Standard practice is that when the Mayfly board goes to sleep in between measurements, it turns off all power supplied to the sensors and radio module. So the power consumed when sleeping is just the bare minimum to keep the Mayfly in sleep mode, which is usually a little less than 1 milliamp. There are ways to make it use even less in sleep mode, but it’s usually not necessary since the overwhelming majority of the power used is during the sensor sampling and radio transmitting time. Power-hungry sensors with motorized wipers or large current draw, and radios that need long connection times are the most challenging peripherals to use, but 3 soil moisture sensors and an unltrasonic sensor will use very little power when sampling, so they won’t stress a 4400mAh battery at all when matched with a decent solar panel like the 3.5w or 5w panels we usually recommend. I don’t know what Xbee module you’re using since they make wifi, cellular, and RF modules, but your transmit time and duty cycle will determine the overall power usage.