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7. Soil moisture monitoring

Soil moisture monitoring (SMM) devices provide information about the water status of soil. Knowing the soil water status can help you plan when to irrigate and how much water to apply. SMM is used to assist with scheduling irrigations to minimise plant stress and the economic losses that under-irrigation and over-irrigation can have on crop yield and quality.

There are two main types of commercially available soil moisture sensors: suction based and volumetric based systems.

Suction based sensors measure how tightly water is held within the soil. The measurement relates directly to how hard the plant must work to extract water and is therefore consistent across different soil types. Suction based tools that are commonly used are tensiometers and gypsum blocks.

Volumetric SMM systems measure the total amount of water in the soil. To estimate how much of this water is “readily available” to plants, the soil type needs to be known. Volumetric moisture monitoring tools can be used to guide not only when to irrigate, but how much water to apply.

Capacitance probes and “total domain reflectometry” (TDR) capacitance spikes are examples of commonly used volumetric monitoring tools. Capacitance probes measure soil moisture at increments (usually 10 cm) down the soil profile to a depth of 0.8 m to 1.2 m.

There are many different SMM products on the market. Irrigation suppliers can provide general advice on SMM as well as providing SMM equipment. Other local farmers who are willing to share their experiences with SMM equipment can be a great source of information, particularly those who have used the technology for similar crop types.

For further information refer to:

For further information contact:

Agriculture Victoria

Tatura – (03) 5833 5222

Echuca – (03) 5482 1922

Kerang – (03) 5473 0180

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