Monday, July 4, 2016

Sodium Induced Wilt

Bring the rain!!
We have received .65" of rain since the third week of May and humidity has been mostly non-existent. This is wonderful for outdoor activities compared to those oppressively humid days but brings challenges to those keepers of the turf. The fairways have developed numerous dry spots and there are a few issues causing this situation I'd like to address.
We have been keeping the golf course on the dry side for the last 7 years to allow for better plant health, play-ability, and and fewer cart path only days. When running on this edge to keep those conditions some browning out will occur. Grass kept on the wet side doesn't allow for any ball roll and diseases can become a serious issue.  When constantly watering,  rooting also becomes a problem as the plants do not need to dive in search of water. With the severe lack of rainfall on our course this past month coupled with high temps and low humidity, irrigating on a regular basis has become the norm. I have commented on this issue in the past when we are forced to irrigate for long stretches without a decent rainfall.
High temps during summer combined with a lower relative humidity dries out the plants rapidly. ET is known as evapo-transpiration and is a measurement of how much water is lost from the plant and soil during a 24 hour period. ( for example; an acre of corn will lose 3-4000 gallons of water per DAY and a 80ft oak tree will lose 40,000 gallons of water per year.) As the plants transpire or perspire more water is pulled from the roots to cool off the plant. On a 85 degree day with a relative humidity of 30%,  a whopping .33" of moisture is lost. To irrigate this amount back to the plant almost 700,000 gallons must taken from the pond. Our irrigation pond on holes 14,17 contains about 2.5 million gallons. One fact to realize is that to water this amount down on greens tees and fairways it would require the pumps to run from 10PM to 1:30 the next afternoon. Obviously this is an impossibility as my crew begins work at 5:00 am and tee times start at 7-7:30. The amount that can be put down before we start work is .18" which is practically a 50% loss.
The other issue when solely relying on pond water is the make up of that water. Our irrigation water contains very high levels of sodium and bicarbonates.  When we consume a very salty meal we become dehydrated and must drink copious amounts of clean water to feel good again. If you put a teaspoon of salt in your water you would still remain dehydrated. This is actually what is happening on the fairways and rough. The term is known as sodium induced wilt. The more water we put down to keep up with the ET rates, the more sodium is introduced and the faster the plant dries out. I have installed a wetting agent tank that is connected to the irrigation pumps and will slowly feed this product as we water to help break through the dry compacted soil and allow for some water retention. When we finally get a good soaking rain the sodium will be flushed away and we can start over.


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