Macherey-Nagel Visocolor Manual

Macherey-Nagel Visocolor Manual Manual pdf 31 page image

Manual VISOCOLOR® reagent case for soil analysis31Manual VISOCOLOR® reagent case for soil analysis 03.14MNForest sedimentation analysis according to KRUEDENER2.12 Determination of soil type (sedimentation analysis)Procedure:A soil sample is crumbled with the fingers in the screen andcoarse contents (stones, etc.) are removed. The crushed sampleis placed in the test glass (22) and compressed a little with theglass stamper (10) There must be sufficient soil in the test glassto reach the E mark. If necessary, the test glass must be knockedseveral times in the flat of the hand. The glass is then filled withwater up to the F mark below the top of the glass. The additionof 10 drops of pyrophosphate solution (32) prevents flocculationof the clay particles.10 x®Neumann-Neander-Str. 6-8 · D-52355 DürenMACHEREY-NAGELPyrophosphatlösungPyrophosphate SolutionSolution de pyrophosphateSolución de pirofosfato3222 10The glass is closed with the screw cap and shaken thorough-ly until soil and water are evenly dispersed. When very loamysoils are involved, the samples are first of all “softened” and thenshaken thoroughly. Shaking is then stopped suddenly and thetest glass is positioned vertically.After 18 s, the sand particles have sedimented; the height of thesand fraction will have reached one of the lower 4 marks afterthese 18 s. Read off the identification letter and refer to the tableabove to establish the soil type.The closed test glasses can be checked again after a few days(particularly when heavy soils are involved), when the clay frac-tions have also settled. The separation of all the fractions in theglass is then to be seen very clearly. In this case, the volumeratio of the fractions “sand” and “elutriatable matter” can also bedetermined more accurately.Example: Filling height = E after 18 s = A markEvaluation: Sand: < 40 %Elutriatable matter: > 60 %Soil type: ClayClassification of soil types according to the German soil es-timation regulation [3] [6]Mark Sand (%) Soil typeE 100–91 SandD 90–87 Slightly loamy sandC 86–82 Loamy Sand81–77 Very loamy sandB 76–71 Sandy loam70–54 LoamA 55–40 Heavy loam40– 0 Clay3. Procedure for photometric soil analysisThe VISOCOLOR® reagent case fully satisfies the requirementsfor rapid determination of nutrient supply and fertilizer require-ment. Together with the VISOCOLOR® test kits the reagentcase with PF-3 provides with quick and user-independent in-formation on soil samples. For more extensive investigations,there is the possibility to use the PF-3 in combination with theNANOCOLOR® system.The following chapters describe the preparation of soil extractsand the determination of ammonium, nitrate, potassium andphosphate with the PF-3. Further they give information about theuse of other NANOCOLOR® photometers and NANOCOLOR®test kits*.3.1 Preparation of soil extract AFSoil extract AF, which is prepared with extraction solution A (cal-cium chloride solution, 0.0125 mol/dm 3 , see 2.5, page 28 ) isused to analyze pH value, ammonium, nitrite and nitrate. Thecomposition of this soil extract differs from soil extract A.Procedure:Soil extract AF is produced from the non-dried soil sample, butit should not be too wet and it should, if possible, be screened.Remove all coarse and untypical constituents. Weigh out 100 gof the soil sample prepared in this manner in a shaking bottle.Add 200 mL of the extraction solution A with the aid of the mea-suring cylinder. Close shaking bottle. Shake bottle vigorously for5 min, allow solid matter to settle briefly. Place plastic funnel ina measuring cylinder 100 mL, insert an MN 616 ¼ folded filter.Filter suspension. If the solution is initially cloudy, pour it backinto the folded filter.Filtrate = soil extract AF3.2 Determination of pH valueThe pH value is determined in soil extract AF using colorimetryor pH indicator strips, a photometric determination of the soil pHis not possible.Procedure:Insert the pH 4.0–10.0 color disc in the VISOCOLOR® HE com-parator block. Fill both measuring glasses up to the ring markwith soil extract AF and place them in the comparator (if the soilextract is colorless, the glass on the left can be filled with clearwater). Add 4 drops of pH 4–10 to the right glass, close and mix.Look through the glasses from above, compare the colors of thetwo glasses and turn the color disc until the colors match. Readoff the result from the marking on the front side of the compara-tor block. Intermediate values can be estimated. After use, rinseboth round glasses thoroughly and close.When pH values of less than 4.5 are measured, an additionalmeasurement is carried out with pH-Fix 2.0–9.0 test strips.Fill a test tube with ring mark with soil extract AF to a height of ap-prox. 3 cm, insert pH test strip in the sample. After 5 min, removethe test strip and compare with the color scale, read off pH value.* The preprogrammed submethods (mg/kg and mg/100 g) for soil analysis in our NANOCOLOR®photometers account for all steps and dilutions in the sample preparation during the calculation ofthe measurement result and therefore only give reliable results using the methods and prepara-tion steps described in this handbook. The amendments CAL (calcium acetate lactate) and AF(Soil extract AF) in the submethod names refer to the extraction solutions to be used. In case ofchanging the procedure, we recommend to use the submethod with the unit mg/L and a conver-sion to the desired unit for soil analysis by accounting for dilutions manually.