Agriculture Reference
In-Depth Information
should be available to plants, taking the soil pH and chemical forms of the
nutrients into account. Nitrogen availability is shown as equivalent amounts
of ammonium (NH ) and nitrate (NO ) nitrogen. Phosphorus, being chemic-
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ally reactive, is found in many different chemical compounds in the soil and
is defined as the equivalent of P O (phosphorus pentoxide), regardless of
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2
the chemical forms actually present. Potassium is reported as equivalents of
K O (potassium oxide or potash).
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2
TABLE 4.2
Preplant Phosphorus Fertilizer Rates
Rates are in P O , based on soil tests. Soil test P can be determined
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by several procedures, three of which are shown here: sodium acetate
(NaOAc), Bray I method, or by sodium bicarbonate (NaHCO ). Sodium bi-
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3
carbonate should not be used on soils with pH values less than 6.2. Use
the column indicated by your soil test report.
