“Slow Release Taskforce Update” Dick Harrell Nu-Gro Technologies Inc. ASFFPCO Dallas, Texas June 24 th 2003

Remembering When? The 15% rule was adopted Slow Release meant that it took a long time to get out of jail You thought chicken manure was great Growth regulator was an experimental drug that first failed when given to Kareem - Abdul - Jabbar And lastly you have been around to long if you remember Myrtle Beach

Why Did We Need A “NEW” Slow Release Rule EPA Wanting to Regulate Fertilizers Time to examine existing rules New Products Coming On to the Market

SRTF Accomplishments Acceptance of Mission and Goals 1996 Proposed Methodology 1997 “AOAC Protocol Approved” Collaborative Study Completed 1998 AAPFCO Policy Statement 1999 (pp 105 #56) “Slow Release and Stabilized Fertilizers” Revision of Methodology 2000 “Streamline Procedure & Reduce Time”

Review of Goals 1.Develop a Structure to Categorize Materials 2.Status of Current Materials Will Not Change (Any Material Currently Making Slow Release Claims Would Still Be Classified as “Slow Release”) 3.Method Can Be Run in an Analytical Laboratory 4.Method Can Be Analyzed In Less Than 7 Days 5.Method Must Be Able To Gain Wide Acceptance 6.Would Be Applicable to Both Materials & Blends 7.Can Be Correlated to Agronomic Data 8.Can Be Used to Extract Multiple Nutrients (N-P-K and Possibly Secondary & Minor Nutrients)

Revised Method Advancements Objectives Based On Collaborator Input Problem Detection Limits & Low N Concentration in Liquid Sample Specific Method Required Pressure Buildup Too Much Operator Attention Column Problems (Leaks/Temp.) Maintain Flow & Temp Control Transfer of Extract to 1 L Flask Data Calculation & Reporting Solution Increase Sample Size & Concentration Modify Extraction Solutions/Protocol Develop/Use Material Standards Balance Flows & Omit Flask in Bath Reversible Variable Speed Pump New all Glass Chrom. Column Use Flow Indicators & New Clamps Direct Collection In 500 ml Flask Modify Calculation & Fix Input Form

LABORATORY METHOD REVIEW 30 g SAMPLE IN JACKETED CHROMATOGRAPHY COLUMN UTILIZE AIR AND UPWARD SOLUTION MOVEMENT REVERSE FLOWS TO COLLECT EXTRACT 4 INCREASING AGGRESSIVE EXTRACTION SEQUENCES: EXTRACTION # 1 EXTRACTION # O C WITH WATER EXTRACTION # 2 EXTRACTION # O C WITH 0.2% CITRIC ACID EXTRACTION # 3 EXTRACTION # O C WITH 0.2% CITRIC ACID EXTRACTION # 4 EXTRACTION # O C WITH 0.2% CITRIC ACID

Jacketed Chromatography Columns Are Used In Sets of 12 to Control Temperature

Peristaltic Pumps, Flow Meters and Water Baths Control and Monitor Solvent Flows and Temperature

Recent Developments Completion of Lab Method Rewrite Additional Runs with Lab Method on New Materials and Blends Development of the Soil Correlation Incubation Method by Dr. Sartain Development of Correlation (with R 2 >0.9) Predicting Soil Method Results with Lab Data

DEVELOPMENT OF SOIL INCUBATION METHOD FOR CHARACTERIZATION OF SLOW RELEASE FERTILIZERS J.B. SARTAIN, W.L. HALL, R.C. LITTELL, AND E.W. HOPWOOD

OBJECTIVES 1. ESTABLISH RELEASE CURVES FOR SLOW RELEASE MATERIALS IN AN ACTIVE SOIL MICROBIOLOGICAL ENVIRONMENT 2. ESTABLISH A RELATIONSHIP BETWEEN SOIL INCUBATION RELEASE CURVES & LAB EXTRACTION DATA 3. PREDICT % CUMULATIVE RELEASE BASED ON LAB EXTRACTION DATA

Recent Successes Obstacle - NH 3 Volatilization –Solution - Acid Trap to Capture NH3 Obstacle - Death of Nitrifying Bacteria (high pH) –Solution - Stabilize Soil pH by Adding Citric Acid Buffer, This Controls Formation of NH3 Obstacle - Leaching of Nutrient from Soil –Solution - Three Volumes of Water Attaining Complete (> 95%) Nutrient Recovery.

APPARATUS USED inch SECTION OF 3 inch PVC PIPE WITH CAPS 2. ENVIRO CLOTH FOR SOIL SUPPORT g OF SAND AND 90 g ARREDONDO SOIL 4. ADDED 450 mg N FROM EACH N SOURCE 5. MIXED N SOURCE WITH ENTIRE SAND/SOIL MIX 6. ADDED 180 ml WATER (10%) BY WEIGHT 7. PLACED BEAKER CONTAINING 0.2 N SULFURIC ACID ON SURFACE OF SAND FOR AN AMMONIA TRAP 8. PLACED CAP ON SYSTEM AND SEALED WITH STOP-COCK GREASE 9. LEACHED WITH ONE PORE VOLUME (600 ml) OF 0.01% CITRIC ACID USING VACUUM FOR 2 MINUTES 10. LEACHED AT 7, 14, 28, 56, 84, 112, 140 AND 180 DAYS 11. DETERMINED NO 3, NH 4 AND UREA ON LEACHATES

CURVE FITTING METHODOLOGY STEP 1. FIT NON-LINEAR REGRESSION ON N RELEASE DATA TO OBTAIN ESTIMATES OF a, b AND c STEP 2. USE a, b AND c AS ‘DATA’ AND REGRESS ON EXTRACTION DATA TO OBTAIN REGRESSION EQUATIONS FOR PREDICTING a, b AND c FROM EXTRACTION DATA STEP 3. COMPUTE PREDICTED VALUES FOR a, b AND c FROM EXTRACTION DATA STEP 4. PLOT PREDICTED NON-LINEAR REGRESSION CURVE FOR EXTRACTION DATA ALONG WITH OBSERVED NON-LINEAR REGRESSION CURVE AND THE DATA.

POLYON R 2 = RELEASE CURVE R 2 = 0.99 LAB PREDICTION %N = a – b * C -ct REP 2

POLYON R 2 = RELEASE CURVE R 2 = LAB PREDICTION %N = a – b * C -ct REP 3

POLYON R 2 = RELEASE CURVE R 2 = 0.90 LAB PREDICTION REP 1

CONCLUSIONS 1. SOIL INCUBATION METHODOLOGY A. NO VOLATILE AMMONIA B. 97% OF APPLIED SOLUBLE N RECOVERED C. NITRIFICATION OCCURRING - MICROBES ACTIVE D. CV = 9.07% E. %N = a – b * c -ct R 2 = LAB EXTRACTION METHODOLOGY A. EXTRACTION # 1 CV = 3.1% B. EXTRACTION # 2 CV = 2.9% C. EXTRACTION # 3 CV = 3.2% D. EXTRACTION # 4 CV = 3.6%

CONCLUSIONS CONTINUED 3.USING PARAMETERS FROM RELEASE CURVE AND DATA FROM LAB EXTRACTION CAN PREDICT RATE OF N RELEASE - R 2 OF  CURRENT RELATIONSHIPS ARE SPECIFIC TO MATERIAL. NEED TO ACCUMULATE MORE DATA ON INDIVIDUAL MATERIALS AND MIXTURES FOR VERIFICATION OF N RELEASE CURVES 5. ULTIMATELY, OBTAIN APPROVAL BY AOAC AND AAPFCO FOR USE IN STATE FERTILIZER LABS FOR VERIFICATION OF CONTROLLED RELEASE CLAIMS IN LABELING

Future Activities Conduct Second Collaborative Study on Lab Method Using Revised Procedure Move Lab Method Through AOAC/AAPFCO Develop More Data With Soil Incubation Method Include More Materials and Blends Strengthen Statistics And Determine if a Single Predictive Equation Can Be Established for All Materials and Blends Test Differing Soil Types (other than Florida) to Assure Nitrification Microbiology is Not Impacted Test Differing Buffer Concentrations to Assure the Most Natural Microbiological System Possible is Established Report to AAPFCO Slow Release Taskforce in August