Alexandra Sadler, graduate project officer – climate and emissions, and Dale Boyd, seasonal risk agronomist
Soil moisture data is proving to be a valuable tool for farmers planning pasture management and responding to changing seasonal conditions.
Agriculture Victoria has a network of soil moisture probes across the state, providing data that can be used to inform decisions around sowing, pasture management and yield estimates.
A soil moisture probe shows the quantities of plant-available water (PAW) at different soil depths, as well as the summed total, and tracks the change over time.
This shows not only the overall level of saturation in the soil, but also the PAW in the root zone, and where in the profile water is being used. This helps to understand plant activity and the soil's response to rainfall events.
Soil temperature is also a key piece of information provided by the probes, as temperature is a key factor in plant growth and can limit or drive growth as much as water availability.
Soil temperature can be used to time applications of nitrogen and gibberellic acid, as well as sowing, to maximise the pasture response. Most grasses require topsoil temperatures of above 10° C for germination.
Used with other climatic and pasture growth information, soil moisture monitoring data can be used to interpret seasonal conditions and plan pasture management and grazing rotations.
Soil moisture is a limiting factor for plant growth at many times of the year. Knowing this information can help inform decision-making, particularly in terms of feed budgeting and grazing management.
An important use for this information is predicting pasture growth and identifying seasonal risks early, based on current soil moisture and predicted rainfall.
This can then be used to make decisions about purchasing additional supplementary feed or otherwise ensuring adequate feed supply.
The rate of water use in the soil can also help to indicate growth rates of the pasture and the rooting depth of the plants, based on where in the profile water is being used.
