The quality of water flowing from the land into the reef lagoon has deteriorated over the past years. Major floods deliver large levels of pollutants including eroded soil from river catchments onto the reef.
These soils are especially vulnerable to most forms of soil erosion and can affect infrastructure projects such as:. Home Environment, land and water Land, housing and property Land and vegetation management Soil management Erosion Impacts of erosion.
Print Impacts of erosion All soils can suffer erosion but some are more vulnerable than others. Agriculture Soil erosion removes valuable top soil which is the most productive part of the soil profile for agricultural purposes.
The impacts of erosion on cropping lands include: reduced ability of the soil to store water and nutrients exposure of subsoil , which often has poor physical and chemical properties higher rates of runoff, shedding water and nutrients otherwise used for crop growth loss of newly planted crops deposits of silt in low-lying areas. Erosion causing serious damage to a road. Erosion on the driveway of an urban development.
Both scenarios raise the threat of erosion significantly. When topsoil erodes, it carries away many of the nutrients needed to grow abundant, healthy crops. Agricultural runoff is also particularly insidious because it usually contains excessive nutrients like phosphates and nitrates from fertilizer and manure.
When these nutrients run off into local water supplies, they can cause algae overgrowth, oxygen depletion, reduced water quality and the eventual death of many aquatic species. Erosion control measures preserve the nutrient-rich topsoil, help agricultural operations thrive and prevent nutrient pollution. When construction companies cut down trees and clear land for new projects, they also increase the risk of erosion. Using erosion control blankets contains the soil and reduces environmental disruption during construction.
It also makes the construction project more efficient because construction companies will not have to replace eroded soil or remove sediment from sewers or stormwater basins. Erosion control blankets reduce the likelihood that erosion from land development will cause pollution and displace native species. In conservation work, erosion control also has particular benefits for shoreline preservation and stream restoration.
Homeowners, businesses and municipal governments along a bank or coast often want to preserve the shoreline, both to protect the rich aquatic environment and to secure property and infrastructure against encroaching waters. Many properties near shorelines install rip-rap — large rocks intended to hold soil in place. However, rip-rap has a few disadvantages. It is more expensive than vegetated alternatives, it is often less aesthetically appealing and it does not provide the habitat enhancements of vegetated solutions.
Erosion control blankets are often much more practical and cost-effective. Conservation efforts aimed at stream restoration often find erosion control blankets to be appealing options. The blankets blend into the natural environment much more convincingly than other solutions like rip-rap. They also hold their shape much better than straw, which can blow away in heavy winds and pollute the streams it was designed to protect. To see the benefits of soil erosion control at your site, partner with East Coast Erosion Control.
We offer a range of biodegradable and photodegradable erosion control blankets made of natural materials that will minimize erosion for a time — short-term , extended-term or with accelerated degradation — and then degrade naturally into the soil.
We can provide permanent blankets as well. Contact us today to learn more. When shoreline erosion occurs, significant problems arise for the environment and surrounding waterfront properties. In many applications like construction, vegetation removal leaves the landscape vulnerable to erosion, which washes….
Why Are We Essential Erosion control products are designed to protect drinking water nationwide. Stallard , on the basis of past data Meade et al. Second, a significant portion of eroded, C-rich topsoil is buried in different depositional settings, rather than flowing to the ocean. Erosion transports relatively fresh organic matter that is present at or near the soil surface compared with deep soil organic matter [SOM]. After successive erosive events, the C-and nutrient-rich topsoil of the eroding slopes is buried in the depositional lowlands and becomes a subsoil horizon of the convergent slopes or plains figure 1 , probably reducing its rate of decomposition compared with noneroded C on the contributing slopes.
Third, the surface area for terrestrial deposition of eroded C has increased since the beginning of the Industrial Revolution figure 2. The estimated to fold acceleration of erosion rates by anthropogenic activities in recent history has not been accompanied by a concurrent and proportional increase in sediment discharge to the ocean.
The discharge of sediment and C to the ocean has remained approximately constant as a result of hydrologic projects on managed floodplains. Therefore, the recent increase in the rate of soil erosion has led to increased storage of eroded C in different types of depositional basins Stallard Soil erosion results in drastic modifications to the structure as well as the biological and chemical properties of the soil matrix, affecting its productive capacity and ability to sequester atmospheric CO 2.
Erosion affects watershed-level C balance by changing the magnitude of opposing C fluxes of a C input rates and b decomposition and stabilization. Generally, unless the soil is eroded beyond a critical level, NPP on eroding slopes continues, albeit at a reduced rate if nutrients or water becomes limiting Onstad et al. The newly assimilated C at eroded sites replaces, at least partially, C that was transported by erosion.
As demonstrated by Harden and colleagues , this dynamic replacement of eroded SOC is an important variable in maintaining the watershed-level C balance. This is especially important if NPP could be enhanced in eroding slopes with the use of supplements or best management practices, such as fertilization, irrigation, crop rotation, and reduced tillage. In the depositional part of a watershed, the C input is derived not only from fresh plant residue growing in situ but also from deposition of laterally flowing, eroded C.
The rate of NPP in depositional basins is likely to be high, because the deposited topsoil provides additional organic matter, essential nutrients, and water-holding capacity. Soil erosion and deposition can speed or slow the decomposition of SOC at different parts of a watershed.
At eroding slope positions, erosion can increase the rate of decomposition by breaking down aggregates because of rain intensity or shearing during transport and exposing organic matter that was previously encapsulated and physically protected from microbial and enzymatic degradation.
On the other hand, removal of topsoil material from the eroded site exposes subsoil material, typically with less C content than topsoil, and therefore lowers the rate of decomposition. During transport, however, the decomposition of upland SOC can be enhanced, since the eroding material has the potential for further disturbance. For example, in arable lands, if transport rates are slow enough, eroded SOM can be decomposed through the breakdown of aggregates by tillage.
Therefore, conceptually, the net impact on the CO 2 budget depends on the residence times of both the sediment and C Harden et al.
The extent to which soil erosion results in net enhancement of the SOC decay rate is still being debated. At depositional settings, the rate of decomposition of eroded SOC can be reduced by a combination of processes. Some of these processes are biochemical recalcitrance of organic constituents , others physical protection with burial, aggregation, and changing water, air, and temperature conditions , and still others chemical mineral—organic matter associations.
Regardless of the rate of SOM oxidation, detachment and transport of soil particles modify the biochemical makeup of the SOC that reaches the depositional basins. During transport, the labile SOC fraction decomposes quickly, leaving behind a larger fraction of relatively more recalcitrant SOC, compared with the SOC that originates from the eroding hillslope profiles.
In addition, inevitable losses due to, e. During intensive storm events, however, large loads of sediment can be moved from upper slopes directly to lower slope positions and streams. Indeed, it is possible that most of the stream sediment is moved during such events.
With such rapid transport, it is likely that eroded C has little chance to be decomposed and reworked during transport, and that a significant fraction of labile C can enter depositional basins. In this scenario, eroded C remaining near the surface of lowlands could contribute to enhanced decomposition, while the decomposition rate of the eroded C that is buried at the depositional settings is likely to be reduced.
The role of burial during sedimentation is key to the sink-versus-source question for eroded C. Decomposition is generally accepted to be slower in the buried sediments of depositional basins than in the source profiles in the eroding slopes. This is partly because deposition of eroded C down-slope is often accompanied by increased water content, reduced oxygen availability, compaction, and physical protection within inter- or intra-aggregate spaces that collectively can retard the decomposition rate of buried SOC.
Indeed, SOC may be preserved and have much longer residence times in anoxic or suboxic floodplains, riparian ecosystems, reservoirs, or peat lands, compared with aerobic soils in upper watershed positions. Postdeposition diagenetic remobilization and transformations also are reduced in wetter depositional basins, favoring SOC preservation over mineralization Callender and Smith , Gregorich et al. Furthermore, burial facilitates chemical and mineralogical transformations that contribute to C stabilization.
With time, newly weathered, precipitated, or transported reactive mineral particles come in contact with buried C. These mineral particles provide surface area for the chemical stabilization of buried C, allowing the physically protected, labile SOC to form stable or metastable complexes with the mineral surfaces, thereby further slowing down its turnover.
Moreover, during deposition, low-lying native soils are buried by erosion, potentially resulting in a significant reduction of native SOC decomposition Liu et al. Consequently, burial in most cases represents a net C sink, because it constitutes transfer of SOC from more active components in plant biomass and topsoil with short mean residence time typically less than a century to more passive reservoirs in adjacent depositional basins Smith et al.
In summary, the foregoing discussions indicate that the increased C input and reduced decomposition stabilization usually result in increasing the overall C stock in a watershed with erosion and deposition figure 3. How and when does soil erosion result in a C sink in which C uptake rates outpace C release rates across landscapes?
Whether the rates of C uptake are higher than the rates of C loss is determined by several factors: 1 the rate of C input from plant production at the eroded site; 2 the inherent recalcitrance of SOC; 3 the fraction of plant C that enters the SOC pool rather than being mineralized to CO 2 the humification coefficient, or h e ; 4 how much, and to what extent, eroded C is stored in more protected forms at the sites of deposition; and 5 the energy C cost of irrigation- and fertilization-supplemented production.
In other words, what determines whether soil erosion and deposition constitute a C sink is the disequilibrium created by the replacement and stabilization of C in eroding and depositional parts of the watershed, respectively.
Note that, in addition to the above conditions, degradation or reduction of a soil's C stock would increase its sequestration potential, since soils are considered to have a certain intrinsic saturation point for storage of organic matter.
Accordingly, compared with nondegraded, C-rich soils, degraded, C-depleted soils have more potential to accumulate C under favorable conditions that facilitate the delivery of organic matter from fresh plant residue. In conclusion, the criterion that needs to be satisfied for soil erosion to constitute a C sink consists of two components: 1 at least partial replacement of eroded SOC by new photosynthate in the eroded site, and 2 preservation of SOC at the depositional site in more passive pools with a longer residence time than at the eroded site.
In concert, the two components that make up the criterion must produce or stabilize sufficient SOC to compensate for the erosive loss of SOC from the upper part of the watershed.
It is estimated that erosion redistributes about 75 Pg soil annually worldwide Pimentel et al. Typically, f c,s ranges between 1. Accordingly, 1. For lack of a better estimate and for simplicity, here we use an average value of 0. Thus, the SOC deposited within the same watershed or adjacent watersheds C d can be 0.
Taking the lowest value for f d,o of 0. This estimate falls within the range of Stallard's C sink estimate, 0. The magnitude of the erosion-induced C sink depends largely on how the rates of NPP and soil C input change in response to erosion and the physical setting of the depositional environment—for example, how quickly the deposited C is buried by subsequent deposition, and how moist the soils in the depositional environment are.
As long as soil productivity is maintained for example, by fertilization , an even higher C-sink value is possible with an increase in the aerial extent of depositional basins figure 2 , higher C content of eroded topsoil, and more effective preservation of C in aquatic or saturated depositional basins for example, lakes and impoundments versus colluvial footslopes.
Moreover, as Liu and colleagues found, the ratio of erosional to depositional areas affects the magnitude of C sequestration such that, all other things being equal, concentrated deposition within a small area is more effective than redistribution of eroded C in a large depositional area. Using values typical of different types of depositional basins can give considerably different values for the erosion-induced C sink. For example, Smith and colleagues use the rate of water and wind erosion, river discharge, and impoundment sedimentation.
The C-sink size extrapolated from this work is about 1 Pg C per year. On the other hand, extrapolation of Yoo and others' data from an undisturbed watershed yields a global C sink estimate of 0. Considering the aerial distribution of different types of depositional basins figure 2 , the actual value is probably closer to the estimates of Smith and colleagues and Stallard Given the discussion above, it is perhaps puzzling why the debate is still ongoing.
We believe the debate continues because different researchers are addressing two facets of the same issue. Stallard , Smith and colleagues , and Yoo and colleagues calculated the proportion of transported C that arrives in the depositional basins and the potential for that C to be replaced by plant uptake and assimilation into soil and sediment. In these studies, most of the C in depositional basins is assumed to be protected after burial.
In contrast, Lal and colleagues Lal , , a , b , c , Bajracharya et al. These contradictions are amplified by the lack of information about the transfer of C from plant to soil and from soil to sediment SOC pools. This value may be lower for marginal lands, such as eroding slopes and a variety of depositional basins, because of C losses associated with the detachment and transport of soil particles.
Furthermore, the nature of the erosion-induced C sink or source can vary over time, depending on the form of erosion and type of depositional basin. Multiple competing processes can also occur simultaneously at different positions of the same toposequence. It is generally believed that depositional basins at or near their moisture saturation points may promote C stabilization more than aerated colluvial deposits.
At the same time, however, tillage and exposure of deep soil C to the surface can enhance the decomposition of otherwise stable forms of C. Harden and colleagues showed that, in highly eroding Mississippi loess soils, the net C balance of the watershed and strength of the CO 2 sink are dictated by how much inherent soil fertility or fertilization contributes to the perpetuation of C input, and how fast eroded C is decomposed and replaced by new photosynthate.
Despite differences in estimates in the literature of the erosion-induced C flux term and whether it is a source or a sink of atmospheric CO 2 , experimental evidence strongly suggests that erosion and deposition constitute a net sink in the C balance of eroding—depositional watersheds, relative to noneroding basins. Here we illustrate the importance of C protection in depositional environments and the fraction of deposited C that is oxidized using two examples from sites with different erosion rates.
The first example is an annual grassland in an undisturbed, zero-order watershed in northern California Tennessee Valley, Marin County , where erosion is mainly a result of the burrowing activity of pocket gophers and diffusive mass transport Berhe et al.
This site has relatively low erosion rates of 0. The second example is a cropland in central Mississippi Nelson Farm that has been cultivated since and continues to experience high rates of erosion, 4. Primary data representing the two sites are given in table 1. Note that considering only C dynamics in the eroding slope positions and ignoring plant productivity in the depositional basins makes the amount of C s estimated here an order of magnitude less than the C sink estimated by Yoo and colleagues However, under conditions in which deposition of eroded SOC promotes enhancement of the decomposition rate in the depositional site, f d,o would need to be greater than 1 to accurately account for all the loss terms in the C balance model of the depositional site.
In this example, the short-term field measurements and the calculations based on them table 1 are assumed to be representative of the long-term equilibrium conditions at the sites. If the total land area of the eroding slopes source slopes and depositional environments receiving basins is known, the magnitude of the C sink can be computed by multiplying C s by the area.
Here, C s is not likely to be greater than P e , and these formulations are more appropriate for actively eroding sites such as ridgetops or agricultural fields, where most of the eroded C C e is derived from NPP—unlike mid-or foot-slope positions, where a significant amount of C e can be derived from C that is eroded from upslope positions. These calculations table 2 indicate that the highly eroding Mississippi site that has been receiving nutrient supplements stores at least 15 times more C than the naturally eroding California site.
However, in both cases, the amount of C that is deposited and stabilized as a result of erosion and deposition is very small compared with the annual C input P e or the amount that is eroded C e.
Therefore, the discussions surrounding the potential for erosion to constitute a C sink should move beyond the question of how small a fraction of eroded C is deposited in local depositional basins f e,d to refocus on ascertaining the magnitude of the fraction of deposited C oxidized or decomposed after it reaches different types of depositional basins f d,o and its importance to the C balance in eroding and depositional basins.
The magnitude of the erosion-induced C-sink term 0. Second, erosion—deposition dynamics increase the impact of agriculture on atmospheric C exchange by threefold McCarty and Ritchie The erosion—deposition-induced C sink is significant at regional to global scales, but three factors complicate our ability to quantify its actual contribution to C sequestration: 1 the spatial variability in photosynthesis, soil fertility, fertilization Jacinthe et al.
Moreover, in many parts of the world, land degradation further affects the input of organic matter to the soil system by contributing to a decrease in the amount of NPP that is returned to the soil as input to the SOC pool, for example, when farmers burn their crop residue as fuel. Improving agricultural and land-use policies in marginal lands, such as flood-prone agricultural lands, degraded soils, and other eroding landscapes, offers an enormous opportunity for enhancing C sequestration.
Proper soil conservation practices that maintain vegetative cover and enhance plant productivity can promote higher SOC input and storage. Because soil C in eroded, marginal lands generally is depleted by a past history of erosion or intensive land use, rotation to minimum tillage or fallow conditions with a cover of vegetation is likely to increase the soil's potential to store C.
For example, it is estimated that, in some regions, an increase in C storage of 0. Realization of this potential would have significant benefits by reducing atmospheric buildup of CO 2. Moreover, protecting depositional C from oxidation through minimal tillage increases the potential for sequestration.
The dependence of NPP and C sequestration on rates of erosion and deposition for sites with and without conservation measures is shown schematically in figure 5. If we consider eroding and depositional parts of a watershed separately, under a given erosion scenario, as soil erosion increases, NPP decreases; but the C sequestration potential of the soil increases, at least initially, because of the enhanced ability of the degraded upland soils to take up more C compared with undisturbed and undegraded sites McCarty and Ritchie Similarly, at the depositional sites in a given scenario for example, alluvial plain , actual C sequestration follows a pattern similar to what it was at the eroding site, but with a higher rate of sequestration and a smaller decline after the peak, because the depositional sites continue to receive C-rich eroded soil.
The added input of nutrient-rich topsoil at the depositional sites contributes to the maintenance of higher NPP. In the erosion and deposition conditions shown in figure 2 , proper soil and water conservation measures maintain or increase NPP.
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