Pioneers in the Field: Irrigation Scheduling

Over 20 years ago, Richard Wenstrom began using a computerized irrigation scheduling system with 24 center pivots on a 4,200 acre farm near Kinsley, KS. The system he used took into account temperature, humidity, wind, rainfall, and other climate data to determine when and how much water should be applied at any given time.

Irrigation scheduling saves water, energy, and money with estimates of up to 35 percent savings in water and energy. Wenstrom estimated that his system saved between 20-30 acre-feet of water per pivot. Considering that one acre foot of irrigated water equals about 326,000 gallons, each pivot saves between 6.5 and 10 million gallons of water. The fuel and money savings are equally impressive!

The technology Wenstrom used to monitor the function of his center pivot irrigation systems combined with available climate data allowed Wenstrom to develop an irrigation schedule that saved water, fuel and money, he explains:

To grow corn in Kansas, it takes 24 inches of water. Here, we can only pump 18 inches, so we gotta have 6 inches of rain. Well, the last 2 years there wasn’t 6 inches of rain, there wasn’t any rain. So that’s where a scheduling regime would really pay off. Irrigation scheduling is one of the keys to saving water.

Richard and Jane Wenstrom’s 4,200 acres near Kinsley Kansas sits on the Great Bend Prairie aquifer. The Great Bend Prairie aquifer covers a 5,400-square-mile area in south-central Kansas, including all of Kiowa, Kingman, Pratt, and Stafford Counties, and parts of Barber, Barton, Edwards, Pawnee, Reno, and Rice Counties. When the farm was active, they raised primarily corn and soybeans with some alfalfa, and small amount of irrigated wheat. Using a sophisticated irrigation scheduling system to operate 24 center pivots, Wenstrom realized significant savings. Richard Wenstrom pioneered the concept of using climate data and was an early adapter of strip-til technology, two techniques that save water and energy. 

We use a scheduling system that was adapted from some work that the ARS/USDA did in Colorado. And, that was using climatic data. We’ve always had a climate station on the farm or nearby to get climate data to turn into evapotranspiration. And then, the rest of it is just trying to match your irrigation to what the crop is using. So, we started off with simple water budget system that was developed by the ARS, and subsequently to a system with that same concept that has been integrated into a commercial control and scheduling module that can be used on a personal computer.

Water

As far back as the 1970’s, Wenstrom began gathering data and monitoring water use. He started implementing computer software programs starting in 1980, before many farmers even had computers. Danny Rogers, Extension Agricultural Engineer with K-State Research and Extension explains that Richard was an early adopter and innovator of improved irrigation management practices:

He was one of the first large-scale irrigators that used soil-based irrigation scheduling techniques but was also an early adopter of climatic- or ET- based irrigation scheduling. Early ET-based scheduling required a dedicated individual as data collection and processing for the procedure was cumbersome.

Before the internet and GPS systems were commonplace, Wenstrom, in collaboration with Underhill International Corporation, created an innovative computer-based control and irrigation scheduling system that really performed. He recalls,

It was a very powerful system. It not only had a picture of our farm and I could click on any circle and see what it was doing, it would bring up that analysis screen. The screen on the left would show me what the pivot was actually doing…it tracked it around not by GPS, but by dead reckoning.

The system enabled him to play out various scenarios for the center pivot to ensure highest efficiency:

There were a couple of other circles that I could play "What If” games with. I could put in artificial irrigations to see what was the ideal rotation speed for running a center pivot. By doing those "What If” problems I could hone in on what is the correct speed for a center pivot. That is the one thing that nobody talks about, but is critically important. And, it showed me that about a 32 to 40 hour circle was optimum for most of our center pivots.

This built-in flexibility in the program helped him to see the value in identifying the correct speed for the pivots. This critical piece continues to set Wenstrom’s irrigation scheduling system apart from others, even contemporary systems.

If you run your circle too slowly, then by the time you get around to the start point, it is so dry that you’re having crop loss. If you run it too fast, then you just up your evaporation and transpiration losses and you keep wasting water…and that’s not good either. So, the sweet spot is somewhere in between there. With this program I was able to fool around with every circle, and find the sweet spot. I don’t think anybody else has ever looked at that. It’s critically important, and nobody ever talks about that. Nobody ever comes out and says this is how you should run your center pivot. The dealer just sells it to you and says "Here it is….away you go.”

Mr. Wenstrom has seen different techniques work for different people. For farmers that irrigate, they do so with the intention of producing high yields. Wenstrom’s irrigation scheduling impacted yields but also reflects the values of resource conservation and good stewardship that run deep in Kansas.

Resources has quite a bit of ethics with it. Everyone out here wants to make sure that their farm is better for their children and grandchildren than it is for us.

Working with NRCS, Wenstrom took into account soil survey data regarding water infiltration and holding capacity. Monitoring well pumping rates in relation to water holding capacity for every field enabled him to make sure every system was adequately configured.

Well, most importantly, for field information would be the water holding capacity of the soil. And, we’re fortunate in this area that the NRCS has done soil surveys of all of this area, so along with that they provided water infiltration data. We’ve got soil data from them on how fast the water can move down the soil, how much the soil can hold and that’s the critical thing. And, then of course pumping rate…you have to know what the pumping rate is. We’ve measured those. We have meters on every well, so we are pretty close touch with pumping rate. How much water you’re putting on and how much the soil can hold are the two critical ingredients.

Danny Rogers explains, "Richard understands the importance of water to agricultural crop production and the importance of water for other uses and the need to manage water for long term benefits."  Read Danny's guest blog here!

Energy

Irrigation scheduling encourages responsible use of water resources but energy is also saved with these practices. Irrigation is an energy intensive practice. In 2008, there were almost 55 million acres irrigated in the United States with over 2.5 million of those irrigated acres in Kansas. Energy costs for irrigation in 2008 ranged from 36-61 dollars an acre. In Kansas, those numbers are even higher, ranging from $52.78/acre for surface water to $80.36 for water from wells. Several variables affect energy cost in irrigation, see http://www.ksre.ksu.edu/irrigate/OOW/P11/Kranz11a.pdf Evaluating Energy Use for Pumping Irrigation Water for a detailed overview.

Wenstrom’s irrigation scheduling system certainly realized energy – and money – savings:

Well, when we were going strong on our farm here, it was costing me over $2000 a day to pump water. So, if I determined that I didn’t need to pump, and I could be off a day…$2000 right in my pocket. That was just the fuel side.

Census numbers reflect increases in energy cost of 73 percent from 2003. There were 12 percent more pumps used in 2008, which brought the energy expenses for pumps to $2.68 billion. Efficient use of irrigation can save water, save energy, and result in significant financial savings. http://www.agcensus.usda.gov/Publications/2007/Online_Highlights/Fact_Sheets/Practices/fris.pdf

Progress

Richard Wenstrom created an impressive, comprehensive irrigation scheduling system that was way ahead of its time. Unfortunately, the technological advances that Richard Wenstrom employed on his farm did not take off with other farmers the way he had hoped. He recalls, "People just weren’t up to speed on using computers….So, I think the young person coming back to help on the farm today is much more savvy and more willing to use electronics.” Modern technologies like GPS and hand-held computers like iphones make data collection much easier. Still, adoption of irrigation scheduling programs is a missed opportunity for the majority of irrigators in the United States.

According to a 2012 USDA report:

Despite technological innovations, at least half of U.S. irrigated cropland acreage is still irrigated with less efficient, traditional irrigation application systems. Sustainability of irrigated agriculture will depend partly on whether producers adopt more efficient irrigation production systems that integrate improved on farm water management practices with efficient irrigation application systems.

For 2008, fewer than 10 percent of irrigators throughout the West used soil- or plant-moisture sensing devices or commercial irrigation scheduling services. Fewer than 2 percent of irrigators used computer-based simulation models to evaluate crop irrigation requirements based on consumptive use needs by crop-growth stage and local weather conditions.

When asked what the way of the future is, Mr. Wenstrom responded:

I think we will use different cropping patterns, along with newly developed drought resistant crop variety technology. We might have to go back to some sorghum, we might have to do more rotations with wheat. There might be some crops we don’t know about right now that will come along. It will gravitate towards the highest and best use of water because water will continue to get more expensive. There are some really positive things happening right now. I was so impressed with these young people. I think with their grit and their determination and their savvy, I think they can raise irrigated crops for a long time…it just won’t be quite how they’re doing it now.

What I tried to do in my career, was to try to get people to watch each and every day and don’t water if you don’t need to. I think what we’re gonna come to is some sort of a system out here where you decide before you plant what you’re gonna do for water savings on your entire farm. In other words, we may have to leave a certain pivot off for the year, or just plant wheat there to makes sure we hit the water savings that we need. I think that day is coming.


RESOURCES
USDA Rural Energy for America Program
Evaluating Energy Use for Pumping Irrigation Water
Water Conservation in Irrigated Agriculture: Trends and Challenges in the Face of Emerging Demands
2007 Census of Agriculture
Real Ag: Irrigation
Kansas Irrigation Trends by Danny Rogers
RELATED VOICES
Richard Wenstrom, an Early Adopter and Innovator