IRRIGATION

PART 1

Introduction

Nowadays, irrigation is an important and integral part of the turf grass management industry, especially as the demand for better quality playing surfaces has increased. This demand has been largely due to extensive televised coverage of major sporting events. Seeing immaculate aesthetically presented golf courses, football, rugby pitches and horse racing courses has increased the expectations of the players and viewers.

Most, if not all, professional sporting facilities have irrigation systems of one sort or another. Without them, they would not be able to prepare and maintain their playing surfaces.

WHY DO WE NEED IRRIGATION ?

• Water is held in the soil pores by the forces of cohesion between water molecules as well as the adhesive forces between the water molecules and soil particles. The water is spread as a film over the surface of all soil particles.

• A continuing decrease in the soil water content occurs under actively growing turf primarily because of the upward loss by evapotranspiration. A decreasing water film thickness on the soil particles causes an increase in the soil suction and a greater energy requirement for the removal of water and its absorption by the turf. At the wilting point water is absorbed so firmly in the soil, and its mobility is so low that plant roots can no longer extract sufficient water to survive.

QUANTITY OF WATER NEEDED

• At this point turf grass irrigation is needed to maintain the soil water content at a water suction level that is low enough to readily satisfy the water absorption requirement of the turf grass plant without creating a significant internal plant water stress.

• The water held in soils between field capacity and permanent wilting point is called available water, it is the maximum amount of water that the rootzone can supply to plants growing in it.

 What does this mean?

• Here on a normal day, evapotranspiration rate is approximately 10-15 mm. This means 10 – 15 mm of the available water will be lost daily which will have to be replaced.

Media Department; The RS Group.