The aim of this study was a survey of the estimated costs of soil erosion, an issue of fundamental importance in view of the current worldwide discussions on sustainability. A list was drawn up of research papers on erosion (on-site and offsite effects) and their respective costs. The estimates indicate the amount of resources spent in the process of soil degradation, raising a general awareness of the need for soil conservation. On-site costs affect the production units directly, while off-site costs create a burden borne by the environment, economy and society. In addition, estimating the costs of soil erosion should be effective to alert the agricultural producers, society and government for the need for measures that can be implemented to bring erosion under control. Among the various estimates of soil erosion costs between 1933 a 2010, the highest figure was 45.5 billion dollars a year for the European Union. In the United States, the highest figure was 44 billion dollars a year. In Brazil, estimates for the state of Paraná indicate a value of 242 million dollars a year, and for the state of São Paulo, 212 million dollars a year. These figures show, above all, that conservation measures must be implemented if crop and livestock farming production are to be sustainable.
Soil erosion is not only an agricultural problem. It is associated with a host of environmental, social and economic issues. It has also been acknowledged as a major setback for food security and a serious problem for sustainable development.
The soil is eroded by the action of water and wind which break up and disperse soil particles (Miller, 1931; Bennett, 1955; Foth, 1990). One of the factors that accelerate this process is inappropriate soil management, a human activity documented in numerous studies, including those of Bennett (1929), Ellison (1948), Lal (1997), and Bertoni and Lombardi Neto (2008). Water erosion affects most of the planet and is the result of rainfall and surface runoff, aggravated mainly by agricultural management systems (Zachar, 1982). Erosion alters the soil chemical, physical and biological properties, reducing soil fertility and, as a direct result, soil productivity (Pimentel et al., 1995; Lal, 2000, 2006; Morgan, 2005), which has caused concern among researchers in various fields about the losses and costs incurred.
Costs are calculated on the basis of on-site effects (losses within the productive unit) and off-site effects (damage caused beyond the agricultural property). In the United States, the annual cost of soil erosion for both on-site and off-site effects has been estimated at 44 billion dollars a year (Pimentel et al., 1995). In the European Union, the figure is 38 billion Euros a year (Montanarella, 2007).
In addition to physical, chemical and biological losses, soil erosion causes economic losses which can be expressed in terms of the costs incurred by farmers and society to repair the damage arising from this process.
In the United States, soil erosion costs have been estimated at 44 billion dollars a year and in Brazil, in Paraná state alone, they amount to some 242 million dollars a year. The estimated costs of soil erosion vary from the 5 dollars spent to remove each ton of sediment to keep navigation activities in operation, to 45.4 billion dollars a year in the European Union, spent to offset the effects brought about by the loss of soil fertility and sedimentation of water resources.
This gives some idea of the importance of conservation management techniques designed to minimize soil degradation, reduce the erosion effects and also to make it possible, in the medium and short term, to mitigate on- and off-site costs. Therefore, in addition to being in the public and private interest, these land management systems are in line with the principles of sustainable agriculture.
Estimating erosion costs helps economic agencies in decision-making on soil conservation policy and provides governments with tangible evidence of the need to implement public policies aimed at ensuring the sustainable development of economic activities linked to the farming sector.