Deanne Meyer

Ammonia Flux from Open-Lot Dairies: Development of Measurement Methodology and Emission Factors

Abstract Ammonia emissions contribute to the formation of secondary particulate matter (PM) and violations of the National Ambient Air Quality Standard. Ammonia mass concentration measurements were made in February 1999 upwind and downwind of an open-lot dairy in California, using a combination of active bubbler and passive filter samplers. Ammonia fluxes were calculated from concentrations measured at 2, 4, and 10 m above ground at three locations on the downwind edge of the dairy, using micrometeorological techniques. A new method was developed to interpolate fluxes at six additional locations from ammonia concentrations measured at a single height, providing measurements at sufficient spatial resolution along the downwind border of the dairy to account for the heterogeneity of the source. PM measured up- and downwind of the dairy demonstrated insignificant ammonium particle formation in the immediate vicinity of the dairy and negligible contribution of dissociated ammonium nitrate to measured ammonia concentrations. Ammonium nitrate concentrations measured downwind of the dairy ranged from 26 to 0.26 μg m−3 and from 2 to 43% of total PM2.5 mass concentrations. Measured ammonia fluxes showed that liquid manure retention ponds represented relatively minor sources of ammonia in winter on the dairy studied. Ammonia emission factors derived from the measurements ranged from 19 to 143 g head−1 day−1, showing an increase with warmer, drier weather and a decrease with increased relative humidity and lower temperatures.

Ammonia emission factors for open-lot dairies : Direct measurements and estimation by nitrogen intake

Abstract Ammonia (NH3) emissions contribute to the formation of secondary particulate matter (PM) 10 μm and under (PM10). Dairies are significant sources of NH3 in the San Joaquin Valley (SJV) of California, where the National Ambient Air Quality Standard for PM10 is frequently exceeded. Detailed descriptions of diets, animal demographics, and production levels were obtained for two commercial open-lot dairies in the SJV and used to compute nitrogen intake for each feeding group (g N day−1). Models derived from nutrition trials with cows, heifers, and calves were used to estimate urea-N excretion from N intake. Air NH3 concentrations were also measured at the same dairies over 1-week periods in February 1999. NH3 fluxes calculated from vertical profiles of concentrations at two or three locations downwind of the dairies were augmented with estimates of flux based on single-height concentrations measured at five or six additional downwind locations to compute NH3 emission rates. NH3 emission potentials, estimated from urea-N excretion, exceeded NH3 emission rates measured by the micrometeorological methods by 1.5- and 3-fold on the two dairies. A diurnal pattern in NH3 emission factors based on measurements showed peak emission occurring between 1:00 p.m. and 6:00 p.m. at both dairies. NH3 emission potentials and measured NH3 emission rates were higher for Dairy 2, which reported feeding heifers dietary crude protein in excess of National Research Council recommendations.

DEVELOPMENT OF STANDARD METHODS TO ESTIMATE MANURE PRODUCTION AND NUTRIENT CHARACTERISTICS FROM DAIRY CATTLE

Total collection data from many universities were pooled for statistical analyses to evaluate existing data from dairy animals and determine if one or more modifications were needed for Standard Table D384.1. Many of these studies were carried out to evaluate nutritional characteristics associated with different diets. The data collected were sufficient to evaluate total manure, total and volatile solids, and N excretion values. Some experiments had sufficient number of samples analyzed to evaluate P, K, Ca, Mg, Na, Cl, S, and micro-elements. Statistical analyses were conducted to determine if a single column value was appropriate and define the regression equations necessary to estimate excretions if the assumptions of the column inputs were not met. The results indicate that separate classifications are needed for replacement heifers and mature animals. Final classifications for replacement heifers included: milk fed calves, weaned calves weighing less than 274 kg, heifers weighing between 273 and 613 kg, and veal calves. Additionally, classifications for lactating and dry animals are needed. Previously, the estimates for manure production and nutrient excretion were based on body weight. These findings indicate that a better predictor for lactating cattle is daily milk production instead of body weight. Milk production drives feed intake in the lactating animal. It is most appropriate that estimated manure and nutrient excretion values reflect the relationship between feed intake, milk production (nutrient utilization) and nutrient excretion.

Survey of dairy housing and manure management practices in California.

In 2007, a descriptive survey was mailed to all dairies in Glenn (G) and Tulare (T) Counties to identify current and future opportunities of manure management practices on California dairies. The purpose was to provide baseline information for development of outreach curriculum and a decision support tool to quantify potential benefits of various N management options on dairy farms. Such baseline information is valuable to staff regulating dairy facilities (e.g., San Joaquin Valley Unified Air Pollution Control District and Central Valley Regional Water Quality Control Board), dairy trade association representatives, and technology vendors. Response rates for each county were similar at 29.7% (n=19; G) and 26.7% (n=88; T). Mean milking herd size averaged 570 (range 50 to 3,000) cows in G and 1,800 (range 196 to 9,286) cows in T. Survey data are reported by location due to differences between counties in herd size, housing facilities, and climate. Freestalls are common housing facilities (63.2%, G; 38.6%, T) and separated solids and corral scrapings are commonly used as bedding in freestalls (81.8% G and 79.4% T). The most common methods of manure collection were flushing and scraping (18.8%, G; 44.7%, T), only flushing (43.8%, G; 34.1%, T), or only scraping daily or less frequently than daily (37.5%, G; 20.0%, T). Most dairy farms in G (63.2%) and T (70.5%) used some method of separating solids from liquids. However, mechanical separation systems alone were used by 5.3% G and 11.4% T of dairy farms. Storage or treatment ponds were found on 95.9% of dairies. Respondents identified existing manure management practices and did not indicate any new technologies were in use or being considered for manure management. Survey results were used to describe the 2 predominant manure management pathways of manure collection, storage, treatment, and utilization. Survey results will be used to develop and disseminate targeted information on manure treatment technologies, and on-farm evaluation of implemented technologies related to anaerobic digesters, solid liquid separation, and pond additives.

Gas Emissions from Dairy Cows Fed Typical Diets of Midwest, South, and West Regions of the United States

Gas emissions were determined for dairy cows fed three diets formulated to represent feed ingredients typical of the Midwest, South, or West regions of the United States. Dairy cows were housed and monitored in 12 environmentally controlled rooms (4 cows diet). Two experiments were performed, representing two lactation stages (initial days in milk were 115 ± 39 d in Stage 1 and 216 ± 48 d in Stage 2). The results demonstrated that the combination of different dietary ingredients resulted in different gas emissions while maintaining similar dry matter intake (DMI) and milk yield (MY). Diet effect on ammonia (NH) emissions was more prominent in Stage 1. During Stage 1, cows fed the Midwest diet had the highest daily NH emission, corresponding to the highest crude protein (CP) concentration among the three regions. The differences in NH emissions (39.0%) were much larger than the percent difference in CP concentrations between diets (6.8%). Differences in N intake, N excretion, or milk urea N alone may not serve as a strong indicator of the potential to reduce NH emissions. Lower emissions of methane (CH) per unit DMI or per unit MY were observed for cows offered the South diet during Stage 1 as compared with that from cows offered the Midwest or West diets. No diet effect was observed for hydrogen sulfide (HS) emission per unit S intake, nor for nitrous oxide (NO) emission. The measured NH and CH emissions were comparable, but the NO emissions were much higher than those reported for tie-stall dairy barns in the literature.

Survey of Beef Quality Assurance on California dairies

In October 2011, a mail and online survey of California dairy personnel was conducted to assess producer familiarity with and support of the Dairy Animal Care and Quality Assurance (DACQA) program. The DACQA program addresses cattle of all ages (birth to culling) and standard practices that affect the use of dairy cattle for beef. The survey was mailed to a random sample of 1,071 California dairies (65%) stratified by county, proportional to the number of dairies in each respective county. Data from the 158 responses received (15%) showed that 90% of culled cows on California dairies were sold for beef. However, personnel on more than one-half of California dairies (56%) had no knowledge of how their herd cull cows ranked in terms of beef quality measures (body condition score, US Department of Agriculture carcass grade, and hot carcass weight). Survey results showed that a considerable proportion of California dairy personnel were aware of recommended injection practices including a preference for subcutaneous injections (45%). A drug inventory was maintained on approximately 50% of the states dairies. Management at these dairies was twice as likely to test for drug residues compared with dairies that did not maintain a drug inventory. More information about the DACQA program was requested by more than half of California dairies.

A survey of silage management practices on California dairies

The aim of the present study was to gather baseline information on corn silage-management practices to develop an outreach curriculum for dairy producers and growers. In spring 2013, dairy producers in the San Joaquin Valley (California) were surveyed on their silage-management practices. Response rate was 14.5% (n=160) and herd size averaged 1,512 milking cows. Harvest date was set solely by the dairy producer (53.4%) or with the assistance of the crop manager, custom chopper, or nutritionist (23.3%). On some dairies (23.3%), the dairy producer delegated the harvest date decision. Most dairies (75.0%) estimated crop dry matter before harvest, and the preferred method was milk line evaluation. Dairy producers were mostly unfamiliar with harvest rate but the number [1 (35.9%), 2 (50.3%), or 3 to 5 (13.8%)] and size [6-row (17.7%), 8-row (67.3%), or 10-row (15.0%)] of choppers working simultaneously was reported. Most dairies used a single packing tractor (68.8%) and weighed every load of fresh chopped corn delivered to the silage pit (62%). During harvest, dry matter (66.9%), particle length (80.4%), and kernel processing (92.5%) were monitored. Most dairies completed filling their largest silage structure in less than 3 d (48.5%) or in 4 to 7 d (30.9%). Silage covering was completed no later than 7 2h after structure completion in all dairies, and was often completed within 24 h (68.8%). Packed forage was covered as filled in 19.6% of dairies. Temporary covers were used on some dairies (51.0%), with filling durations of 1 to 60 d. When temporary covers were not used, structures were filled in no more than 15 d. After structure closure, silage feedout started in 1 to 3 wk (44.4%), 4 to 5 wk (31.4%), or 8 or more wk (24.2%). Future considerations included increasing the silage storage area (55.9%), increasing the number of packing tractors (37.0%), planting brown mid-rib varieties (34.4%), buying a defacer to remove silage (33.1%), and creating drive-over piles (32.6%). Survey results will serve to develop and disseminate targeted information on silage management practices at harvest, packing, covering, and feedout on Californias San Joaquin Valley dairies.

How to Improve Your Preliminary Dairy Facility Assessment Ratio

Author(s): Meyer, Deanne; Menke, John | Abstract: This publication briefly describes opportunities for dairy operators to improve facility nutrient balance based on the results of the preliminary dairy facility assessment (PDFA), so they can better meet May 2007 requirements for the Central Valley.

California Dairy Quality Assurance Program Environmental Stewardship Certification

The California Dairy Quality Assurance Program Environmental Stewardship Partnership consists of 17 groups, agencies, organizations, and academia. Quarterly meetings are held to improve communications between regulatory agency staff and industry representatives. This voluntary program strives to improve the environment. Compliance through education is the primary objective of the program. Resources from the dairy industry, Federal and State sources, academia, the California Department of Food and Agriculture, and USDA Natural Resources Conservation Service are leveraged to improve producer understanding of environmental regulatory obligations. The program includes classroom teaching, technical assistance, and independent third party evaluations. Environmental Stewardship courses and short courses address compliance issues. The water short course addresses facilities and infrastructure, liquid and solid manure holding capacity, emergency management plans, pollution prevention plans, risk assessment, and an introduction to nutrient management. Once individual Regional Water Quality Control Boards adopt new permits to implement the CAFO rule the short course will be modified to address new requirements. The final Nutrient Management Plan for California will most probably be far more detailed than the requirements identified in the CAFO Rule. Primary environmental problems are nitrate and salt contamination of groundwater. Elevated P concentrations may be a particular concern in some fields but in general, are not a key concern to water regulatory agencies. The air course addressed regulatory concerns, risk assessment, completion of permit application (Title V) and completion of Conservation Management Practices document if needed (2004). On farm evaluations are conducted by individuals working for the Department of Food and Agriculture who are additionally trained in environmental issues. Producers with facilities that are in compliance with Federal, State and Local regulations can certify in Environmental Stewardship and receive a 50% reduction in water permit fees.