INTRODUCTION
We live in an era of increasing concern over the conservation and
management of our renewable and non-renewable resources. We seldom
think of soil in these terms, and yet improper development or natural
erosion can devastate a landscape that nature took centuries to create.
Similarly, the mineral elements in the soil that nourish growing plants can
be depleted through repeated cycles of cultivation and harvest, resulting in
an exhausted soil incapable of supporting healthy plant growth.
The Garden Guide Manual is concerned with the three major mineral
elements which plants absorb in large quantities during growth - nitrogen,
phosphorus and potassium (potash). Soil pH is also considered in detail
because the pH value directly affects the availability of a soil’s mineral
nutrients to the growing plant. Soil texture and organic matter content are
briefly discussed and the manual outlines the proper technique for
collection and preparation of soil samples.
3
SOIL TEXTURE
Through the process of weathering, mineral rocks are broken down over
long periods of time into fine particles of sand, silt, and clay. The presence
of these particles in varying proportions determines a soil’s texture. A
predominance of sand gives the soil a gritty feel when rolled between the
fingers. A soil with a high silt content has a silky feel much like talcum
powder. When moistened, clay is sticky and plastic in texture. A loamy soil
is an equal blend of these three fractions. Garden soils of intermediate
texture - the sandy loams, loams, and silt loams - are easiest to cultivate.
ORGANIC MATTER
Organic matter is composed of partially decayed and partially synthesized
plant and animal residues present in the soil. The decomposition of
organic matter releases mineral nutrients, particularly nitrogen, into the soil
in available forms for plant use. Organic matter also improves tilth and
water holding capacity. The garden hobbyist can improve the organic
content of his soil through the application of compost.
4
SOIL SAMPLING
Representative soil sampling is the first step in successful soil fertility
management. Accurate interpretation of soil test results largely depends
on the care and organization applied to the sampling process.
Get to know your garden. Supplement soil tests with careful observation of
the effects of shade, moisture, temperature, weeds, insects, and other
conditions influencing plant development.
Establish sampling areas. Different plants prefer different soil conditions.
Your garden may contain several soil types. Divide your garden into
distinct sampling areas, so that test results may be interpreted in terms of
the soil type and the plants to be grown in a specific area.
Take composite samples. Within a particular sampling area, collect and
thoroughly mix at least five random samples. The resulting composite
sample insures that test results will be representative of the entire sampling
area. Do not mix samples from separate sampling areas.
Sample the root zone. Collect samples directly where plants are to be
grown and to a depth compatible with root development. The root zone is
where the transfer of nutrients from soil to plant occurs. Samples should be
taken 2-3 inches below the soil surface for garden crops.
Make sure samples are free of foreign objects. Scrape away ground cover
before sampling. Avoid contamination with fertilizers and sprays. Minimize
contact with hands. Use a clean trowel, spoon, knife or soil sampling tube
to collect samples. A sampling tube permits inspection of core samples
and accurate measurement of sampling depth. Collect the composite
sample for a given area in a clean plastic bag, paper cup, or other
suitable container. Label the container to identify the sampling area.
Keep a soil-plant diary. Periodic testing and accurate recordkeeping
provide the only means of correlating test results, fertilizer applications,
and plant growth. Record the specific areas from which soil samples were
taken. Use the form at the back of the manual or devise your own.
SOIL PREPARATION
1. Spread out the composite sample on a clean sheet of paper or plastic.
2. Allow the soil to dry several hours or overnight. Do not bake the
samples to accelerate drying.
3. Remove foreign matter such as leaves, twigs and stones.
4. Gently crush soil to remove lumps.
5. Sift the sample through a screen or flour sifter to give a uniform sample.
5
SOIL pH
The pH scale is a numerical system used to measure the acidity of
alkalinity of a soil. Plants will not thrive on soil that is either too acid or too
alkaline because the soil pH directly affects the availability of mineral
nutrients which plants need for optimum growth. For example, if the pH is
too low, phosphates may be chemically bound and not readily available to
the plant and bacterial action responsible for the production of nitrates
may be reduced. The key to good crop production is to maintain the pH
within the range where plants and microbiological activity can function at
their most efficient level.
To simplify the classification of plants according to their soil pH preference,
they have been divided into two main groups. Those plants preferring soils
whose pH is within the neutral range, 6.0 to 8.0, are placed in Group A.
Plants preferring slightly acid soil are placed in Group B, range 5.0 to 6.0.
Acid
(Sour)
3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0
Neutral Alkaline
(Sweet)
Group B
Plants
Group A
Plants
The Plant-Soil Preference List indicates pH preferences for over 100
common plants. Since most garden hobbyists cultivate a variety of plants,
achieving optimum soil conditions may involve using a different treatment
program in different areas of a lawn or garden. It is important to establish
distinct sampling areas, so that test results may be interpreted in terms of
the plants to be grown in each area.
6
PLANT-SOIL PREFERENCE LIST
Group B Plants (Prefer Moderately Acid Soils)
Name PreferencepHName PreferencepHName Preference
PH
Amaryllis 5.0 - 6.0 Hemlock 5.0 - 6.0 Orchids 5.0 - 6.0
Azalea 5.0 - 6.0 Holly 5.0 - 6.0 Peanut 5.0 - 6.0
Bean, Lima 5.3 - 6.0 Iris, Japanese 5.0 - 6.0 Pine 5.0 - 6.0
Bentgrass 5.5 - 6.5 Jack-in-the-Pulpit 5.0 - 6.0 Potato 4.8 - 5.4
Carrot 5.4 - 6.0 Ladyslipper 5.0 - 6.0 Raspberry 5.0 - 6.0
Cauliflower 5.5 - 6.5 Lily 5.0 - 6.0 Rhododendron 5.0 - 6.0
Chestnut 5.0 - 6.0 Magnolia 5.0 - 6.0 Spruce 5.0 - 6.0
Coreopsis 5.5 - 6.5 Mountain Laurel 5.0 - 6.0 Wintergreen 5.0 - 6.0
Gardenia 5.5 - 6.5 Oak 5.0 - 6.0
7
Group A Plants (prefer slightly acid or neutral Soils)
Name PreferencepHName PreferencepHName Preference
pH
Ageratum 6.0 - 7.0 Gentian 6.0 - 8.0 Pear 6.0 - 8.0
Apple 6.0 - 8.0 Geranium 6.0 - 8.0 Peony 6.0 - 8.0
Arborvitae 6.0 - 8.0 Gladiolus 6.0 - 8.0 Pepper 6.0 - 6.5
Asparagus 6.0 - 7.0 Grape 6.0 - 8.0 Petunia 6.0 - 8.0
Aster 6.0 - 8.0 Grass, Carpet 6.0 - 7.0 Pink 6.0 - 8.0
Beets 5.8 - 7.0 Grass, Bermuda 6.0 - 7.0 Plum 6.0 - 8.0
Begonia 6.0 - 8.0 Groundsel 6.0 - 8.0 Poinsettia 6.0 - 8.0
Bluegrass, KY 6.0 - 8.0 Gypsophila 6.0 - 8.0 Radish 6.0 - 8.0
Box, Common 6.0 - 8.0 Hawthorn 6.0 - 8.0 Redbud 6.0 - 8.0
Broccoli 6.0 - 7.0 Hibiscus 6.0 - 8.0 Rose 6.0 - 8.0
Cabbage 6.0 - 7.0 Iris 6.0 - 8.0 Sage 6.0 - 8.0
Calendula 6.0 - 8.0 Juniper 6.0 - 8.0 Snapdragon 6.0 - 7.0
Cantaloupe 6.0 - 8.0 Kale 6.0 - 8.0 Spinach 6.5 - 7.0
Carnation 6.0 - 8.0 Lettuce, Garden 6.0 - 7.0 Spirea 6.0 - 8.0
Celery 6.0 - 6.5 Lettuce, Quince 6.0 - 8.0 Squash 6.0 - 8.0
Cherry 6.0 - 8.0 Lilac 6.0 - 8.0 Sunflower 6.0 - 8.0
Chrysanthemum 6.0 - 8.0 Linden 6.0 - 8.0 Sweetgum 6.0 - 7.0
Clover 6.0 - 7.0 Maple 6.0 - 8.0 Tomato 6.0 - 7.0
Corn 6.0 - 7.0 Mint 6.0 - 8.0 Tulip 6.0 - 7.0
Crocus 6.0 - 8.0 Mock-Orange 6.0 - 8.0 Turnip 6.0 - 8.0
Cucumber 6.0 - 8.0 Narcissus 6.0 - 8.0 Violet 6.0 - 8.0
Daffodil 6.0 - 6.5 Nasturtium 6.0 - 8.0 Walnut 6.0 - 8.0
Dahlia 6.0 - 8.0 Oak 5.0 - 8.0 Watermelon 6.0 - 7.0
Daylily 6.0 - 8.0 Onion 6.0 - 7.0 Weigela 6.0 - 8.0
Deutzia 6.0 - 8.0 Pansy 6.0 - 8.0 Willow 6.0 - 8.0
Dogwood 6.0 - 8.0 Parsley 6.0 - 8.0 Wisteria 6.0 - 8.0
Egg Plant 6.0 - 7.0 Passion Flower 6.0 - 8.0 Yew 6.0 - 8.0
Elm 6.0 - 8.0 Pea, Common 6.0 - 8.0 Yucca 6.0 - 8.0
Forsythia 6.0 - 8.0 Pea, Sweet 6.0 - 8.0 Zinnia 6.0 - 8.0
Gaillardia 6.0 - 8.0 Peach 6.0 - 8.0
8
LIME-ALUM TABLES
Once the pH of a soil is known, the Lime-Alum Tables are used to
determine the average amount of lime or alum necessary to properly
adjust the soil pH.
Rate Of Application
Rate Of Application
Group A
Plants
Group B
Plants
pH Test
Reading
4.0 1.5 Limestone 165 Limestone 3.5 Limestone
5.0 1.0 Limestone 110 Limestone 2.0 Limestone
6.0 0.5 Limestone 55 Limestone 1.0 Limestone
7.0 None None None
8.0 None None None
pH Test
Reading
4.0 0.75 Limestone 82.5 Limestone 1.5 Limestone
5.0 0.25 Limestone 27.5 Limestone 0.5 Limestone
6.0 None None None
7.0 1.0 Alum 110 Alum 2.0 Alum
8.0 2.0 Alum 220 Alum 4.0 Alum
lbs/sq yd lbs/1000 sq ft tons/acre
lbs/sq yd lbs/1000 sq ft tons/acre
The Average Rates presented here assume the following conditions:
intermediate soil texture, temperate climate, and moderate rainfall. Regular
soil testing before and after lime or alum applications will permit you to
adjust these suggested application rates to suit your particular soil
conditions.
9
LIMESTONE APPLICATIONS Sands and sandy loams require slightly
less limestone per unit of area, while clays and clay loams require a
slightly higher rate of application. Where large amounts of limestone
application are suggested, it is advisable to divide the application over
several months for closer control. Test the soil six months after the first
application to determine if further pH adjustment is required. This allows
sufficient time for the soil to reach equilibrium.
LIMESTONE EQUIVALENTS
100 lbs of Limestone (Calcium Carbonate) is equivalent to 56 lbs Burned
Lime (Calcium Oxide) or 74 lbs Hydrated Lime (Calcium Hydroxide).
ALUM APPLICATIONS Many peats and other organic mulches are
highly acid and will help acidify the soil when incorporated in the soil or
used in the planting mixture.
10
THE MAJOR PLANT NUTRIENTS
The major essential nutrient elements supplied through the soil are
nitrogen, phosphorus, and potassium. The nutrients absorbed from the soil
by plants are supplied by several means. These include minerals released
from the decomposition of native rocks, decomposition of organic matter,
deposition with the soil from flood waters, application of limestone and
commercial fertilizer materials, and the use of animal or plant manures.
Much of the nitrogen, phosphorus, and potassium in the soil is chemically
“bound” and cannot be readily absorbed by growing plants. To provide an
accurate profile of soil fertility, LaMotte soil tests measure strictly the
available forms of these nutrients.
• AVAILABLE NITROGEN
Nitrogen is a part of every living cell. As a component of amino acids, the
building blocks of protein, nitrogen is a vital link in the world’s food
supply. Nitrogen is directly involved in photosynthesis. It stimulates
above-ground growth and produces the rich green color characteristic of
healthy plants. Nitrates, the available forms of soil nitrogen, are produced
through the decomposition of organic matter, the application of nitrogen
fertilizers, and the fixation of atmospheric nitrogen by microorganisms
growing on legume roots. Soil nitrogen is depleted through harvesting of
crops, leaching by rain water, and return of nitrogen to the atmosphere by
volatilization.
• AVAILABLE PHOSPHORUS
Young plants absorb large amounts of phosphorus, which speeds seedling
development and promotes early root formation. Rapid, early growth
means hardier, stronger plants. In mature plants, phosphorus is vital to the
development of healthy seeds and fruits which contain large amounts of
this essential nutrient. Only a small percentage of soil phosphorus is in an
available form and these phosphates move more slowly through the soil
than other nutrients.
• AVAILABLE POTASSIUM (POTASH)
Potassium acts as a catalyst, a chemical agent which facilitates a number
of chemical processes in the plant. Potassium promotes various aspects of
plant metabolism -photosynthesis, efficient use of water, and the formation
of strong roots and stems. Well-described as a “tonic” for plants,
potassium strengthens natural mechanisms for the resistance of disease
and extremes of weather.
11
FERTILIZER APPLICATION
Of greatest practical help to modern growers is the ability to reliably
estimate the actual plant food requirements of the crops they wish to grow
each season. Many of these results can be used as a yardstick not only for
insuring proper feeding of the plants but also to achieve these results with
controlled econ
FERTILIZER RECOMMENDATION TABLE
The Fertilizer Recommendation Table is used to interpret the soil test
results. The tests provide a relative measure of the major nutrients present
in the soil in available form, and the table indicates how much fertilizer
should be added to achieve optimum soil conditions.
Read down the nitrogen column to locate the application rate
corresponding to the nitrogen test result. Do the same for phosphorus and
potash. These three figures (in lbs per 2000 sq ft) enable you to determine
what fertilizer mixture to select and how much of it to apply.
Pounds to be Added per 2000 Square Feet
Test Result Nitrogen Phosphorus Potash
Very High
High
Medium High
Medium
Medium Low
Low
Very Low
2 4 3
4 6 4
5 7 5
6 8 6
7 9 7
8 10 8
10 12 10
NOTE: Evergreens, shrubs, and berry plants should be treated at one-half
the rates given in the table.
12
Commercial Fertilizer Mixtures show a three-number formula indicating
percentages of nitrogen, phosphorus, and potash. Use the example below
to select the proper mixture.
Test Results
Fertilizer Recommendation
Formula of Fertilizer Mixture
Nitrogen Phosphorus Potash
Medium Low High
6 lbs 10 lbs 4 lbs
6% 10% 4%
100 lbs of the 6-10-4 mixture contain 6 lbs nitrogen, 10 lbs phosphorus,
and 4 lbs potash. Apply 100 lbs of this mixture per 2000 sq ft (50 lbs per
2000 sq ft for evergreens, shrubs, or berries). Smaller areas require
proportionally smaller applications.
If unable to find a formula that matches the values obtained in the
recommendation table, use a formula with approximately the same
proportions as the recommended values. Always consult manufacturer
recommendations.
13
SOIL TEST RECORD
Sampling
Area ID #
Date of
Sample
Plant Grown
Type of
Soil Test Results
Soil (pH)
Reaction Nitrogen Phosphorus Potash
Comments
or
Observations
14
LaMOTTE COMPANY
Helping People Solve Analytical Challenges
PO Box 329 • Chestertown • Maryland • 21620 • USA
800-344-3100 • 410-778-3100 (Outside U.S.A.) • Fax 410-778-6394
Visit us on the web at www.lamotte.com
SM
36250 • 03.10
Loading...