The production of food, meat and forest products in the States are economic acti
ID: 107235 • Letter: T
Question
The production of food, meat and forest products in the States are economic activivties result in large-scale soil loss. They do however employ something like a half-million people, and are significant part of our economy. Noting that the amount of soil loss is driven by the economics of a global market beyond our control, it is argued that we need to accept this in the interests of preserving the hald-million jobs which these activities support. The argument is that we as a society can make decisions about how these resources get used, providing that we are guided by a popular agreement on what is best for our collective interests. Considering the subject matter, critique the ethics of this argument.
Explanation / Answer
Erosion can be defined as the wearing away of the land surface by physical forces such as rainfall, flowing water, wind, ice, temperature change, gravity or other natural or anthropogenic agents that abrade, detach and remove soil or geological material from one point on the earth's surface to be deposited elsewhere. When used in the context of pressures on soil, erosion refers to accelerated loss of soil as a result of anthropogenic activity, in excess of accepted rates of natural soil formation. The loss of soil leads to a decline in organic matter and nutrient content, the breakdown of soil structure, a reduction of the available soil water stored, which can lead to an enhanced risk of flooding and landslides in adjacent areas. Nutrient and carbon cycling can be significantly altered by mobilization and deposition of soil, as eroded soil may lose 75 - 80 % of its carbon content, with consequent release of carbon to the atmosphere. Soil erosion impacts strongly on the environment and has high economic costs; to mitigate these effects, soil and water conservation strategies are required.
Soil erosion by water is one of the most widespread forms of soil degradation. This estimate is slightly lower compared to the previous estimations. This reduced rate is mainly due to the application of management practices against soil erosion which have been applied during the last decade. The mean rate of soil loss from the arable lands is 10 % higher than the overall soil loss rate. Permanent crops have a high mean soil loss rate, as most of the vineyards and olive trees are located in hilly Mediterranean areas with high rainfall erosivity. The mean annual soil loss rate in pastures is 2.02 tonnes per hectare per year, mainly due to higher vegetation densities and, as a consequence, lowers C-factors.
The heterogeneous agricultural areas have a higher overall mean rate of soil loss than do arable land areas, despite the fact that their C-factor is lower. The latter is due to the differences in topography as the arable lands are typically located in flat or gently sloping areas. The prevention of soil erosion and maintenance of soil organic matter were two of GAEC requirements, which each Member State was obliged to address through national/regional standards such as: i) minimal soil cover maintenance; ii) minimum land management reflecting site specific conditions to limit soil loss and iii) maintenance of soil organic matter level through appropriate practices including the ban on burning arable stubbles. The implementation of GAEC in the agricultural lands of Member States has helped to reduce soil loss rates.
There has been much discussion in the literature about thresholds above which soil erosion should be regarded as a serious problem. This has given rise to the concept of ‘tolerable’ rates of soil erosion that should be based on reliable estimates of natural rates of soil formation. Nevertheless, there may be a need to propose different thresholds of rates of soil erosion that are tolerable in different parts of Europe. However, this aspect needs further elaboration. Soil is a valuable, non-renewable resource that offers a multitude of ecosystems goods and services. Soil erosion is the wearing away of the land surface through the action of water and wind, and is exacerbated by tillage and other disturbances (e.g. removal by crop harvesting, dissolution and river bank erosion).
At geological time-scales there is a balance between erosion and soil formation. However, in many areas of the world there is an imbalance with respect to soil loss and its subsequent creation, caused principally by anthropogenic activities (mainly as a result of land use change) and climate change. Soil erosion requires immediate attention and irreversible degradation is to be avoided in certain landscapes. Climate, vegetation cover, land use, topography and soil characteristics as well as conservation practice have a strong impact on soil erosion rates. Soil erosion reduces the ecological functions of soil over time. The main on-site consequences affect the biomass production and crop yields. In some areas, erosion has reached a state of irreversibility with the complete removal of all soil material.
Given the increasing threat of erosion by the detachment of soil particles by water in Europe, and the implications this has on future food security and water quality, it is important that land managers are provided with accurate and appropriate information on the amount of soil that is actually being lost. It is impractical and technically difficult to measure soil loss across whole landscapes and thus research is urgently needed to improve methods of estimating soil erosion using modelling, upon which mitigation can be implemented. A wide variety of models are available for soil water erosion estimation. The selection of a model depends mainly on the purpose for which it is intended and the available dataset. Some models are designed to predict soil erosion from single storms while others predict long-term effects. Models such as the Universal Soil Loss Equation (USLE) and derived versions are developed to predict only sheet and rill soil erosion and do not take into account other processes like gully erosion. Most models have been designed for local scale applications. Therefore, several problematic issues occur when applying quantitative soil erosion models at regional-level or for smaller scale mapping.
Soil erosion costs the economy a large amount of money. Main consequences of soil erosion are: loss of fertile land due to disrupted nutrient cycles, loss of organic carbon and biodiversity, destruction to infrastructures (roads, dams, water supply networks, railways, etc) due to excessive sediment load, diffuse pollution of surface water, negative effects on aquatic ecosystems and biodiversity, restrictions to land use impeding redevelopment and reducing the area for agricultural, forestry and recreation activities, depreciation of land value, flood risk and transfer of sediments to ports. On-site effects of water soil erosion (loss of organic matter and nutrients, soil structure degradation, plant uprooting, reduction of available soil moisture, etc.) are particularly important on agricultural areas resulting in a reduction of cultivable soil depth and a decline in soil fertility.
The loss of soil productivity following erosion may be significant. Topsoil, which is the most fertile layer of the soil, is the most exposed to erosion; also the mechanisms of soil erosion preferentially remove soil organic matter, clay, and fine silt material. Soil erosion also reduces the volume of soil available for plants roots and degrades soil physical properties (such as water holding capacity). In most cases extra fertilizer can compensate the impacts of soil erosion on soil fertility, but it represents an extra cost for farmers, and does little to offset the physical impacts of erosion on soil productivity. An additional on-site cost which cannot be easily quantified is the impact on tourism due to ecosystem degradation. Conversion of lands to agriculture in the prairies has resulted in the loss of 87% of native short-grass prairie habitat, 81% of native mixed-grass prairie habitat, almost all the tall-grass prairie habitat and 84% of the native aspen parkland habitat. Unfortunately, increased demands for food production are further accelerating the rate of conversion of lands with moderate agricultural value to farmland.
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