
2 minute read
Predictive soil moisture probes
Predictive soil moisture probes are the way forward
By Jim Hargreaves, SCADAfarm.
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There are many excellent tools now available for assessing or measuring soil moisture under your crop or pasture in real time. Soil moisture monitoring is now universally accepted as a vital tool in driving decisions around irrigation applications and timings, which maintain crop production while mitigating environmental impacts.
Soil moisture tools fall into two main categories: • Remote sensing, e.g. satellitebased vegetation index, waterbudgeting services, etc. • Local sensing, e.g. soil moisture probes and tapes.
Remote sensing is incredibly convenient (no local sensors required, generally) and is unrivalled for providing broadacre views. The disadvantage is that information is indicative, as soil moisture levels are calculated instead of measured directly, and information on soil moisture levels deeper down is often not available.
Local sensing measures right in the rootzone where all the action is happening. It is able to provide a vertical soil moisture profile and is generally accurate and reliable. The comparative disadvantage is that you are only measuring a point in a paddock, and in some cases, measurements taken are out of sync with the rest of the irrigated area.
Both methods clearly have their respective merits.
Whatever technology is adopted, the ability to predict soil moisture status in the days ahead due to weather and irrigation activities is key. You need to see where things are heading to enable good choices.
One technology gaining popularity is predictive soil moisture probes.
This brings together the certainty and confidence of soil probes that produce soil moisture values in the present with the predictive power of farmbased weather stations and globallysourced forecasting. This combination generates a future soil moisture trace so operators can preview moisture level changes in response to irrigation choices and predicted weather events. It effectively draws on the strengths of both local and remote sensing technologies.
This approach enables a conventional soil moisture line to be projected into the future, while allowing for different irrigation scenarios. The tool helps answer scheduling questions such as: • If I continue irrigating at the same rate, how long will it take until I exceed field capacity and possibly cause drainage? • Rain is coming. Do I turn off irrigation now to save water and what is the risk of doing so if the rain doesn’t arrive? • Soil moisture is tracking at a healthy level now. Can I shut off for a day or two to save some water and reduce a potential drainage event if rain arrives later? • If I turn off irrigation today, how many days’ storage do I have before I must irrigate?
To help farmers with decisionmaking, powerful algorithms can generate recommendations and guide farmers on what to do. Important limit alarms and alert messages, notifying of things such as an imminent soil drainage event or heavy rain forecast, can be sent directly to devices, therefore shortening response times. As an added advantage, these messages can often be logged and provide a valuable evidencebased tool for proving Good Management Practices (GMPs), particularly for farm environment plan (FEP) audits.
From relatively humble beginnings some 15 years ago, soil moisture technology has matured into a comprehensive and powerful management tool helping farmers irrigate with greater certainty and insight. Now is as good a time as any to have a fresh look at what’s on offer in this constantly improving space.

