Developing a Modeling Framework to Characterize Manure Flows in Texas

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Abstract

In recent years, sharply rising costs of inorganic fertilizers have contributed to an increased demand for manure and compost in crop production acreage, transforming cattle manure from a valueless waste to a viable alternative to commercial fertilizer. If additional demand for manure as a bio-fuel were to arise manure could take on two distinct values, a fertilizer value and a fuel value. This potential “dual” value of manure begs several questions. What would the fertilizer and fuel markets of manure look like? Is there enough manure supply for the markets to operate independently? If not, which market would prevail? In essence, how, if at all, would manure’s potential value as a bio-fuel distort the traditional Panhandle manure market? A modeling framework was developed to assess the potential impacts of a manure-fired ethanol plant on the existing Texas Panhandle manure fertilizer market.  Two manure-allocation runs were performed using a spreadsheet model. Run #1 allocated all available manure from dairies and feedlots to cropland as manure fertilizer; run #2 first allocated fuel manure to the ethanol plant and then allocated the remaining manure to cropland. Both model runs assumed a time horizon of one year and no antecedent nutrients in cropland soils. Other constraints included only irrigated acreages received manure and no supplemental fertilizer was used. The model revealed a 6.4% increase in cost per acre of fertilizing with manure for fields whose nutrient requirements were fully satisfied in both runs. The increase in cost per acre was likely due to an increase in hauling distances attributed to fewer CAFOs available for fertilizer manure. The model is not presented as a dynamic, systems model, but rather a static model with the potential to be incorporated into a more dynamic systems-based modeling environment. Suggestions for further model development and expansion including GAMS integration are presented.

Why Model Manure Transport and Use?

To demonstrate the potential for systems modeling to characterize manure flows in response to fertilizer prices,  biofuel demand, and other externalities in the Texas Panhandle

Conceptual model diagram.

What Did We Do?

We develeloped a spreadsheet based modeling framework to evaluate how both manure use and transport might be affected by regional changes in fertilizer prices, crop composition, and biofuel demand.  Specifically, we evaluated how traditional fertilizer valued manure flows might be affected by potential biofuel based flows stemming from a proposed manure-fired ethanol plant.  Two model simulations representing manure flows with and without biofuel manure demand from the proposed plant were performed.

Explicit model boundary shown with TNRIS satellite imagery used to locate and identify center pivot irrigated fields.

What Have We Learned?

Although the cattle industry in Texas Panhandle generates a substantial volume of manure, almost all of it is land applied as fertilizer.  However, the introduction of manure-fired facilities such as the proposed ethanol plant would undoubtedly change the dynamics of the existing manure market by introducing at least additional demand, if not a second value-based market.  Assuming only transportation costs of acquiring manure for biofuel, our model simulations suggested a 6.4% increase in cost per acre for lands whose manure requirements were fully satisfied in both simulations.  Assuming that manure for biofuel received an allocation preference for proximity to the plant, we propose that costs associated with having to transport manure over longer distances significantly contributes the the increased cost per acre for fertilized lands.

In terms of what we learned about systems modeling, we have experienced (although anticipated) that translating broad, systems based conceptual modeling ideas into an explicit, user friendly, and robust modeling interface can be extremely challenging. Although systems-based modeling efforts occur largely at a macro level, they often require extensive supplemental datasets.  We have experienced difficulty in identifying software packages that are equipped to adequately handle both aspects of systems modeling.

Future Plans

We plan to continue to develop and expand the current modeling framework by incorporating  a GIS-based water availability aquifer component, expanding the current crop-composition database, and providing logic algorithms for producer-based management decisions using GAMS (General Algebraic Modeling System) optimization modeling.

Manure allocation map for model run #1 (232 LMU cells allocated).

Authors

Brent Auvermann, Professor of Biological and Agricultural Engineering, Texas A&M AgriLife Research, b-auvermann@tamu.edu

Gary Marek, Postdoctoral Research Associate, Texas A&M AgriLife Research; Brent W. Auvermann, Professor of Biological and Agricultural Engineering, Texas A&M AgriLife Research; Kevin Heflin, Extension Associate, Texas A&M AgriLife Extension

Additional Information

Please contact Gary Marek, Postdoctoral Research Associate, Texas A&M AgriLife Research, 6500 Amarillo Boulevard West, Amarillo TX, 79106, Phone: 806-677-5600, Email: gwmarek@ag.tamu.edu or  Brent W. Auvermann, Professor of Biological and Agricultural Engineering, Texas A&M AgriLife Research, 6500 Amarillo Boulevard West, Amarillo TX, 79106, Phone: 806-677-5600, Email: b-auvermann@tamu.edu.

Acknowledgements

Special thanks to Dr. Raghavan Srinivasan and David Shoemate of the Texas A&M University Department of Ecosystem Science and Management Spacial Sciences Laboratory for their help in GIS processing scripts.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Effects of Waste Management Techniques to Reduce Dairy Emissions from Freestall Housing

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Dairy
Use Area: Animal Housing
Technology Category: Management
Air Mitigated Pollutants: Volatile Organic Compounds, Ethanol & Methanol

System Summary

Recent dairy emission research has identified alcohols (methanol and ethanol) as the major volatile organic compound (VOC) group originating from fresh waste (Shaw et al., 2007; Sun et al., 2008). Effective control of these alcohols from dairies will help the dairy industry meet regulatory standards, satisfy public concerns, and improve local and regional air quality. Enhancing industry typical freestall waste management practices, which currently are predominant practices like flushing and scraping of fresh waste, may provide a large impact on mitigation of oxygenated VOC emissions in a cost effective manner.

Our research has shown that flushing is more effective than scraping in reducing methanol (MeOH) and ethanol (EtOH) emissions from barns. Flushing three times daily versus scraping three times daily yields an emission reduction efficiency of 50% for both MeOH and EtOH. Furthermore, flushing frequency by itself significantly reduces emissions. A comparison of 3 times versus 6 times flushing daily showed decreased emissions by 79% for MeOH and 63% for EtOH.

Applicability and Mitigating Mechanism

  • Oxygenated VOC (e.g., alcohols MeOH and EtOH) are produced by fermenting microbes present in fresh waste
  • Frequent waste removal effectively mitigates MeOH and EtOH emissions from fresh waste
  • VOC alcohols are water-soluble and become effectively trapped in water when flushed
  • Flushing is more effective than scraping, and increasing flushing frequency further decreases VOC emissions

Limitations

  • Scraping methods leave a thin film of manure on concrete ground that continues to produce emissions

Cost

There is no cost associated with increasing the flushing frequency of a liquid manure handling system. Essentially, flushing frequency is increased, while the amount of water per flushing event is decreased. Since the water used to flush barns is recycled water from the lagoons, there is no cost to re-circulate lagoon water through the barn alleys.

Authors

M. Calvo, K. Stackhouse, Y. Zhao, Y. Pan, Ts Armitage, and F. Mitloehner, University of California, Davis
Point of Contact:
Frank Mitloehner, fmmitloehner@ucdavis.edu

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

Effects of Sodium Bisulfate in Reducing Emissions from Dairy Cow Slurry

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

This Technology is Applicable To:

Species: Dairy
Use Area: Animal Housing
Technology Category: Amendment (chemical)
Air Mitigated Pollutants: Ammonia, Methanol and Ethanol

System Summary

Sodium bisulfate may provide an effective management practice for the reduction of alcohols and ammonia emissions from dairy housing conditions. Application of sodium bisulfate (Parlor Pal) has been demonstrated to be effective in the mitigation of both ammonia and alcohols (methanol and ethanol) emissions from fresh dairy slurry. Ammonia emissions decrease with increasing levels of SBS treatment. Methanol and ethanol emissions also decrease with an increase in the amount of SBS applied.

Product should be applied to dairy drylots with a fertilizer spreader twice per week at a rate of 50 – 75 lb/1000 ft2 for control of ammonia, methanol, and ethanol emissions. However, SBS should not be spread evenly but rather topical around highly frequented cow areas (feed bunk, water troughs). Studies conducted at the University of California at Davis (UCD) showed reduction of ammonia of 61% from fresh manure. Application to enclosed drylots at UCD showed reductions of methanol and ethanol of 15-30%.

Applicability and Mitigating Mechanism

  • Emission of gaseous ammonia and alcohols from fresh slurry is dependent on pH, temperature, microbial activity and etc.
  • Bedding/surface manure pH is important factor for controlling NH3 volatilization
  • Application of SBS lowers pH of slurry and as a result reduces ammonia, methanol, and ethanol fluxes
  • Reduction in pH reduces bacterial population

Limitations

  • Sodium bisulfate must be applied consistently to manure to maintain constant emission reduction as the substance looses its effectiveness over time
  • In locations that are sensitive to salt or areas with existing high salt loading in soils, applications of SBS should be considered with care because sodium is on of its components
  • SBS is a mineral acid. Appropriate measures, as defined by the chemical supplier, should be used during the handling of SBS

Cost

Bulk cost of product delivered to the farm is $660.00/ ton. Application at 50 – 75 lb / 1000 ft2 2X / week equates to costs of between $33.00 – $49.50 / 1000 ft2 / week. Treatment of heavy use areas, approximately 30% of the total pen area, reduces total pen cost by 70%. Cost / cow assuming 4 cows / 1000 ft2 of pen area would be $2.48 – $3.71 / week treating only the heavy use areas.

Authors

Kim Stackhouse1, Jeffrey McGarvey2, Yuee Pan1, Yongijing Zhao1, Huawei Sun1, Wendi A. Jackson1, Lisa M. Nuckles1, Irina L. Malkina1, Veronica E. Arteaga1, and Frank M. Mitloehner 1University of California, Davis, 2 USDA-ARS, Albany CA
Point of Contact:
Frank Mitloehner, fmmitloehner@ucdavis.edu

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.