Some interesting research from Texas A&M AgriLife Extension has come out recently on the water-use attributes of old and new wheat varieties, and progress being made with newer releases.
The overall objective of the program is to better understand the physiological responses of different wheat genotypes to drought stress and water-limited conditions, says Dr. Qingwu Xu a crop stress physiologist for the university at Amarillo. “We have an overall goal to improve the water-use efficiency and yields of wheat,” he told AgriLife Today.
Utilizing a center-pivot irrigation system, he’s been growing the top 20 varieties for the High Plains under three to five different water treatments, ranging from dryland to limited and full irrigation, since 2011. They’re looking at the soil-water dynamics in difference varieties developed from the 1970s to the most recent, and how the soil-water extraction is correlated to yield and yield components.
They’ve found newer varieties have better capability to utilize soil water. They found the earlier wheat was using water only from the 3-4 foot soil profile in the dry season of 2011, but plots harvested in 2016 used water from 6-8 feet.
“That’s very important when you look at the roots and the soil-water dynamics,” Xue says. “In very dry seasons, the roots cannot go deep enough to take advantage of the water.” This was very evident when looking at TAM 105 compared to TAM 111 and TAM 112.
The researchers suggest the best way to improve soil-water storage is, “allow for sufficient fallow periods with good residue management,” Xue says.
Yes, that’s a start. Good residue management is certainly important to help preserve soil moisture and keep the soil surface from baking at 100 F or more and bringing soil microbial activity to a near halt. But their suggestions stopped short of mentioning no-till, and it’s not clear if tillage systems were part of this study. I’ve asked that question, and if I receive an answer I will report what I learn.
But I will have to argue that utilizing fallow and leaving a little residue on the ground isn’t enough, in most cases, to take soils to the next level with soil water storage or productivity. Many growers have realized having a living root in the ground for a longer period is needed to build organic matter and water-holding capacity for the long term, so they’re experimenting with cover crops.
It’s great to see researchers are making progress in breeding wheat varieties that can take better of advantage of water stored deeper in the soil profile. But I also think farmers who are doing more to actively improve their soil health will be more able to take advantage of these genetic advances in wheat than those who keep following the same old paradigm.
