Impact of cattle graz ng on températe coastal salt marsh soils

DI BELLA, C.; RODRIGUEZ, A; JACOBO, E; GOLLUSCIO RA; TABOADA MA

SOIL USE AND MANAGEMENT

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 31 p. 299 - 307

0266-0032

Over thelast two decades, grazing intensity has increased in the temperate salt marshesof Samborombon Bay (Argentina) due to agricultural expansion and thedisplacement of domestic livestock to these areas. We investigated the effectof cattle grazing on soil chemical and physical properties in the higher (HE),medium (ME) and lower (LE) elevation levels of this temperate salt marsh. Soildata were collected from both a National Park, where cattle grazing has beenexcluded for more than 35 yrs, and an adjacent commercial livestock farm continuouslygrazed by cattle. We found that soil salinity was greater on the grazed than onthe ungrazed sites, especially those in the ME and LE. This could be related tothe upward flow of salts from the saline groundwater, driven by the increase inthe proportion of bare soil on grazed sites. The increase in soil salinitychanged the plant community structure through the increase of salt-tolerant andnon-palatable species and the decrease of palatable species. Soil physicalvariables (soil bulk density and soil bearing capacity) were also higher on thegrazed than on the ungrazed sites, which can be related to the decrease in soilorganic matter (SOM), and suggest an incipient compaction process; however, thevalues were still lower than those considered critical for plant growth in claysoils. These results suggest that continuous grazing management in thistemperate salt marsh might have negative consequences for animal production andecosystem conservation, mainly related to the increased soil salinity. Further researchwill be necessary to evaluate the suitability of switching to intermittentgrazing management.