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ARS Home » Midwest Area » West Lafayette, Indiana » National Soil Erosion Research Laboratory » Research » Publications at this Location » Publication #110014
Title: SOIL SURFACE ROUGHNESS CHANGES AS AFFECTED BY TILLAGE, COVER AND RAINFALL EROSIVITY

Author
item ELTZ, F - UFSM, SANTA MARIA, BR
item Norton, Lloyd

Submitted to: Proceedings Brazilian Soil Science Society
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Information about the behavior of soil roughness as a function of rainfall erosivity and the influence of canopy cover on the surface roughness decay is limited. In this field study, the effect of different covers, tillage systems and cumulative rainfall (EI3) on soil surface roughness was analyzed using a portable laser scanner to measure the soil relief elevations with measurements each 2mm, in an area of 25 to 40 cm. Tillage treatments consisted of conventional (moldboard plowing + disking), chisel plowing and chisel plowing + a drug chain. Cover treatments consisted of bare soil and soybean canopy with four repetitions. The soil cover was measured photographically. Four surface roughness indices were calculated from the elevation data files: Random Roughness, Standard Deviation, Tortuosity and Roughness Functions expressed by D (fractal index) L. As a general tendency, all indices, except D decreased with cumulative rainfall erosivity. The D index increased quadratically with cumulative rainfall erosivity, showing that the smaller aggregates on soil surface disappeared. In all cover levels and tillage systems, soil surface roughness, measured by Random Roughness and Standard Deviation indices decreased quadratically, while Tortuosity and L indices decreased exponentially with cumulative rainfall erosivity. Soybean cover provided a decrease of 7 percent in the surface roughness decay, as measured by L index, when compared with bare soil. The L index was the most sensitive index to changes in cumulative rainfall erosivity. The roughness functions, with D and indexes calculated, seems to be an appropriate way to characterize surface roughness at small scales, as an example in between crop rows.