{"id":1719,"date":"2017-11-08T15:10:05","date_gmt":"2017-11-08T14:10:05","guid":{"rendered":"http:\/\/www.challenge-agriculture.fr\/?page_id=1719"},"modified":"2021-06-11T12:24:02","modified_gmt":"2021-06-11T10:24:02","slug":"watermark-sensors","status":"publish","type":"page","link":"https:\/\/dev.challenge-agriculture.fr\/en\/equipment\/watermark-sensors\/","title":{"rendered":"WATERMARK \u00ae sensors"},"content":{"rendered":"

How does it work ?<\/h2>\n

Tension is naturally equilibrating beetween the soil and the internal media of the sensor, as soon as the contact with the soil is established. Focus on the importance of the installion technique, to secure a quick and perfect contact (see \u201cInstallation\u201d). We measure an internal resistivity, tightly correlated with water tension. The gypsum buffer saturates the internal media, that becomes independant of soil salinity of (up to 3 mS\/cm). The incidence of soil temperature (1 % per \u00b0C) is automatically compensated, thanks to a soil temperature measure.<\/p>\n

Caracteristics<\/h2>\n

Sensors are rustical, no maintenance, no disconnection, frost resistant. Installation can be enterely underground (on perrenial crops). They offer a good realibility up to 4K measures, high reproductibilty inter-batch, now good accuracy beetween batches.\u00a0The range of mesaure is from 0 \u00e0 239 Cbars (ou KPa).<\/p>\n

Kinetics<\/h2>\n

Behaving of WATERMARK\u00ae sensors
\nA WATERMARK\u00ae sensor, correctly installed, is permanently equilibrated with the soil tension. Its own response time is a few seconds. This can easily be verified by playing with sensors out of the soil.
\nThe soil imposes its speed.\u00a0
\nObserving soils can be surprising.
\nFor example, the time needed by certain soils to \u201ccome back\u201d from a deep drought, or the time others need to drain, etc \u2026
\nIncluding degradation of soil structure, that slows down the natural tension equalization.
\nExtreme dessication :
\nWe have let a soil dry in our test cylinders to reach an extreme and long lasting drought. To allow observe the behavior of the soil and sensors, during recovery phase. Resulst on batches 2004 and F7 show that Watermark sensors equilibrate without delay and do not keep any memory of the event.
\n\"TestsSondes\"<\/a><\/p>\n

Sensibility<\/h2>\n

Watermark\u00ae sensors have an excellent sensitivity, comparable to tensiometer\u2019s.
\nSince 2014, all Monitors (R2-DM, R2-DL, R2-DX, R2-DXS) activate a second measuring circuit, beetween 0 and 30 cbars, to get an excellent sensitivity at low tension end** .\u00a0 This allows new applications.
\n** unlike lack of sensibility beetween 0 and 10 cb, that was falsely lended to the sensor, in the 90\u2019s. In fact, dued to the former reading meter.<\/p>\n

Longevity<\/h2>\n

20 years of experience, intensively using more than 200 000 WATERMARK\u00ae sensors (ourselves and our customers) , plus systematic testing of sensor batches, gives us recurrent data :
\non annual crops, longevity is classicaly of 6 campains of 3-4 months or 5 campains of 5-6 months, or 4000 measures.
\nOn perennial crops, longevity of sensors is 4 entire years or 4000 measures. After, one observes a drift, generally upward.<\/p>\n

Variability<\/h2>\n

WATERMARK\u00ae sensor is constituted of natural materials :<\/p>\n