On-farm evaluation of ridging and residue management practices to reduce wind erosion in Niger

Wind erosion is regarded as a major contributor to the desertification process in the Sahel, Set little quantitative information is available for that region on soil losses by wind erosion under different land management practices. A 3-yr, on-farm experiment was, therefore, set up to assess the effect of ridging and either banded or broadcast millet stover mulches (2000 kg ha(-1)) on soil loss in a millet-coo,pea intercrop, For wind directions approximately perpendicular to the orientation of ridges and residue bands, sediment mass balances were calculated from the change in horizontal sediment mass fluxes measured across the experimental plots with Big Spring Number Eight sand traps. Mass balance calculations for 16 events over 3 yr indicated an average soil loss of 17.5, 15,4, and 18.0 Mg ha(-1) On control plots, and deposition of 15,5, 15,3, and 7.4 Mg ha(-1) on banded residue plots in 1995, 1996, and 1997, respectively, Broadcast and banded residue mulches were not significantly different (P = 0.05) in terms of their sediment trapping efficiency. During the same time period, ridges reduced soil losses by an average of 57% compared with the control plots, but their efficiency was reduced to less than 15% after 100 mm of cumulative rainfall as ridges collapsed. Linear regression analysis using the incoming sand fluxes as the independent variable was used to estimate potential soil losses for all events with sediment fluxes <25 kg m(-1) irrespective of wind direction. The calculations indicated potential soil losses of up to 79 Mg ha(-1) on control plots and deposition of 41 Mg ha(-1) on broadcast residue plots in a single gear. For wind erosion control, broadcast millet stover mulching constituted the most effective control technique because it effectively protected the soil against erosion and its trapping efficiency is expected to be independent of wind direction

Changes in wind erosion over a 25-year restoration chronosequence on the south edge of the Tengger Desert, China: implications for preventing desertification

Wind erosion is a primary cause of desertification as well as being a serious ecological problem in arid and semi-arid areas across the world. To determine mechanisms for restoring desertified lands, an unrestored shifting sand dune and three formerly shifting sand dunes (desertified lands) that had been enclosed and afforested for 5, 15, and 25 years were selected for evaluation on the south edge of the Tengger Desert, China. Based on sampling heights between 0.2 and 3 m, the critical threshold average wind speed was 6.5 m s-1 at 2 m where the sand transport rate was reduced from 285.9 kg m-2 h-1 on the unrestored dunes to 9.1 and 1.8 kg m-2 h-1 on the sites afforested and enclosed for 5 and 15 years, respectively. The percentage of wind eroded area was reduced from 99.9% on the unrestored dune to 94.5, 9.0, and 0.5% on the sites afforested and enclosed for 5, 15, and 25 years, respectively. Wind erosion was effectively reduced after 15 years. Although there were different driving factors for wind erosion mitigation on the different restoration stages, an increase in the vegetation cover, surface roughness, soil shear strength, soil clay content, organic matter, and reduction in the near-surface wind speed were the primary variables associated with the restoration chronosequence. We conclude that reducing the wind speed and developing a biological crust through vegetation restoration were the critical components for restoration of desertified land.National Natural Science Foundation of China [31660232, 41061030]; Foundation for Innovative Research Groups of Gansu Province [145RJIA335]; National Basic Research Program of China [2012CB723203]; National Key Technologies R&D Program of China [2012BAD16B0203]; National people's livelihood project of science and technology12 month embargo; published online: 23 August 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Ecohydrological implications of aeolian processes in drylands

Aeolian processes, the erosion transport and deposition of soil particles by wind, are dominant geomorphological processes in many drylands, and important feedbacks are known to exist among aeolian, hydrological, and vegetation dynamics (Field et al. 2010; Ravi et al. 2011). The wind, a natural geomorphic agent, has been active as an erosive agent throughout geological times in many parts of the world. Outstanding examples are the extensive loess deposits along the Huanghe River (Yellow River) in China and along the Missouri and Mississippi rivers in the United States. Climatic changes and anthropogenic activities can greatly accelerate soil erosion by wind with implications for soil and vegetation degradation (Kok et al. 2012; Webb and Pierre 2018; Nauman et al. 2018). For instance, in the 1930s, a decreased precipitation coupled with intensive agricultural activities caused a dramatic increase in wind erosion in the Great Plains of the United States, resulting in the so-called Dust Bowl. Wind erosion can be activated also by land-use change. An example is provided by the Mu Us region in North China with an annual precipitation of 400 mm, which was once a grassland partially covered with forest, yet now is one of the major sources of dust in the world as a result of overgrazing and agricultural practices (Wang et al. 2005; Miao et al. 2016)