With each issue, Trib+Water brings you an interview with experts on water-related issues. Here is this week's subject:
Wenwei Xu is a professor and corn breeder based at the Texas A&M AgriLife Research and Extension Center at Lubbock. He directs the corn breeding program that focuses on drought tolerance, heat tolerance, insect resistance and mycotoxin contamination. Xu recently released a study on irrigation and corn silage quality. He received his Ph.D. degree in genetics from the University of Missouri-Columbia. He did his postdoctoral research at University of Missouri-Columbia and later at Texas Tech University. He worked for DeKalb Genetics Corporation from 1996 to 1998.
Editor's note: This interview has been edited for length and clarity.
Trib+Water: How did you see the impact of water on the silage of corn?
Wenwei Xu: The crop production in the Texas High Plains pretty much depends on the use of irrigation water from Ogallala Aquifer water. In that area, in the last 10 years, the dairy industry has expanded very quickly. We can import a corn ground from the Midwest, but you can’t import silage. The silage needs to be produced near by the dairy farm. Producing the silage requires a lot of water.
Our goal was to look at what is the best combination with genetics and irrigation management to maximize the production profitability and also to try to conserve the underground water.
Trib+Water: Did you know what the major factors would be, going into this study?
Xu: We know water is a significant factor, but we did not know what was the minimum irrigation water to produce the maximum yield.
Currently, the producers basically irrigate the corn crop based on the ET, the amount lost in evaporation and transpiration. We applied water at 100 percent ET, and irrigated the amount of water the plants lost through transpiration in the ground. We also had another treatment, at 75 percent, 65 percent and 50 percent ET.
The current ET estimation was established 20 years ago at 100 ET, based on the old hybrids. Now we have new genetics, and these new hybrids have a much higher water use efficiency.
We found that if you reduce the water by 25 percent, based on 100 percent ET, there was no significant yield reduction.
If you water your plants based on 100 percent ET, then you over-water the plants.
Trib+Water: How is the silage impacted by that difference?
Xu: When we look at the silage quality, there was a very limited impact from 100 percent to 75 percent ET. So if you reduce 25 percent irrigation, the yield and quality was not significantly impacted.
When we feed silage corn, we want to make sure the quality doesn’t change, the digestibility and energy. When you feed animals, you want to maintain a high quality. From 25 percent, the quality remained the same. But more than that 25 percent, and the quality becomes very poor.
Trib+Water: What does this kind of finding mean to farmers, trying to estimate the proper amount?
Xu: It means you manage the water irrigation scheduling more carefully. Using 100 percent ET in that particular environment, we applied 27 inches of water per acre, down in the Dumas area. If we take 25 percent out of that 27, we may produce the same amount if we manage the crop carefully, without reducing the quality.
Trib+Water: Why was 75 percent the right number?
Xu: Obviously when the farmers do careful measurements, they don’t do that to reduce by 25 percent, maybe only 15 percent. Based on our resources and facility, we wanted to see what happened when we reduce in that kind of range.
When we looked at dropping it from 75 percent to 65 percent, only 10 percent more, then the biomass of the yield, and quality went down significantly.
Trib+Water: What made you look into this?
Xu: I’m a corn breeder and at the Texas A&M corn program; our goal is to provide the producers the best corn hybrids and the best irrigation management practices to sustain the agriculture here. We know the Ogallala Aquifer water is declining. So we want to slow down the process and sustain production.
So the idea is that if we change change a crop by developing drought and heat tolerant corn hybrid, improve water use efficiency and optimize irrigation, we can conserve water and produce more crop products.