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Current Project: N and P availability and losses as affected by N requirement and P removal based liquid dairy manure and composted separated dairy solids


Quirine Ketterings (NMSP), Greg Godwin (NMSP), Karl Czymmek (PRODAIRY), Shawn Bossard (CCE of Seneca County), Joe Lawrence (CCE of Lewis County), and Bill Cook (Aurora Ridge).


Phosphorus (P) transport in erosion and runoff from animal feeding operations (poultry, swine, dairy and beef) is a major contributor to surface water eutrophication in the US. High P levels in the main streams and reservoirs have led to local, state and federal attempts to regulate fertilizer and manure application on large confined animal feeding operations (CAFO’s) that tend to have the most unbalanced nutrient budgets.

The P index aims at identifying fields that have high levels of P and are likely to generate runoff. A field with a NY P index <50 is classified as a low risk field for P runoff. Manure applications can be balanced on N requirements of the crop. If the P index is 50-74, it falls in the medium risk class and N based management with the application of best management practices is recommended. Fields with a P index of 75-99 are considered to be high-risk fields that should receive applications of manure and/or fertilizer that do not exceed crop removal. For fields that have a very high vulnerability for P risk through runoff (P index of 100 or higher) should not receive any P application. The P index is not the solution to P imbalances on dairy farms. However, it is a management tool that steers producers towards improved environmental management of the nutrients on their farms while export options are being investigated and evaluated.

One such export mechanism is separation of solids and composting. Unknown is what the nutrient value is of such composted separated solids. Furthermore unknown are the effects of P removal based organic nutrient management on N and P dynamics, soil physical characteristics such as soil bulk density, water holding capacity, aggregation and compaction, availability of micronutrients and general farm economics. In addition, it is unknown what the effects are of organic management on crop quality.

A large-scale field trial was initiated in Aurora, NY, in the spring of 2001 to address several of these questions.


With this experiment, we aim to study:

  1. Build-up of P under N requirement and P removal based organic and inorganic fertility management of corn.
  2. N fertilizer equivalents of composted dairy solids versus liquid dairy manure.
  3. Timing of the N release peaks as affected by organic N source.
  4. Effect of time of sampling on soil test results for pH and Morgan extractable P, K, Ca, Mg, Fe, Mn and Zn.
  5. Effect of N source on organic nitrogen buildup (evaluation of the aminosugar N test)..
  6. Effect of N source and application method on soil bulk density, water holding capacity, aggregation and compaction.
  7. The effects of organic based nutrient management on corn silage and grain yield and yield quality.


In the spring of 2001, a trial with ten treatments in five replicates was established at the
Musgrave Research Farm at Aurora, NY. The ten treatments are:

  1. 20,000 gallons/acre liquid manure (N requirement according to Cornell’s database);
  2. 7,000 gallons/acre liquid manure (estimated P removal);
  3. 34 tons/acre composted separated dairy solids (N requirement according to Cornell’s database);
  4. 20 tons/acre composted separated dairy solids (estimated P removal);
  5. 20 lbs N/acre in the starter band;
  6. Treatment 5 plus 30 lbs N/acre at sidedressing time;
  7. Treatment 5 plus 80 lbs N/acre at sidedressing time;
  8. Treatment 5 plus 130 lbs N/acre at sidedressing time (N requirement according to
    Cornell’s database);
  9. Treatment 5 plus 180 lbs N/acre at sidedressing time;
  10. Treatment 5 plus 220 lbs N/acre at sidedressing time.

Each organic plot is 40 feet wide (16 rows) and 180 feet long. The inorganic plots are 20 feet wide and 180 feet long (8 rows). Soil fertility parameters (pH, organic matter, nitrate and Morgan extractable P, K, Ca, Mg, Fe, Mn, and Zn) are determined on a bimonthly basis throughout the growing season. Aminosugar N levels are being tracked over time as well. The corn is harvested for silage and grain and both for dry matter and quality. The experiment was continued under corn for 5 years and then rotated to alfalfa. We are currently in the 4th year of alfalfa production, investigating yield and soil fertility dynamics over time (i.e. drawdown of P and K levels).

For Further Information:

Information on this project can be obtained from Quirine Ketterings ( or 607-255-3061). You can also write to: Quirine Ketterings, Nutrient Management Spear Program, Department of Animal Science, Cornell University, 323 Morrison Hall, Ithaca NY 14853.