Zhang Jiaqiong, Yang Mingyi, Liu Zhang, Zhang Fengbao
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Ministry of Water Resources of the Chinese Academy of Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
Very few studies have so far focused on tillage translocation and erosion although they have presented since humans cultivation activity started. Tillage translocation and erosion were discovered in the middle of the 20th century but have attracted limited attention among researchers. Scientists rediscovered these processes by the end of the 20st century when visible changes occurred in slope farmlands and systematic research on these processes started since then. Tillage translocation and erosion are triggered by tillage and are mostly influenced by gravity force. They are the main processes that cause the redistribution of soil in farmlands on hill slopes, and are among the main processes for soil erosion on slopes. They also greatly influence the evolution of slope landform, soil properties and nutrients, land productivity, and carbon pool. Based on the results of previous research, the present study summarized the processes and mechanisms, influencing factors, research methods and techniques, and erosion rates of tillage erosion, and then discussed the weakness of the previous work as well as possible research aspects in the future. Unlike wind and water erosions, tillage erosion is caused by human activity on hill slopes, but not by wind or rainfall. Therefore, tillage erosion is different from wind and water erosions on most aspects. Tillage erosion is influenced by both anthropogenic and natural factors. The anthropogenic factors refer to the tillage management of farmlands, which acts as the dynamical conditions of tillage erosion. Such factors mainly include the characteristics of tillage tool, plough direction, speed, and depth. The natural factors mainly include the shape and size of the tilled area, the terrain and gradient of slope and soil properties, in which slope is the terrain base of tillage erosion. Strong erosion by tillage usually occurs at areas near the top of a slope and areas where slope curvature greatly changes. The study methods for tillage erosion differ from those of water and wind erosions owing to the great difference in their characteristics. Tillage erosion is mainly studied using tracer methods and model simulations. Limited number of reports can be found on the erosion rates of water and tillage erosions, and few reports on wind and tillage erosions so far. Further study on erosions by water, wind and tillage at crisscross regions is important to determine the erosion processes and mechanisms at these multiple-force erosion regions. The main obstacle is the lack of general study methods for these processes. Nevertheless, radionuclide tracing techniques (e. g. 137Cs) could be well applied to tillage, water, and wind erosions, providing a possibility to separate the rate and contribution of each erosion processes from the total erosion in crisscross erosions by erosion forces.