preliminary soil salinity assessment - Mid Western Regional Council

drainage in the floor of the livestock pens in the previous saleyard facility. The evidence of leachingsupports this assumption with water used to wash the pens likely to have increased leaching in theupper soil layers. The subsoil (C Horizon) at Site 1 was medium, orange brown clay with red andorange mottling and contained reddish brown gravel less than 20mm diameter. Visual observationsof the profile indicate the soil at this location has moderate to slow drainage.Site 2 had a relatively shallow, pale, grayish brown, loamy topsoil (A Horizon). The upper subsoil (BHorizon) was orange clay and the lower subsoil (C Horizon) a pale, greyish yellow clay with asignificant portion of angular rocks and shale up to 100mm diameter. The subsoil contained blackgravel chips and dark grey mottling throughout. Concrete chips were also found in the throughoutthe subsoil. It appears this soil profile may have been previously disturbed with gravel and concreteused in construction of the saleyards incorporated into the subsoil during construction ormaintenance activities at the site. The profile also indicates water is likely to have caused leaching ofiron compounds in the upper layers with some waterlogging lower in the profile possibly due topoorer drainage. The subsoil at this location was very hard relative to the other soil pit locations.Due to the presence of bitumen like gravel and concrete throughout the subsoil at this site and thestrong possibility that this profile has been disturbed, the subsoil at this site was sampled as onelayer described as ‘subsoil’.Site 3 had lighter soil than the other sites with a light brown, sandy loam topsoil (A Horizon). Theupper subsoil layer (B Horizon) was a light, grey clay loam containing red and brown gravel up to50mm diameter. The lower subsoil (C Horizon) was yellow clay containing a high portion of shale andother rocks up to 150mm diameter. There appeared to be a slightly wetter, compacted layer or ‘soilpan’ at the top of the C Horizon.Site 4 was located on the northern side of Saleyards Lane. This soil pit location was selected for soilsampling and analysis as information regarding the old saleyard facilities indicates that the areaaround Site 4 is likely to be relatively undisturbed and may represent a more natural salinitysituation than across the remaining area of DP534336. The topsoil (A Horizon) at Site 4 was a friable,orange brown loamy soil. The upper subsoil soil (B Horizon) was slightly darker in colour with thelower subsoil (C Horizon) changing to a heavy brown clay that was moist and puggy to dig. Very littlegravel was found within the profile at Site 4.Site 5 was located approximately 2m north of the truck washdown concrete pad and approximately10m west of the SES building. The topsoil (A Horizon) was brown loamy soil containing black angulargravel chips to 40mm. The upper subsoil (B Horizon) was leached light grey and orange sandy loam.Below this the lower subsoil (C Horizon) was a yellow brown clay soil containing sub-angular blockygravel less than 30mm. Some black and red mottling was observed. It appears this clay layer is slowto drain and may have have contributed to leaching of the upper subsoil due to waterlogging.Site 6 was selected to provide an indication of salinity in the top 1.3m of soil in the area immediatelynorth of the remaining leachate pond. The topsoil (A Horizon) was found to be a light brown clay.The upper subsoil below this (B Horizon) was friable sandy loam brown soil containing a smallportion of gravel less than 40mm. The lower subsoil (C Horizon) was a heavier brown clay soil.PRELIMINARY SOIL SALINITY ASSESSMENT10