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Nutrient enrichment can lead to excess algae growth

Nutrient enrichment can lead to excess algae growth. Colorado Phosphorus Index Risk Assessment. Version 1.0 November, 2000. Introduction .

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Nutrient enrichment can lead to excess algae growth

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  1. Nutrient enrichment can lead to excess algae growth

  2. Colorado Phosphorus IndexRisk Assessment Version 1.0 November, 2000

  3. Introduction The Colorado Phosphorus Index (COPI) Risk Assessment is a tool for planners, consultants, and producers that may be used to rank the relative potential for phosphorus movement to surface water resources from agricultural fields.

  4. Introduction The COPI has been developed cooperatively by the Natural Resources Conservation Service and Colorado State University to comply with the Revised National Nutrient Management Policy (USDA, April, 1999).

  5. Introduction A risk assessment is required when manures or other organic by-products will be land applied to determine if application rates should be based on crop nitrogen, or crop phosphorus requirements.

  6. Objectives • Terminology • Site-specific information requirements • Preliminary Phosphorus Risk Screening Tool • COPI Risk Factors • COPI Risk Interpretations • Example

  7. Terminology Contour Buffer Strip - Narrow strips of permanent, herbaceous vegetative cover established across the slope and alternated down the slope with parallel, wider cropped strips.

  8. Terminology Cover Crop - Grasses,legumes, or other herbaceous plants established for seasonal cover and conservation purposes to: (1) protect the soil surface from erosion during periods when it would otherwise be bare; (2) scavenge excess nutrients from a previous crop to prevent nutrient loss; or both.

  9. Terminology Current Crop Rotation - A planned sequence of crops growing in a regularly recurring succession on the same area of land, as contrasted to continuous culture of one crop or growing a variable sequence of crops.

  10. Terminology Current Soil Test - Current soil tests are those no older than 5 years. State or local regulations may require soil testing at more frequent intervals for some types of operations.

  11. Terminology Filter Strip - A strip or area of vegetation situated between cropland, grazing land, or disturbed land (including forest land) and environmentally sensitive areas.

  12. Terminology Surface Water Resources - Includes water bodies such as continuous or intermittent streams, irrigation ditches, drainage ditches, lakes, and wetlands, etc.

  13. Site-Specific Information Requirements • Current Crop Rotation • Manure Application History • Current Soil Test and Extraction Method • Field Proximity to Surface Water Resources • Soil Series • Phosphorus Application Rates • Phosphorus Application Methods

  14. Preliminary Phosphorus Risk Screening Tool A screening tool is included with the index to make an initial determination as to whether or not a COPI Risk Assessment needs to completed for an individual field and crop rotation.

  15. Preliminary Phosphorus Risk Screening Tool Question 1 Will manures or other organic nutrients be applied to this field? If No, a COPI is not needed for this field. If Yes, go to Question 2.

  16. Preliminary Phosphorus Risk Screening Tool Question 2 Is soil test Phosphorus greater than: 10 ppm AB-DTPA; 30 ppm Bray P1; 30 ppm Mehlich3, or; 20 ppm Olsen (NaHCO3)? If No, a COPI is not needed for this field. If Yes, go to Question 3.

  17. Preliminary Phosphorus Risk Screening Tool Question 3 Can field runoff or irrigation tailwater reach a surface water body? (continuous or intermittent stream, ditch, lake, or wetland, etc.) If No, a COPI is not needed for this field. If Yes, complete a COPI Risk Assessment.

  18. COPI Risk Factors • The COPI is an additive index based on 4 site and management risk factors. • Each risk factor is rated and assigned a numeric score of 0, 1, 2, 3, or 4. • The numeric scores for each factor are then added together to determine the relative risk of phosphorus movement off-site.

  19. COPI Risk Factors 1. Runoff Class Runoff class is based on field slope and the least permeable soil layer in the top three feet of the soil profile. Steep slopes with slow permeability pose a greater risk than flat slopes with rapid permeability.

  20. COPI Risk Factors

  21. COPI Risk Factors 2. Soil Test Phosphorus Samples forphosphorus soil tests should be pulled from the top 2 to 3 inches for continuous no-till cropland, hayland and pastures, and from the top 8 to 12 inches for tilled cropland.

  22. COPI Risk Factors

  23. COPI Risk Factors 3. Phosphorus Application Rate This is the amount of phosphorus annually applied, or average annual application rate calculated for the current crop rotation, from both organic and inorganic sources. Organic nutrient content may be estimated from lab results or book values.

  24. COPI Risk Factors

  25. COPI Risk Factors

  26. COPI Risk Factors 4. Phosphorus Application Method The longer phosphorus is exposed on the soil surface, thegreater the risk for phosphorus loss. Use the highest risk applicable for multiple phosphorus applications. Sprinkler applications that do not exceed soil infiltration capacity are considered to be a low risk.

  27. COPI Risk Factors

  28. COPI Risk Factors 5. BMP Implementation Credits Specific BMPs may be implemented to decrease the potential for phosphorus loss. Subtract one point from the gross score for each of the following BMPs implemented on-site.

  29. COPI Risk Factors 5. BMP Implementation Credits (cont.) • Cover or Green Manure crops • Filter Strips • Polyacrylamide (PAM) • Contour Buffer Strips

  30. COPI Risk Interpretations < 8 Low risk Nitrogen based 8 to 11 Medium risk Nitrogen based 12 to 15 High risk Phosphorus base d (crop removal) 16 Very high risk Phosphorus based (no application)

  31. Example • Continuous minimum till grain corn • Soil Permeability - Slow • Slope - 3 to 5 % • Soil test P - 30 ppm Olsen (NaHCO3) • Manure - 20 tons applied every 2 years • App. Method - Fall/winter broadcast/disk

  32. Example

  33. Example

  34. Example

  35. Example

  36. Summary • Terminology • Site-specific information requirements • Preliminary Phosphorus Risk Screening Tool • COPI Risk Factors • COPI Risk Interpretations • Example

  37. For Additional Information... • Jim Sharkoff (720) 544-2812 jim.sharkoff@co.usda.gov • Reagan Waskom (970) 491-6103 rwaskom@lamar.colostate.edu • Jessica Davis (970) 491-1913 jgdavis@lamar.colostate.edu

  38. Finis

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