Testing soils and plants

  • Fact sheet
  • August 2015
testing-soils
When establishing pasture, take care to avoid land degradation

Through the production of wool, meat, grain and vegetables, nutrients are removed (via plants) from the soil. This “nutrient bank” can be severely depleted if the nutrients are not replaced.

Several diagnostic tools are used to monitor the nutrient status of soils and plants.

Soil and plant testing can help you to:

Testing can determine whether soil improvement is required. As the needs of soils and enterprises vary, we recommend you contact your local agronomist or farm management consultant for specific information.

What makes up soil?

Three properties in soil have an effect on plant growth, they are:

Physical properties

The physical properties important to soil fertility include:

The physical properties of soil can affect soil fertility by altering the movement of water through the soil profile, the penetration of plant roots into the soil, and waterlogging.

Biological properties

A variety of organisms live in the soil, including bacteria, fungi, nematodes, earthworms and insects. These organisms perform a number of vital processes, including enhancing the cycling of nutrients, converting nutrients from one form to another and  assisting plants to uptake nutrients from the soil.   

Chemical properties

Soil nutrients are essential for plant growth and must be maintained in appropriate quantities to avoid toxicity to plants. Soil pH influences the availability of nutrients to the plants.  Low pH soils can affect plant health by reducing the availability of nutrients to the plant and the amount of nutrients held in the soil,

Testing

By testing the physical, biological and chemical properties of the soil, you can:

Soil Tests

The results from soil testing help you to determine the right application of fertilizer and other ameliorants.

Many factors can influence soil test results. To build up a soil history, test soils at the same time each year. This will allow a comparison of results. Check with your local agronomist for the best time to collect soil samples in your area. Always send your samples to the same laboratory, as results can vary between testing methodologies.

When collecting samples from a paddock, collect a broad representative sample as soils can vary significantly across a paddock. Instructions on how to collect soil samples are provided with soil testing kits.

Tissue tests

Tissue testing involves the analysis of plant tissue to determine whether the plant has sufficient nutrients for optimum growth and production at the time of sampling.

Plant analysis is useful to determine whether fodder/pasture is meeting the nutritional requirements of livestock. Various testing options are available.

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