Reducing water erosion in a gypsic soil by combined use of organic amendment and shrub revegetation

Degraded gypsic soils in the centre of Spain can be rehabilitated with organic amendment and shrub revegetation. Erosion has been measured on plots of 2×0·5 m² under simulated rainfall of 70 mm h⁻¹ and a kinetic energy of 18 J mm⁻¹ m⁻². Samples of water runoff and sediments were studied in the summer of the years 2002 and 2003. The presence of shrub Atriplex halimus (Chenonodiaceae) significantly reduces runoff from 16·9 to 6·7 ml m⁻² min⁻¹ and sediments from 0·16 to 0·02 g m⁻² min⁻¹. When sewage sludge is applied the differences among plots with and without bushes disappear. Although both treatments independently applied are efficient as erosion control measures, the combined use of revegetation and organic amendment allows a reduced dose of sewage sludge with the same effect on erosion. A low dose of sludge is desirable in view of the accumulation of toxic chemicals. Copyright © 2005 John Wiley & Sons, Ltd.