Infiltration and sediment production as affected by soil surface conditions in a shrubland of Patagonia, Argentina.

Abstract

Infiltration and sediment production of eroded and uneroded shrub interspace soils were evaluated in December 1986 in a severely grazed, arid range site in northeastern Patagonia. A rainfall simulator and small plots were used to collect the data. A desert pavement embedded in a vesicular crust characterized the surface soil of the eroded areas that occupy the lowest position in the microtopographic pattern. A granular, fine, and weak structured A horizon characterized the soil of uneroded areas. Slopes were similar for the eroded and uneroded areas. Surface soil bulk density, electrical conductivity, clay and organic matter content were significantly greater for the eroded than for the uneroded soils. Litter cover was significantly higher for the uneroded soils. Plant cover, although higher for the uneroded areas, was low (& 5%) for both eroded and uneroded areas. Mean infiltration rate at the end of 35 min, with the soil initially dry, was 0.8 and 6.1 cm/hr for the eroded and uneroded soils. respectively. For the soil initially at field capacity, infiltration decreased to 0.6 cm/hr and 4.1 cm/hr. Soil losses were higher from the eroded areas (606 kg/ha and 687 kg/ha) than for the uneroded areas (291 kg/ha and 556 kg/ha) when the soils were initially dry and at field capacity, respectively. Regression analysis indicated infiltration rate was positively related to litter cover and negatively related to gravel cover, whereas sediment production was negatively related to bulk density, plant, and gravel cover characteristics of the site.