PROBLEM TO BE SOLVED: To achieve both power saving on the sensor side and appropriate control during irrigation. A irrigation system communicates with a plurality of communicable soil condition detection sensors, a plurality of valves attached to a irrigation pipe, and a control that communicates with a plurality of soil condition detection sensors and drives and controls the plurality of valves. And a device. The plurality of soil condition detection sensors communicate with the control device by making a communication request to the control device at a set communication interval. When predicting that irrigation will be performed within a predetermined time, the control device sets the communication interval shorter than the time before predicting that irrigation will be performed when first communicating with a plurality of soil condition detection sensors thereafter. [Selection diagram] Fig. 3【課題】センサ側の省電力化と灌水時の制御の適正化の両立を図る。【解決手段】灌水システムは、通信可能な複数の土壌状態検出センサと、灌水用パイプに取り付けられた複数のバルブと、複数の土壌状態検出センサと通信を行なうと共に複数のバルブを駆動制御する制御装置と、を備える。複数の土壌状態検出センサは、設定された通信間隔で制御装置に通信要請を行なうことにより制御装置と通信を行なう。制御装置は、所定時間内に灌水が行なわれると予測したときには、その後で最初に複数の土壌状態検出センサと通信を行なったときに通信間隔を灌水が行なわれると予測した以前より短く設定する。【選択図】図３
