- Author: Nikolai Schweitzer
- Author: Nikolai Schweitzer
Sierra Foothill REC has been collecting and recording rangeland forage production data since 1979. Every year when rangeland forage production values are recorded, explanations as to the results of pounds per acre grown are based on past forage production values & statistics, plus a CIMIS weather station which resides at 660' elevation; whereas, the Forage Plot lies at 1470' and 1.3 miles away from #084 Browns Valley CIMIS Station. SFREC has recently installed replicated soil temperature sensors (5-10 cm in depth), soil water content sensors (5-10 cm, 25-35 cm, & 56-65 cm in depth), air temperature sensors, and a precipitation gauge. Two replicated soil sensor stations were each placed under canopy and in the open. Illustrated below are tables and graphs depicting rangeland forage production values and trends, newly installed soil sensor data (Open and Canopy), and a dramatic comparison (Forage Plot vs. CIMIS) in precipitation values.
There were two major developments during this rangeland forage production season (Nov 1, 2017 thru March 1, 2018). The first being that we had the highest level of forage production for the month of February (1637 lbs/ac) in our recorded history. The warm February we had may be a contributing factor to this. The other major development is the significant differences in monthly/total precipitation values between the CIMIS and the forage plot.
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- Author: Dustin Flavell
Samples taken in the SFREC's forage plot through the month of January (Clipped on Feb. 1) indicated 943 lbs/ac. This is 183% of the 34 year average of 516 lbs/ac. Our rain gauge indicates that we have received 28.14 inches of precipitation as of October 7th, only 0.3 inches shy of our total season precipitation average of 28.48 inches.
Will this productive start to the season mean a bigger peak crop? Perhaps not, looking at recent years that had similar germination forage values and similar forage production through January, this may not be the case. In the 2012-13 forage season (highlighted red) forage production through January was very similar. However, at the end of the forage growing season, peak standing crop was average. Looking at 2005-06 (highlighted yellow) there was a later first germination of November 7th, and near average forage production at 404 lbs/ac. It is more similar to this year, however, because the forage production through January was 983 lbs/ac, and that year ended with 139% of the average total season forage production.
In my 16 years of measuring production and reviewing the data, one thing is for certain. Predicting overall forage production in the early part of the growing season is difficult. Measurements taken in February, and even March, do not indicate a clear path as to how a forage production season will end up at peak standing crop. Click here to further explore over 30 years of forage production and weather data at SFREC. Looking at our production through April will certainly produce a clearer, more predictable picture of how this current year may end up.
- Author: Lauren Hallett
- Author: Katharine Suding
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.
- Author: Nikolai Schweitzer
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.