It has become far too apparent in the turf care industry that the number one problem plaguing us is water. While there isn’t a way for us to create rain, we can educate and be better educated for our clients on the best and most effective way to water. Aside from obvious factors (misplaced heads, clogs, broken heads, misaligned….) the most common watering issue we face is lack of water. The main cause of this is convenience. The “set it and forget it” model of sprinkler programming is now common place in today’s world.
Sprinkling systems are a blessing and a curse for lawn care. On the one hand they provide allot of jobs and recurring revenue for allot of people, provide water to lawns in areas regularly prone to drought conditions and allow for cultivars to grow in areas where they shouldn’t. On the other hand, they can be wasteful, terribly inefficient, and cause more problems than they solve. For the common homeowner, programming a sprinkler timer is right up there with brain surgery. So, once that timer is set, it’s not getting changed. The effects of this are two-fold;
- There is way too much water being applied during rainy or cool seasons.
- There is way too little being applied during heat and drought seasons.
A lot of people have adopted the “20 minutes per station” model of watering 3x per week. This is mainly because that’s what their buddy does who helped them turn the thing on when they bought the house. There is no scientific reasoning behind most watering schedules unless someone actually conducted a watering test. This is easily accomplished with cat food or tuna fish cans. I am not going to bother explaining it here… Google it if you don’t know what I mean. This knowledge is powerful for a tech or business owner to because you can calculate inches of water by turning on a sprinkler for five minutes and multiplying time to get the resulting inches. The reason this is important is that you can tell a client when they should adjust timers throughout the season in your monthly newsletter or with your billing statements.
Take a look at the charts below, this is the seasonal average temperatures and rainfall for Salt Lake City Utah. I have used this to illustrate the bell curve for watering efficiency. Now, go ahead and throw out the winter months and look at the data from March-November, or what would be considered “Turf Season.” You can see daytime average temps, as well as expected precipitation, and the number of days that are average for that level of rainfall. The dominant grass in Utah is Kentucky Blue with some fescue, but that is mostly prevalent in older homes and has been all but phased out. The piece missing from this chart is average daily humidity. In the summer, humidity in the high desert will be between 18-23%… Dry.
|Average high in °F:||38||44||53||61||71||82|
|Average low in °F:||26||31||38||43||52||61|
|Av. precipitation in inch:||1.46||1.5||2.2||2.32||2.09||1.14|
|Days with precipitation:||10||9||10||9||8||5|
|Hours of sunshine:||137||155||227||269||329||358|
|Average snowfall in :||11||10||6||3||0||0|
|Average high in °F:||90||89||78||65||50||40|
|Average low in °F:||69||67||58||46||36||27|
|Av. precipitation in inch:||0.59||0.71||1.54||1.65||1.77||1.61|
|Days with precipitation:||4||6||5||6||7||9|
|Hours of sunshine:||377||346||306||249||171||135|
|Average snowfall in :||0||0||0||0||7||10|
Now, if we overlay the information from above into the chart below, we can see where we need to adjust water based upon what is naturally falling throughout the month. Bluegrass likes to have roughly 1.75” of water per week throughout its effective growth cycle or an average of 7” per month. This is what is considered healthy to maintain a stand of grass of this variety.
Now here’s the kicker, most watering schedules are set to a certain time that come on too early in the season, stay on too late, and water the same amount week in and week out through the season. This will create a shallow root system that makes it IMPOSSIBLE for grass to be healthy without overwatering in the heat! We end up with people wasting water in the spring and fall and the hand watering (more waste) in the summer to make up for the difference!
|Irrigation||Avg. Temperature (°F)|
Enter the ET controller. This is a fantastic device, but is still unaffordable for the average Smith in a zero lot line neighborhood. It’s really too bad that it is so expensive because the technology is wonderful and it does the work for you on the needs of the grass based on slope, temp. wind, and other factors of evapotranspiration. Most sprinkler system timers have an input for this device, but ultimately it is up to the homeowner whether or not they will spend the money on the equipment and monthly service contract.
Back to it… this is all well and good, but it puts us back into the “perfect world” scenario that just doesn’t exist in our business. Below you will see the “bell curve” model of irrigation, this follows the growth cycle of turf and is the exact OPPOSITE of a Nitrogen feeding schedule.
So let’s run some numbers. Let’s say that it takes a station 20 minutes to put out 1/2” of water and it does this 3x per week starting in early April. This would give us an effective irrigated water supply of 1.5” per week. Add that number to rainfall on average for April and you get 8.5-9” of water on the lawn for the month. This is a bit high and will keep roots shallow especially because the temps are cool and the water isn’t effective. Take this out through the season until sprinkler turn-off time and the resulting volume of irrigated water for the season is 50”. If a person were to run a modified or “bell curve water program” the resulting total inches would be less than 36. This represents more than a 25% SAVINGS IN OVERALL WATER. Not only that, the water becomes more effective due to the modification of when and how much water per week is applied. A heavy watering will fill the “pan” under the ground and allow for greater space between watering while retaining color and health. The best way to have healthy and drought resistant turf is to stress it at the beginning of the year. This drives roots deep and prepares for hot summers.
One of the greatest overlooked aspects of watering is biological. Water is always cooler than the air, which means that it is cooler than the ground, which means that when it’s hot, this will slow down particular soil microbiology that can cause “hot spots” in lawns. The best way to create a metaphor for this is simply, when do you want to jump in a pool? When it’s hot outside or cold? Soil is the same way, the roots are the “core” of the plant. All things metabolic begin there and because the roots are in the soil, the soil dictates the overall health. That’s right; with water as with fertility, the soil is the soul.