Idaho Administrative Code
Title IDAPA 02 - Agriculture, Department of
Rule 02.04.14 - RULES GOVERNING DAIRY BYPRODUCT
Section 02.04.14.031 - PHOSPHORUS MANAGEMENT

Universal Citation: ID Admin Code 02.04.14.031

Current through September 2, 2024

Dairy farms shall utilize either Phosphorus Indexing (Section 031.01) in accordance with the Idaho Phosphorus Site Index, or Phosphorus Threshold (Section 031.02) pursuant to the 1999 Idaho NRCS Nutrient Management Standard 590 to manage nutrient application.

01. Phosphorus Indexing. The dairy farm shall utilize phosphorus site indexing (PSI) for each field where dairy byproducts and/or commercial fertilizers are land applied and for each pasture utilized for grazing, in accordance with the Idaho Phosphorus Site Index Standards. The PSI shall be calculated by a Nutrient Management Planner, certified by the Department, and be included as a component of the DNMP in the dairy farm's Environmental Management Plan. It shall be the dairy farm's responsibility to provide updated information, including annual soil test results, to the Nutrient Management Planner for calculation of the PSI on all fields and pastures on an annual basis. Failure to abide by the nutrient application and management provisions of a field or pasture's PSI risk classification in the DNMP shall constitute a non-compliance and the producer may be penalized as provided in these rules.

a. Notwithstanding anything to the contrary in the Idaho Phosphorus Site Index Standards, no land application of phosphorus shall be permitted on any fields or pastures that possess a soil phosphorus level exceeding three hundred (300) parts per million, as determined by the required annual soil test (via Olsen method). Further, the dairy farm shall not receive BMP Coefficient credit for implementing any best management practice designed to reduce phosphorus loss on fields exceeding three hundred (300) parts per million, via Olsen method.

b. The Department may award zero (0) or partial BMP Coefficient credit when a dairy farm implements a best management practice designed to reduce phosphorus loss from fields that does not fully conform to NRCS standards or the standards set forth in the Idaho Phosphorus Site Index Standards BMP definition section.

c. Amendments to the Idaho Phosphorus Site Index Standards must be approved by three (3) scientists from research institutions identified as partner institutions of the USDA National Institute of Food and Agriculture (NIFA), as found at https://www.nifa.usda.gov/land-grant-colleges-and-universities-partner-website-directory. Amendments shall be based on a minimum of three (3) peer-reviewed research publications that are relevant to Idaho's climate, soil, cropping system and irrigation.

02. Phosphorus Threshold. If the regulatory or producer soil tests reveal that phosphorus thresholds on fields and pastures have exceeded the levels established in the 1999 Idaho NRCS Nutrient Management Standard 590, the producer shall only apply phosphorus at the appropriate phosphorus crop uptake rate. Subsequent regulatory soil test(s) on fields and pastures that were identified as exceeding the phosphorus threshold will be conducted. If two (2) out of three (3) tests reveal the phosphorus index continues to trend upward, the producer will be penalized as provided in these rules. These tests shall be taken in the top one (1) foot of soil.

Effective July 1, 2024

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