Melvin R. George

Spatial and temporal patterns of cattle feces deposition on rangeland

The objective of this study was to identify and model environmental and management factors associated with cattle feces deposition patterns across annual rangeland watersheds in the Sierra Nevada foothills. Daily cattle fecal load accumulation rates were calculated from seasonal fecal loads measured biannually on 40 m2 permanent transects distributed across a 150.5 ha pasture in Madera County, Calif. during the 4 year period from 1995 through 1998. Associations between daily fecal load per season, livestock management, and environmental factors measured for each transect were determined using a linear mixed effects model. Cattle feces distribution patterns were significantly associated with location of livestock attractants, slope percentage, slope aspect, hydrologic position, and season. Transects located in livestock concentration areas experienced a significantly higher daily fecal load compared to transects outside of these concentration areas (P < 0.001). Percent slope was negatively associated with daily fecal load, but this association had a significant interaction with slope aspect (P = 0.02). Daily fecal load was significantly lower during the wet season compared to the dry season (P = 0.002). Daily fecal loading rates across hydrologic positions were dependent upon season. Our results illustrate the opportunities to reduce the risk of water quality contamination by strategic placement of cattle attractants, and provide a means to predict cattle feces deposition based upon inherent watershed characteristics and management factors.

Effects of cattle grazing on blue oak seedling damage and survival

Cattle grazing has been suggested as a principal cause for poor oak recruitment in Californias hardwood rangelands. This study evaluated the effects of stock density and season of grazing on blue oak (Quercus douglasii H. & A.) establishment. In December 1989, seven hundred and twenty blue oak seedlings were planted on 3-m centers in 30 plots in 3 annual grassland pastures at the Sierra Foothill Research and Extension Center east of Marysville, Calif. The treatments consisted of 3 seasons X 3 stock densities plus 1 nongrazed control. During January, April, and July of 1990, steers and heifers (mean = 318 kg) were allowed to graze 1 plot per week at low, medium, and high stock densities (2.5, 7.5, and 15.0 head/ha, respectively). Control plots were used to monitor wildlife browsing. One half of all seedling sites received an application of glyphosate prior to transplanting to eliminate grass competition. Browsing and trampling damage were estimated at the end of each treatment. Total damage (sum of browsing and trampling damage), browsing damage, trampling damage, and survival to April 1991 were significantly different for the 9 season and stock density treatments (P < 0.05). Spring and summer grazing tended to be most damaging and resulted in the lowest survival rates. Within each season total damage increased with stock density but survival did not change significantly. Weed control around oak seedlings had no apparent effect on total damage or survival. There were significant differences in browsing damage between seasons but not between control and grazed plots within seasons (P < 0.05). Survival in ungrazed plots was not significantly different (P < 0.05) from the spring and summer grazed plots. Consequently, the contribution of wildlife to reduced blue oak seedling survival in grazed oak woodlands should not be underestimated.

Effect of canopy and grazing on soil bulk density

Abstract This study compared soil surface bulk density between: 1) sites not grazed by cattle > 26 years; 2) sites not grazed for 6 years; 3) sites grazed for 15 years to October residual dry matter levels of > 1100 kg ha−1; 4) sites grazed for 15 years to October residual dry matter levels of 670 to 900 kg ha−1; 5) sites grazed for 15 years to October residual dry matter levels of < 450 kg ha−1; and 6) sites subject to concentrated cattle use (trails, corrals, and supplemental feed-water stations). Sites were collected from across the 1,772 ha San Joaquin Experimental Range (SJER) in Madera County, Calif. to represent canopy cover (open grassland, blue oak (Quercus douglasii Hook and Arn.), live oak (Quercus wislizenii A.DC.), foothill pine (Pinus sabiniana Douglas), wedgeleaf ceanothus (Ceanothus cuneatus (Hook) Nutt.), and ceanothus interspace) and topography (swale, uplands) typical of the rocky coarse sandy loam soils of the southern Sierra Nevada foothill oak savannah. Soil surface (0 to 7.62 cm) bulk density (g cm−3) was determined for 1489 soil cores collected across all available combinations of grazing management, canopy cover and topographic position at the SJER. Soil surface bulk density was 0.23 to 0.30 g cm−3 lower under canopy compared to open grasslands. Bulk density was not different (P > 0.05) between sites not grazed > 26 years and sites not grazed for 6 years. Grazing to residual dry matter levels of > 1100, 670 to 900, and < 450 kg ha−1 created bulk densities which were 0.08, 0.18, and 0.21 g cm−3 greater than non-grazed sites, respectively. Cattle concentration sites had bulk densities 0.37 to 0.47 g cm−3 greater than areas not grazed > 6 or 26 years. For the purpose of maintaining soil surface bulk density current residual dry matter recommendations for sites with canopy cover > 50% appear appropriate, but recommendations for open grasslands need additional review. In particular, residual dry matter level must be directly linked to soil surface infiltration capacity.

Cryptosporidium parvum transport from cattle fecal deposits on California rangelands.

Cryptosporidium parvum is a fecal borne protozoan parasite that can be carried by and cause gastrointestinal illness in humans, cattle, and wildlife. The illness, cryptosporidiosis, can be fatal to persons with compromised immune systems. At question is the potential for C. parvum in cattle fecal deposits on rangeland watersheds to contaminate surface water. First, C. parvum oocysts must be released from fecal deposits during rainfall, becoming available for transport. In 1996, we examined the transport of C. parvum oocysts in overland flow from fecal deposits under natural rainfall and rangeland conditions at the San Joaquin Experimental Range in Madera County, Calif. Our null hypothesis was that C. parvum oocysts are not released from fecal pats and transported 1 m downslope as overland flow with rainfall. Paired plots were located on 10, 20, and 30% slope sites. Each plot was loaded with four, 200 g fecal pats dosed with 10 5 oocysts g -1 . Pats were placed 1.0 m above the base of each plot. Composite runoff samples from each plot were analyzed for oocyst concentration following each of 4 storm events. Oocysts were transported during each storm. Slope was a significant fac tor in oocyst transport, with oocyst transport increasing with slope. Although not significant, there was an apparent flushing effect of oocysts across storms, with the majority transported in the first 2 storms. A pilot rainfall simulation experiment also revealed a flushing phenomenon from pats during individual rainfall events. C. parvum oocysts in fecal pats on rangeland can be transported from fecal deposits during rainfall events, becom ing available for transport to water-bodies. Future studies need to examine surface and subsurface transport of oocysts on range land hillslopes for distances greater than 1 m.

Viewpoint: livestock influences on riparian zones and fish habitat: literature classification.

A key was used to classify articles about livestock influences on riparian zones and fish habitat into 3 classes: papers that contained original data, those that were commentary, and reports about methodology such as classification systems, policies, and monitoring criteria. Four hundred and twenty-eight of the total articles were directly related to grazing impacts on riparian zones and fish habitat. Only 89 of these grazing impact articles were classified as experimental, where treatments were replicated and results were statistically valid. This analysis revealed several limitations of riparian grazing studies that included: (1) inadequate description of grazing management practices or treatments, (2) weak study designs, and (3) lack of pre-treatment data. More long-term, replicated treatment studies are needed in the future.

Control of Medusahead (Taeniatherum caput-medusae) Using Timely Sheep Grazing

Abstract Medusahead is among the most invasive grasses in the western United States. Selective control of this noxious winter annual grass is difficult in California grasslands, as many other desirable annual grasses and both native and nonnative broadleaf forbs are also important components of the rangeland system. Intensive grazing management using sheep is one control option. This study was designed to determine the optimal timing for sheep grazing on heavily infested medusahead sites, and to evaluate the changes in species composition with different grazing regimes. Midspring (April/May) grazing reduced medusahead cover by 86 to 100% relative to ungrazed plots, regardless of whether it was used in combination with early spring or fall grazing. Early spring (March) or fall (October to November) grazing, alone or in combination, was ineffective for control of medusahead. In addition, midspring grazing increased forb cover, native forb species richness, and overall plant diversity. At the midspring grazing timing, medusahead was in the “boot” stage, just prior to exposure of the inflorescences. The success of this timely grazing system required high animal densities for short periods. Although this approach may be effective in some areas, the timing window is fairly narrow and the animal stocking rates are high. Thus, sheep grazing is unlikely to be a practical solution for management of large medusahead infestations. Nomenclature:Medusahead, Taeniatherum caput-medusae (L.) Nevski ELYCA.

Social Associations and Dominance of Individuals in Small Herds of Cattle

Abstract A series of 6 daylight observations was made each summer and again each winter over 2 years to map cattle distribution on a California foothill pasture. Sixty animals were used in the study with no animals appearing in > 1 observation series. During daylight hours, small herds of cows containing between 14 and 16 animals were scan-sampled and videotaped every 15 minutes. A global positioning system was used to record the position of the camera to aid in accurately locating individual animals. Animal locations and individual identifications were then entered into a geographic information system (GIS) by on-screen digitizing using color orthophotographs. Animal positions were determined to be within 5 m of their true location. Association software, ASSOC1, was used to analyze animal positions to determine cattle subgroups and herd units. This position-based grouping was compared with observation-based grouping by researchers. Direct observation also identified dominant herd members. Older animals, up to 16 years of age, were generally dominant over younger animals, and subgroups tended to be composed of animals of similar age. The size of naturally occurring subgroups was between 3 and 6 animals. Some animals exhibited independence in their actions and behaviors compared with subgroup members. ASSOC1 produced grouping results consistent with direct observations. However, accurate interpretation of the ASSOC1 results depended on direct observational data. ASSOC1 identified close association patterns in 3 of the observations that defined the dominant animals in the herd. Forage availability and thermoregulatory needs influenced the distance between associated subgroup members. Distance between animals decreased when animals sought shade in summer or shelter in winter. Computer analysis of spatial data from GPS collars may be able to determine the social structure and identify dominant animals in herd situations. Incorporating knowledge of cattle social behavior should improve management of cattle on the range.

Correlation of degree-days with annual herbage yields and livestock gains

On Caiilomia’s winter a~ud r8ngdanda precipitation controls the beginning and end of the growing season while temperature Lirgely controls se8sonai growth tmtes within the growing season. Post-germination accumulated degree-days (ADD) account for the length of the growing season and variation of daily temperature. Simple correlations of ADD and herbage yield or resultant livestock gains were determined at 5 locations in ammal type range in northern California. Degree day values were determined by summing daily degree-days from the beginning of the growing season after germinating rainfail until the ciipphrg or weigh dates. Accumulated degree-days accounted for 74 to 91% of the variation in seasonal herbage yield while accumuiated days (AD) accounted for 64 to 86% of the variation. Together, ADD and AD accounted for 94 and 8696, respectively, of the variation in stocker cattle weights. Regression coefficients relating ADD to herbage yield appear to predict maximum site productivity. A procedure for estimating a seasonai herbage yield profile based on key growth curve intlection points and using shnple field observations with 3 clipping dates and ADD is proposed. Year-to-year variation in range herbage yield has frequently been attributed to variations in precipitation (Sneva and Hyder 1962). However, Duncan and Woodmansee (1978) were unable to show a relationship between herbage yield and precipitation on California annual rangeland. Pitt and Heady (1978) identified 5 annual range weather variables that explained 73% of the variation in March standing crop. Three of these variables were temperature related. Another set of 5 variables explained 90% of the variation in June standing crop. Two of these were temperature variables. The annual range growing season can be partitioned into fail, winter, and spring periods, Fall precipitation and cooling winter temperatures determine the length of the fail growing season. The duration of slow winter growth is variable depending on the beginning and ending dates of the cold season. The length of the rapid spring growth period is also variable depending on the date that warm spring temperatures begin and the date spring soil moisture becomes depleted. Thus, precipitation controls the beginning and end of the whole growing season while temperature controls the end of the fail and beginning of the spring growing season.

Predicting peak standing crop on annual range using weather variables.

Wide yearly fluctuations in peak standing crop on California annual-type range are largely explained by temperature and precipitation patterns. The objective of this study is to improve the predictability of functions relating weather patterns and peak standing crop by including degree-days, dry periods, evaporation, season start dates, and lengths and precipitation as independent variables. Peak standing crop was regressed on these independent variables for the University of California Hopland Field Station (HFS) and San Joaquin Experimental Range (SJER). Fall and winter precipitation, winter degree-days, and longest winter dry period were related to peak standing crop at HFS (R2=0.61). Spring precipitation, growing season degree-days, winter evaporation, and winter and spring start dates were related to peak standing crop at SJER (R2=.72). The relationship of peak standing crop to accumulated precipitation on 20 November using 33 years of data (r2=0.34) was weaker than previously reported for the rst 16 years (r2=0.49). This study suggests that timely prediction of peak standing crop may be possible at HFS but more difficult at SJER.

Effectiveness of nutrient supplement placement for changing beef cow distribution

Assessments of conservation effects are being conducted to determine the effectiveness of agricultural conservation practices. The practice of nutrient supplement placement to improve livestock distribution has not been designated a “best management practice” by the USDA Natural Resources Conservation Service (NRCS). Three studies in California visually and statistically document the effectiveness of nutrient supplement placement for changing livestock distribution. The initial study conducted in the Sierra Nevada foothills demonstrated that use of riparian patches could be reduced with strategic placement of dehydrated molasses supplement. A study on an adjacent ranch found that during the dry season, supplement placement effectively redistributed livestock by attracting them into a zone that extended out to about 600 m (1,980 ft) from the supplement. In a study on a coastal ranch in San Luis Obispo County, nutrient supplements were used to attract cows into an ungrazed forest adjacent to grazed grassland. The results of the studies reported here support the effectiveness of supplement placement for changing livestock distribution. Integration of supplement placement practices into best management practices and into NRCSs prescribed grazing standard is supported by this research.