Testing the variety weather

By Clark Neely

In 2020, the WSU Extension Cereal Variety Testing Program (VTP) teamed up with the Washington State University (WSU) AgWeatherNet Program (AWN) to install weather stations near variety trials around Eastern Washington. Between winter and spring variety trials, the VTP manages 27 different locations. Efforts in the past have installed stations in close proximity to some of these sites, but not all.

Out of the 27 locations, about 15 were five or more miles away from the nearest station and some as many as 20 miles away. Because topography and weather vary considerably over short distances in the Pacific Northwest, five miles can make a big difference. With funding support from the Washington Grain Commission, U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) and the Lincoln County Association of Wheat Growers, new weather stations were purchased and installed at all 15 remaining trial locations.

As most growers know, wheat end-use quality can be greatly influenced by environment, especially when it comes to grain protein and falling numbers. Of particular interest are conditions responsible for the expression of late maturity alpha-amylase (LMA) and preharvest sprouting (PHS), two causes of low falling numbers. Researchers believe sharp swings in air temperature or simply cool temperatures during the soft dough stage of grain filling can trigger LMA in certain varieties. Much remains to be learned about the exact temperature or humidity conditions that cause LMA in northwest wheat.

Preharvest sprouting is triggered by rain before harvest. However, weather during grain development can impact the degree of grain dormancy and susceptibility to preharvest sprouting when it rains before harvest. Moreover, there is interest in learning if heavy dew or fog can trigger PHS in wheat.

Dr. Camille Steber with USDA-ARS in Pullman, Wash., specializes in this field and has documented and shared falling number data from the WSU variety trials since 2013. She has used VTP and AWN data to examine whether low falling numbers was caused by LMA or PHS. However, site-specific weather data was not always available, and that limited her ability to home in on exact conditions that triggered the low falling numbers problem. Her research has documented trends in certain varieties that are more prone to low falling numbers and led to changes in planted varieties across the state. In the future, this additional weather data could contribute to models used to predict when LMA will occur and for which varieties. This would be incredibly useful to breeders and researchers, as well as growers and elevators. The ability to anticipate grain quality issues before harvest would help growers and elevators with marketing and storage plans.

In addition to LMA and PHS, other researchers will invariably benefit from the additional weather stations, including anyone interested in disease or insect outbreak forecasts. A group of researchers at WSU are also pairing the weather data with growth notes from variety trials to help develop a tool that would model wheat crop growth in order to notify growers when critical growth stages are going to occur and when to apply fertilizer or pesticides. In the meantime, local growers and the VTP benefit from simply having real-time, site-specific weather data to plan field activities for spraying and fertilizing, and season-long precipitation will be value-added data to pair with yield or other performance data from the variety trials themselves.

Major advancements in technology and cost made now a good time to add weather stations. The new, all-in-one weather station, “Atmos 41” by the METER Group, combined with the ZL6 datalogger, makes these “Tier 2” stations comparable to weather data acquired from “Tier 1” professional stations (Campbell datalogger and individual sensors mounted on a tripod or tower). Accuracy between Tier 1 and Tier 2 stations is essentially the same, the differences being that Tier 1 stations have the capability of recording data in five minute intervals compared to every 15 minutes for Tier 2, and wind speed is recorded at 10 meter height compared to a two meter height.

Another primary motivation for making the Atmos 41 the standard station for Tier 2 sites in the AWN program was reduced maintenance. The design of this station is completely sealed to insect intrusion with no moving parts to wear out. The associated ZL6 datalogger has a built-in solar panel and runs on AA rechargeable batteries. Measurements collected by the Atmos 41 includes air temperature; dewpoint; vapor pressure; barometric pressure; wind speed and direction; solar radiation; precipitation; leaf wetness; soil temperature; and soil water potential.

Internet connection is achieved through wireless cellphone service with very little bandwidth needed. As cell phone towers and coverage continue to increase, so has the range of sites that stations can be placed. Still, there are numerous places in Eastern Washington with limited connectivity, but in some cases, the AWN was able to alleviate the problem by installing a directional antennae to boost reception.

In addition to the newly purchased stations, the VTP is working closely with the AWN program to identify cooperators when other stations need to be moved for various reasons. This mutually benefits AWN by providing reliable contacts to host stations on their property and the VTP by moving stations closer to variety trials in some cases.

This article originally appeared in the July 2021 issue of Wheat Life Magazine.

Picture of Clark Neely, Ph.D.

Clark Neely, Ph.D.

Clark Neely is the cereal variety testing lead and extension agronomist at Washington State University. His research interests include dryland cropping systems and advancing cereal variety testing. Read more about Dr. Neely.

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