Using magnetic susceptibility to assess soil degradation in the Eastern Rif, Morocco

Abstract

The soil in the Rif, Morocco, is at serious risk because increasing anthropogenic pressures are gradually transforming large natural areas into farmland. The distribution of magnetic minerals within the soil profi le can be used to assess soil development and degradation. The soils in the study area are severely eroded because of a combination of highly erodible soils, intense rainstorms and scarce vegetation cover. To sample of representative soil profi les, lithology, slope gradient and land use were considered. The ranges of magnetic susceptibility in the soil profi les distinguished between two primary soil groups. Magnetic susceptibility varied in the soil profi le and along the soil toposequence, and the variations were related to the differences in the original magnetic composition and the infl uence of main erosion factors. Lithology is the main factor contributing to the variation in magnetic susceptibility. The magnetic susceptibility values in soils on Tertiary marls (χ = 13·5 × 10 −8 m 3 kg) differed significantly from those on Quaternary terraces (χ = 122·1 × 10 −8 m 3 kg −1). Slope affected the distribution of magnetic susceptibility because of the continuous loss of topsoil in some parts of the slope and the deposition of eroded soil in others. Elimination of the natural vegetation cover and a shift to cultivated land for cereals has had a negative impact on soil development and, on similar slopes and substrates, magnetic susceptibility decreased signifi cantly in cultivated soils. The soils on steep slopes that had natural vegetation cover retained the magnetic minerals better than did those on gentler slopes that were under cultivation. Grazing, clearing and, especially, tilling has weakened the soil and made it much more vulnerable to erosion. An analysis of the main factors causing erosion will help to promote rational use of the land and to establish conservation strategies in such fragile agroecosystems.

Use of magnetic measures to assess soil redistribution following deforestation in hilly region

“…Moreover, the transportation of nano-particles of magnetic minerals along with clay and fine particles further contributed to the increase. These results are consistent with the finding of Sadiki et al (2009).…”

“…RUSLE under predicted denudation relative to the results obtained using the magnetism-model in the over upper slopes, but over predicted denudation in the lower slopes. Sadiki et al (2009) found that the effects of land use seemed a key factor influencing the distribution of magnetic susceptibility in the soil profiles.…”

Erosion factors and magnetic susceptibility in differet compartments of a slope in Gilbués-PI, Brazil

“…The RE results are consistent with those in Table 1, showing that the larger the MS the higher the RE. SADIKI et al (2009) used the magnetic susceptibility to assess the degradation of tropical soils. Thus, studies that relate the variability of erosion with MS may contribute to the development of strategies aimed at sustainable land use.…”

Assessing Magnetic Susceptibility Profiles of Topsoils under Different Occupations

“…In general, there are many factors that cause magnetic susceptibility variations (MS), such as the differences in lithology (lithogenic/geogenic), soil forming processes (pedogenesis), and anthropogenic contribution of magnetic material [2,10,13]. Saddiki et al [14] confirmed that the lithology is the main factor contributing to the magnetic susceptibility variation.…”