![ Litter decomposition supplies nutrients to the soil
solution, which renders them available for plant and
soil microbial uptake. In addition to litter quality,
other factors affect decomposition including
moisture, temperature, soil nutrient availability, and
particle size. Faster decay rates may result in more
efficient nutrient cycling; thus, more plant biomass
is produced per unit of nutrient. This is particularly
true when losses after decomposition are limited.
Litter decay rates vary, but typically 40%–60% of
warm-season grass litter decays per year [27].
Combining litter deposition, nutrient concentration,
and decay rates allow for the estimation of litter
nutrient release [28]. It is important to account for
both above- and below-ground litter when
estimating litter nutrient contribution, but
understanding processes involving below-ground
litter presents significant challenges.](https://image.slidesharecdn.com/litterdecompositionandnutrientdynamics-210310085100/85/Litter-decomposition-and-nutrient-dynamics-12-320.jpg)
Litter decomposition and nutrient dynamics
- 2. PARVATI TAMRAKAR 2ND SEM, MSC. FORESTRY, GGU BILASPUR
- 3. What is litter? Litter decomposition process Decomposition rates Nutrient dynamics
- 4. Litter or duff is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon ("O" for "organic"). Litter is an important factor in ecosystem dynamics, as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil fertility.
- 5. Litter is characterized as fresh, un-decomposed, and easily recognizable (by species and type) plant debris. Items larger than 2 cm diameter are referred to as coarse litter, while anything smaller is referred to as fine litter or litter. The type of litter is most directly affected By ecosystem type. In soil science, soil litter is classified in three layers, which form on the surface of the O Horizon. These are the L, F, and H layers- • L – organic horizon characterized by relatively un- decomposed plant material (described above). • F – organic horizon found beneath L characterized by accumulation of partly decomposed organic matter. • H – organic horizon below F characterized by accumulation of fully decomposed organic matter mostly indiscernible.
- 7. Litter decomposition is defined as the process through which dead organic material is broken down into particles of progressively smaller size, until the structure can no longer be recognized, and organic molecules are mineralized to their prime constituents: H2O, CO2 and mineral components. During the process, recalcitrant organic compounds are formed and dissolved organic carbon may be leached to the mineral soil. It is also universally recognized that there are three main processes through which decomposition occurs: (1) leaching of soluble compounds into the soil, (2) fragmentation of litter into smaller sizes and (3) catabolism by decomposer organisms (i.e. micro- organisms and fauna).
- 9. Rates of leaf litter decomposition provide another indicator of ecosystem function widely used in rivers (Boyero et al., 2011; Sponseller and Benfield, 2001). Typically, this involves leaving preweighed leaf litter in mesh bags for several weeks at a site and then determining how much biomass is lost over the period. Bags are best secured close to the stream bed to reduce the influence of hydraulic conditions; bags floating in the water column can influence decay rates (Mutch et al., 1983). In many cases, leaf litter decomposition will be size-dependent, so it can be useful having multiple bags with different mesh apertures and different detritus sizes (Boulton and Boon, 1991). A key difficulty with leaf litter decomposition is that it can be difficult comparing between sites if leaf litter composition is not the same, as some leaves and twigs will decompose faster than others. An alternative technique that may circumvent that issue is using cotton strips and popsicle sticks instead of leaf litter (Tank and Winterbourn, 1996; Hildrew et al., 1984; Egglishaw, 1972). Cotton decomposition can be either measured as loss of biomass or loss of tensile strength. Cotton strips and popsicle strips are inexpensive and considerably reduce sample variability.
- 10. The biological degradation of litter is mainly performed by microbial decomposers, including bacteria, fungi, and actinomycetes, which have lower C:N ratios than most litter types. For instance, forest-leaf litter has a C:N ratio of 58:1–88:1 (McGroddy et al., 2004); microbial C:N ratio is approximately 9:1 (Cleveland and Liptzin, 2007). In general, for microbial activity, an optimal litter C:N ratio is 20–30. If the litter C:N ratio is < 20:1 during litter decomposition, then mineralization likely occurs. If the ratio is > 30:1, then immobilization possibly occurs. In this sense, forest litter has a higher C:N ratio to support normal microbial activity. Experiments have shown that litter decomposition can be enhanced when C:nutrient ratios are altered by adding nutrients. For instance, adding P and micronutrients enhance leaf- litter decomposition in a lowland Panamanian forest; Na shortage slows the carbon cycle (Kaspari et al., 2009). These results have suggested that tropical forests are a non-Liebig world of multiple nutrient limitations, with at least four elements shaping the rates of litterfall and decomposition (Kaspari et al., 2008).
- 11. Manzoni et al. (2008) showed that N loss occurs slower than C loss for most litter decomposition at a global scale. Thus, semi-decomposed litter N likely accumulates, and the N:C ratio of the litter increases throughout decomposition. This result has suggested that decomposers prefer the strategy of lowering their carbon-use efficiency to exploit residues containing low- initial nitrogen concentration. Furthermore, microorganisms use their own stoichiometry to a particular transformed material during decomposition because these organisms have a relatively fixed C:N ratio. Thus, C-rich litter causes microorganisms to release more C in the form of CO2 into the atmosphere as microbes attempt to maintain a favorable C:nutrient ratio (Manzoni et al., 2008).
- 12. Litter decomposition supplies nutrients to the soil solution, which renders them available for plant and soil microbial uptake. In addition to litter quality, other factors affect decomposition including moisture, temperature, soil nutrient availability, and particle size. Faster decay rates may result in more efficient nutrient cycling; thus, more plant biomass is produced per unit of nutrient. This is particularly true when losses after decomposition are limited. Litter decay rates vary, but typically 40%–60% of warm-season grass litter decays per year [27]. Combining litter deposition, nutrient concentration, and decay rates allow for the estimation of litter nutrient release [28]. It is important to account for both above- and below-ground litter when estimating litter nutrient contribution, but understanding processes involving below-ground litter presents significant challenges.
- 13. Nutrient release from decomposing litter is important, but in some cases, the timing of nutrient release may not match crop nutrient demand. In semiarid regions, litter deposited during the dry season accumulates until the beginning of the following rainy season because limited moisture during the dry season prohibits decomposition. Likewise, regions with cold temperatures during the winter have reduced litter decomposition. As a result, a flush of decomposition occurs at the beginning of the rainy, warm season with a surplus of nutrients. Often, during this time of the year the forages are in the early stages of regrowth after the prolonged dry (or cold) season. Many times the shortage of forage during this period forces land managers to stock pastures to take advantage of this fresh regrowth. This will result in nutrient losses via excreta and reduced regrowth due to overgrazing. From a nutrient management perspective, an efficient practice is to allow the forages more time to regrow by utilizing efficiently the nutrient surplus from litter that occurs at the beginning of the season
- 14. C. Liu, X. Sun, in Reference Module in Earth Systems and Environmental Sciences, 2013. José C.B. Dubeux Jr., Lynn E. Sollenberger, in Management Strategies for Sustainable Cattle Production in Southern Pastures, 2020. C.M.N. Panitz, in Coastal Plant Communities of Latin America, 1992. Adam D. Canning, Russell G. Death, in Encyclopedia of Ecology (Second Edition), 2019 www.hindawi.com www.researchgate.net www.sciencedirect.com