Soil Testing.pdf

not indicated a crop response to their use, or recommend-

ations are more accurately made based on soil conditions

and speciic crop needs (nitrogen, boron, molybdenum).

Table 2. Guidelines for Selecting Laboratory Tests

Extension

Test

Crop

Location

General Conditions

PB1061

Basic All

The basic soil test is suggested for all crops, lawns and gardens for

developing and maintaining fertilization programs.

Selecting the Proper Tests

Most crop fertilization problems in Tennessee are as-

sociated with the lack of and improper use of nitrogen,

phosphorus, potassium and lime. Therefore, the great-

est need for soil test information arises from these four

variables. The need for secondary and micronutrient soil

tests is much less, since research and demonstrations

indicate responses are limited to certain crops and soil

conditions. Situations where the various soil tests are

most likely needed are shown in Table 2. Tests desired for

each sample must be indicated on the information sheet.

The basic plus soil test is suggested for precision ag and speciic

problem-solving applications.

Calcium (Ca) Tomatoes and Peppers Tomato and pepper

producing areas

Sandy or light-textured soils. Where

blossom-end-rot is an annual problem.

Soil

Magnesium

(Mg)

Tomatoes, Tobacco,

Cabbage, Grapes

Cumberland Plateau,

Highland Rim

Sandy or light-textured soils. Magnesium

deiciencies in each of these crops may be

induced by excessive amounts of potassium

or ammonium fertilizers.

Testing

When soil pH is above 6.0 or lime is applied

and phosphate is high.

Iron (Fe) Ornamentals (only) Isolated or problem areas High soil pH.

Manganese (Mn) Soybeans

Computer Soil Test Report

Results of each soil test and corresponding recom-

mendations are printed by computer and mailed to the

grower. In addition, a copy of each report is retained by

the laboratory and one copy is sent to the grower’s county

Extension ofice.

Each nutrient tested is reported in pounds per acre and

assigned a soil test rating. The ratings for phosphorus and

potassium are low (L), medium (M), high (H) and very high

(VH). The secondary and micronutrients tested are rated as

either suficient (S) or deicient (D). Interpretations of ratings

are printed on the back of the soil test report form.

Recommendations for ield crops are reported in pounds

of plant nutrients and tons of agricultural limestone to apply

per acre. For lawns and garden, recommendations are re-

ported in pounds of actual fertilizer grades and agricultural

limestone to apply per 1,000 square feet. Recommendations

for lowers and shrubs are reported in pounds per 10 and

pounds per 100 square feet respectively.

Growers should keep a ile of all soil test reports

arranged by ields or areas.

Isolated or problems areas Sandy or light-textured soils with a pH

above 7.0.

Boron (B) Tobacco

All

Soluble Salts

Isolated or problem areas Excessive fertilizer rates.

Organic Matter

The organic matter test is offered as a guideline for the selection and use of

certain HERBICIDES. Interpretations for other uses will not be made.

Nitrate-Nitrogen Corn

The nitrate-nitrogen test is offered to assist with nitrogen management

decisions in corn production systems, especially when manures are being

used.

Greenhouse Container Media

Tests available for greenhouse media and the cost per

samples are indicated in Table 3. When submitting samples,

growers should complete the form “Soil and Media Information

Sheet” to indicate test(s) desired. However, soil boxes may be

used for media samples. Two completely illed soil boxes per

sample are needed to provide suficient media for completion

of the container media test.

After testing, a copy of the laboratory results reported in

parts per million (ppm) is mailed to the grower, the county

Extension office and the Extension specialist. Fertilizer

recommendations are prepared by the specialist and mailed

to the grower.

Pre-sidedress Nitrate-N Soil Test

(PSNT)

The laboratory offers a special soil test for nitrate-ni-

trogen to assist with nitrogen management decisions in corn

production systems. Samples are analyzed for nitrate-N using

an ion-selective electrode procedure. The cost of analysis

(Table 1) is $3 per sample for regular processing or $5 for

a guarantee of results phoned or faxed within three days of

sample arrival to a number which you provide.

Growers should complete the form, “Soil and Media

Information Sheet,” when submitting samples for analysis.

See Extension factsheet SP427 for detailed information on

the PSNT procedures.

Table 3. Laboratory Tests and Fees for

Greenhouse Container Media

Test* Cost Per Sample**

pH, P, K, Ca, Mg, Ammonium

and nitrate nitrogen, soluable salts $20

07-0235 PB1061-5/07(Rev)

*Determination made using saturated media extract procedure.

**Add $1 additional per sample for reports to be faxed.

Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences, and resource development.

University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating.

UT Extension provides equal opportunities in programs and employment.

Basic Plus Precision Ag,

Problem-Solving

Zinc (Zn) Corn, Snapbeans Cumberland Plateau,

Middle Tennessee

Soil Testing

Hubert J. Savoy, Associate Professor,

Biosystems Engineering & Soil Science

originally written by

John R. Jared, Professor Emeritus, Plant and Soil Science

ations are to be made. A composite sample should be collected,

consisting of small portions of soil taken from approximately

20 locations. For ield crops, soil portions should be taken

from an area not to exceed 10 acres (Figure 1). For lawns and

gardens, soil portions should be collected at random from eight

to 10 locations. Areas of contrasting soils, problem spots or

portions of ields where crop response is signiicantly differ-

ent should be sampled separately, provided the area can be

fertilized separately.

Depth of Sampling

packaged and mailed. Wet samples are dificult to handle,

more subject to being lost during mailing and greatly delay

laboratory testing. Wet samples cannot be analyzed for

nitrate-nitrogen.

How Often to Test Soils

The following general guidelines may be used to de-

termine how often soils should be tested. However, the fre-

quency can vary depending upon cropping intensities, soil

types, fertilization rates, tillage methods, weather conditions

and new research indings.

1. Continuous Row Crops (conventional) - every two to

three years.

2. Double-Cropping Systems - every two years.

3. Continuous No-Till Soybeans (only) - every three to

ive years.

4. Continuous No-Till Corn or Cotton - every two years.

5. Hay Systems - every two years.

6. High-Value Cash Crops (Tobacco, Vegetables) -

annually.

7. Lawns, Gardens and Pasture Crops - every three to

ive years.

8. Any time a nutrient problem is suspected.

9. At the beginning of a different cropping rotation.

1-inch Strip

Growers who follow soil test recommendations can

expect higher fertilizer eficiency, more balanced nutrient

levels for crops and optimum beneits from their lime and

fertilizer investments. Thus, soil testing should be the irst

step in planning a sound fertilization program. With a soil

test, the guesswork of knowing how much lime and fertilizer

to apply is eliminated.

Field No. 2 (10 Acres)

Figure 3. Removing a portion of soil from a soil slice.

The Concept of Soil Testing

When you submit a sample to the University of

Tennessee Soil, Plant and Pest Center, modern chemical

analyses are combined with up-to-date research to make

each lime and fertilizer recommendation. Levels of available

nutrients present in the soil are determined in the laboratory,

while nutrient needs and fertilizer responses are determined

by the Agricultural Experiment Station on the major soil

types across the state. As a result, the university’s soil testing

program is geared to the crops and soils in Tennessee, and

provides a vehicle for carrying the latest scientiic information

to individual growers.

Figure 1. Sampling pattern for collecting a

representative soil sample.

Figure 4. Mixing and packaging a soil sample.

Laboratory Tests and Fees

The University of Tennessee Soil, Plant and Pest Center

is located at the Ellington Agricultural Center in Nashville. It

is equipped for routine soil analysis to make lime and fertilizer

recommendations and offers its services to all Tennesseans.

The Mehlich No. 1 (Double Acid) extractant for nutrient

determinations and a Buffer for measuring lime requirements

are presently used by the laboratory.

Soil tests available and the cost per sample are listed

in Table 1.

Routine tests for other nutrients are not offered because

either University of Tennessee research and ield trials have

K, micronutrients and organic matter, take soil samples to a

depth of 6 inches. For NO-TILL row crops, collect the sample

to a depth of 6 inches for pH and nutrient determinations

and to a depth of 2 inches for organic matter determinations.

For determination of soluble salts, sample within the root-

ing zone of the affected crop or the expected rooting zone

if sample is taken prior to crop establishment. For the corn

pre-sidedress nitrate-nitrogen test, collect samples to a depth

of 12 inches.

Soil portions for each composite sample should be placed

into a clean container and thoroughly mixed. From this, re-

move enough soil to ill a sample box (Figure 4). When sam-

pling for nitrate-nitrogen, the sample should be thoroughly

dried within 36 hours to obtain the best results.

Information Sheets and Sample Boxes

Information sheets, soil sample boxes and sampling in-

structions should be obtained from your local UT Extension

ofice. These materials provide necessary information and

guidelines for collecting and mailing samples to the labora-

tory. The F394 "Soil and Media Information Sheet" should

be illed out as accurately as possible.

For each sample number listed in the left column, you

may request up to three recommendations. Use the UT crop

codes list to determine the appropriate codes to list under the

“Crop Code” column. If your crop is not coded or if you are

uncertain about which code to choose, then list the name of

the crop in place of a code. When codes are not used, you

must also, for perennial crops, indicate whether the recom-

mendation is needed for establishment or for maintenance of

an existing crop.

Soil sample boxes should be properly labeled with

sample numbers corresponding to those shown on infor-

mation sheets.

6 in.

Deep

Figure 2. Soil sampling tools and depth to sample

for pH, P, K and micronutrients.

Sampling Tools and Depths to Sample

Several types of tools can be used for collecting soil

samples. One is the soil tube or probe. A uniform portion of

soil is collected rapidly and accurately by pushing the tube

into the ground to the desired depth and removing a soil core

(Figure 2).

The most common tool used is a shovel or spade. With

this tool, a uniform portion of soil is collected by irst making

a V-shaped cut into the soil to the depth of sampling. Next, a

1-inch thick vertical slice of soil to the same depth is removed

from the smoothest side of the cut (Figure 2). From this, a

1-inch strip of soil the length of the slice is removed, as indi-

cated in Figure 3. If other tools are used for sampling (garden

trowel, auger, etc.), make sure that a uniform amount of soil

is collected to the desired depth from a suficient number of

sites within the sampling area.

Remove organic debris, rocks and trash from the soil sur-

face before collecting the sample. For determination of pH, P,

Table 1. Laboratory Tests and Fees for Field,

Lawn and Garden Samples*

Test

When to Sample

Although soils can be tested any time during the year,

fall is a very desirable time. Fields are usually drier and more

accessible and the laboratory is less rushed than in the spring.

Also, testing in the fall allows recommended rates of lime,

phosphate and potash to be applied well in advance of spring

planting. By sampling at approximately the same time each

year, it is easier to compare soil test results with previous

results from the same ield.

Soils should be dry enough to till when sampling. If wet

samples are collected, they should be air-dried before being

1. Basic (pH, Buffer pH, P, K, Ca, Mg, calculated

CEC and base saturation) $6

2. Basic Plus ( all the above, plus Zn, Mn, Fe, Na, B) $15

3. Calcium, Magnesium, Zinc, Manganese, Iron, Boron,

Copper, Sodium $3 each

4. Soluble Salts (1 Soil:2 Water V/V) $4

5. Organic Matter $5

6. Nitrate-Nitrogen $3 - $5**

*Add an additional $1 per sample for reports to be faxed.

**Rush test includes fee for fax.

The Sampling Area

Soil test results can be no better than the sample collected.

Thus, each soil sample submitted to the laboratory should be

representative of the area for which fertilizer recommend-

Cost per Sample*

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