Water...your lawn can't survive without it! (05-23-2005)

Water is one of the most unique, mobile and abundant compounds on earth and any living thing cannot survive without it. Our lawns are no exception and as the days become warmer our lawn's demand for water will be even more critical.

I am often asked how much water does a lawn need each day or week. As a general rule the answer is somewhere between one to three tenths of an inch per day, or one to one and a half inches per week when the turf is actively growing. Of course these amounts vary depending on a host of environmental and physical conditions such as temperature, wind, clouds, traffic, soil type, turf species, etc.

When supplemental irrigation is needed it should be applied in thorough, but less frequent, applications to moisten the soil to a depth of three to four inches and encourage a stronger deep-rooted turf. A light sprinkle each day encourages shallow rooting and greater evaporation loss.

Understanding the functions of water to a lawn will help determine when your lawn needs water.

• Water is essential for the uptake and transport medium for nutrients into the plant.
• Water serves as the solvent or catalyst for metabolic processes and is required for photosynthesis.
• A healthy lawn is a tremendous air conditioning system as it transpires water to moderate temperature changes of plant cell protoplasm, maintain cell turgidity and opening of stomata.
• Water is also necessary for seed germination and the survival of beneficial bacteria and fungi that help decompose mowed leaf clippings.

When all of these functions are going on at the same time the lawn will demand and require the highest level of water.

Excess water can often be as detrimental as too little water. Compacted soils with poor internal soil drainage will reduce soil oxygen resulting in lower root mass and depth. With a much smaller, stressed root system the turf plant can't take in the water and nutrients needed for optimum growth and appearance.

Published May 23, 2005

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu