Impact of soil conditions on hydrology and water quality for a brown clay in the north-eastern cereal zone of Australia

Abstract

Abstract. Hydrology and water quality impacts of alternative land management practices are poorly quantified for semi-arid environments in the northern Australia cropping zone, yet wide-scale changes in tillage practices and land use were being recommended based on experience from other environments.The objective of this study was to explore changes in soil profile and catchment hydrology and water quality associated with different soil surface conditions created by different tillage and grazing practices. Soil water, runoff, and suspended sediment concentrations were monitored on 4 contour bay catchments over an 18-year period. Soil conditions were described by soil moisture, soil cover, and surface roughness in order to explore functional relationships between management, hydrology, and water quality. The site was chosen to represent the drier margins of cropping in southern Queensland where clay soils with high water-holding capacity, in conjunction with fallowing to store water for later crop growth, are an essential risk management tool.Accumulation of soil water in fallows was inefficient, with fallow efficiencies ranging from -7 to 40% due to high evaporation and runoff losses. Runoff amount was determined by soil water content, which was strongly influenced by antecedent rainfall, water use, and evaporation patterns. Surface cover and roughness had subtle influences on runoff, and a greater effect on suspended sediment concentration. Runoff and suspended sediment losses were considerably lower under pasture than cropping.A participative approach between farmers and scientists was demonstrated to be an efficient method to carry out an extensive and long-term catchment study at a remote location. This study provides benchmark data for future hydrologic and water quality investigations.

Terrestrial pollutant runoff to the Great Barrier Reef: An update of issues, priorities and management responses

“…Erosion studies in grain cropping lands (Freebairn et al, 2009) have demonstrated the importance of soil type and conditions of erosion rates. Murphy et al (in press) showed that considerable quantities of sediment, nutrient (from fertiliser) and herbicides (in this case metolachlor) can be lost under conventional management in dryland grain cropping.…”

Investigating suspended sediment dynamics in contrasting agricultural catchments using ex situ turbidity-based suspended sediment monitoring

“…Sediment losses from agricultural areas are commonly attributed to arable practices (Walling et al, 1999;Wass and Leeks, 1999;Freebairn et al, 2009;Van Oost et al, 2009;Duvert et al, 2010), especially where bare or freshly tilled soils are exposed to rainfall-runoff processes (Regan et al, 2012). Arable farming typically involves the mechanical redistribution of soil through ploughing and seed bed preparation, and via erosion from compacted and/or bare fields and down-slope tramlines (Chambers and Garwood, 2000;Withers et al, 2006;Boardman et al, 2009;Silgram et al, 2010;Regan et al, 2012;Soane et al, 2012).…”

Modelling Deep Drainage Rates of Irrigation Strategies Under Cropping Sequence in Subhumid, Subtropical Australia

“…The current results on other components, for example soil evaporation (66% of fallow rainfall, results not shown elsewhere), also agree with similar studies (e.g. Silburn et al ., ; Thornton et al ., ; Freebairn et al ., ; Robinson et al ., ) that found soil evaporation at 65–73% of fallow rainfall.…”