Shadow analysis of soil surface roughness compared to the chain set method and direct measurement of micro-relief

[摘要] Soil surface roughness (SSR) expresses soil susceptibility to wind and watererosion and plays an important role in the development and the maintenanceof soil biota. Several methods have been developed to characterise SSR basedon different methods of acquiring data. Because the main problems related tothese methods involve the use and handling of equipment in the field, thepresent study aims to fill the need for a method for measuring SSR that ismore reliable, low-cost and convenient in the field than traditional fieldmethods. Shadow analysis, which interprets micro-topographic shadows, isbased on the principle that there is a direct relationship between the soilsurface roughness and the shadows cast by soil structures under fixedsunlight conditions. SSR was calculated with shadows analysis in thelaboratory using hemispheres of different diameter with a diversedistribution of known altitudes and a surface area of 1 m².

Data obtained from the shadow analysis were compared to data obtained withthe chain method and simulation of the micro-relief. The results show arelationship among the SSR calculated using the different methods. Tofurther improve the method, shadow analysis was used to measure the SSR in asandy clay loam field using different tillage tools (chisel, tiller androller) and in a control of 4 m² surface plots divided into subplots of1 m². The measurements were compared to the data obtained using thechain set and pin meter methods. The SSR measured was the highest when thechisel was used, followed by the tiller and the roller, and finally thecontrol, for each of the three methods. Shadow analysis is shown to be areliable method that does not disturb the measured surface, is easy tohandle and analyse, and shortens the time involved in field operations by afactor ranging from 4 to 20 compared to well known techniques such as thechain set and pin meter methods.

[学科分类] 地球化学与岩石