In the Tunisian arid zones, where the soils are sandy and very poor in organic and mineral matters, wind erosion process is very active and triggered the departure of the thinnest elements of the soil and the appariti...In the Tunisian arid zones, where the soils are sandy and very poor in organic and mineral matters, wind erosion process is very active and triggered the departure of the thinnest elements of the soil and the apparition of dune building. Facing to these situations, many simple and efficient practices for combating desertification had been tested since many years in the Tunisian arid zones. The mulching of the olive mill wastewaters is one of these techniques. Otherwise, an olive mill wastewaters spray experimental device, with these respective doses of 50 m3/ha, 100 m3/ha and 200 m3/ha next to a witness parcel without OMW, has been putted in place since 1995 in the Chammakh-Zarzis, Tunisia. The mulching of the OMW, in the southern Tunisian regions constitutes an interesting alternative for the controlled and rational evacuation of this polluting sewage on the one hand and for the soil cohesion improvement by： （i） the increase of the organic matter rate which raised, in proportion to the dose, from 0.06% to 1.27% after 10 years of OMW mulching, and （ii） the improvement of the soil structural stability or ~＇the mean weight diameter＂ where the aggregation rate superior to 2 mm is increased until 34% with the dose of 200 m3/ha. Therefore, that treatment will bind the sand particles and thereof control of sandstorms is gained. Indeed, the results in wind tunnel tests on the soil treated with these different doses of OMW showed that the threshold friction velocity u,t was raised from 8.5 m/s to 12 m/s for 50 m3/ha and 200 m3/ha, respectively.展开更多
文摘In the Tunisian arid zones, where the soils are sandy and very poor in organic and mineral matters, wind erosion process is very active and triggered the departure of the thinnest elements of the soil and the apparition of dune building. Facing to these situations, many simple and efficient practices for combating desertification had been tested since many years in the Tunisian arid zones. The mulching of the olive mill wastewaters is one of these techniques. Otherwise, an olive mill wastewaters spray experimental device, with these respective doses of 50 m3/ha, 100 m3/ha and 200 m3/ha next to a witness parcel without OMW, has been putted in place since 1995 in the Chammakh-Zarzis, Tunisia. The mulching of the OMW, in the southern Tunisian regions constitutes an interesting alternative for the controlled and rational evacuation of this polluting sewage on the one hand and for the soil cohesion improvement by： （i） the increase of the organic matter rate which raised, in proportion to the dose, from 0.06% to 1.27% after 10 years of OMW mulching, and （ii） the improvement of the soil structural stability or ~＇the mean weight diameter＂ where the aggregation rate superior to 2 mm is increased until 34% with the dose of 200 m3/ha. Therefore, that treatment will bind the sand particles and thereof control of sandstorms is gained. Indeed, the results in wind tunnel tests on the soil treated with these different doses of OMW showed that the threshold friction velocity u,t was raised from 8.5 m/s to 12 m/s for 50 m3/ha and 200 m3/ha, respectively.
