Development and evaluation of an automated pulse irrigation system

Abstract

Irrigation sector consumes more than 80% of the fresh water resources in India. The irrigation efficiencies of the major irrigation systems in India are around 40%, increasing of which could save large amounts of water. The irrigation efficiencies could be increased through the adoption of cost-effective and efficient irrigation technologies, which will reduce water demands, increase agricultural production, minimize soil and water pollution and reduce the cost of agricultural production. Drip/Trickle irrigation is a highly efficient irrigation method which could save tremendous amounts of water when adopted in the place of the wild flooding irrigation. Pulse drip irrigation technology enables lower application rates - that will permit sufficient aeration in the root zone and alleviate plant stress due to inadequate root respiration– from an emitter with a higher application rate by intermittent water applications. This study attempted to develop and evaluate a sensor based automated pulse drip irrigation system which is affordable to the low-income farmers of the nation. The soil properties of the experimental field were used to estimate the parameters of several soil water characteristics curve (SWCC) models. Among the models; van Genuchten (1980) model of SWCC, was found to be the best in representing the soil moisture retention characteristics of the soil used in the study. An open-source electronics platform, the Arduino was used for the development of the automation system using moisture content sensors and solenoid irrigation valves controlled through relays, by writing program coding in the Arduino programming language. The sensors were calibrated to read the moisture content, which was compared to the management allowed deficit (MAD) and field capacity (FC) soil moisture content values to control the start and stop of irrigation water application. Pulse irrigation design methodology was used to derive the ON and OFF time periods for the pulse cycle. The system was programmed to start the water application as per the designed pulse cycle at a moisture content defined by the MAD moisture content and to stop the water application at the field capacity (FC) moisture content sensed by the moisture sensor. The wetting front movements and the soil moisture contents in the root zone were measured at different time intervals of 1 hour, 2 hours and 3 hours after the start of water application using both continuous irrigation and pulse drip irrigation under 2 LPH, 4 LPH and 8 LPH online drip emitters. The soil aeration was also determined for these treatments and was found to be better during the pulse irrigation as compared to the continuous drip irrigation. The pulse irrigation application was also found to be decreasing the deep percolation loss of water. The developed automated pulse drip irrigation system is found to provide the required aeration in the root zone with reduction in deep percolation loss of water.