Does Manure Treatment Affect Soil Nitrogen Availability?

2008 Annual Report for LNC07-287

Project Type: Research and Education
Funds awarded in 2007: $76,034.00
Projected End Date: 12/31/2009
Region: North Central
State: Wisconsin
Project Coordinator:
Christopher Baxter
University of Wisconsin - Platteville

Does Manure Treatment Affect Soil Nitrogen Availability?


An incubation study will be conducted using five soils representative of Wisconsin soil groups and 22 manure samples that represent untreated and treated (anaerobically digested, solid-liquid separated, or composted) manures. Rates of inorganic nitrogen (N) release from the various manures will be evaluated and cumulative N released will be correlated to various compositional factors. Outputs will include fact sheets, scientific publications, and presentations aimed at producers, agronomists, and the scientific community. Outcomes will be evaluated through audience questionnaires and by quantifying the increased use of manure treatment and manure analysis for predicting available N.

2008 Summary

Raw and treated manures were incubated with five typical Wisconsin soils for 112 d. Net N mineralized from the different N sources were compared. Overall, the digested slurry and the digested separated liquid mineralized more N than the raw slurry. The digested separated solid mineralized significantly less N than the other manures. Net N mineralization as a percent of total N applied was 39, 58, 49, and 17 % for raw, digested slurry, digested separated liquid, and digested separated solids, respectively, when averaged over all soils. Manure C:N ratio preliminarily appears to be the most useful predictor of N mineralization.

Objectives/Performance Targets

  1. Finalize methodology for nitrate and ammonium – N analysis of soil incubations.

    Conduct N mineralization incubation study with soils and manures collected in 2007.

    Analyze data and summarize preliminary findings.

    Present preliminary findings at International Agronomy meeting.

    Begin preparation of final results and publications.


All objectives/performance targets for year two were achieved. Final data analysis and preparation of results is ongoing, and expected to be completed in Spring 2009.

Impacts and Contributions/Outcomes

Results presented to date have been received with great interest by producers and agronomy professionals. A poster presentation on this work titeld “Nitrogen Availability of Raw and Treated Manures” was presented at the ASA/CSSA/SSSA International Meetings in Houston, TX. Results indicating that treated manures. The research will likely lead to field studies to determine if compositional factors observed to effect N mineralization in laboratory incubations can be related to N uptake by crops.