«University of California Division of Agriculture and Natural Resources Committee of Experts on Dairy Manure Management September 2003 February 2004, ...»
Managing Dairy Manure
in the Central Valley of California
University of California
Division of Agriculture and Natural Resources
Committee of Experts on Dairy Manure Management
February 2004, Revised
July 2004, Revised
June 2005, Revised
University of California
Division of Agricultural and Natural Resources
Committee of Experts on Dairy Manure Management
Andrew Chang, Professor and Associate Director
Center for Water Resources, University of California
Thomas Harter, Associate CE Hydrology Specialist Department of Land, Air, and Water Resources, University of California, Davis John Letey, Professor and Director Center for Water Resources, University of California Deanne Meyer, CE Livestock Waste Management Specialist, Department of Animal Science, University of California, Davis Roland D. Meyer, CE Soil Fertility Specialist Department of Land, Air, and Water Resources, University of California, Davis Marsha Campbell Mathews, Farm Advisor UC Cooperative Extension Stanislaus County Frank Mitloehner, Assistant CE Air Quality Specialist Department of Animal Science, University of California, Davis Stu Pettygrove, CE Soils Specialist Department of Land, Air, and Water Resources, University of California, Davis Peter Robinson, CE Dairy Nutritionist Department of Animal Science, University of California, Davis Ruihong Zhang, Associate Professor Department of Agricultural and Biological Engineering, University of California, Davis Table of Contents LIST OF TABLES
LIST OF FIGURES
CHAPTER 1 - INTRODUCTION
1.1 THE DAIRY INDUSTRY IN CALIFORNIA
1.2 REGULATORY FRAMEWORK
1.3 ENVIRONMENTAL CONCERNS OF REGULATORY AGENCIES
1.4 THE ROLE OF THE UNIVERSITY OF CALIFORNIA
1.5 THE ROLE OF THIS REPORT
CHAPTER 2 - MANURE AND NITROGEN EXCRETION
2.2 METHODS TO ESTIMATE MANURE NUTRIENT EXCRETION BY COWS
2.3 UC COMMITTEE OF CONSULTANTS ESTIMATE OF NITROGEN EXCRETION BY DAIRY COWS
2.4 CALIFORNIA REGIONAL DIFFERENCES THAT EFFECT ESTIMATES OF NITROGEN EXCRETION BY DAIRY COWS
2.5 ROLE OF DIET IN NITROGEN EXCRETION BY DAIRY COWS
CHAPTER 3 - DISTRIBUTION OF MANURE ON DAIRIES
3.2 PARTITIONING OF MANURE ON SURFACES WITHIN THE DAIRY
3.3 PARTITIONING OF MANURE NUTRIENTS INTO SOLID AND LIQUID FORMS
3.4 SURFACE RUNOFF
CHAPTER 4 – ATMOSPHERIC N LOSSES FROM LIQUID DAIRY MANURE PRIOR TO LAND APPLICATION.. 28
4.2 ESTIMATING ATMOSPHERIC N LOSSES AT EXISTING DAIRIES.
4.3 POTENTIAL ATMOSPHERIC N LOSSES FROM LIQUID MANURE IN CALIFORNIA DAIRIES
CHAPTER 5 - DEVELOPING NITROGEN APPLICATION RATE GUIDELINES
5.1 NITROGEN CYCLE IN CROP FIELDS
5.2 SOURCES OF NITROGEN (NITROGEN INPUTS)
5.3 CROP N UPTAKE AND HARVEST REMOVAL
5.4 NITROGEN LOSSES
5.5 MINERALIZATION OF ORGANIC NITROGEN
5.6 LONG-TERM DYNAMICS OF THE SOIL ORGANIC NITROGEN POOL
5.7 NITROGEN RATE GUIDELINE: PUTTING IT ALL TOGETHER
5.8 NEEDS FOR FURTHER STUDY
CHAPTER 6 - PHOSPHORUS AND POTASSIUM IN MANURE APPLICATIONS
CHAPTER 7 - SALTS IN DAIRY MANURE AND SALINITY ISSUES IN LAND APPLICATION
7.2 SALT INTAKE AND EXCRETION BY LACTATING DAIRY COWS IN CALIFORNIA
7.3 FIELD SALT LOADING
7.4 AGRONOMIC IMPACTS OF SALINITY
7.5 PRODUCTION OF FEED IN THE CENTRAL VALLEY: REGIONAL SALT BALANCE ANALYSIS
List of Tables
TABLE 2-1: 1973 WATER QUALITY TASK FORCE OF THE UC COMMITTEE OF CONSULTANTS ESTIMATE OF TOTAL
MANURE AND N EXCRETION OF DAIRY COWS IN CALIFORNIA. N EXCRETION WAS OBTAINED FROM THE
DIFFERENCE BETWEEN INTAKE AND OUTPUT. ALTHOUGH PHYSIOLOGICALLY NOT ACCURATE (SOME OF THE NGOES TO ANIMAL GROWTH), IT IS A REASONABLE APPROXIMATION FOR ADULT ANIMALS.
TABLE 2-2: N BALANCE OF LACTATING DAIRY COWS IN CALIFORNIA
TABLE 3-1: SUMMARY OF ESTIMATED RESIDENCE TIME FOR MILKING COWS ON CONCRETE SURFACES AND ESTIMATEDPERCENT OF MANURE COLLECTED AS A LIQUID
TABLE 3-2: PARTICLE SIZE DISTRIBUTION OF FRESHLY COLLECTED DAIRY MANURE
TABLE 4-1: NITROGEN EMISSION CALCULATIONS FROM LAGOONS
TABLE 4-2: ESTIMATED ATMOSPHERIC N LOSS (KG N/HEAD/YR) FROM DAIRY MANURE IN THE PRODUCTION AREA OF ATYPICAL FREESTALL DAIRY IN THE SJV ASSUMING 169 KG N EXCRETED/COW/YR
TABLE 5-1: DAIRY FORAGE FIELD N INPUTS AND HARVEST REMOVALS.
TABLE 5-2: TOTAL NITROGEN INPUT [IN LBS N/A] FROM IRRIGATION WATER APPLICATION AS A FUNCTION OF THE
NITRATE-N CONCENTRATION IN THE IRRIGATION WATER (LEFT COLUMN) AND OF THE AMOUNT OF IRRIGATION
WATER APPLIED (TOP ROW). IN METRIC UNITS, 1 MG/L NITRATE-N IN 10 CM IRRIGATION WATER IS EQUIVALENTTO 1 KG N/HA
TABLE 5-3: PERCENT OF TOTAL MID-APRIL NITROGEN UPTAKE IN N. SAN JOAQUIN VALLEY BY PERIOD..................39
TABLE 5-4: RANGE OF ESTIMATED LOSSES OF N INPUTS TO FORAGE CROPS IN THE CENTRAL VALLEY BASED ONLITERATURE VALUES
TABLE 6-1: THE PHOSPHORUS (AS P2O5) BALANCE OF BIFS DAIRIES DURING 20001.
TABLE 6-2: THE POTASSIUM (AS K2O) BALANCE OF BIFS DAIRIES DURING 20001
TABLE 7-1: APPROXIMATE RANGE OF NITROGEN AND SALT EXCRETION [KG/HA/YEAR] AS A FUNCTION OF THE ANNUAL
CROP NITROGEN UPTAKE [KG/HA/YEAR]. RANGES OF NIR AND N LOSSES ASSUMED ARE DESCRIBED IN CHAPTERS
4 AND 5. IN THIS TABLE, “SALTS” REFERS TO THE SUM OF K, NA, AND CL ONLY AND DOES NOT INCLUDE CA,MG, HCO3, SO4, AND N AND P SALTS (SEE ABOVE)
TABLE 7-2: SALT LOADING OF DAIRY WASTEWATER APPLICATION FIELDS AFTER ADJUSTING FOR K UPTAKE.............58
TABLE 7-3: GROSS VALUES OF ALFALFA HAY PRODUCTION IN SAN JOAQUIN VALLEY AND SOUTHERN CALIFORNIACOUNTIES IN 2001 – 02.+
TABLE 7-4: PRODUCTION ACREAGES OF SELECTED CROPS IN FRESNO COUNTY IN 2002.
TABLE 7-5: PRODUCTION ACREAGES OF SELECTED CROPS IN KERN COUNTY IN 2002
TABLE 7-6: PRODUCTION ACREAGES OF SELECTED CROPS IN MERCED COUNTY IN 2002
List of Figures
FIGURE 3-1: PARTICLE SIZE DISTRIBUTION IN THE FECES AND URINE OF FOUR MILKING COWS THAT WERE FED
ALFALFA BASED TOTAL MIXED RATIONS. FECAL DRY MATTER CAN REPRESENT 88% TO 95% OF DAILY DRYMATTER.
FIGURE 3-2: NITROGEN DISTRIBUTION AMONG PARTICLE SIZES IN FOUR MILKING COWS THAT WERE FED ALFALFA
BASED TOTAL MIXED RATIONS. MOST OF THE NITROGEN IN FECAL MATTER IS ASSOCIATED WITH THE SMALLEST
PARTICLE SIZES. NOTE THAT FECAL N REPRESENTS ONLY 35% TO 50% OF THE TOTAL DAILY N EXCRETION (THEREMAINDER BEING IN URINE). SHOWN HERE ARE RESULTS FOR TOTAL MANURE (FECES + URINE).
FIG. 5-1: MAJOR COMPONENTS OF THE NITROGEN CYCLE IN A FORAGE CROP FERTILIZED WITH DAIRY MANURE ANDCOMMERCIAL FERTILIZER.
FIG. 5-2: POTENTIAL N UPTAKE RATE OF FOR SILAGE-CORN/WINTER FORAGE DOUBLE CROP IN THE CENTRAL VALLEYOF CALIFORNIA
FIG. 5-3: HYPOTHETICAL N BALANCE FOR A FORAGE CROP FERTILIZED WITH DAIRY MANURE AND COMMERCIAL
FERTILIZER. BASED ON 100 LBS N REMOVED IN HARVESTED CROP. N LOSSES BY DENITRIFICATION, LEACHING,AND MANURE AMMONIA VOLATILIZATION ARE SET AT 10%, 15%, AND 15%, RESPECTIVELY. N IN HARVESTED
CROP EQUALS 85% OF TOTAL PLANT N UPTAKE. DIRECT LOSS OF AMMONIA FROM PLANTS IS ASSUMED TO BEZERO.
Appendix A: Example Dairy Nitrogen Production Appendix B: Mass Transfer-based Mathematical Model for Ammonia Volatilization from Lagoons Appendix C: Illustration of Nitrogen Leaching Losses in Manured Systems subject to Organic Nitrogen Mineralization Appendix D: Mineralization – Conceptual Model and Field Studies Appendix E: Nitrogen Mineralization Dynamics in Soils Receiving Dairy Manure Appendix F: Field Studies of N Use Efficiencies Appendix G: Reality Check - Nitrogen Mineralization and Leaching Losses Estimated from Shallow Groundwater Observations in a Dairy System with Sandy Soils Appendix H: Fate of Liquid Dairy Manure Nitrogen in an Irrigated Double Crop CornGrain Rotation, California Appendix I: California Biosolids Mineralization Research Appendix J: Salt Balances of Fields Receiving Dairy Wastewater Applications
There are approximately 1.7 million lactating dairy cows in California. Sale of milk from these cows is estimated at $4.6 billion of the state’s $30 billion agricultural market. Nearly 73% of the cows are located in the San Joaquin Valley, which consists of San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare and Kern counties. The Central Valley Regional Water Quality Control Board submitted a list of questions to Vice President Gomes requesting specific information related to dairy manure. The answers to these questions are the basis for this report.
The responsibility of the Committee was to answer these questions and, in areas where data were not available, conduct research (if short term research would provide insight) or work toward long term research objectives to provide more complete answers for the future. The following lists the original six groups of questions with a summary answer of the committee to these questions.
2. Nitrogen Excretion
A. How much N is excreted by the average lactating dairy cow?
B. How much N is excreted by dry stock?
C. Are there regional differences in California and, if so, what factors should be applied to design criteria for lactating and dry cows due to the geographic area of the dairy?
D. Does diet play a role in the amount of N excreted and, if so, what are the adjustments that should be made in N generation rates based on various common diets?
The recommended average excretion of N by lactating dairy cows in California is 462 g N/head/day, and by dry cows it is 195 g/head/day. However the Committee stresses that these are average numbers, that the trend will be to higher values in the future as milk production per cow increases, that actual values will vary sharply among dairies, and that there are techniques available to make very accurate site specific estimates.
Short of measuring feed intake N, which allows for highly accurate estimates of manure N excretion using, e.g., the UC Dairy Animal Waste Model, the Committee believes that expressing manure N excretion relative to milk production, rather than body weight or ‘animal units’, is the biologically most sensible assessor on within site efficiency of animal N use, as manure nutrient production is primarily a function of feed intake and feed intake is primarily a function of milk yield. There is no evidence that regional differences in California are of a sufficient magnitude to require additional region specific design criteria for dairy farms.
Dairies feeding better formulated diets will tend to have higher efficiencies (i.e., the lowest N excretion relative to milk production) while poorly managed dairies, where cows may be fed poorly formulated diets, will tend to have lower efficiencies (i.e., the highest N excretion relative to milk production). In contrast, the better managed dairies with higher per cow milk production will tend to have the highest manure N excretion per cow, thereby demonstrating the error in expressing manure N excretion on a per cow basis, rather than on the basis of milk produced.
There is no evidence that diet formulation principles that are based upon nutrients differ among regions of California, even if the cost effective access to different feedstuffs varies among regions. Hence, different ‘region typical’ diets need not be considered.
3. Manure Distribution Three categories describe most cow and manure management systems in California, these being freestalls with flush systems, corrals with flush alleys, and corrals with no flush alleys. Dairies frequently have more than one type of management system.
A. What percentage of each type of waste enters the retention ponds, and what part remains in corrals, under the three operations?
B. How much N is carried with rainwater from the corrals into the liquid waste storage?
Manure distribution patterns vary depending on the facility infrastructure and operational and managerial decisions. Most likely, the manure distribution pattern will not be the same in any two dairies. Even within the same dairy, the deposition pattern shifts as operational parameters change. The amount of manure collected in liquid will vary from 8% (only manure excreted in the milking parlor) to 100% (manure from animals always living on concrete). More intensively managed systems (freestalls) will collect 42 to 100% of manure on a daily, monthly, or yearly basis.
There are no specific data to quantify the nutrients carried from the corral to the retention pond as a result of rain runoff. Data from Florida suggest this number is minimal.
Solids removal from mechanical and gravity flow separation systems are quite poor (under 25%) to good (consistently 50%). However, nutrient removal cannot be described based on a percent of solids removed. Soluble nutrients and salts predominantly remain in the liquid system.
4. Nitrogen losses
A. How much N is lost between generation and land application of the liquid waste under different waste handling scenarios?
B. How much N is removed with solids separation, and is there a difference when mechanical as opposed to gravity separators are used?