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Sensor-based irrigation scheduling
Proceedings of the 2020 Mississippi Water Resources Conference
Year: 2020 Authors: Sui R.
Though annual precipitation in the Mississippi Delta is approximately 130 cm, only about 18% of the precipitation occurs during June to August when crops require a large quantity of water to grow. Furthermore, heavy rainfall in summer causes extensive amounts of runoff, resulting in only a small amount of the precipitation infiltrating into the soil for crop use. Uncertainty in the amount and timing of precipitation is one of the most serious risks to the crop production in this region. To reduce the risk and increase farming profit, irrigation acreage has been increasing. Groundwater pumped from Mississippi River Valley alluvial aquifer provided about 95% of the water used for irrigation and fish culture in the Mississippi Delta. Due to the large withdrawals, water levels of the aquifer have significantly declined. It is necessary to develop improved water management tools for sustainable agriculture in the region. Advanced irrigation scheduling technologies can increase water use efficiency and reduce the groundwater withdrawal in irrigation. A sensor-based irrigation scheduling (SBIS) method was developed and evaluated for irrigation management. Soil moisture sensors were installed in soil profile at three depths (15 cm,30 cm, 61 cm). Soil volumetric water content (VWC) was automatically measured by the sensors in a time interval of an hour during crop growing season. The VWC data were transferred through a wireless sensor network so that the data could be accessed online. Sensor-measured VWC at all the depths were interpreted using a weighted average method to reflect the status of soil water in plant root zone. Irrigations were triggered as the sensor-measured VWC dropped down to a threshold which was determined according to the soil properties. An antenna mounting device was developed and implemented to avoid the soil moisture measurement being interrupted by some agricultural activities such as applications of pesticide and fertilizer. The SBIS method has been used in cotton, corn, and soybean crops, and it indicated that this method could be a useful tool in irrigation management.