Drip Irrigation For Farmstead Shelterbelts

Trickle or drip irrigation is a controlled method of watering that makes efficient use of available water. It is a method that holds promise for use with shelterbelts, particularly in the establishment of conifers in drier areas such as southern Saskatchewan. The system delivers the water required by a tree seedling, drip by drip, through a small emitter in PVC or polyethylene pipe to an area directly around the plant. The plant can then use the water with little water loss to seepage or evaporation. Drip irrigation is suitable for a wide range of soils and topography.

A drip irrigation system consists of a "head" and a distribution network. The head of the system is composed of the water source, pump, filter system, pressure regulator and necessary pressure gauges. It may also include a water meter or electronic controller. The distribution network includes the mainline and laterals or dripper lines located down the plant rows.

A study evaluating a typical drip irrigation system was initiated by the PFRA Shelterbelt Centre, Indian Head in 1985 because of increased interest in this irrigation method. The drip system in the study utilized a water supply tank (2270 L), mounted on a trailer. The water was supplied using 1 " centrifugal pump driven by a 3/4 hp electric motor. A pressure regulator valve maintained pressure at 20 psi to deliver the desired flow. A plastic filter with a 155 mesh synthetic regulator on the main supply line. The faucet provided water for washing the screen after use. The drip system used was constructed of 15.2 mm (5/8 in.) polyethylene tubing for the header line and 12.4 mm polyethylene tubing for the dripper line. Button emitters with a flow rating of 2.75 L/hr (.5 gal/hr) were installed in the dripper line at the desired spacings. Emitters were positioned 30 cm (12 in.) away from conifers to promote adequate root development.

The system was installed on a farmstead shelterbelt with two rows of conifers. Irrigation was begun on July 4, 1985. Approximately six hours were required to deliver 2270 L of water through 150 emitters on the two dripper lines. Plots were irrigated once every three weeks until the end of August. The cost of this system was approximately $1.30/tree, excluding the cost of the tank and pump.

A drip irrigation system can be a tremendous aid in establishing coniferous trees such as Colorado spruce in drier areas of the province. Without this extra water, some trees will likely have to be replaced yearly for several years. The extra moisture, besides increasing survival will also increase the tree growth. Once the conifers are established, the system can be sold or passed on to other tree planters. Normal cultivation to control weeds and grass is then all that is needed to ensure an effective shelterbelt. Farmstead shelterbelts produce many proven benefits and every effort should be made to ensure their rapid establishment around the farmyard.