In order to guide water-saving irrigation of citrus orchards through real time collecting soil moisture with a low cost way

a soil water content sensor is developed

according to the principle that soil resistivity varies with the soil moisture content.In order to eliminate or reduce polarization effects caused by probe electrode when measuring with a constant DC voltage

a measuring method

which uses the positive and negative and intermittent voltage pulse generated by a H bridge circuit instead of a constant DC voltage as the excitation signal

is put forward.A wireless transceiver module CC2420 is invovled to realize wireless communication between the sensor and upper computer.Batter

y life is improved by imploying power management and sleep mechanisms.The sensor is calibrated

and experiments of validation for the sensor is taken with the soil moisture content from 13.6%

50.2%

and the results show that the average error of the sensor is 2.8%

when the soil moisture content is in range of 21.1%

41.5%;the average error is 5.2%

when soil moisture content is beyond the range.