This paper describes a complete wireless sensor and irrigation control system that reduces water consumption for residential turfgrass irrigation. It has been estimated that 50-75% of residential water use is for irrigation. Current systems are exceptionally poor at adapting irrigation to meet demand, primarily due to incomplete information for system operators who rely either on visual inspection or periodic irrigation programs. This results in over-watering and fertilizer and soil leaching. Our approach couples easy-to-deploy wireless soil moisture sensors nodes with an adaptive irrigation controller that waters on demand without user input. The result is a system that requires less user intervention, lowers water consumption, and adapts to changing climatic conditions.

The LEACH algorithm for selecting cluster heads is a probabilistic method which produces clusters with a large variation of link distances and uneven energy consumption during the data transmission phase. To address this issue, a RF signal strength algorithm based on link quality is presented. Using a competitive distributed algorithm, nodes attempt to reduce the overall energy required for transmission in addition to forming favourable clusters based on Received Signal Strength Indication (RSSI) density and quality. Cluster heads form in areas of high node density leading to a significant reduction in transmission link length, a reduced variance in link length distribution and greater opportunity for energy savings through data aggregation. Simulations show that cluster heads selected by this algorithm form clusters with a lower average link length and have less link distance variability. This produces a lower and more evenly distributed energy cost per node in the network.

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