Application of drag reducing commercial and purified guargum for reduction of energy requirement of sprinkler irrigation and percolation rate of the soil

Drag reducing polymers reduce the drag in a turbulent flow while increase the drag in a laminar flow, due to an increase in shear viscosity. This feature of drag-reducing polymers has been utilised in reducing the energy requirements of sprinkler irrigation system and increasing the area of coverage as well as reducing the percolation loss of water added with drag reducing polymers. Two types of polymers at various concentrations were studied at the Indian Institute of Technology, Kharagpur. Two different methods of injection of polymers were also tested to determine the effect of polymer on mode of injection. The concentrations of 100, 250, 300 and 450 ppm of commercial guargum and 50, 100 and 150 ppm of purified guargum were used for homogenous injection (T₁). The concentrations of 100, 300, 600, 1000 and 1500 ppm of commercial guargum and 50, 100, 200, 350 and 500 ppm of purified guargum were used for injection at the suction side of the pump(T₂). The infiltration characteristics of the soil with polymer added water was tested for 300, 1000 ppm of commercial guargum and 100, 500 ppm of purified guargum. For T₁, the maximum power reduction of 28% was obtained in case of 300 ppm commercial guargum and approximately the same percentage was obtained in case of 100 ppm purified guargum. The maximum drag reduction was 35.5% at 300 ppm of commercial guargum and 38% at 100 ppm of purified guargum. The maximum increase in the radius of coverage at 500 ppm commercial guargum was estimated to be 33 and 37% at 150 ppm of purified guargum. For T₂, the maximum power reduction at 1000 ppm of commercial guargum and at 500 ppm of purified guargum was 31.25%. The maximum increase in radius of coverage at 1000 ppm of commercial guargum and at 500 ppm of purified guargum was 37 and 38.2%, respectively. The maximum drag reduction of 40% was obtained at both 1000 ppm of commercial guargum and 500 ppm of purified guargum. The reduction in the infiltration rate at 1000 and 300 ppm of commercial guargum was found to be 56.52 and 27%, respectively, whereas the reduction in the infiltration rate at 100 and 500 ppm purified guargum is 15 and 22.8%, respectively. The study reveals great potential of using drag reducing polymers for irrigation water management.