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another soil test question

Discussion in 'Organic Lawn Care' started by roccon31, Jul 16, 2009.

  1. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    A solution can become supersaturated with an ion (i.e. > 100% or SI > 0) if the conditions are right.

    I started to write a long reply explaining why this is not as simple as you are trying to make it, and some of it is just wrong, but instead I will just point you to the docs I have previously referenced.


    Pay particular attention to sections 3, 6-8.

    With respect to P, please check up on solubility constants of different P species/compounds and how that may or may not affect availability at low pH. Once again, these micro/macro nutrient problems with respect to high soil P are mostly associated with high pH soils, not low, as is the case here.

    SOC (soil organic carbon) is not comprised of strictly humus (humic compounds). Also, you cannot compare a "soil" comprised strictly of humus to one that is a mix of humus and mineral components. Where are you getting this information?

    Also your same inputs and productivity example does not pan out. Why would you apply the same inputs on a soil with a higher CEC (i.e. nutrient retention) as a soil with low CEC?

    I think the more important relationship to draw is fewer inputs are required to get the same level of productivity in soils with higher CEC/SOM strictly due to better nutrient retention, soil structure, etc.... If anything, I would expect a decline in productivity in a strictly humus soil if fertilized at the same rate as, say a sandy soil, due to the potential for nutrient toxicity over time.


    Just because no "visible" improvement is noted does not mean there is not an improvement. More likely that not, a "visible" improvement was not noted because there were no limiting nutrients (i.e. luxury consumption was the case) or limiting conditions, not because the SOM was at 9%.

    While we are at it, please define "enough available OM". Available for what?
  2. growingdeeprootsorganicly

    growingdeeprootsorganicly LawnSite Senior Member
    Messages: 766

    soil test... sul-po-mag + lime plus lots of post, that guys area receives lots of rain each year so to me mineral augmenting would be wise

    a soil with high P and low pH one would think not have a micro nute issue simply because of the soil's pH. no?

    pure clay soil vs humus soil...? mudd, i respectfully disagree again

    bills little story? bill what are you telling people???:hammerhead:
  3. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    I agree with you completely, what I was trying to point out was the point of view of the customer and how simple and flat the thought process was, I should probably move this to another thread.

    Although these are some very bright folks with degrees and obviously smart business folks it still came down to one thing "I didn't SEE any improvement" and was told that compost obviously does not have the affects that I told them it did.

    The customer still had the fertilizer mentality, apply something at 8AM and by 4PM its green. directly feeding the plant rather than growing soil fertility

    No I did not go into a porosity, CEC, cation debate with them
  4. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    And you just made a recommendation to apply sulfur without any reguard to the soiltest results. (Hint, sulfur was not reported on the soil test shown) So for that I will respectfully disagree with your recommendations.

    Actually the addition of sulfur would probably also be necessary, I am just disagreeing because S was not a part of this soil sample and therefore it isnt possible to say whether or not S or any other nutrient is needed.

    As for the clay and humis part of this discussion. Clay has about half the nutrient holding ability of pure humis and it isnt to likely that anybody would plant anything in a pure humis solution, altho I have in my greenhouse and results support my statements that plants potted in clay will outperform the plants potted in the humis. My point is simply that a mixture of humis and clay will make a better growing median than either of the materials by themselfs. There is a point of demished returns on how much humis is enough, for me its generaly around 7%, which seems to also be supported by ICTbills little story. Once enough has been applied, anything else would be a luxury and not necessary more productive.
  5. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    There is only a need for about a half unit change in pH to bring it within "acceptable" levels (around 6.00). I would not be concerned about P availability until the pH is around 7.00 and higher, or below 5.00. Regardless of what species P forms with other cations at that pH (~ 6.00), IMO they will still largely be plant available (i.e. not locked up in "insoluble" compounds) at the current and potential target pH.

    Once again, these cations do not change/cause pH.

    You have not considered pH. Organic matter carries a pH dependent charge, which increases with increasing pH. Clays can be either pH dependent, permanent, or both, however is typically more stable with respect to CEC and changes in pH. While organic matter may potentially contribute more to a soils CEC (pH dependent), it alone does not define what a soils CEC is.

    You also have not considered soil structure and parent material contributions to plant available nutrients. Once again, you do not judge a soils fertility on CEC alone. Now if you have said, which soil can retain nutrients better, then that would have been better, but still depends on other dynamics of the system such as soil moisture & other water relations, temperature, gaseous exchange, pH, structure, etc...

    This may or may not be true. Could you please define humus as you see it?
    IMO, compost is not humus (per SSSA), however it can/will contain humic substances.

    Compost: Organic residues, or a mixture of organic residues and soil, that have been mixed, piled, and moistened, with or without addition of fertilizer and lime, and generally allowed to undergo thermophilic decomposition until the original organic materials have been substantially altered or decomposed. Sometimes called "artificial manure" or "synthetic manure." In Europe, the term may refer to a potting mix for container-grown plants.

    Humus: The well decomposed, more or less stable part of the organic matter in mineral soils. Humas is an organic soil material which is also one of the USDA textures of muck (sapric soil material), mucky peat (hemic soil material), or peat (fibric soil material.) Most likely it is muck.

    Humic Substances: A series of relatively high-molecular-weight, yellow to black colored organic substances formed by secondary synthesis reactions in soils. The term is used in a generic sense to describe the colored material or its fractions obtained on the basis of solubility characteristics. These materials are distinctive to soil environments in that they are dissimilar to the biopolymers of microorganisms and higher plants (including lignin). See also humic acid, fulvic acid, and humin.

    This is anecdotal, not scientific. To state the above you need to present methodology, environmental conditions, data, etc... to support that statement. Just as in Bills case, an "observation" without knowing why is meaningless. Your observation could be completely unrelated to OM%. One example might be higher soluble salts in one over the other leading to lower productivity.

    Furthermore, you have presented an unrealistic scenario, one of all "humus" (I assume you mean compost), and one of all clay (I assume you mean your native soil). We will never have an all compost case in a landscape .... well at least I would hope that will never happen, so why would you make that comparison?

    With respect to Bills story, it illustrates nothing more than an unscientific conclusion made about the virtue of compost based on a "visual" assessment. Lets not even mention that the vast majority of the months between application and this "observation" were in the winter when essentially nothing was going on, microbially or otherwise. The conclusion they drew is nothing short of ridiculous.

    Do you know of any published studies that supports your OM > 7% results in a negative impact on productivity?

    I'm not trying to bust your balls here, and generally I agree with most everything you post, however sometimes you speak in absolutes which are not appropriate given the complexity of the systems we are talking about.
  6. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

  7. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    IMO, for landscapes it doesn't have to be optimum, or anything even close to optimum. Get your pH to a level where your inputs are reduced. If your soils already have the nutrients there, then there is no need to add more. Anything in the 5.7-6.3 range generally speaking is good enough IMHO.

    You think? It doesn't have to be a perfect ratio, that "rule" is an extremely general one. The target here should be getting pH to around 6, not achieving the perfect base saturation. I thought you were in the SLAN camp anyhow ... why would you care about optimal base saturation?


    I asked Bill this, but I'll ask you as well. What is sufficient, in what type of soil, and to what depth? Personally I would like to see a consistent OM% in at least the top 8-12", regardless of what you are growing. You may have "sufficient" OM in the top 1-2", but we don't want our effective roots zones to be restricted to that depth, do we? Part of effective land management is utilizing the native soils and the resources they have to offer. This means promoting and developing good soils at a depth greater than 1-2". The only way to achieve this is by continued inputs of organic matter, assuming your typical mineral landscape soil with almost no OM.

    While this may unfortunately be true, it doesn't make it right. We as industry professionals, who should know better, should not cater to public misperception. In my eyes, if I can go an entire season with zero inputs, or even a 75% reduction, due to a compost application with an over seed in the fall, that is a major benefit which not only continues to promote soil health and development, but saves money.

    I have tried to think of a way to put it simpler, without much success.
  8. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

  9. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    Perhaps, if you use sodium (bi)carbonate.

    Who said anything to the contrary? I will add here that just because you have an "ideal" base saturation also does not mean a soil is fertile.

    HUH? What elements other than hydrogen are an option when we are talking acidity? The point in adding lime is to remove hydrogen from the exchanger so it can react with the carbonate, which essentially removes it from the active pool (i.e. it no longer contributes to the acidity of the soil).

    There is already more than enough Ca for turf, so it is not a concern. In fact, the only reported nutrient that I see which has the potential to become limiting in the short term is potassium.

    Sufficient Levels of Available Nutrients - i.e. determine what is needed by individual nutrient analysis, not using ideal base cation ratios.

    Not that I am one to typically use the USGA as a reference (damn turf promoters), but this pub covers the issue.


    Not following you Mudd. Why are you hung up on providing sufficient nutrients (SLAN) if your approach is management via base saturation (BCSR)? The two approaches are not the same. Either you follow Albrecht's theory or you don't. IMO base saturation is more important with respect to soil structure and subsequently overall soil health than it is for nutrients. You yourself have said on many occasions just because you have the correct ratio does not mean you have sufficient nutrients. Personally I use both methods when making management decisions based on a soil test. SLAN to address nutrient needs, BCSR for overall soil structure and health.

    So lets look at the OP's soil again. What would be the reason for adding lime if it was not for raising pH? Just to get your base saturation "optimal"? Is there a visible Ca deficiency in the ops turf? Is there a problem with soil structure due to high levels of Mg or Na? No indication of either has been given by the OP or the soil test.

    If you really want to play the ratio game, both Ca and Mg levels are sufficient for turf (ppm) and the ratio is 6:1, which is close enough to "ideal" IMO. The only good reason for adding lime would be to increase pH which will lead to better overall nutrient availability. As a bonus you get your base saturation into a more "ideal" range, if that is what you are concerned with. Doesn't really matter how you look at it ... correcting one "problem" will correct both.

    Now one needs to understand here that an addition of lime in this case needs to come with an addition of potassium as well because the addition of lime will more likely than not result in potassium becoming limiting. If you want to kill two birds with one stone, then amend with wood ashes.

    BTW, "nutrients" don't necessarily drive a systems acidity. Potential causes of soil acidity are environment (areas of high precipitation), decomposition of SOM (CO2), parent material & soil type, management practices, etc.... Soils low in OM & clay are more likely to be acid in areas where rain is plentiful because they are highly leached.

    HUH! Compost not only adds microbes but adds a food source too. Can't have a microbe farm and build SOM without food source now can you?

    Generally true, but HIGHLY dependent on the soil type and structure. With respect to the rest ... ?

    Compost is applied primarily as a source of SOM/SOC, secondarily as a source of nutrients. If the compost is lacking in a particular nutrient that is needed, then obviously that will need to be addressed. The reason why you keep applying it is because it does take a lot to make a difference to a sufficient depth.

    Top dressing compost is the typical practice in landscapes, which means vertical movement of OM will take a long time, how long depends on the soil and environmental conditions. You cannot promote better soil structure and subsequent microbial activity if you don't have a continued source of OM.

    Might I also point out once again we are talking about landscapes here, NOT Ag.

    Ideal/optimal soil available nutrients is NOT a requirement for landscapes. There is absolutely NO need to manage a landscapes soil (with respect to nutrients) the same as you would in Ag.

    DUSTYCEDAR LawnSite Fanatic
    from PA
    Messages: 5,132

    compost always seems to help but it takes time

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