Project title: Determination of manure P availability as affected by manure type.

Principal investigator:

Charles Wortmann

Martha Mamo

Duration: 2002 to 2003

Funding: INTSORMIL; State funds

Contact:

Charles Wortmann Department of Agronomy and Horticulture, UNL, 154 Keim Hall, Lincoln NE 68583-0915, (402)472-2909 cwortmann2@unl.edu

Martha Mamo Department of Agronomy and Horticulture, UNL, 242 Keim Hall, Lincoln NE 68583-0915, (402)472-8493

Project description: Manure phosphorus availability is expected to vary with manure type with agronomic and environmental implications. The objectives of this research are to refine the procedure for extraction of readily soluble manure P for ease of implementation and repeatability of results, and to characterize a range of manure types for water extractible P and available P. Several studies were conducted to refine the procedure for sequential extraction of manure P to determine the proportions of total P that are water (WEP) and sodium bicarbonate (BiEP) extractible. A study of how WEP and BiEP vary with manure type was also conducted. A pot study is underway to determine how P uptake by plants varies with manure type.

Key results:

A suitable procedure for determining WEP and BiEP was developed and applied in the characterization of 45 samples representing a range of animal manure types. Assuming that WEP is the best indicator of the potential for contamination of ground or surface water with dissolved reactive P, the greatest concern is with swine manure and the least concern with poultry manure when similar rates of total P are land applied. P availability to plants in the first season after application is expected to be greatest for finishing swine and beef manure, and less for manure of poultry, farrowing swine or yearling beef.