Preliminary study on distribution characteristics of soil moisture in apple orchard

Wireless sensor networks (WSN) can be used to sense the objectivity environmental information, and have been applied in agriculture widely. When WSN are applied in apple orchards, the environmental information can be monitored, then the right decisions can be made. Soil moisture is one of the most important factors that can affect apples爷 quality and yield. Research on the distribution characteristics of soil moisture in apple orchard can provide support for WSN node deployment. Field tests were performed in a common apple orchard in Beijing, and the soil moisture at lots of points at different soil depths in three typical sub-zones was measured. The results showed that the soil moisture content increased with the increased distance to the root, mean square errors in three soil depths were computed in the three subzones and in the whole orchard, and 91.7% of them were between 2% and 3%. So, the soil moisture had similar dispersion degree at each sub-zone or at the whole orchard. The mean square errors of the soil moisture at different positions in each sub-zone were computed, the values between 1% and 2% accounted for the largest proportion being 48.2%. The mean square errors in the horizontal direction were bigger than that in the vertical direction on the whole. A soil moisture sensor deployment strategy targeting one apple tree and focusing on the whole orchard冶was proposed based on the results.