Discussion in 'Organic Lawn Care' started by Smallaxe, Mar 23, 2011.

  1. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    Bill & Barry ..... this is the man you choose to defend, your example of positive and constructive input on this forum ...... and yet somehow you find fault with me presenting and expecting accurate information. I commend you on your choice. :clapping:

  2. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253

    There is no way you can extrapolate this study of tilled farming to turfgrass SOM. When you till up a field it exposes the SOM to oxidation. When you harvest the crops it removes OM. These are huge loses that you would not encounter in turf. Turf covers the soil and we know from numerous studies that proper fertilization increases the SOM to a point of equilibrium. I have plenty of experience with grasslands and can promise you that you'll increase SOM with proper fertilization.

    Why don't you look at studies of turf? because it supports my statement of course! And btw my statement was that in grasses, fertilizer+surface applied OM will increase SOM more so than just Surface applied OM alone.

    Show me that the statement is wrong - prove it or bow down sucker.
  3. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    If organic matter (grass clippings) is left on the lawn, it is eventually translate into SOM, especially with thepresence of worms... Correct?

    What the article said, is that it may not do much for SOC, is that true?

    Don't really care about 'SOC', in the sense... I am interestted in having more humus in the soil for CE sites, Drainage and water retention capabilities... Grass clippings can do that and N will help...
    With focus one that one, single point it should be true... Correct?... :)
  4. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253 Mamta Hari Om.pdf?osu1187117113

    Because you insist that a corn field and turf stand are the same you can read this study:

    "Farmyard-manure additions for 25 y increased soil organic-matter (SOM) content by 3.8 g kg–1 (13.6%) in the FYM1 treatments and by 7.8 g kg–1 (27.8%) in the FYM2 treatments, compared to a 3.2 g kg–1 decrease (11.4%) in the FYM0 treatments. Overall, the results suggest that mineral fertilizers can maintain high yields, but a combination of mineral fertilizers plus farmyard manure are needed to enhance soil organic-matter levels in this soil type."

    Turf SOC

  5. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    I see Quack ... no way to extrapolate .... no relevance at all.

    How about no-till operations? Given you didn't even read the study .... how do you even know the plots were tilled? What about the multitude of other studies referenced that correlates the findings of the linked study? Are all those systems tilled? Do you till a pine tree plantation too? Isn't core aeration effectively tilling the soil .... plug by plug? When you bag your clippings you also remove organic matter. Are you saying that no one bags clippings in this industry?

    Then by all means quack, please present your scientifically rigorous studies on these grasslands. I honestly am interested in seeing this data.

    I'm not the one who keeps bringing them up. Obviously you have reviewed all these studies so it should be relatively easy thing for you to provide references to them. If you had bother to read the study you would have seen where the authors also discussed the inherent problems with other studies that claim the opposite of their findings. Perhaps you would like to comment on that?

    I presented a study (which you didn't even read) the demonstrates that synthetic N, even with the organic matter inputs, can lead to a net decrease in SOC. These findings were correlated in a wide variety of different management systems and crops.

    If you cannot even read the study, and cannot see the relevance of the findings of this study in turf grass management, then this discussion is over.
  6. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    It eventually end up, in part, in the SOC pool.

    SOM is a part of the SOC pool. When you have a lab measure organic matter content, it is most likely a measure a SOC as the typical method of measurement for your basic test is combustion.

    It may or may not, that was the point of posting the study. One cannot assume that SOC will increase with synthetic N fertilization. Quack made a statement stating it WILL lead to an increase. I posted an extremely well referenced study with a multitude of correlating studies showing one cannot assume it will, and that in fact it could lead to a net decrease in SOC over time.
  7. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253

  8. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    The "study" suffers from at least one of the problems the authors of the study I referenced noted .... too shallow of a sample depth as noted below.

    In contrast to the foregoing evidence, reports that N fertilization can increase SOC sequestration are by no means uncommon in the literature. Typically, such findings do not meet the fundamental requirement for baseline data in assessing SOC changes over time (e.g., Jenkinson, 1991; Campbell et al., 2000; VandenBygaart and Angers, 2006) but rely on a comparison relative to an unfertilized control (e.g., Larson et al., 1972; Havlin et al., 1990; Malhi et al., 1997, 2002; Solberg et al., 1997; Dormaar and Carefoot, 1998; Raun et al., 1998; Nyborg et al., 1999; Liebig et al., 2002). The same erroneous conclusion could be reached if this approach were applied to the 2005 data reported in Table 2 because soil C content was often greater for fertilized than unfertilized subplots. Misinterpretations can also arise when (i) inorganic fertilizer inputs are confounded by current or previous manure practices (e.g., Liang and MacKenzie, 1992; Darmody and Peck, 1997), (ii) SOC data represent only a very limited depth of surface soil (e.g., Varvel, 1994; Solberg et al., 1997), or (iii) the study period is inadequate for detecting SOC changes (e.g., Liang and MacKenzie, 1992; Varvel, 1994; Dormaar and Carefoot, 1998). Moreover, N fertilization can have a positive effect on SOC sequestration if acidity generated during NH4
    + oxidation is not controlled, thereby impeding C decomposition (e.g., Fog, 1988; McAndrew and Malhi, 1992; Ismail et al., 1994; Malhi et al., 1997; Vanotti et al., 1997).

    Furthermore it is not a journal publication. Please keep your references to journal publications.

    Where did I say or insist they were the same Quack. Another case of you putting words in my mouth.

    Good for you quack, you found a study that showed an increase .... I think. I don't have access to this study, so I can't comment on it or potential problems with methodology, nor do I know what the treatments noted entail. However, this directly related study notes some interesting details left out of the abstract you linked.

    Soil organic C (SOC) content can increase by managing land use practices in which the rates of organic C input exceed those of organic C mineralization. Understanding the changes in SOC content of Black soils (mainly Typic Halpudoll) in northeast China is necessary for sustainable using of soil resources there. We used the RothC model to estimate SOC levels of Black soils under monoculture cropping corn in a long-term fertilization trial at Gongzhuling, Jilin Province, China. The model outputs for the changes in SOC were compared with measured data in this long-term fertilization/manure trial. The sound performance of model in simulating SOC changes suggests that RothC is feasible with Black soils in the temperate climatic region of northeast China. The modeled and measured results indicated that the treatment without fertilizer/farmyard manure (FYM) addition led to a continuous decline in SOC during the study period and N and NPK fertilization were inadequate to maintain the SOC levels in the plow layer (upper 20 cm) unless FYM was added under the current conventional management associated with no above-ground crop residues returning into the soil. Soil organic carbon could follow the same path of decline if the same management practices are maintained. Model results indicate that returning above-ground crop residues to the soil from 2002 to 2022 would increase SOC by 26% for the treatment without fertilization addition, 40% for N treatment, 45% for NPK treatment, and 38% and 46% for N and NPK treatments with FYM addition, compared to the levels in the corresponding treatments in 2002. The simulation results suggest that the RothC model is a feasible tool to assess SOC trend under different management practices, and returning above-ground crop residues into the soil would lead to a remarkable increase in SOC of Black soils in the region.

    Can you please comment on the red text and the percentages reported for the model simulation, especially given the model was validated against the study you linked.

    Beyond all this, this study in no way invalidates the findings of the study I posted.

    Irrelevant and inapplicable to this discussion. No organic matter was top dressed, all plots received the same amount of N fertilizer (i.e. no control with respect to N)

    All plots were fertilized with 150 kg ha−1 N annually from 2002 to 2005.

    Same thing as previous study. No indication that the study looked at changes in SOC strictly as a function of synthetic N applications, nor does it indicate it looked at top dressing + synthetic N per your initial definitive statement. Given I don't have access to this study as well, I can't comment any further on it other than it is inapplicable to this discussion.

    So you potentially have found a single study here that is applicable to the discussion. Good job.
  9. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

  10. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253

    Show me a study that shows topdressing + fertilizing decreases SOM in grass sites.

    That is all you would have to, seems simple doesn't it?

    Like I said, over 300 square miles of revegetation work using compost alone, or with various fertilizers has proven to me that fertility plays a huge part in raising SOM levels in grasses. I know for a fact that plots receiving just compost raised SOM levels less so than plots receiving compost + fertilizer.

    You can fight this from your desk by using examples of anything but grass studies if you want, but its clear as day you have nothing but jealousy and arrogance to display at this point.

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