- Author: Helen Dahlke
To overcome the problems that have plagued traditional tracer studies we have developed a new tracer concept that utilizes bio-molecular nanotechnology. We use short, artificially made DNA sequences that are wrapped into a safe, biodegradable polymer composed of polylactic acid (PLA) to protect the DNA from being eaten by microbes during the transport process. Because DNA is made of the four basic building blocks adenine (A), thymine (T), guanine (G) and cytosine (C) (Fig. 1), which can be combined in any random order, our unique DNA-based tracers allow, in theory, fabrication of an enormous number of unique tracers (approximately 1.61 x 1060) with identical transport properties. Because of their unique DNA sequence the tracers have unique IDs, thus, we can use multiple tracers at the same time in the same watershed. The amount of tracer present in a streamwater sample can be estimated with real-time quantitative polymerase chain reaction (qPCR), a method commonly used in molecular biology, which determines the number of DNA copies present in a sample. Finally, during the tracer fabrication process, we can alter the size of the tracer particles to anything from 200 nanometers (size of a virus) to 1 micrometer (size of colloids or bacteria), which helps mimicking the physical transport properties of the pollutant of interest.
In the next two years we will test differently sized DNA tracers in a well-studied, small experimental watershed at SFREC to test their use for identifying hydrologic flow pathways. This study will provide invaluable information for the understanding of processes in hydrologic systems that can be used to improve hydrological and biogeochmical models used to predict transport of pollutants from hillslopes to streams. To achieve this broader goal, we will distribute 5 different DNA tracers at 5 different locations at incrementally increasing distances from a trenched hillslope at SFREC and measure the tracer breakthrough curves in a runoff collection system and the watershed outlet. The injection locations will be chosen to represent a range of specific soil-landscape characteristics such as places with relatively deep soils, shallow soils and areas where flow visually concentrates in the landscape. With the tracer experiments we also hope to quantify preferential flow pathways (e.g. macropore flow) in the watershed. Preferential flow is hypothesized to lead to shorter travel times of water and pollutants through soils and the vadose zone. Because of the variable size of our DNA tracers (0.1-0.4 µm) they could be particularly useful for quantifying macropore and preferential flow because we expect that a small fraction of the tracers will be filtered out in the soil matrix while the majority of the DNA tracers will move along the most rapid flow pathways. The results from these experiments, if successful, will provide improved estimates of the time it takes for water and solutes to travel through the soil to streams, which will allow us to more accurately predict the risk of pollution of streams and surface water bodies during storm events.
- Author: Ben Granholm
Nearly 60 individuals gathered at SFREC for the 6th Annual Lower Yuba River Accord Symposium on July 15th to dive into the history, management and future of the Lower Yuba River. Attendees listened to presentations and asked questions of those involved in the river's preservation.
Speaking on the goals of the River Management Team and the current Monitoring and Evaluation Program, Tom Johnson of the Yuba County Water Agency discussed efforts to develop optimum flow schedules, record temperature performance and ensure the smooth implementation of Yuba Accord operations.
Looking at the year-round temperatures of the Yuba River, Casey Campos and Duane Massa with the Pacific States Marine Fisheries Commission, talked of what these temperatures mean for the spawning and livelihood of fish inhabiting the river, particularly the habitats of the Chinook salmon. Campos explained that the Yuba River is among the coldest in the Central Valley.
Symposium coordinators, Gary Reedy of the South Yuba River Citizen League spoke on the need for habitat enhancement, giving a summary of previous actions, while Beth Campbell of the U.S. Fish & Wildlife Service (FWS) discussed enhancement initiatives implemented by FWS.
The symposium concluded with lunch at the Yuba River Education Center, followed by a float down the beautiful Yuba River.
- Contributors: Madison Easley, Larry Forero and Nikolai Schweitzer
For this project, researchers and staff regularly monitor and assess four factors associated with the production of foothill flood irrigated pasture utilizing pipe and ditch delivery methods. These factors include the amount of water applied to the pasture, the amount of water run-off, the effectiveness of irrigation, and the production of the pasture (measured in biomass and AUM harvest).
Preliminary findings indicate that the interval between irrigations could be lengthened in the fall as the days shorten and become cooler. Fewer applications result in less water being used, saving ranchers time, money, and stress. The monitoring for this project will continue through the summer and fall, so check back for additional updates.
With July being “Smart Irrigation Month” this is the time for ranchers to explore opportunities for more efficient irrigation methods using resources like those offered in this post.
- Author: Megan G Osbourn
Adaptation to changing weather and economic conditions is fundamental to farm and ranch survival but this year's drought is pushing variable adaptation strategies to their limit. The international community is closely watching how this dire situation is progressing in California and on June 19th the Canadian Broadcast Company (CBC) visited the Sierra Foothill Research & Extension Center (SFREC) to document how ranchers are adapting to these extreme events and the implications these events have on agriculture and ultimately food production worldwide. Filming involved capturing interviews of three ranchers to explore their perspectives as well as a tour of SFREC to examine potential adaptation strategies to drought.
Joe Fischer, cattle rancher and President of the Placer County Farm Bureau, told CBC the economic impacts and emotional toll of the drought on ranching families have forced ranchers to rethink their management strategies and find innovative ways to manage the land. “Ranchers tend to be profitable if the land is productive,” Fischer said. “We have to look ahead five to ten years or more and try to be as conservative as possible with our stocking rates. Under these conditions, we have a much smaller margin for error so we have to be more precise than ever with our management strategies.”
SFREC Director Jeremy James and Livestock and Natural resource Advisor Glenn Nader used SFERC as an opportunity to demonstrate how intensive grazing management, agricultural by-products and culling strategies could be deployed to mitigate some of the impacts of drought. Many producers with limited feed sources are utilizing agricultural by-products that are available in their area in order to sustain the nutritional requirements of their livestock. Nader, pointed out that almond hulls are high in energy and have limited protein, which allows cows to more efficiently digest hay and can limit the quantity of hay they need to consume. Nader warned that the almond hulls fed must contain a low level of almond shell, in order to avoid problems with rumen digestibility. Rice straw and rice bran are more local agricultural by-products that, under the right conditions, have been utilized as dietary supplements for cattle.
To view the proceedings from the January 29th SFREC Drought Workshop, click here.
- Author: Maddison Easley
Water - the focus of countless issues, headlines, and studies - is arguably a more precious resource than gold. 
Individuals involved with the University of California's Division of Agriculture and Natural Resources are actively evaluating management practices to ensure and develop water-wise irrigation methods. At the Sierra Foothill Research and Extension Center, many research projects have focused on water quality, runoff, and irrigation efficiency. A current project led by Livestock Farm Advisor Larry Forero monitors surface runoff and soil moisture content in flood irrigated pastures at SFREC. 
Gold may be in high demand - with the current value exceeding $1320 per ounce - but once water becomes scarce, it is truly priceless. By taking the initiative to research innovative water management practices and develop a better understanding of sustainable irrigation methods, SFREC and the entire UCANR division are enabling water availability and conservation for the future.
