Application of indigenized soil moisture sensors for precise irrigation of wheat crop under various irrigation methods
Authors: Iqbal Usman 
Published: May 2022

Real time soil moisture monitoring using sensors has potential to save irrigation water and improve water productivity. Field experiments were carried out for two successive years (2016-17 and 2017-18) to produce wheat crop at the Water Management Research Center, Postgraduate Agricultural Research Station, University of Agriculture, Faisalabad. Field irrigation methods included flood irrigation (canvas pipe), perforated pipe irrigation, and drip irrigation under different planting geometries and irrigation designs. The sensor-based irrigation systems were developed using locally available material to minimize the cost of equipment development and energy consumption for crop irrigation. Seven wheat crop treatments used in this experiment were T1-flood irrigation flat sowing by rabi-drill, T2-flood irrigation bed furrow planting with 0.254 m furrow, T3-perforated pipe irrigation bed furrow planting with 0.254 m furrow, T4-perforated pipe irrigation bed furrow planting with 0.203 m furrow, T5- perforated pipe irrigation bed furrow planting with 0.152 m furrow, T6-drip irrigation flat with 0.914 m lateral spacing and T7- drip irrigation on beds with 0.914 m lateral spacing. An IT-based web server was developed for monitoring soil moisture status to serve as decision support system for applying irrigation to the crops. The developed sensors sent soil moisture signals on cloud for data storage, reuse and sharing purpose using coding. The irrigation was applied based on soil moisture status. The system based on micro-controller was tested for irrigating wheat crop. Raspberry Pi-3 (Model B) controlled hardware in distribution box (DB) made excellent use of indigenized soil moisture sensors for calibration and irrigation water management. Type-I (Single probe) and Type-II (Double probe) steel sensors performed best due to high R2 values of about 0.99 and RMSE in the range of 3.30% - 3.50% during calibration. The calibration further improved the accuracy of both steel and copper sensors. Since the sensors were designed, developed, and calibrated during the 1st year (2016-17) and properly installed in 2nd year (2017-18), therefore, have affected crop and soil parameters positively. Drip irrigation treatments (T6 = 359.56 mm and T7 = 358.65 mm) required significantly lowest mean amount of water than those by all the other treatments and the flood irrigation treatments (T1 = 431.55 mm and T2 = 424.95 mm) required significantly greatest (α = 0.05) amount of mean irrigation depth. Drip irrigation treatments (T6 and T7) produced high mean water productivity values (14.30 and 14.20) than those under flood irrigation treatments (T1 = 9.6 and T2 = 10.30) and perforated pipe irrigation treatments (T3 = 12.66, T4 = 12.43 and T5 = 12.30). The mean yield of wheat grain over two years was greater under drip irrigation treatments (T6 = 5145.1 kg/ha and T7 = 5091 kg/ha) than those under flood (T1 = 4139 kg/ha, T2 = 4371 kg/ha) and perforated pipe irrigation treatments (T3 = 4969 kg/ha, T4 = 4872 kg/ha, T5 = 4775.7 kg/ha). Perforated pipe irrigation treatments had significantly greater (α = 0.5) wheat grain yield than those under flood irrigation treatments.