Ohio State University Extension Bulletin

Ohio Livestock Manure Management Guide

Bulletin 604-06

Appendix G - Phosphorus Soil-Test Risk-Assessment Procedure

Table 28. Ohio NRCS Phosphorus Soil-Test Risk-Assessment Procedure
Criteria Applicable to All Soil-Test Levels:
  1. All applications are based on current soil-test results (not more than three to five years old).
  2. No manufactured P2O5 applied above 40 ppm (Bray-Kurtz P1 soil test) or equivalent soil test, unless recommended by appropriate industry standards or the land-grant university for specialty crops, vegetable crops, etc.
“P” Soil-Test Level Application Criteria
Bray-Kurtz P1 < 40 ppm(< 80 Lbs/Acre)
OR
Other Equivalents(e.g., Mehlich 3)

LOW POTENTIAL		 Recommended N or P2O5.Manure or other organic by-products can be applied to meet the succeeding crop’s recommended NITROGEN requirements for non-legume crops or the NITROGEN removal for legume crops; OR the recommended P2O5 but not to exceed the NITROGEN needs of the succeeding crop.
Bray-Kurtz P1 40-100 ppm(80 - 200 Lbs/Acre)
OR
Other Equivalents(e.g., Mehlich 3)

MODERATE POTENTIAL		 Recommended N or P2O5 Removal, whichever is less.The field shall have > 30% ground cover at the time of application or the manure or other organic by-products shall be incorporated within one week. The manure or other organic by-products can be applied to meet the succeeding crop’s recommended NITROGEN requirements for non-legume crops or the NITROGEN removal for legume crops; OR P2O5 removal (annual or multiple year applications) whichever is less.
Bray-Kurtz P1 100-150 ppm(200-300 Lbs/Ac)
OR
Other Equivalents(e.g., Mehlich 3)

HIGH POTENTIAL		 Recommended N or P2O5 Removal, whichever is less PLUS additional distance criteria from drainage way/water source or other sensitive area, OR filter strips. Manure or other organic by-products can be applied to meet the succeeding crop’s recommended NITROGEN requirements for non-legume crops or the NITROGEN removal for legume crops; OR P2O5 removal (annual or multiple year applications) whichever is less IF:
  1. The field has > 50% ground cover at the time of application or the material is incorporated within seven days on areas with < 50% cover.

    2. AND
  2. Unless the manure or other organic by-products are incorporated within 24 hours, no manure or other organic by-products are to be applied within 100 feet of a drainage way, water source, or other sensitive area; OR, the width of a vegetative filter strip (minimum width 33 feet) maintained adjacent to the drainage way, water source, or sensitive area.
Bray-Kurtz P1 > 150 ppm(> 300 Lbs/Ac)
OR
Other Equivalents(e.g., Mehlich 3)

VERY HIGH POTENTIAL		 No additional P2O5—Use P2O5 draw-down strategies.
Source: Ohio Natural Resources Conservation Service (NRCS) Field Office Technical Guide, Section 1, FOTG, page 9. Used by permission.
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