LaMotte AST User Manual

TABLE OF CONTENTS

Introduction..............................................4

Accessories...............................................4

TestMethods............................................. 5

UseoftheOcta-SlideViewer............................... 5

UseoftheDirectReadingTitrator........................... 6

SamplingDilutionTechniques ............................... 7

UnitsofMeasure .......................................... 8

Fertilizer Applications ...................................... 9

SoilSamplingProcedures .................................. 10

HowtouseaFunnelandFilterPaper ......................... 10

Test Procedures:

pH .................................................. 11

Extraction ............................................ 13

NeutralizationofSoilFiltrate ............................. 15

NitrateNitrogen ....................................... 16

Ammonia Nitrogen ..................................... 18

NitriteNitrogen ....................................... 19

Phosphorus ........................................... 20

PhosphorusinAlkalineSoils .......................... 21

Potassium ............................................ 22

Iron ................................................. 23

Sulfur................................................ 24

Copper .............................................. 26

Calcium&Magnesium .................................. 27

Chloride ............................................. 30

Aluminum............................................ 32

Manganese ........................................... 34

Humus............................................... 36

GreenPlantTissueTests ................................. 38

INTRODUCTION

This instruction manual was written for use with LaMotte’s AST Series Soil Test Kits. The Model AST-5 (5410) includes tests for pH, Nitrogen, Phosphorus, Potassium, and Humus. The AST-15 (5412-01) contains all of the tests included with Model AST-5, plus Calcium and Magnesium, Ammonia Nitrogen, Manganese, Aluminum, Nitrite Nitrogen, Sulfur, Chloride, Ferric Iron, and Copper. Instructions for all tests are included in this manual.

ACCESSORIES

QUANTITY CONTENTS CODE

1 Brush, Test Tube 0514 1 Spoon, 0.5 g 0698 1 Demineralizer Bottle 1155 100 Soil Sample Bags 0615-J 2 x 50 Soil Test Report Forms 1626 1 AST Instruction Manual 36071 1 Improving Soil Sampling Accuracy 36150 1 A Study of Soil Science 1530 1 LaMotte Soil Handbook 1504

To reorder individual reagents or test kit components, use the specified code numbers.

Read the Demineralizer Bottle Instruction Manual before proceeding. This will be the source of all deionized water used in the tests.

TEST METHODS

Mott

pH, Nitrate Nitrogen, Ammonia Nitrogen, Nitrite Nitrogen, Phosphorus, Iron, and Sulfur test results are determined using an Octa-Slide Viewer. In this method, the color or turbidity of the reacted sample is matched to plastic color standards mounted in a black color bar.

TheOcta-SlideViewershouldbeheldso non-direct light enters through the back of the viewer. With sample tube inserted at top, slide the Octa-Slide bar through the viewer and match with color standard.

Humus, Aluminum and Manganese test results are determined using a color chart. After the reaction is performed on a spot plate, the resulting color is matched to a printed color standard on a laminated chart.

The Copper test result is determined by a simple drop count. A standard solution is added a drop at a time to an unreacted sample until it matches the color of a reacted sample.

The Potassium test uses a Double Tube to measure the turbidity of the sample formed by the reacted potassium.

Calcium, Magnesium, and Chloride test results are determined using a Direct Reading Titrator, where small amounts of a titrant are added to the sample until a specified color change occurs.

USE OF THE DIRECT READING TITRATOR

The Direct Reading Titrator consists of a plastic barrel, a plastic plunger, and a plastic adapter tip. The adapter tip reduces the size of the drops that are dispensed, increasing the precision of the test results. Detailed instructions for the use of the Direct Reading Titrator are provided on page 6.

see next page

Result:

50 ppm

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

BarrelPlunger Adapter tip

1. Fill the test tube to the specified line with the water sample.

2. Add the reagents as specified in the instructions for the individual

test method. Cap the tube with the special test tube cap. Mix by swirling gently.

3. Depress the plunger of the Titrator to expel air.

4. Insert the adapter tip into the special plastic plug in the titrating

solution bottle.

5. Invert the bottle. Hold the bottle and the Titrator firmly together. Slowly pull out the plunger until the large ring on the plunger is opposite the zero (0) line on the scale.

6. If an air bubble appears in the Titrator barrel or the adapter tip, partially fill the barrel and pump the titration solution back into the inverted reagent bottle to expel the bubble. Repeat this pumping action until the bubble disappears.

7. Turn the bottle right-side-up and remove the Titrator.

8. Insert the adapter tip into the opening in the test tube cap. Slowly

depress the plunger to dispense the titrating solution. Gently swirl tube to mix.

9. Continue adding the titrating solution until the specified color change occurs. If the color change has not occurred when plunger reaches the bottom of the scale, refill the Titrator to the zero (0) line. Continue the titration until the color change occurs.

10. Read the test result directly from the scale where the large ring on the plunger meets the Titrator barrel. If the Titrator was refilled to reach the final color change, add the total amounts of titrant used to determine the final test result.

11. If no additional tests are to be made, discard the titrating solution in the Titrator. DO NOT return the titrating solution to the reagent bottle. Thoroughly rinse the Titrator and the titration tube. DO NOT remove the plunger or the adapter tip from the Titrator.

SAMPLE DILUTION TECHNIQUES

In some tests the sample color may be darker than the darkest color standard. When this occurs, the original sample must be diluted so an accurate measurement can be made. Multiply the reading by the appropriate dilution factor.

EXAMPLE: Measure 5 mL of the sample into a graduated cylinder. Fill to the 10 mL line with deionized or distilled water. The sample has been diluted by one-half, and the dilution factor is therefore 2. Run the test procedure, and multiply the reading by 2 to obtain the final result.

The following table provides dilution factors for several sample sizes:

Size Of Sample

Distilled Water To Bring

Volume To 10 mL

Multiplication

Factor

10 mL 0 mL 1

5mL 5mL 2

2.5 mL 7.5 mL 4 1mL 9mL 10

0.5 mL 9.5 mL 20

NOTE: It is important to use pipets and graduated cylinders to make accurate dilutions.

UNITS OF MEASURE

All tests in the AST kits measure the concentration of the nutrients that are available to the plants. The tests are conducted on soil extract, the liquid formed by removing the nutrients from the soil. Since extraction procedures remove varying amounts of nutrients, the test is dependent upon the time and extracting solution used.

Test results are expressed in the following terms:

Parts Per Million (ppm)

Pounds Per Acre (lb/acre) Low To High

Calcium Nitrate Nitrogen Manganese Magnesium Phosphorus Aluminum Copper Potassium Humus Sulfur Ammonia Nitrogen Chloride Nitrate Nitrogen Iron

Pounds per acre represents the number of pounds of soil in an acre to a depth of 6 inches, or 2,000,000 pounds. Conversion from pounds to acre to parts per million, or vice versa, can be accomplished using the following equations:

ppm x 2 = lb/acre

lb/acre x 0.5 = ppm

FERTILIZER APPLICATIONS

Test results should not be the only consideration when establishing a fertilizer program. Soil composition, drainage, climate, previous fertilizer programs, and the type of plant must also be considered when determining the type and amount of fertilizer needed. The following table offers quick-reference general guidelines to correlate soil test results and fertilizer application rates. These guidelines can be supplemented by the information in the LaMotte Soil Handbook (Code 1504). Consult your local agricultural extension services for advice on establishing a fertilizer program specific to your area.

General Guidelines For Fertilizer Application Rates

Nitrogen Phosphorus Potash (K2O)

Test Result

Add

(lbs/acre)

Test Result

Add

(lbs/acre)

Test Result

Add

(lbs/acre)

10 220 10 260 100 180 20 180 25 220 140 150 40 130 50 180 180 130

60 110 75 150 220 110 100 90 100 130 300 90 150 40 150 90 400 70

SOIL SAMPLING PROCEDURES

Detailed soil sampling procedures are described in the LaMotte Soil Handbook (Code 1504) and in Improving Soil Sampling Accuracy (Code

36150). The following procedure is recommended for sampling greenhouse soils.

1. Collect soil before watering.

2. Remove any mulch covering the soil. Use a soil sampling tube or

spoon to take a sample from the entire plant rooting surface, top to bottom. Take 8 to 10 samples from the area.

3. Thoroughly mix the individual samples to form a composite sample. Spread the mixed composite sample on a sheet of paper or plastic to dry.

NOTE: A composite sample insures representative test results.

4. Sift the dried sample through a 10 mesh wire screen or 2 mm sieve.

Collect the soil. Discard particulate which remains on top of screen.

HOW TO USE A FUNNEL AND FILTER PAPER

A funnel and filter paper are used in the preparation of soil filtrate and plant tissue extracts, and to filter the soil extract for the Phosphorus in Alkaline Soils, Chloride, and Humus procedures.

1. Fold a piece of filter paper (0465) in half. Fold in half again.

2. With pointed end at the bottom, gently push corners together to

form a cone. NOTE: There should be three layers on one side of the opening

and one layer on the opposite side.

3. Place in funnel (0459). Place funnel in container for collecting filtrate.

4. Pour liquid through the funnel and filter paper to filter solution.

pH is a measure of alkalinity or acidity. The pH of soil ranges from 3.5 to

11.0, but research has found plants grow best in the range of 5.0 to 8.5.

In soils with low pH, some nutrients may reach toxic levels, and the activity of soil microbes may be drastically reduced. Soils with a high pH generally have a lower availability of micro-nutrients, and some nutrients may not be present at sufficient levels.

A distilled water extraction procedure with a Flocculating Reagent provides a clear liquid extract, to which *Wide Range Indicator is added. The resulting color is matched to a color standard to determine the pH.

QUANTITY CONTENTS CODE

500 mL Tricon Flocculating Reagent 5941-L 30 mL *Wide Range Indicator *2218-G 1 Test tube, plastic, w/cap 0106 1 Spoon, 0.5 g, plastic 0698 1 Pipet, 1.0 mL, plastic 0354 1 Octa-Slide Viewer 1100 1 pH Wide Range Octa-Slide Bar 3424

*WARNING: Reagents marked with an * are considered to be potential health hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents go to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or fax.

PROCEDURE

Read Use of the Octa-Slide Viewer on page 5 before proceeding.

1. Fill a test tube (0106) to 5 mL line with Tricon Flocculating Reagent (5941).

2. Use the 0.5 g spoon (0698) to add 3 level measures of the soil sample. Cap and slowly invert back and forth for one minute to mix. Wait for soil particles to settle.

3. Use a pipet (0354) to fill another tube (0106) to the 2.5 mL line with the clear solution above the settled soil particles.

4. Add 6 drops of *Wide Range Indicator (2218). Cap and mix.

5. Insert test tube into Octa-Slide Viewer (1100). Slide the pH Wide

Range Octa-Slide Bar (3424) into the viewer. Match sample color to a color standard. Record as pH.

NOTE: Liming tables are found in the LaMotte Soil Handbook (Code 1504).

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