Over the last few years Californians have grappled with how to manage lands during times of both drought and plentiful rainfall. At SFREC and on Central Valley rangelands, one question is whether management that promotes high forage in wet years alters ecosystem resilience in dry years. For example, promoting highly productive grasses is a common goal. While drought years can negatively affect productive grasses, less productive species, particularly forbs like filaree, do relatively well in drought years due to decreased competition. Over the last several years the Suding lab and SFREC crew have been building ever-larger drought manipulations to test how different management practices, and associated species mixes, affect forage across good and bad rainfall years.

 

In the first iteration of this project, we looked at how grazing practices and rainfall interact to affect forage over dry and wet years. We hypothesized that grazing practices that maintained a diverse mix of grasses and forbs would promote more stable forage across wet and dry conditions. To test this, we first varied grazing intensity over four years within a pasture to describe how grazing alters grass and forb abundances (Figure 1a). Second, we implemented rainout shelters and irrigation over three years to create “dry” and “wet” plots within areas of different grazing histories (Figure 1b). We found that moderate grazing practices maintained a diverse mix of grass and forb species. This mixture better maintained vegetation cover and biomass across rainfall conditions compared to low-grazed areas dominated only by grasses (Figure 2) (Hallett, Stein, Suding conditionally accepted, Oecologia).

 

In the second iteration of this project, we are exploring how rainfall timing alters grassland diversity and forage production. We hypothesized that early-season drought will alter which species recruit that year, with higher forb abundance in dry falls and higher grass abundance in wet years, whereas late-season drought would reduce overall production. To test this, we have implemented large shelters with roofs that are pulled in place to create early-season, late-season and continuous drought as well as a control (Figure 3). We are finding that periodic early-season drought helps to maintain forb diversity in California rangelands. Working with Dr. Whendee Silver, we are also testing the effect of rainfall timing on nutrient cycling and greenhouse gas emissions. We are finding that previous-season rainfall as well as current season alters greenhouse gas emissions, which may be important for managing rangelands for multiple ecosystem services going into the future.

The Sierra Foothill Research and Extension Center in Browns Valley, CA utilizes 130 acres of summer irrigated pasture for cattle grazing. SFREC's irrigation water is supplied by a local water district via pipelines and open ditch distribution sources. The irrigation delivery system applies water through sprinklers, open ditches, and gated pipes. Each irrigated pasture at SFREC is managed for 1) Forage Production, 2) Water Quality, and 3) Soil Quality.

SFREC staff measures forage production in 15 enclosed cages throughout five different irrigated pastures. The treatments within each cage include leaving 4-6 inches of residual grass and measuring Total Forage Production (TFP). Guidelines for general irrigation and pasture management production based on past and current research recommend leaving 4 to 6 inches of residue/grass growth after each grazing period. The basis of this recommendation is to increase forage production (by leaving increased amounts of foliar surface area), improve root development, decrease weeds, cause less stress for forage grasses and increase water infiltration. Total Forage Production is measured by clipping the grass all the way to the ground. This center project is measuring the two treatments (4-6 inches & TFP) on their respective pounds/acre production. Each month (from April through October) forage is clipped from each cage, dried, and weighed (pounds/acre). After the samples are clipped, each enclosed area is leveled to its prescriptive treatment.

During the last two years of field sampling on irrigated pasture at SFREC, there was an increase in forage diversity in the Total Forage Production subplot. Clovers, birdsfoot trefoil, and filaree became increasingly abundant due to the increased sunlight and less crowding from competitive grasses. While the increase in clover and other forbes growth lends to an increase in forage quality, there is an overall decrease in forage production per acre in the TFP treatments when compared to the treatments with 4-6 inches of residual grass.

Numerous other factors can potentially impact irrigated pasture forage growth. Fertilization (rates, composition, timing), irrigation (frequency, amount, duration), grazing (stocking density, class/age of animal), species composition, physical structures (water location, loafing areas, rubbing zones, mineral location), soil properties, aspect,  and slope, are other important components to manage or consider.

On Wednesday, October 5th, SFREC hosted over 170 high school students enrolled in FFA and 4-H programs across six counties for the 3rd Annual Beef & Range Field Day. Students had the unique opportunity to engage with UC researchers and industry leaders, exploring key topics related to beef cattle and rangeland management.

The field day kicked off with a keynote address by Congressman, John Garamendi (CA-3), who spoke with students about the roles they will be able to pursue within agriculture and food productution as they chart out their future careers. Garamendi encouraged his audience to think outside of the box when it comes to creating solutions to the many challenges agriculture will face in years to come.

Following this address the students rotated through five hands-on learning demonstrations developed by UC researchers that explored major topics in beef cattle and rangeland management. Dr. Nancy Martin, DVM, discussed health issues in beef cattle with Dr. John Angelos from the UC Davis School of Veterinary Medicine following up by highlighting his research in the development of a vaccine for pink eye in cattle. UCCE Farm Advisor, Jeff Stackhouse discussed the use of technology in managing livestock and wildlife, while Dr. Roberto Sainz of the UC Davis Department of Animal Science explored the ruminant digestive system. Roger Ingram, UCCE Advisor in Placer/Nevada/Yuba & Sutter counties demonstrated principles related to dryland and irrigated pasture management. Students had the opportunity to evaluate soil properties, classify rangeland plants and observe beef cattle grazing behavior.

This event was made possible by the following Sponsors: PG&E, Yuba-Sutter Farm Bureau, California Beef Council and Farm Credit West. We are grateful for this generous support. The time donated by FFA leaders and UC staff was instrumental in making the third year of this annual event a major success and a great opportunity for students to interact with ongoing research led by the University of California.   

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Over the past 15 years there has been an increase in the craft beers trade and contruction of micro-breweries throughout the North State. One of the byproducts of the brewing process is wet brewers grain (WBG), which must be disposed of in a biohazard manner because it has been through the fermentation process. Disposal can be costly for breweries; however, WBG is an excellent source of protein and energy for cattle. Thus, utilizing WBG as a feedstuff for cattle grazing annual rangelands may provide an additional source of income for breweries and significant cost savings for cattle producers.

Researchers in the College of Agriculture at CSU, Chico in collaboration with Sierra Nevada Brewing Company (Chico, CA), UC Cooperative Extension agents, Glenn Nader and Josh Davy, and the Sierra Foothill Research and Extension Center (SFREC) are working to determine the effect of supplementing nursing cows with either WBG or molasses tubs on cow body condition, reproduction, and calf performance.

During the 2014 and 2015 grazing seasons (i.e., ~ November 1 - January 30), 50 angus-influenced cows and their calves were randomly sorted into two treatment groups. Control cows received ad libitum access to a 29% CP (crude protein) molasses protein tub and the treatment group was supplemented three times per week with WBG (29% CP). Both the control and treatment supplements offered 1.5 lbs CP/hd./day. Cow body weight, body condition scores, and calf body weight were collected in 28 day intervals.

The third and final supplement study will begin this November at SFREC; however, preliminary results indicate that WBG is an efficient source of protein for cows grazing winter annual rangeland. In addition to investigating this important nutritional interaction, this collaboration has provided an excellent outdoor classroom for Chico State students pursuing a degree in animal science and land resource management. Students are able to gain hands-on research experience by helping to collect animal performance data as well as vegetation samples from the pastures where the cows are grazing.