A Process-Based Nutrient Model for the Bedpack Manure of Confined Beef Systems

Project Overview

Project Type: Graduate Student
Funds awarded in 2012: $9,860.00
Projected End Date: 12/31/2014
Grant Recipient: South Dakota State University
Region: North Central
State: South Dakota
Graduate Student:
Faculty Advisor:
Dr. Erin Cortus
South Dakota State University

Annual Reports


  • Animals: bovine


  • Animal Production: manure management
  • Crop Production: nutrient cycling
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    Runoff and manure management are of growing concern for beef cattle producers and the general public. At the same time, the manure, including any bedding material (bedpack), is a valuable fertilizer. Thus, it would be a great advantage for the producer to control the manure by predicting its quantity, quality, and fertilizer value. This includes estimating the loss of valuable nutrients to the environment in form of gaseous emission. Proper manure management optimizes nutrient retention and fertilizer value while reducing air pollution and increasing profitability. My objective is to develop a process-based model that estimates quantity, quality, and fertilizer value for the bedded manure mixture. Processes within the bedpack are impacted by transformations of nutrient compounds, and mass transfer within the bedpack as well as into the air. Stakeholder input in this project is an important factor to measure the range of practices on bedpack handling, and understand which input and output data stakeholder desire from the model. To understand how manure handling impacts nutrient flow and transformations in the bedpack, the core experiments are conducted in lab-scale bedded packs in collaboration with USDA-Meat Animal Research Center (MARC). Bedpack samples from beef barns, with corresponding emission data recorded at the time of sampling will verify the model. The expected project outcome is beef producers have a tool that estimates how bedpack characteristics (depth, material, storage time), temperature, pH, and microbiology impact nitrogen, phosphorus, and potassium transformations to guide management decisions and operate a sustainable beef cattle facility.

    Project objectives from proposal:

    My work focuses on the manure bedpack of beef cattle under roof. I hypothesize that 1) N, P and K transformations are a function of temperature, bedpack characteristics (depth, material, porosity, pH), enzymatic activity, and microbial activity, diversity and populations. The model will simultaneously address N, P, and K transformations and mass transfer in the bedpack of a cattle pen, and account for producer decisions about bedpack material and maintenance practices. I hypothesize that 2) microbial growth increases with higher temperatures and advanced storage time, thus, increasing both gaseous emission and nutrient content; microbial growth is inhibited with certain bedding material, thus, reducing both gaseous emission and nutrient content in the bedpack.
    To reach my objective, I conduct simulated lab-scale experiments using simulated bedded packs with two different bedding materials that are commonly used by beef cattle producers (ground corn stover and soybean stubble) and fresh cattle feces (urine and feces) at three different ages, depth and two different temperatures. During the experiment, I collect samples of different bedpack zones, analyze these for dry matter, short-term potential nitrification and dinitrification enzyme activity, NPK, measure pH and temperature and analyze GHG and ammonia from each treatment. I will do the same analysis for representative samples of feces, urine, and bedding material in the beginning and end of the study, except for gaseous emission.
    With the data, I develop a process-based model that can be used to improve manure management practices in confined beef cattle barns and manure value (as a valuable fertilizer source), thus, facilitating producer’s work and increasing profitability.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.