Leaching: Why is it Necessary?

I have been asked on occasion why we put down so much water on the greens and why they seems soft or slow.

Here is a article form Pace Turf that explains the reasons why we perform this procedure.

Leaching: Why is it Necessary?

Bottom line:

Greens leaching programs are designed to keep turf healthy by re­ducing soil salts. Un­fortunately, there are some tempo­rary side effects — wet greens and sur­rounds, softer turf, and slower greens. Are the benefits of leaching worth the inconvenient side ef­fects? The answer is definitely “yes”, and we will explain why here.

Salts, deadly poison for turf: What do you think is the most serious problem affecting the health and quality of putting greens? Most people believe that diseases, insects or weeds are the biggest threats, and indeed these pests can cause significant turf damage. But an even more serious threat is the build-up of soil salts.

The importance of rain: When there is enough rain, salts are rarely a problem. This is be­cause rain helps to leach, or wash away, the salts that ac­cumulate near the soil sur­face. Rain pushes salts down into the soil, beneath the area where plant roots grow.

But during periods of low rain­fall, this natural leaching does not occur, and salts build up.

Salts hurt turf in three dif­ferent ways: The most im­portant of these is known as physiological drought. When this occurs, the plant can’t get water from the soil, even when the soil is moist; this is­because salts in the soil liter­ally suck water away from the plant roots. The effect can be devastating, particularly to salt-sensitive turf such as an­nual bluegrass and bentgrass.

Secondly, accumulation of so­dium salts in the soil damages the structure of the soil itself. This can result in poor drain­age, low soil oxygen and poor water infiltration – all of which result in even more stress to the turf.

Finally, salt stress on turf makes it more susceptible to diseases, weeds and insects.

The key is to keep turf healthy by avoiding the build-up of soil salts BEFORE damage to turf occurs. And the best way to avoid salt build-up is to imple­ment a leaching program.

It’s all about balance: Main­taining a balance between soil salts and turf quality is a sig­nificant challenge.

To keep salt levels low, it is necessary to conduct leaching programs during periods of low rainfall. High leaching vol­umes (a few inches of water in an 8-hour period) of irrigation water are required to drive salts below the root zone.

This is why greens and sur­rounds can be soggy and soft following leaching. But the benefits are enormous. When done on a preventive basis– before turf damage due to salts is serious – turf and soil will become healthier, pest damage will decrease, and greens will remain green. It’s just that simple.

©2010 PACE Turf, 1267 Diamond Street, San Diego CA 92109 www.paceturf.org