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A mechanical soil sampling system to encourage increased use of bioassay tests for soil borne cereal diseases

I.T. Mock and N.W. Wright,

Department of Agriculture and Rural Affairs Mallee Research Station, Walpeup, Victoria, 3507 and Swan Hill District Centre, Victoria, 3585.

Management strategies have been developed to minimise the effect of cereal cyst nematode (CCN) and take-all, two diseases which cost Victorian cereal farmers in excess of $56 million a year in crop losses. As part of these strategies paddock soil tests are used to predict their possible impact in any one year. The Sironem(R) Bioassay test for CCN has been widely used throughout the Mallee/Wimmera regions and a "Take-all" Bioassay test was recently made available through Ag.Chem Pty Ltd.

Both tests require the random collection of at least 50 surface soil samples from 100 hectares for each bioassay kit. Sample depths are 150 mm for CCN and 50 mm for take-all. The recommended time for sampling is December - February for CCN and February - April for take-all. The number of samples required, the time of sampling and the time taken are responsible both for the low adoption rate of the procedures and for short cuts in sampling which jeopardise their value as a management tool.


A mechanical sampler has therefore been developed to alleviate some of these problems. It is based on the 'Speedy Soil Sampler' manufactured by Concord (U.S.A.). It can be readily mounted on most utilities or tray type vehicles and will collect multiple soil samples without the driver having to leave the cabin. It consists of a 12 volt DC driven hydraulic power unit delivering 13 L/min (no load). The system pressure is set at 2500 p.s.i. and directed by a solenoid control valve, which activates a vertically mounted hydraulic cylinder, 43 mm X 900 mm, with a sampling probe directly connected to the shaft. The probe sizes are exchangeable between 14 mm and 50 mm square. The maximum force exerted on the probe is approximately 3 tonnes (limited by vehicle weight). Cycle time for each sample is 20 seconds and the soil sample self-ejects from the probe into a stainless steel catching bucket. The unit weighs 80 kg and costs approximately $3700.

Results and discussion

The standard unit sampled a range of soil types to more than 250 mm, whether the soil was cultivated or not. A limit switch was fitted to give precise depth control which is triggered by an adjustable collar on a slide attached to the sample tube. It returns the control valve to neutral, preventing further hydraulic flow, thereby providing a positive but passive limit to sample depth.

The unit can be fitted to most vehicles in approximately 15 minutes, without the need for modification. A hand lever has also been fitted on the sample tube, enabling the unit to be secured for highway travel.

The mechanical soil sampler described here is ideal for the rapid and accurate collection of samples for soil-borne cereal disease bioassays or soil nutrient analysis.

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