Soil roughness indexes and their relationship with water erosion

Fernanda Zangiski,David José Miquelluti,Júlio César Ramos,Ildegardis Bertol

doi:10.1590/s0100-204x2018000600012

Abstract

Abstract: The objective of this work was to express soil roughness through statistical, geostatistical, and fractal indexes, comparing and relating them to soil and water losses in different experimental conditions. The study was conducted from 2012 to 2015, in the municipality of Lages, in the state of Santa Catarina, Brazil, in a completely randomized design with two replicates. Three treatments were evaluated: T1, scarified soil at the end of the ryegrass (Lolium multiflorum) crop cycle after removal of the shoot residue; T2, scarified soil at the end of the vetch (Vicia sativa) crop cycle after removal of the shoot residue; and T3, scarified soil without cultivation and without cover. The heights of the microrelief were read with a surface roughness tester with rods. Soil roughness was analyzed through the statistical, geostatistical, and fractal indexes. The fractal dimension and intersection distance showed a clear difference between the treatments with cultivation. All indexes, except R1, are associated with soil losses in the treatments with cultivation. As for water losses, there is only an association with the fractal dimension index and only in the treatment without cultivation.

Highlights

Soil surface roughness is constituted by the microrelief or microtopography of the ground and is characterized by the sequence of microelevations and microdepressions, spatially distributed on soil surface (Zoldan Junior et al, 2008; Vidal Vázquez et al, 2010a).Different elements of the soil, as well as preparation marks and even patterns of relief, contribute, in varying scales, to soil roughness (García Moreno, 2008), which is related to soil intrinsic factors, such as intensity and type of preparation, humidity prior to preparation, amount and type of plant residue, type of soil, and terrain declivity (Siqueira et al, 2012)
The R1, R2, R3, limiting difference (LD), and D indexes presented a symmetric unimodal frequency distribution and mesokurtic distribution, a behavior that is indicative of compliance with the normality hypothesis (Ferreira, 2009) (Table 1)
The R1 index, with an average value of 0.149, showed the lowest values among the statistical indexes. This is due to the application of log transformation to the vertical data of the microdepressions and microelevations, the removal of the effects of slope and soil preparation marks, and the exclusion of 10% of the lower and higher values (Allmaras et al, 1966; Kamphorst et al, 2000)

Summary

Introduction

Soil surface roughness is constituted by the microrelief or microtopography of the ground and is characterized by the sequence of microelevations and microdepressions, spatially distributed on soil surface (Zoldan Junior et al, 2008; Vidal Vázquez et al, 2010a).Different elements of the soil, as well as preparation marks and even patterns of relief, contribute, in varying scales, to soil roughness (García Moreno, 2008), which is related to soil intrinsic factors, such as intensity and type of preparation, humidity prior to preparation, amount and type of plant residue, type of soil, and terrain declivity (Siqueira et al, 2012). Soil surface roughness is constituted by the microrelief or microtopography of the ground and is characterized by the sequence of microelevations and microdepressions, spatially distributed on soil surface (Zoldan Junior et al, 2008; Vidal Vázquez et al, 2010a). The two main forms of surface roughness are: roughness at random and soil surface roughness. The first is characterized by the completely random spatial distribution of micromodulations on the surface of the terrain (Linden & Van Doren Jr., 1986; Bertol et al, 2008; Zoldan Junior et al, 2008). The second may include the joint effect of terrain declivity and soil preparation marks or only the effects of the latter, in which case it is called orientated roughness (Vidal Vázquez et al, 2007; PazFerreiro et al, 2008). Given the importance of soil roughness in the soil erosion process and in water

Objectives

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Conclusion