Infiltration Rates and Sediment Production following Herbicide/Fire Brush Treatments

Abstract

Termhtal infiltration rates were simiiar in soils on which a heavy whitebrush (Abysia lycioides) cover had been aerirny treated with 2 kg/ha (active ingredient) of 20% tebuthiuron pellets 4 years previously or on tebuthiuron-treated plots which had been prescribed burned the winter about 9 months prior to infiltration measurements, compared to untreated sites. However, sediment production was greater from plots treated with the herbicide than from areas subjected to the herbicide-fire system or from untreated plots. Only minor variations in infiltration rates occurred among sites originaiiy dominated by running mesquite (Prosopis reptuns) which were aerially sprayed with 2,4,5-T + picioram (1:l) at 1.1 kg/ha 3.5 years previously, burned 10 months previously, subjected to the herbicide-fire system or left untreated. However, sediment production on the running mesquite areas which had been sprayed tended to be greater than on untreated plots. Sediment production on areas subjected to the herbicide-prescribed burning system tended to be less than from brush-covered plots. Differences in sediment production In both experiments were generally attributed to siightly reduced mulch loads and mulch covers where the brush was removed as a leaf mulch donor by herbicide treatment. Prescribed burning apparently compensated for 10s~ of brush leaf mulch by promoting grass cover on herbicide-treated areas.

Rangeland degradation in a semi-arid South Africa—II: influence on soil quality

“…The increase in soil compaction and decrease in litter (Gifford and Hawkins, 1978;Knight et al, 1983;Stroosnijder, 1996;Mwendera and Saleem, 1997;Snyman, 2005) with rangeland degradation are of the most important reasons for the slower infiltration rate (Fig. 4) in the soil after a rain shower obtained in this study in rangeland in poor condition (Allison, 1973;Du Preez and Snyman, 1993;Holm et al, 2002).…”

“…A double-ring infiltrometer, similar to that described by Knight et al, (1983) and Wood (1987) was used to determine infiltration rate of the soil in the different rangeland conditions. Three replications randomly distributed over the plots were conducted over a soil water gradient (upper limit soil-water holding capacity to lower limit plant-available water -Snyman, 2000).…”

Physical impact of grazing by sheep on soil parameters in the Nama Karoo subshrub/grass rangeland of South Africa

“…A double-ring infiltrometer, similar to that described by Ueckert et al (1978) and Knight et al (1983), was used to determine infiltration rate of the soil at the different stocking densities. In each paddock four plots of 10 Â 10 m were randomly selected and the centre of each was marked with permanent steel rods (Fig.…”

Post‐fire runoff and erosion from rainfall simulation: contrasting forests with shrublands and grasslands

“…In Table II, larger sediment yields were associated with higher fire intensities, whereas smaller sediment yields were associated with studies of areas subjected to low-intensity fire, often which was prescribed burning (Roundy et al, 1978;Knight et al, 1983;Simanton et al, 1990). Further, in one natural rainfall study after controlled, low-intensity fire was applied, a higher-intensity wildfire occurred by chance, and allowed for comparison of the relative effects of low-severity and higher-severity burning (Soto and Diaz-Fierros, 1998).…”