§ 83.293. Determination of nutrient application rates.
(a) Application rate. Application rates shall be developed to protect surface water and groundwater using BMPs as described in the plan. The manure application rate shall be the lesser of the following:
(1) A rate equal to or less than the balanced manure application rate based on nitrogen as determined under subsection (b).
(2) The rate as determined under subsection (c).
(b) Nitrogen. Land application of manure and other nutrient sources on cropland, hayland and pastures shall be managed to minimize the effects of nitrogen losses from fields. The rate may not exceed the amount of nitrogen necessary to achieve realistic expected crop yields or the amount of nitrogen the crop will utilize for an individual crop year.
(1) The balanced manure application rate based on nitrogen shall be determined by first subtracting the amount of available residual nitrogen and any applied nitrogen, such as nitrogen applied in starter fertilizer, from the amount of nitrogen necessary for realistic expected crop yields, and then dividing that amount by the available nitrogen content of the manure as determined under § 83.291 (relating to determination of available nutrients).
(2) The calculations and variables used for determining the balanced manure application rates based on nitrogen shall be recorded in the plan.
(c) Phosphorus. Land application of manure and other nutrient sources on cropland, hayland and pastures shall be managed to minimize the effects of phosphorus losses from fields. Methods for determining and managing the risk of phosphorus loss, and related water quality impacts, must comply with the following:
(1) Determine the risk of phosphorus loss and related water quality impacts based on relevant factors including the following:
(i) Soil phosphorus levels.
(ii) The method, rate and timing of phosphorus application.
(iii) Runoff and soil loss potential for the application area.
(iv) Distance to surface water.
(v) The type of phosphorus source being used.
(2) Based on the risks and impacts determined as described in paragraph (1), establish appropriate BMPs such as methods, rates and timing of application designed to minimize the effects of phosphorus losses from fields. These may be addressed by a range of options, including:
(i) Manure application is limited to nitrogen requirements of the crop, if the application of phosphorus to the soil is not expected to pose an immediate risk of impacts to surface water.
(ii) Phosphorus application is limited to the level of phosphorus removal from the soil by the crop, if the application of phosphorus to the soil would be expected to pose an immediate risk of impacts to a surface water unless the risk is managed by limiting the application based on phosphorus.
(iii) Phosphorus application is completely restricted, if the application of phosphorus to the soil would be expected to pose an immediate risk of impacts to a surface water which cannot be managed by limiting the nutrients based on phosphorus.
(3) For CAOs and VAOs existing on October 1, 2006, the Commission will allow a phase-in period until December 31, 2010, to fully meet the requirements of paragraph (2).
(i) The phase-in shall allow flexibility in controlling phosphorus loss, as long as the phosphorus application rates on any crop management unit where the phase-in is used do not exceed the levels of phosphorus removal from the soil by the crops.
(ii) The phase-in in this paragraph also applies to operations that import manure from NMP operations existing on October 1, 2006.
(4) The phase-in period in paragraph (3) does not apply to the following:
(i) An operation that commences after October 1, 2006.
(ii) An operation that becomes defined as a CAO, due to an increase in animal numbers, after October 1, 2006.
(iii) An operation that increases the total AEUs on the operation by 20% or more after October 1, 2006.
(iv) An operation that adds a new animal type after October 1, 2006.
(v) Fields where the nearest downgradient stream segment which receives runoff from the fields is classified as a special protection water under Chapter 93 (relating to water quality standards).
(5) The criteria and procedures in the current phosphorus application guidance issued by the Commission may be used to comply with paragraphs (1)—(4), including the use of a Phosphorus Index contained in the guidance.
(6) If the criteria and procedures in the phosphorus application guidance issued by the Commission are not followed, an alternative method of meeting paragraphs (1)—(4) will be approved by the Commission.
(7) For pastures which require complete restrictions on phosphorus application as determined under this section, § 83.294(j) (relating to nutrient application procedures) applies.
(d) General nutrient calculation. The plan must include calculations for each crop management unit indicating the difference between the amount of nitrogen, phosphorus and potassium necessary for realistic expected crop yields under § 83.292 (relating to determination of nutrients needed for crop production) and the nitrogen, phosphorus and potassium applied through all planned nutrient sources, including, but not limited to, manure, biosolids, starter fertilizer and other fertilizers and residual nitrogen. A nitrogen availability test may be used to determine supplemental nitrogen needs.
Source The provisions of this § 83.293 amended June 2, 2006, effective October 1, 2006, 36 Pa.B. 2636. Immediately preceding text appears at serial page (232359).
Cross References This section cited in 25 Pa. Code § 83.201 (relating to definitions); 25 Pa. Code § 83.204 (relating to applicability of requirements); 25 Pa. Code § 83.261 (relating to general); 25 Pa. Code § 83.262 (relating to identification of CAOs); 25 Pa. Code § 83.371 (relating to plan amendments); 25 Pa. Code § 83.272 (relating to content of plans); 25 Pa. Code § 83.281 (relating to identification of agricultural operations and acreage); 25 Pa. Code § 83.294 (relating to nutrient application procedures) and 25 Pa. Code § 83.301 (relating to excess manure utilization plans).
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