements, that show up in such tests are mostly in unavailable form. Ironically, lacing a site with superphosphate tends to kill the very symbionts (mycorrhizae) that convert the unavailable P into an available form and supply it to the photosynthesizers in exchange for carbon (sugars). 

In the sudden flush of NPK following fire or other disturbance, "weedy" plants flourish, and if nothing is done to replace the complex ecosytem, especially its mycorrhizal nets, weeds will persist until the very (relatively) slow process of re-colonization by indigenous species, both above and below the surface, the process will be even slower, especially if the biologically-active true soil is removed or otherwise damaged. All "restoration" practitioners can do is accelerate the process by setting up conditions favorable to that process. 

Much N is lost to the atmosphere following disturbance (especially fire), but free-living and nodule-forming N-fixing bacteria are apparently able to compensate for said loss, available to all-comers, weeds and secondary successional colonists, native or alien. However, since (this is highly simplified, but I hope adequate) most weeds evolved in riparian zones and went rampant in cultivated fields where they hybridized into many of the "monsters" we know, and indigenous components of the complex ecosystem evolved together over the millennia, the indigenous species (or aliens adapted to similar environments) will tend, eventually to (more quickly, one hopes with THE RIGHT KIND of "help") regain dominance over the weeds and aliens, subject, of course, to the absence of further disturbance and other environmental changes. 

Adding N and other fertilizers just makes weediness worse--a kind "eutrophication," as it were . . . 

Many "weeds," particularly indigenous ones, are simply part of the "succession" process-organisms doing what they can, where they can, when they can. Spraying herbicides only makes the chem companies richer and it does far more damage than good, however viscerally righteous it might make its practitioners and amateur weed-haters feel. 

Even alien weeds can perform functions that are beneficial to ecosystem restoration processes in many cases--especially where their presence is primarily due to continued site disturbances such as by alien animals. 

If any soil testing is relevant at all, it would have to be performed many times over a period of time to illustrate the trend of nutrients. Sampling of nutrients in the tissue of living organisms might be more useful in terms of exposing deficiencies, but the take-home lesson is that the lower the available nutrients are (sequestered by plants and other organisms), the lower the weed populations and stature. 

WT

  ----- Original Message ----- 
  From: Robert Layton Beyfuss 
  To: craig at astreet.com ; apwg at lists.plantconservation.org ; craig at ecoseeds.com 
  Sent: Friday, September 20, 2013 7:21 AM
  Subject: Re: [APWG] What caused surprise results in Poppy Project?--Test soil for soil nutrient thresholds

  Hi All

  Most home soil test kits are useless based on my experience comparing their results with legitimate (University) lab results. Nitrogen or even N0 3 levels are impossible to accurately gauge due to the fact that this nutrient is constantly changing in soils in form and availability over even short periods of time.  Even home pH testers are woefully inaccurate. I would never suggest a fertilizer program without bona fide data to back it up. I am not aware of any laboratories that provide nutrient guidelines for native plants in the Northeast, but this may not be the case in the west. Most of our university soil labs (sadly) can recommend nutrient levels for agronomic crops or ornamental crops only!! 

  Apparently this what you did on BLM land. Glad that at least some labs are doing this!     

  I like the concept of "default weeds". All weeds are default weeds in the sense that they grow when conditions grant them the opportunity (opportunistic weeds?) Some thrive in nutrient poor soils while others thrive in soils that have far too many nutrients as is the case here in the northeast. Farmers plant lagoons of reeds and cattails to suck up extra nutrients and most waterways that are lined with exotic weeds are overloaded with nutrients also.   The biomass that plants such as knotweed (formerly Polygonum cuspidatum) produce each year is astonishing to see along many waterways here and this is due to high nutrient levels. Wish that someone would harvest this stuff and burn it for energy instead of planting willows and adding 75  pounds of N per acre to get them to grow well. 

  Of course there are other factors such as soil organic matter levels, soil compaction (surely an issue in overgrazed land?) and possibly allelopathic effects of exotics. 

  I do like the quick and dirty idea of actually observing what is going on and then trying to address the specific problems, instead of simply spraying herbicides on the exotics and hoping that the natives will return on their own. Unfortunately, that approach has seemed to dominate invasion biology thinking for far too long but when funding for "restoration" has come from weed killing entities, it is to be expected. 

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  From: APWG [apwg-bounces at lists.plantconservation.org] on behalf of craig at astreet.com [craig at astreet.com]
  Sent: Wednesday, September 18, 2013 4:34 PM
  To: apwg at lists.plantconservation.org; craig at ecoseeds.com
  Subject: Re: [APWG] What caused surprise results in Poppy Project?--Test soil for soil nutrient thresholds

  Dear Robert and All,

  Thanks for your question.  

  About testing for the soil nutrient threshold, you can do it at least three ways:

  1.) HOME TEST KIT. Use a simple garden store soil test kit on at least three locations for a native species--(a) Where you see native seedlings surviving, (b) Where you see established native plants and no seedlings, and (c) No native plants nearby existing native plants.  It costs about $10 to these three tests.

  2.) SOIL TESTING LAB. Do these same three tests but send them to a lab and have the N-P-K-pH run and get the threshold for each species in PPM for the nutrients.  That is what we did on the BLM land for the 600 acres of pipeline north of Reno.

  3.) WATCH THE PLANTS. Sow native seeds or seedlings either on site or in ex situ test pots, and add measured amounts of fertilizers to see the responses.  Use a native that easily shows nutrient problems, so you can correct any problems rapidly so the seedlings do not die on you before you can correct the problem.  I use the California poppy and the broad-leaved California brome, because they have a rapid response to nutrient problems.  A species not to use, is the Stipas or the needlegrasses, because their responses are slow and they have very narrow leaves that are hard to read.  Broad leaved grasses or fast growing forbs are best.

  Once you find your native seedling soil nutrient thresholds, you can then take a look at local weed infestations, and see if the root cause of their spread, instead of being invasive plants, is that they are only Default Weeds,  able to grow where the soil levels are too poor for local native seedling survival, like cheatgrass, thistles, medusahead, etc.

  I also use this technique of checking for soil nutrient problems by watching the leaves, for my Haiti farming project, with corn to check N-P-K and pepper leaves to check calcium, that you can see information at http://www.ecoseeds.com/clear.html and http://www.haitiag.org.  

  Sincerely,  Craig Dremann (650) 325-7333

  ====================

  > So, did you test the soils for nutrient levels? Have you learned the
  > optimal nutrient levels for the natives that you are trying to reestablish
  > and compared them to the soils you are now working with?
  >
  > ________________________________

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