Concerns about ranching and

Transcription

1 Understanding the Science of Ranch Water Quality Ken Tate UC Davis Concerns about ranching and Microbial quality Erosion and sedimentation Riparian and stream health Sensitive aquatic species Stream temperature Etc. Significant research has been conducted on CA rangelands on most of these issues, Most of it collaboratively with ranchers and range managers, Focus on microbial quality today Livestock Forage Water quality Weeds Soils Riparian Wildlife Carbon High Priority Low Survey of 500 CA ranchers, years of studies on microbial WQ?? C. parvum Microbial Water Quality & CA Range Watersheds The Big Picture Sources human Outbreaks recreational contact E. Coli O157:H7 wildlife livestock surface polluted drinking irrigated fresh food crops Salmonella companion animals shellfish consumption 1

2 Fecal Indicator Bacteria total coliforms FIB Water Quality Standards fecal coliforms indicator E. coli? Pathogens Cryptosporidium parvum Giardia duodenalis Salmonella pathogenic E. coli (Stx 1 &2, O157:H7) Fecal Indicator Bacteria (FIB) are non-pathogenic indicators regulated with intent to keep pathogens and outbreaks low. Microbial Water Quality & CA Range Watersheds Livestock Sources human wildlife livestock surface polluted Outbreaks recreational contact drinking irrigated fresh food crops Pathogens are microbes which can create disease/outbreaks and thus pose a real threat to human health. companion animals shellfish consumption 10 years of data from 8 annual rangeland sheds Stocking rate ( heavy, moderate, no grazing), and runoff long calving during rainy rainy in runoff prior to and Stream Water Quality Mean generic E. coli and fecal coliform concentrations from 4 oak woodland sheds at UC-HREC near Hopland, CA during 2001 WY. Grazing Intensity Sediment mg/l Nitrate mg/l E. Coli cfu/100ml None lb/ac RDM Moderate 800 lb/ac RDM Heavy 500 lb/ac RDM Concentratio on (cfu/100ml) Watershed E. coli fecal coliform no graze 1955 A B C D

3 Soil Bulk Den nsity (g cm 3 ) Root and H 2 O Restriction Threshold Not Grazed Light Graze Moderate Graze Heavy Graze Corral Compaction Increases Trail Trough Soil Properties Dictate Resilience to Compaction Soil Texture Root and H 2 O Restrictive Bulk Density (g/cm 3 ) Sand 1.80 Loam 1.70 Sandy Clay 1.60 Silt Loam 1.55 Clay 1.40 Steps to Maintain Soil Health 1. Get to know your soils 2. Careful with stock density sensitive soils when they are wet 3. Encourage landscape utilization with supplement and 4. Avoid continuous heavy grazing, and runoff long calving during rainy rainy in runoff prior to and Cryptosporidium dynamics in wildlife and livestock Animal % infected range beef cow 1 5* range beef calve < 4 mo 10 20* back country pack stock 0 feral pig pg 4 13 ground squirrel 7 15 *May not infect humans!, and runoff long calving during rainy rainy in runoff prior to and 3

4 Research Result Management Implication Over 60% of cattle fecal loading is near livestock attractants in summer We can position salt, feed, to attract cattle and pathogens to safe not near streams or runoff Away from creek, in with low runoff Do you know where your supplement is? Move existing supplement and Stream sites away from streams. Evaluate trails leading to and from existing and proposed sites do they link site to Supplement stream during storms? Stream Opportunity CA rangelands have great capacity to filter microbial and other pollutants ed in surface runoff Research Result >90% of E. coli retained in the fecal pat or trapped within 1 ft Rainfall An additional 70% to 99.9% trapped within 1 yard of pat cowpat We examined filtration of pollutants in pasture runoff by two wetlands stream Management Implications Keep pats out of creeks. Move cattle, pats away from critical with distribution tools. Narrow buffer strips are effective. Maintain soil infiltration rates. Moderate stocking rates. Functioning Wetland Channelized Wetland 4

5 Reduction of Pollutants due to Wetland Distribute cow pats away from streams and the whole range is a buffer Functioning wetland Channelized wetland Percent red duction fecal pat E. coli Sediment (TSS) NO 3 -N Total N Total P PO 4 -P >90% trapped at fecal pat 30-99% trapped each additional 1 yard 30-80% trapped in riparian Opportunity, and runoff long calving during rainy rainy in runoff prior to and Microbial pollutants die fast in fecal pats during Spring, Summer, Fall C. parvum survival in cow pats on range Fencing to manage grazing along streams. Research Result Translation Management Implication Days until >90% dead Fecal Pat Temperature (F) <1 104 Once temperature in a cow fecal pat exceeds 104 o F all of the C. parvum in that pat die within a matter of hours. Fecal pats in direct sun achieve 104 o F once air temperature reaches 78 o F. We can use this fact to time grazing in critical runoff so that there are enough days above 78 o F to neutralize any C. parvum in cattle fecal pats prior to rainfall and runoff. Exclusionary buffers, vegetation management for weeds, fuels, N uptake, etc. Riparian, integrate into rotational grazing program based on timing, intensity, frequency of use. 5

6 Manage time spent in and near - difficult during dry without fencing. Fencing Along Streams? Control time of use near stream. Control intensity of use near stream. May not be needed. Some Risk Factors Heavy grazing - excessive soil compaction, riparian degradation, reduced filtration, heavy fecal loading. Livestock allowed frequent contact with surface. Grazing sensitive. Fecal deposition in of high runoff. Some Opportunities Pathogen prevalence low in beef cattle, confined to certain classes. Rangelands have great capacity to filter pollutants in runoff. Pathogens can die quickly in fecal pats during spring-fall. Think tool box not silver bullet., and runoff long calving rainy during rainy in runoff prior to and California Rangeland Watershed Laboratory 6