Development Of An Arduino-based Automatic Irrigation System

In cities,green infrastructure has been used to mitigate food risk,improve water quality,and harvest precipitation as a water source.Effective maintenance of green infrastructure(e.g.,green roof)requires optimal irrigation of plant root during the prolonged drying period.Based on the measurement of soil moisture,various drip irrigation systems have been developed.However,most of the irrigation methods are surface irrigation,which has the disadvantage of loss of soil moisture through evaporation.In addition,the growth of plants is mainly dependent on subsurface soil moisture,especially within the root zones.Therefore,there is a need to develop an automatic system regulating soil moisture at different depths.The research in this study includes three parts:(1)Developing an Arduino-based irrigation control system.The system measures the soil volumetric water content(VWC)through EC-5,a kind of soil moisture sensor.It regulates the VWC of soil within a set range through Lab VIEW program.And a one-dimensional soil column test was conducted to demonstrate its performance,then reducing the error between the actual situation and the set range.(2)Green roof experiment verifies the feasibility and necessity of installing automatic irrigation device.Soil moisture monitoring was carried out on green roof infrastructure in Nanjing for two months.The samples includes bare soil samples and amended samples.The amended samples were added biochar,which can affect soil water retention rate.Experimental records were recorded to observe whether the natural rainfall in summer could meet the operation of the green roof.(3)Adjusting irrigation method to improve water utilization efficiency of root area.According to the different sensor set places(irrigation places),including 5 cm,10 cm and 15 cm.Four kinds of irrigation methods were carried on the comparison.The comparisons were based on irrigation frequency,irrigation quantity and the total water amount of per unit time.The results in the research includes:(1)The system enabled the regulation of soil water content within the specified range(12–20%)with an error of 2%.The error was further minimized by recalibrating the upper limit of the system.(2)Green roof experiments have shown that the addition of 3% biochar can significantly improve the water retention efficiency of green roof.However,automatic irrigation system is necessary in the operation of green infrastructure both with and without soil improvement.(3)After comparing various types of irrigation methods,it concluded that multi-point irrigation at the root depth of conventional green roof vegetation(20 cm)is more efficient than single point irrigation.The irrigation method monitoring irrigation at 5 cm and 15 cm was more suitable.Experimental results showed that the number of sensors and distance between them would affect the performance of automatic irrigation system.In conclusion,this study provides an improved green infrastructure irrigation system that can effectively control the water distribution on the root surface of plants.Future experiments should combine the vegetation used by conventional green roofs to prove the feasibility of the system in large-scale green infrastructures.