SEMINAR: Soil&Water Seminar, Oct 18:
|Soil&Water Seminar, Oct 18: : "Under zero-tillage, soil water content is poorly related to soil water repellency"
The Soil&Water Seminar at 1pm on Tues, Oct. 18th will be given by Dr Margaret Roper from CSIRO, an invited speaker for Soil Science Australia (WA Branch). All welcome!
TITLE: “Under zero-tillage, soil water content is poorly related to soil water repellency”
In southern and western Australia more than 5 million hectares of farmed land is water repellent. The majority of these soils are sandy and therefore highly susceptible to erosion. This has led to the adoption of practices such as minimum tillage and stubble retention. However, retention of stubbles can lead to increases in soil organic matter and consequently increased soil water repellency. A group of farmers on the south coast of Western Australia observed that in a system with stubble retention and zero-tillage (with the minimum of disturbance) the expression of water repellency ‘disappeared’. In a 3-year study on these sandy soils, water infiltration and water repellency, soil C and crop performance were monitored in treatments comparing zero-tillage vs cultivation and stubble retention vs stubble removal (by burning or grazing). Stubble retention and zero-tillage promoted higher levels of soil C than cultivation and stubble removal. As expected, in soil samples collected from each treatment, soil water repellency (as measured by the Molarity of Ethanol Drop (MED) method) followed a similar pattern to soil C with the worst repellency under zero-tillage and stubble retention and least under stubble removal and cultivation (R2 (%C vs MED) ranged from 0.75-0.83). However, soil water content measured in the field using a hand held time domain reflectometer (TDR) contradicted the findings on water repellency and indicated that water infiltration was best under zero-tillage and stubble retention and poorest under stubble removal and cultivation, and this impacted on crop performance. The results suggest that mechanisms other than just soil water repellency are involved. It is hypothesised that under zero-tillage, bio-pores formed by roots and small animals are preserved and provide pathways for water movement in the soil.
These findings challenge traditional thinking on soil water repellency and potentially have implications for crop management.
Dr Margaret Roper, CSIRO
Agriculture Lecture Theatre (G.013), in the Agriculture NW wing
: 6488 1508
Tue, 18 Oct 2011 13:00
Tue, 18 Oct 2011 13:45
Ursula Salmon <[email protected]>
Wed, 26 Sep 2012 13:03
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