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Collaborative Testing Services, Inc.   anniversary

P.O. Box 650820, Sterling, VA, USA 20165-0820  1-571-434-1925


Working together for a better Agriculture Interlaboratory Program

Agricultural laboratories now have a more reliable and useful way to assess their performance. CTS and Dr. Robert O. Miller joined forces in 2007 to create an Agricultural Laboratory Proficiency (ALP) Program that extends well beyond any previous testing program in this field. Combining CTS' lengthy and extensive experience in operating interlaboratory programs with Dr. Miller's noted expertise in agricultural testing, the ALP Program offers a wide array of analyses on soils, botanicals and water.

Audit of measurement performance for precision agriculture 

The scope of this program allows laboratories to audit a large portion of their activities on an ongoing basis critical to dealing with the changing dynamics of staffing, equipment maintenance and training. Measurement performance is the cornerstone upon which precision agriculture is built. Dr. Miller is ALP's Technical Director and prepares test samples, assists with interpreting the collected data and provides a summary report. CTS prepares and distributes the Individual Performance Analysis Report, which contains results for all properties and samples for which a laboratory submitted data during a testing cycle.

Serving agriculture laboratories

While CTS is well-known for its clear, concise and actionable reports, we realize that laboratories may at times require more guidance. Therefore, Dr. Miller is available to help laboratories in interpreting their results as well as provide technical support for improving laboratory performance. Finally, the ALP Program assists participants with state certification requirements.

An Experienced & Knowledgeable Director

Dr. Robert Miller serves as the ALP Program Technical Director. Dr. Miller has wide-ranging expertise in agricultural laboratory analyses, coordinating multiple interlaboratory proficiency programs and laboratory QA/QC.
Dr. Miller received his BS and MS degrees from the University of Nebraska. He went on to manage a plant nutrition laboratory at Texas A&M University before earning his Ph.D. degrees at Montana State University in Soil Fertility and Soil Chemistry. He served as the Director of the Division of Agriculture and Natural Resources Diagnostic Laboratory at the University of California Davis and as Extension Soil Specialist from 1988 to 1997. While director, in 1992, he co-founded the Western States Proficiency Testing Program, a pioneering agricultural interlaboratory program in the western United States.
In 1997 Dr. Miller joined the faculty of Colorado State University as an affiliate Professor in Soils and Crop Sciences, where he was a leader in the development of the North American Proficiency Testing program, which superseded the Western States Program. He worked closely with state agencies, which certified Ag analysis laboratories. In 1997 he founded interlaboratory proficiency programs for geo-technical materials for the United States Golf Association and the Compost Analysis Proficiency Program (CAP) for the United States Compost Council; he continues to coordinate both programs. In 2002 he co-authored a US-EPA grant with the Minnesota Dept. of Agriculture (MDA) to support the Manure Analysis Proficiency (MAP) Program, which today he coordinates with MDA.
Dr. Miller conducts educational lab workshops, provides consulting services and continues to conduct research into agricultural analysis. He has authored over twenty five papers in the agricultural analysis and authored chapters in: Soil, Plant and Water Reference Methods for the Western Region, (1996 and subsequent editions); contributed multiple chapters in Test Methods for the Examination of Composting and Compost and Soil Test Methods from the Southeastern United States.  He has served as president of the Soil and Plant Analysis Council and Council Secretary, serves as Chair of the USGA Putting Green Advisory committee and is internationally recognized for his expertise.
With more than three decades coordinating soil analysis proficiency programs and related PT programs, Dr. Miller has developed extensive knowledge of statistical analysis, method performance, and laboratory quality.

CTS encourages all ALP participating labs to contact Dr. Miller with analysis and proficiency questions at

CTS ALP Program Schedule

Enroll at any time during the year. A subscription includes three cycles, which are outlined below. Note that data due dates occur approximately 6 weeks after a shipment date and that results must be submitted on or before a data due date in order to be included in the report. Participants can track shipments, submit data and access reports through the CTS Customer Portal.

Enroll Between August 16 - February 15

Samples Ship Data Due Report Issued
March April May
June August September
September October November

Enroll Between February 16 - May 15

Samples Ship Data Due Report Issued
June August September
September October November
March April May

Enroll Between May 16 - August 15

Samples Ship Data Due Report Issued
September October November
March April May
June August September

Properties & Soils

You can view information about soil collection sites since 2006.
You can also view our sub test codes by MODUS code here. (Excel file; this will download to your harddrive.)

Our extensive list of properties for soil, botanicals and water analyses is presented below.

Properties tested: Soil Analyses

   Sat. Paste Moisture  (%)
    pH - sp
   PO4 - sp (mg/L)
    ECe - sp  (dS/m)
    HCO3 - sp  (mmolc/L)
    K - sp  (mmolc/L)
    Ca - sp  (mmolc/L)
    Mg - sp  (mmolc/L)
    Na - sp  (mmolc/L)
    SAR - sp     
    Cl - sp  (mmolc/L)
    SO4 - sp  (mmolc/L)
    NO3 - sp  (mmolc/L)
    B - sp  (mg/L)
Soil pH & EC 
  Soil EC (1:1)  (dS/m)
  Soil EC (1:2)  (dS/m)
   pH  (1:1) Water       
   pH  (1:2) Water       
   pH  (1:1) 0.01M CaCl2        
   pH  (1:2) 0.01M CaCl2
   pH (1:1) 1.0M KCl    
Soil EC (1:5)  H2O  (dS/m)
Soil pH (1:5)  0.01 M CaCl2   
Buffer pH, Lime Req. 
    SMP Buffer pH       
    Sikora Buffer pH
    Sikora 2 Buffer pH    
    Adams-Evans Buf pH        
    Woodruff Buf. pH  
    Mehlich Buffer pH
    H+ cmol/kg 
Inorganic Nitrogen (NO3-N & NH4-N)        
     NO3-N Cd. Rd.  (mg/kg)
     NO3-N ISE  (mg/kg)
     NO3-N CTA  (mg/kg)
     NO3-N Ion Chr.  (mg/kg)
     NH4 - N   (KCl Extr.)  (mg/kg)
     Amino Nitrogen  (mg/kg)
Phosphorus and Sulfur
    PO4-P   Bray P (1:10)  (mg/kg)
    PO4-P   Bray P1 (1:7)  (mg/kg)
    PO4-P   Olsen/Bicarb (1:20)  (mg/kg)
    PO4-P   M. Morgan Spec  (mg/kg)
PO4P M. Morgan ICP (mg/kg)
    PO4-P   Mod. Kelowna  (mg/kg)
    PO4-P   Strong Bray (1:10)  (mg/kg)
    PO4-P   Water Soluble  (mg/kg)
    SO4 - S  (PO4 Extr.)  (mg/kg)
 Bases (1:10)   
     K Ammonium Acetate  (mg/kg)
     Ca Ammonium Acetate  (mg/kg)
     Mg Ammonium Acetate  (mg/kg)
     Na  Ammonium Acetate  (mg/kg)
     Bray Extractable K  (mg/kg)
     K- Bicarb.  (mg/kg)
     K Modified Morgan  (mg/kg)
     Ca Modified Morgan  (mg/kg)
Mg Modified Morgan (mg/kg)
Zn Modified Morgan (mg/kg)
Cu Modified Morgan (mg/kg)
Mn Modified Morgan (mg/kg)
     Aluminum KCL Extr.  (mg/kg)
 Mehlich-1 Multi Element (scoop)     
     P  (mg/kg)
     K  (mg/kg)
     Ca  (mg/kg)
     Mg  (mg/kg)
     Mn  (mg/kg)
     Zn  (mg/kg)
 Mehlich-3 Mult-Element       
    Scoop Density  (g/cm3)
     P   Colorimetric  (mg/kg)
     P    ICP-AES  (mg/kg)
     K  (mg/kg)
     Ca  (mg/kg)
     Mg  (mg/kg)
     Na  (mg/kg)
     S  (mg/kg)
     Al  (mg/kg)
     Zn  (mg/kg)
     Mn  (mg/kg)
     Fe  (mg/kg)
     Cu  (mg/kg)
     B  (mg/kg)
     Zn - DTPA  (mg/kg)
     Mn - DTPA  (mg/kg)
     Fe - DTPA  (mg/kg)
     Cu - DTPA  (mg/kg)
     Zn - HCl  (mg/kg)
     Mn-H3PO4  (mg/kg)
     Cl - Ca(NO3)2 Extr.  (mg/kg)
     B - Hot Wat.  (mg/kg)
     B-DTPA/Sorbitol  (mg/kg)
Soil Organic Matter    
   Soil Kjeldahl N  (%)
   Soil TN (combustion)  (%)
Soil Total Carbon (%)
   Soil TOC (Combustion)  (%)
Soil Inorganic C (pressure Trans)
Soil Inorganic C (TC-TOC)
   SOM - Walkley-Black  (%)
   SOM - LOI ( % Wt loss)  (%)
   SOM - Actual (Unregressed)  (%)
    CaCO3 Content Gravimetric  (%)
CaCO3 Content Effervescent (%)
    CEC - Cation Displacement  (cmol/kg)
    CEC - Estimation  (cmol/kg)
    Soil Density (Scoop)  (g/cc)
Particle Size Analysis 
   Sand  2000 - 50 um  (%)
   Silt   50 - 2 um  (%)
   Clay   2 - 0 um  (%)
  Field Moisture Capacity (FC)  (%)
  Permanent Wilting Point  (%)
Available Water Content  (%)
Total Soil P (EPA-3050/3051/3052)  (mg/kg)
Solvita CO2 Soil Respiration Test  (mg/kg)
Soil Nitrogen Mineralization Potential  (mg/kg)
DTPA-sorbitol extractable S  (mg/kg)
DTPA-sorbitol extractable Al  (mg/kg)
ISU Wet Soil K test  (mg/kg)

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Properties tested: Botanicals Analyses
Dry Matter  (%)           
NO3 - N  Cd Rd.  (mg/kg)
NO3 - N   ISE  (mg/kg)
NO3 - N   Oth.  (mg/kg)
NH4-N  (mg/kg)
PO4 - P  (mg/kg)
SO4 - S  (mg/kg)
Cl  (%)
TKN  (%)
N- Dry Comb. (%)
S- Dry Comb.  (%)
C- Dry Comb (%)
Wet Digestion
    P  (%)
    K  (%)
    Ca  (%)
    Mg  (%)
    S  (%)
    Na  (%)
    Al  (mg/kg)
    B  (mg/kg)
    Zn  (mg/kg)
    Mn  (mg/kg)
    Fe  (mg/kg)
    Cu  (mg/kg)
    Mo  (mg/kg)
Dry Ash          
    P  (%)
    K  (%)
    Ca  (%)
    Mg  (%)
    Na  (%)
    Al  (mg/kg)
    B  (mg/kg)
    Zn  (mg/kg)
    Mn  (mg/kg)
    Fe  (mg/kg)
    Cu  (mg/kg)
    Mo  (mg/kg)
Heavy Metals 
    As  (mg/kg)
    Ba  (mg/kg)
    Cd  (mg/kg)
    Co  (mg/kg)
    Ni  (mg/kg)
    Pb  (mg/kg)
    Sr  (mg/kg)

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Properties tested: Water Analyses

  EC  (dS/m)
  Ca  (mmolc/L)
  Mg  (mmolc/L)
  Na   (mmolc/L)
  K   (mmolc/L)
  NH4-N  (mmolc/L)
  Sum Cations  (mmolc/L)
  HCO3  (mmolc/L)
  CO3  (mmolc/L)
  Cl  (mmolc/L)
  NO3  (mmolc/L)
  SO4  (mmolc/L)
  Sum Anions  (mmolc/L)
  Cation-Anion Difference      
  Boron  (mg/L)
  PO4-P Phosphorus - Spec  (mg/L)
  Phosphorus - ICP (Total)  (mg/L)
  TKN  (mg/L)
  Nitrogen Combustion (Total)  (mg/L)
  Total Organic Carbon  (mg/L)

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Summary Reports


Portal Links

Participants in CTS ALP Program tests can access Test Instructions on the CTS Customer Portal.