Litter Decomposition - Science topic

I think hypochlorite and DCAP

Les champignons sont aussi très importants pour la décomposition de la matière ligneuse.

The 3-pool model can be fitted to experimental data using non-linear regression that minimizes the sum of simulation errors. Probably the simplest way is just the standard Solver in MS Excel. I am sure that non-linear regression solutions are available in other software packages like R, Python, Matlab, etc. Having said that, I confirm the opinion expressed by Andrew Paul McKenzie Pegman : the pooled decay model ignores interactions and generally true mechanisms of decomposition. It is not only an oversimplification of reality but rather a misconception, a wrong interpretation of the soil process. A discussion can be viewed in RG, see 'How fast can soil organic matter loss occur?'

Seafloor debris litter should into consideration for better management and utilization.

Dear Dr. Sen Yang ,

See the work below. The authors used DNA-SIP to analyze the microbial community associated with sugarcane via assimilation of 13C by microbial cells. It is not quite what you intend to do, but it can give you insight into how to do your research.

Sen Yang The Very First thing you really need to do is write out your research question. Once your goals are known it becomes much easier to help you. Best wishes, David Booth

Dear Freja

Your question is good and you likely refer to the equation ascribed to Olson (1963)

This model, was first proposed by Jenny et al. (1949), and later elaborated by Olson.

The equation gives a ’first-order kinetics’ and a basic condition for applying this equation is that the process runs at the same rate (constant fractional rate), irrespective of the amount of material left at any given point in time, and that one component (‘unified chemical composition’) is considered as active in the process.

The formula is often used in this form

ln(Mt / M0) = -k t

M0 is the initial mass of organic matter or carbon, Mt is the mass of organic matter or carbon, t, is time (e.g. year or day) and kS is the constant for decay rate. The equation also implies that all substrate is used up, decaying at the same rate.

You asked about positive or negative sign on the k value that you calculate. Although it may seem strange – no problem. The numerical value is the same. Let us say that Mo above is the initial amount, for example in a decomposition experiment and Mt is the remaining amount at time t. This mean that the amount decreases and you get a minus sign.

I once talked with Jerry Olson and quoting him ‘this is probably the most common question that I get – the one about plus or minus and it is of no consequence.’

Anyway, there is a lot of further things to comment on as regards k. For example the litter substrate is almost never decomposing at a constant rate and not ‘completely’.

I have developed this in a chapter in my book – please write a mail to my address bb0708212424@gmail.com and I will be happy to send you an e-copy (for free).

Best regards

Björn Berg

While doing leaf litter decomposition experiment following Olsen (1963) we got k value (per year) 0.18 and half life 3.85. However, 54.01% weight has already lost at the end of first year. How can we interprete the value of half life and weight loss?

Dear James Des Lauriers, Andrew Paul McKenzie Pegman and Elia Guariento

Thank you very much for your precious contribution.

I read a lot of articles and book about ants and how affects on nutrient cycles but very few study releated to ants and litter decomposition. Also, most of them determined litter decomposition in the ant nest. In this point I have a problem because I put litter bag adjacent the ant nest.

Keep working...

Thank you very much again

Meriç

Hi Francisco. Not really clear about your question, as the true coprophils are already in the dung when it is excreted - they require a passage through the herbivore gut to stimulate spore germination. If dung is dry when collected it can be kept in paper bags for months, even years, and will produce the normal growth of fungi when rehydrated and incubated. Coprophilous fungi alone are not responsible for decomposition - they will be interacting with the bacteria and fauna in the dung. I suppose you could do something along the lines of Webster and his students, e.g sterilise dung and then inoculate with different species, alone and in combination, and record the decomposition rate by weighing at intervals.

Dear Fan

Check this link to access article entitled:

Carbon and nitrogen limitations of soil microbial biomass in desert ecosystems.

Hope be useful.

Please have a look at enclosed PDF...

The leaf litter mass loss and decomposition rate constant (k) computed using a single negative exponential decay function first of Olson (1963). The decay constant (k) estimate by Regressing - ln (Xt/Xo) vs t, where Xt is weight remained at time t, X0 is the initial weight of leaf litter, and t is time in days, months or years (it depends on the experimental length or period). Therefore, the slope of - ln (Xt/Xo) vs t is decay constant (k).

Check Manuel Graca and Tim Moulton works.

Dear M. Tarafdar and M. van Haaren,

Thank you for your answers,

Best regards,

Brian F

Dear M. Tarafdar,

Thank you for your answer,

I will check this litterature soon.

Best regards,

Brian F

Thanks for the insight Andrew. I am trying to find studies that have simultaneously looked at the relative contributions. For example mast fruiting can generate a substantial increase/change in nutrients on the forest floor. But I have not encountered any studies that have quantified biomass/organic matter/ carbon/ nitrogen  in the same place and at the same time for the different components: litter, fallen fruit, above ground biomass... Amazon and/or Guiana Shield......

Narayanan,

Thanks. Although not exactly what I am looking for, I appreciate your reply.

More a philosophical statement from someone who enjoyed eating than scientific research, but nevertheless, as Brillat-Savarin observed, we are what we eat sure enough.

Yes, such an experiment may be done in a laboratory. You may use plastic buckets filled with soil and litter on the top to simulate natural soil and litter. Bury a litterbag in the bucket just like you would do in a terrain study. 1 bucket = 1 sample. You may create various condition in buckets to test your predictions (humidity, temp., litter type, nitrogen, nutrients, stoichiometry, organisms and their diversity, etc.). It would be the best to store these buckets in a climatic chamber to control environmental factors. If not possible, you may create mesocosms. Along with litterbags you should bury some temperature and humidity recorders.

This book may help you to choose factors:

Kind regards,

Michał Filipiak

It would depend on specific composition and an empirical stability factor that is the ratiobetween resistance and perturbation, http://link.springer.com/article/10.1007/s11258-004-5801-4 and practices like agroforestry as http://agris.fao.org/agris-search/search.do?recordID=TH2002003126. Season and erosion are coupled to litter movement.

I prefer a sequential fiber analysis followed by acid detergent fiber lignin.  I use an AOAC method for neutral detergent fiber by Mertens et al.  This is derived from the Van Soest method you cite above.You can do Neutral Detergent Fiber, then Acid Detergent Fiber on the residue, then Lignin.  The NDF represents mostly cellulose, hemicellulose, and lignin (and a little protein, and ash, which you can subtract by ashing after lignin and determining).  ADF is cellulose and Lignin.  So to get cellulose, subtract Lignin from ADF.  To get hemicellulose, Subtract ADF from NDF.

87

You are welcome

Thanks for all of your suggestions. The tea bag method (or the other bags suggested by Quentin and Kevin) will not help in terms of faunal decomposition and this is the focus of my study. I think we are just opting for our usual sewing weekend, I just hate wasting time on this...

Dear Gina,

we simply use a transect made of string of desired length to which we tie teabags (for this one can use short strings, clips or staple gun; staples work well for us) at regular intervals (50 cm works well for us). We leave long empty part at the beginning of the whole string. We bury the whole string and tie the long empty part to the stick (we use barbecue sticks) marked with colored tape to easily find it in the future. We also mark a tree or a shrub nearby to be visible from a distance (this helps very much with finding the right place!). Thanks to this, when time comes, we just pull the string out.

Best!

Dear Sen Yang,

I agree with Michael and Maren, working on harvested biomass is not the right method due to changes in chemical composition during senescence (think about difference between green wheat hay and wheat straw).

However you are working on grassland, not on deciduous forest, so you must adapt the method. Grass litter derive from senescent material (leaf blade and tillers) which are poorer in N and soluble sugars than harvested live biomass. Senescence process increase probably during drought or cold season, and is minimal in spring.

If you find many forbs, the aerial parts die probably in autumn before being incorporated to litter.

In both cases, you should probably pick manually senescent material just before it incorporate the litter, in order to run analyses and litterbag decomposition method.

Hi,

I have data on Phragmites australis leave litter (green leaves and after litter fall). I am not sure if this could be of any help. The data are published in Flury and Gessner 2014 (Effects of experimental warming and nitrogen enrichment onleaf and litter chemistry of a wetland grass, Phragmitesaustralis). If they are of any help I could send you the raw data.

FRI dehradun may also be good...

Thank you for your answer, Shilpa.

Energy (carbon-rich compounds are only source of energy, not biomass needed to grow tissues) is not the problem here, since it is relatively easily available for considered arthropods. The problem is matter needed for growth, development, body-building and maintenance (biomolecules rich in elements other than COH).

Excretion of specific substances by fungi is not the mechanism of diet supplementation. I meant that fungi themselves are diet supplements. They are eaten by arthropods and ‛give’ to the arthropods molecules composing fungal mycelia. They are so called ‛butter’ that covers ‛bread’ of carbon-rich, hardly digestible dead plant matter.

This is how it looks in theory. But how exactly this mechanisms works? What specific nutrients play main role here and what amounts of these nutrients must be eaten by the arthropods to make this mechanisms reasonable?

Kind regards! 

Such studies can be carried out using buried screen bag analysis , where rate of decomposition is computed based on priodical differences the loss in weight.

Dear Dr. Srivastava.

Thank you for your questions, all of which raise extremely interesting points. I'll attempt to answer a few of these as follows:

Firstly: rate of litter decomposition is likely influenced by a range of factors, relating to meteorological factors (such as temperature; precipitation and air movement as it influences microclimate at the soil/plant litter/air interface); soil factors (including physical, chemical and mostly biological properties of the soil in question); the physical/chemical nature of the litter itself (perhaps mostly in terms of its content of such complex chemical components as lignification, suberins, waxes and oils: collectively conferring upon the residue what is called the "litter quality); and biotic factors such as previous management practices applied to the soil in question. I've no doubt there are many more factors, but for now, I'll leave it at that.

I fully agree with Dr Eslamikhah's point that the process of litter decomposition is not always beneficial for rhizosphere health, since decomposition of litter under conditions of soil water-logging(and hence, anaerobic conditions) may result in derivatives that do not support healthy growth of roots, and which therefore (through possible effects on root exudation of plants so affected) do not benefit the rhizosphere.

I'd like to comment on your third question (how does rate of litter decomposition vary temporally and spatially?) as follows. I recommend that any pruning debris from such as citrus trees be put through a suitable wood-chipper and scattered on the surface of the soil underneath the drip zone of tree canopies, and that mown grasses and herbs from the orchard inter-rows (I do not recommend use of herbicides to 'control" vegetation growing in this valuable area of the orchard) be strewn on top of the wood chip residues under the trees, and so on every year.

  These residues are NEVER worked into the soil: they are just added to the surface in a series of layers, every year. What is evident is that, depending upon the irrigation system used, the fastest breakdown of litter is always at the soil litter boundary. What we see within a few years of using this practice is that the bottom of the litter layer and the top of the soil layer become very much the same, and become filled with perhaps the healthiest roots that the trees produce. With trees under drip irrigation, the top of the litter layer dries out and seems to remain more or less intact (depending on climatic conditions such as rainfall and temperature). However, where trees are irrigated with micro-sprinklers, which wet an extended area of the soil surface, the entire layer of litter seems to break down more uniformly and also more rapidly.

Your fourth question concerns the extent to which fertiliser applications may be reduced where active decomposition of plant litter is evident. I can only offer an opinion based on my practical experiences, where on mature orange trees (a seedless valencia cultivar called 'MidKnight', we were able to reduce N applications by 50% (from about 250 units N [per ha/per year] ) and K applications by 33% (from about 140 units K) for the same yield (about 58 tonnes/ha), but with fruit under the "reduced N and K treatment: colouring four weeks earlier, showing higher fruit brix % (about 20% higher); lower titratable acidity (which resulted in superior brix/acid ratio), and according to subjective assessments, a deeper orange juice colour and superior flavour. I would advise great caution in your interpretation of this: this was not a scientific trial, merely an on-farm proof of concept field trial, although each 'treatment"  comprised about 3000 trees. What I will say is that my experience suggests that growers fertilise their citrus trees to maintain leaf N levels at about 2.0 to 2.2% N (compared with a "standard" of 2.6 to 2.8%) and K levels at about 08 to 1% (compared with 1.2 to 1.4% recommended). Tissue sampled in this case were leaves picked behind the fruit on a fruit-bearing terminal, which is standard practice in South Africa.

I hope these thought have been of interest to you. With warmest wishes.

In case you have to maintain 60% gravimetric moisture content (see comment of Brian Karl Richards) it is easy - oven dry your soil, measure its weight, calculate 60% of this weight and that this weight of water you have to add to you soil.  Measure the total weight inclduing the pot and ensure that you water your pot every time up to this weight.

In case you have to maintain 60% volumetric water content, you have to measure the volume of the soil, then oven dry it and put it back to the container.  Add 60% of the volume in water.  Measure the total weight of the pot and every time water the pot up to this weight.

Dear Dr Wang

I guess that this answer may be developed but I will start. The microbial decomposition of litter is the dominant one and as microorganisms, e.g. fungi, grow into the litter they have a need for nutrients, among them carbon, nitrogen, phosphorus, and sulfur plus further nutrients for their growth. For growth they need to synthesize e.g. protein, DNA and cell walls and that is wehere N,P and S come in.. Often all these three nutrients are limiting for microbial growth and you can thus obtain a positive relationship between N, P and S and litter mass loss, at least for newly shed litter.. In my experience N does not always give the best relationship. Much of the N in litter is tied up in complex compounds which are less available to the decomposing microroganisms.

Often enough a relationship to P becomes better than to N. Further, the relationship you mention seems to be one that is best observed for newly shed litter, but not for all - e.g. N2-fixing plkant tend to have an excess of N also in newly shed litter. Later on, after some decomposition the relationship to N may change. 

Best regards

Björn Berg

A successful method to retrieve nematodes from organic material is a mist chamber (Seinhorst). In a mist chamber a very fine mist of warm water (20 degrees) is sprayed from nozzles every half an hour during 15 minutes. The organic material is wet all the time; the nematodes emerge and move through a 150 u sieve and are collected in a collection dish with overflow. The nematodes sediment to the bottom of the dish. This takes some time depending on the toughness of the plant tissue, The method might work for litter too, If suitable send an e-mail for more details.

regards Thomas

You may refer attached article here and use the pyrolysis rector design and method described in this paper. Hopefully it may help you.

The respiration rate must be expressed as amount of CO2 (ug or mg or g of CO2-C or mmol of CO2) per amount of soil (g, kg) per unit time (min, hr, day or even week/month/year).

If you see the published data with the missed time units, then it is qualified as error made by authors and editors.

What is better, mg of CO2-C or mmol of CO2? In a C-balance studies mass units of carbon are better. In the studies of metabolic pathways (e.g. degradation of PCB in soil), the molar concentration is preferable.

What is better, ug, mg or g of CO2? g or kg of soil? hr or day? No strict rules, just make your numbers easy to read. There was a tendency to unify the units to international standard but it is not always justified.

Finally, per g of soil or per m^2 of soil surface? Depends on technique you use, whether you measure a flux of CO2 by chambers or incubate few g of soil in a vessel.

Complete decomposition of leaf litter has exactly the same effect as adding ash. The organic acids in litter are completely oxidised, and the anions that disappear are replaced by carbonate, thus making the product of decomposition or ashing more alkaline.

I think you should really have a look at:

Cornwell,W.K., et al. 2008. Plant species traits are the predominant

control on litter decomposition rates within biomes worldwide.

Ecology Letters 11: 1065–1071.

You would probably find the answer among the cited references.

Terzahi thanks for sharing your idea. Yeah the factors you mentioned will definitely play a role in decomposition, but until and unless we put some material in bags, we cannot determine the loss of weight. That is why the bag is vital in this type of research.

Dear Christina,

I do not have any recent paper regarding your question even in knowledge from literature recently.

However, based on my experiences, i can say young individual tree has better efficiency to perform ecosystem functional attributes rather than old aged individual tree. In young stage, for quick acclimatisation and establishment in an ecosystem where it is, plants do some functional changes like litter chemistry (possibility of manufacturing low quantity of lignin in leaf litter for getting more nutrients via decomposition process). In general, detrivore community prefer quality of leaf litter during decomposition (high N and carbon containing carbohydrate, definitely not lignin) for their energy and structure.

Other assumption, plants could be able to produce high quality of leaf litter at young stage. You just compare young aged individual tree leaf litter with 10-20 years old one at the same time and from same abiotic environmental condition. I am sure you will have wonderful findings!

Good luck

Hello Dear, Micro-Kjeldahl N is the total amount of N present either any form released after acid digestion. You can say TKN (total kjeldahl Nitrogen), it is equivalent to total N while available N is the mineral form which is available by mineralization of organically bounded material or OM. About 98 % N is present in the soil or plant in organic form and only 2 % N is released as from mineral form in the ions e.g. Nitrate and Ammonium N.

So dear, if you want to estimate total N plaese follow protocol of Jackson, 1958 or Inderson and ingram, 1993.

however, about 28 forms of N found in the plant and soil, for example, geo-genic, biogenic, geologic, organic and in mineral form etc.