An investigation of runoff from raised beds and other tillage methods in south-western Victoria

This review combines 4 articles from the same site in Victoria.

Level 1 General description

Purpose:

To determine the effect of raised beds on runoff, air-filled porosity, soil structure and solute transport in south-western Victoria.

Methods (brief)

• Holland et al (2007) collected undisturbed soil samples for resin-impregnation and image analysis. This enabled several descriptive parameters of macropore structure to be calculated. Large, undisturbed soil samples were also collected for a solute transport experiment using a KCl solution. A convective log-normal transfer function was used to model Cl− movement.
• Holland et al (2008) compared soil water properties, air-filled porosity, plant dry matter, and grain yield for raised beds and conventional cultivation treatments during 2003 and 2004.
• Holland et al (2012) measured rainfall characteristics, runoff volumes, and soil properties such as the soil water content, bulk density, and hydraulic conductivity for three tillage treatments (raised beds, conventional cultivation, and deep cultivation) over 6 years.
• Holland et al (2007) found that the raised beds had greater pore connectivity and were able to transmit solute faster and more efficiently than the conventionally cultivated soil. Raised bed soils are better structured and provide less risk from water-logging than conventionally cultivated soils. However, there is greater potential for preferential flow of pesticides and solutes in raised bed soils.
• Holland et al (2008) found that the soil under raised beds was significantly better drained than conventionally cultivated soil, and therefore was consistently drier and had improved soil aeration. There was no significant grain yield benefit from raised beds during 2 years of below-average rainfall.
• Holland et al (2012) found that raised beds significantly increased the amount of runoff relative to the other treatments when above-average rainfall was received, but there was little difference in runoff in years of below-average rainfall. No consistent effect of runoff on crop biomass was detected nor could any differences in runoff be attributed to differences in soil water content, hydraulic conductivity, and bulk density between treatments. The furrows between the raised beds acted as conduits for the flow of surface water during the larger storm events.
• Wightman et al (2004) investigated changes in hydrology among conventional non-bedded flat-crop and pasture systems.

Key findings (brief)

• Holland et al (2007) found that the raised beds had greater pore connectivity and were able to transmit solute faster and more efficiently than the conventionally cultivated soil. Raised bed soils are better structured and provide less risk from water-logging than conventionally cultivated soils. However, there is greater potential for preferential flow of pesticides and solutes in raised bed soils.
• Holland et al (2008) found that the soil under raised beds was significantly better drained than conventionally cultivated soil, and therefore was consistently drier and had improved soil aeration. There was no significant grain yield benefit from raised beds during 2 years of below-average rainfall.
• Holland et al (2012) found that raised beds significantly increased the amount of runoff relative to the other treatments when above-average rainfall was received, but there was little difference in runoff in years of below-average rainfall. No consistent effect of runoff on crop biomass was detected nor could any differences in runoff be attributed to differences in soil water content, hydraulic conductivity, and bulk density between treatments. The furrows between the raised beds acted as conduits for the flow of surface water during the larger storm events.
• Wightman et al (2004) found that the intensity, duration and timing of rainfall during the season are significant contributors to measured differences in run-off volumes between raised bed and flat-cropped treatments. When rainfall intensity exceeds soil infiltration capacity, raised beds tend to release greater volumes of run-off than conventional flat-cropping and pasture treatments.

Location

Mt Pollock, Victoria (- 38^o 10’S, 144^o05’E)

Related studies

N/A

Level 2, level 3, level 4 and level 5