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    c o m p u t e r s a n d e l e c t r o n i c s i n a g r i c u l t u r e 6 4 ( 2 0 0 8 ) 212224

    a v a i l a bl e a t w w w . s c i en c e d i r e c t . co m

    j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c o m p a g

    A comprehensive GIS-based poultry litter management

    system for nutrient management planning and litter

    transportation

    M.S. Kang a,, P. Srivastava b, T. Tyson b, J.P. Fulton b, W.F. Owsley c, K.H. Yoo b

    a Rural Systems Engineering, Seoul National University, Seoul, Republic of Koreab Biosystems Engineering, 200 Corley Building, Auburn University, Auburn, AL, USAc Animal Science, Auburn University, Auburn, AL, USA

    a r t i c l e i n f o

    Article history:

    Received 28 August 2007

    Received in revised form

    21 April 2008

    Accepted 8 May 2008

    Keywords:

    Broiler litter

    Poultry litter

    Decision support system

    Comprehensive nutrient

    management plan

    Transportation analysis

    Geographic information system

    a b s t r a c t

    Confined poultry (broiler) production in Alabama results in about 1.8 million tons of lit-

    ter annually. Because poultry production mainly occurs in the Appalachian Plateau region

    of north Alabama, this region suffers from excessive land application of litter, resulting in

    buildup of phosphorus (P) in soils and runoff of pathogens and P from land-applied areas.

    Conversely, the Black Belt region of south-central Alabama suffers from depressed agri-

    cultural economy because of poor soil fertility. In order to achieve optimal poultry litter

    management in Alabama, litter produced in the concentrated production areas within the

    Appalachian Plateau region mustbe optimallydistributed in this region or transported south

    for utilization in the Black Belt region. Hence, a comprehensive system to provide improved

    waste management strategies (optimal land application and transportation) for sustainable

    on- and off-farm litter utilization in Alabama is needed. The primary focus of this study

    was to develop a comprehensive, geographic information system (GIS)-integrated poultry

    litter decision support system (PLDSS) for on- and off-farm management of poultry litter in

    the Appalachian Plateau and Black Belt regions of Alabama. The PLDSS is a user-friendly,

    comprehensive system that supports nutrient management planning, transportation anal-

    ysis, anddata management for poultry litter management using ArcObjects, Visual Basic for

    Applications (VBA), and Network Analyst in ArcGIS. Important functional components and

    analytical capability of ArcGIS 9.1 were implemented in several sets of customized tools.

    Because the PLDSS allows efficient development of nutrient management plan, it can help

    to reduce over-application of poultry litter. Also, through PLDSS transportation analysis,

    the litter can be optimally transported to nutrient deficit areas. Therefore, the PLDSS will

    helppoultry producerswith optimal, cost-effectiveand environmentallysound poultry litter

    management in Alabama.

    2008 Elsevier B.V. All rights reserved.

    1. Introduction

    Alabama consistently ranks in top three, with Arkansas and

    Georgia, in broiler production. Currently, more than 4000 poul-

    Corresponding author. Tel.: +82 2 880 4582; fax: +82 2 873 2087.E-mail address: [email protected] (M.S. Kang).

    try growers (out of 25,000 in US) operate about 12,000 broiler

    houses (out of about 85,000 in US) in Alabama. In 2004,

    Alabama broiler producers marketed more than 1 billion birds

    with receipts of $2.41 billion (an increase of 31% over the

    0168-1699/$ see front matter 2008 Elsevier B.V. All rights reserved.

    doi:10.1016/j.compag.2008.05.013

    mailto:[email protected]://dx.doi.org/10.1016/j.compag.2008.05.013http://dx.doi.org/10.1016/j.compag.2008.05.013mailto:[email protected]
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    c o m p u t e r s a n d e l e c t r o n i c s i n a g r i c u l t u r e 6 4 ( 2 0 0 8 ) 212224 213

    previous year) and accounted for nearly 44% of total farm

    and forestry receipts (USDA-NASS, 2005). However, confined

    broiler (referredto as poultry hereafter)productionin Alabama

    alone results in about 1.8 million tons of poultry litter annu-

    ally, containing high levels of nitrogen (N), phosphorus (P),

    pathogens, and other potential contaminants (e.g., Arsenic,

    Copper, and Zinc) (Kingery et al., 1994). Land application of

    the large amount of litter generated from poultry productionis confined primarily to relatively small areas of perennial tall

    fescue pastureland in the Appalachian Plateau region of north

    Alabama.

    Because application of poultry litter to pastures and row

    crops serves as a cheap alternative to commercial fertilizer,

    over the years, application of poultry litter based on agro-

    nomic N requirements of forage has resulted in soil P buildup

    because of high P to N ratio in poultry litter. Even though P is

    an essential nutrient for plant growth, runoff of P can accel-

    erate eutrophication, resulting in severe impairment of water

    bodies that support aquatic, recreational and drinking water

    uses (Carpenter et al., 1998; Daniel et al., 1998). Additionally,

    nationwide, P losses from agricultural areas have emerged asa critical Total Maximum Daily Load (TMDL) issue. In addi-

    tion to P, other waterquality issues(e.g., pathogens) associated

    with massive amount of litterproduced each year threaten the

    sustainability of poultry industry in the Appalachian Plateau

    region.

    In order to minimize discharge of pollutants from land-

    applied poultry litter, Alabamas National Pollutant Discharge

    Elimination System (NPDES) rules for Animal Feeding Opera-

    tions (AFOs) requiresall AFOs to implement best management

    practices (BMPs) to protect water quality. While the rules

    for the larger Confined Animal Feeding Operations (CAFOs)

    require a registration procedure and a Natural Resources Con-

    servation Service (NRCS) approved waste management plan,all size AFOs are required to implement BMPs (Mitchell and

    Tyson, 2001). A comprehensive nutrient management plan

    (CNMP) and a phosphorus (P)-Index is a way to help meet BMP

    requirements for AFOs.

    Contrary to the Appalachian Plateau region which suf-

    fers from excessive amount of nutrients in the form of

    poultry litter, the Black Belt region located in south-central

    Alabama suffers from depressed agricultural economy that

    stems from poor soil fertility in pasture, hayfields, and row

    crops. Also, intensive row crop producing regions such as

    the nearby Tennessee Valley region use very little poultry

    litter as an alternative to commercial fertilizers in spite of

    extensive research which has demonstrated its value for

    cotton, corn, and other crops (Mitchell and Donald, 1995;

    Sims, 1987; Wood et al., 1993). In order to achieve an opti-

    mal poultry litter management in Alabama, poultry litter

    produced in the concentrated production areas within the

    Appalachian Plateau region must be optimally distributed

    and land applied in this region or should be transported

    south for utilization in the Black Belt region (Kang et al.,

    2006). Important poultry litter management issues particu-

    lar to Alabama (which are similar to issues in other poultry

    producing states) include limited use of nutrient manage-

    ment planning and P-Index by farmers, over-application of

    litter to small areas near the production facility, and lack of

    transportation infrastructure for transportation of excess lit-

    ter to nutrient deficit areas. Thus, to address many of these

    issues (i.e., to help Certified Animal Waste Vendors (CAWVs)

    and County Conservation District staff to efficiently develop

    a CNMP and a P-Index for AFOs and CAFOs, and to transport

    excess litter, for a cost-effective and environmentally sound

    management of poultry litter) a comprehensive decision sup-

    port system (DSS) is needed. A CAWV is a person who is

    certified to transport and land apply (on another farm afterdeveloping a nutrient management plan and P-Index) excess

    litter produced at a particular poultry facility. Further, since

    CNMP, P-Index, and transportation analysis are all spatial in

    nature, integration of such a comprehensive DSS with GIS is a

    must.

    A DSS has been defined in many different ways, but

    it can be regarded, in general, as an interactive, flexible,

    and adaptable computer-based information system especially

    developed for supporting the recognition and solution of a

    complex, poorly structured or unstructured, strategic manage-

    ment problem for improved decision-making (Berlekamp et

    al., 2007). A DSS often become spatial decision system (SDSS)

    by integrating functionalities or coupling with existing GIStools. Recent studies related to environmental SDSSs have

    been mostly limited to land and water quality management

    (Choi et al., 2005; Berlekamp et al., 2007; Dorner et al., 2007;

    Reichert et al., 2007; Rudner et al., 2007; Schluter and Ruger,

    2007; Ochola and Kerkides, 2004). An environmental SDSS

    for poultry litter management often consists of various cou-

    pled environmental models, databases and assessment tools,

    which are integrated under a graphical user interface (GUI),

    often realized by using spatial data management functionali-

    ties provided by a GIS.

    Currently, a number of spatial and non-spatial animal

    waste/nutrient management planning tools are being devel-

    oped and/or supported. Examples of these tools includeManure Management Planner (MMP) developed by the Purdue

    University(http://www.agry.purdue.edu/mmp/ ); Spatial Nutri-

    ent Management Planner (SNMP) developed by the University

    of Missouri (http://www.cares.missouri.edu/snmp/); NRCS

    Animal Waste Management Software (http://www.wcc.nrcs.

    usda.gov/awm/); Purdues web-based Nutrient Manage-

    ment Availability Calculator (http://www.agry.purdue.edu/

    mmp/); AFOPro (De et al., 2004; http://www.esri.sc.edu/

    Projects/usda/milestone.asp); AFOWizard (http://ip.research.

    sc.edu/catalog/00299.htm); Crop Nutrient Tool (http://npk.

    nrcs.usda.gov/nutrient body.html); WebGro (Paz et al., 2004);

    and web-based conservation planning worksheets (Steiner et

    al., 2006). In some studies on poultry litter, the environmentalimplications of excessive nutrients (Kingery et al., 1994; Ritter,

    2000; Cabrera and Sims, 2000) and the value of poultry litter

    as a fertilizer (Mitchell and Donald, 1995; Bukenya et al., 1999;

    Bagley and Evans, 1998; McKinley et al., 2000; Binford et al.,

    2001; Mitchell and Tu, 2005) have been quantified. A number

    of tools or systems have been, or are being, developed in

    response to the regulations mandating CNMP. However, appli-

    cation of current tools in Alabama is limited because quite

    often these tools are difficult to use County Conservation

    District staff, CAWVs, and farmers; do not support record

    keeping (to demonstrate compliance) required by Alabama

    land application of animal waste regulations; and do not

    integrate GIS-based transportation analysis for efficient,

    http://dx.doi.org/10.1016/j.compag.2008.05.013http://dx.doi.org/10.1016/j.compag.2008.05.013http://dx.doi.org/10.1016/j.compag.2008.05.013http://dx.doi.org/10.1016/j.compag.2008.05.013http://www.agry.purdue.edu/mmp/http://www.cares.missouri.edu/snmp/http://www.wcc.nrcs.usda.gov/awm/http://www.wcc.nrcs.usda.gov/awm/http://www.agry.purdue.edu/mmp/http://www.agry.purdue.edu/mmp/http://www.esri.sc.edu/Projects/usda/milestone.asphttp://www.esri.sc.edu/Projects/usda/milestone.asphttp://ip.research.sc.edu/catalog/00299.htmhttp://ip.research.sc.edu/catalog/00299.htmhttp://npk.nrcs.usda.gov/nutrient_body.htmlhttp://npk.nrcs.usda.gov/nutrient_body.htmlhttp://npk.nrcs.usda.gov/nutrient_body.htmlhttp://npk.nrcs.usda.gov/nutrient_body.htmlhttp://ip.research.sc.edu/catalog/00299.htmhttp://ip.research.sc.edu/catalog/00299.htmhttp://www.esri.sc.edu/Projects/usda/milestone.asphttp://www.esri.sc.edu/Projects/usda/milestone.asphttp://www.agry.purdue.edu/mmp/http://www.agry.purdue.edu/mmp/http://www.wcc.nrcs.usda.gov/awm/http://www.wcc.nrcs.usda.gov/awm/http://www.cares.missouri.edu/snmp/http://www.agry.purdue.edu/mmp/
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    214 c o m p u t e r s a n d e l e c t r o n i c s i n a g r i c u l t u r e 6 4 ( 2 0 0 8 ) 212224

    cost-effective, and environmentally sound regional/statewide

    management of poultry litter.

    Hence, the objective of this study was to develop a com-

    prehensive GIS-based poultry litter decision support system

    (PLDSS) to assist with nutrient managementplanningfor AFOs

    and CAFOs, assist with record keeping of litter application

    activities, and to provide transportation analysis functions

    for optimal, cost-effective and environmentally sound, poul-trylittermanagement in Alabama. Such a system will not only

    help sustain and enhance poultry industry in the Appalachian

    Plateau region, but will also help row crop agriculture to grow

    in the Black Belt region of Alabama.

    2. Development of the PLDSS

    DSS are computer-based systems that share several key

    characteristics, including (1) assisting users in their decision-

    making in a flexible and interactive manner; (2) solving all

    classes of problems, including ill-structured ones; (3) hav-

    ing a powerful and user-friendly interface; and (4) having adata analysis and modeling engine (Franck et al., 2000). A

    comprehensive GIS-based PLDSS for on- and off-farm usage

    of poultry litter in the Appalachian Plateau and Black Belt

    regions of Alabama was developed for potential use by County

    Conservation District staffs who have access to ArcGIS sys-

    tem.

    The user interface and the analysis routines in PLDSS were

    developed by programming the Visual Basic for Applications

    (VBA) with ArcObjects available in ArcGIS. Important func-

    tional components and the analytical capability of ArcGIS 9.1

    were implemented in several sets of customized and user-

    friendly tools. The VBA development environment consists of

    two primary tools: the customized dialog box for interactivelymodifying the user interface and the Visual Basic Editor for

    creating user forms and for writing, testing, and debugging

    Visual Basic code. This system incorporates a poultry litter

    database management system (PLDBMS) that was developed

    using MySQL 5.0 for the efficient management of poultry litter

    data. Since ArcGIS supports VBA for integrated macro devel-

    opment and MySQL is one of the worlds most popular open

    source database, they were used to development of PLDSS.

    The systems GUI allows users with limited computer

    knowledge to use the PLDSS by customizing its applications.

    For example, for the users convenience, the GUI provides an

    instrumental operating system with pull-down menus. Fur-

    thermore, it aids the users decision-making process regardingpoultry litter management, transportation, and evaluation by

    displaying the projected results of various alternatives in the

    form of graphical images, tables, and charts. To make the

    system user-friendly, this system was designed to provide

    detailed help on theinput parameters byclicking on the ques-

    tion box buttons in the sub-modules input windows. Further,

    in order to facilitate the process of determining the ideal

    input parameters, the system was designed so that placing

    the cursor on the input parameters input window the system

    suggests default value for the applicable parameter.

    The PLDSS has four modules (Fig. 1), namely, the CNMP

    Decision Module, the Transportation Analysis Module, the

    CNMP Assessment Module, and the PLDBMS Module. More

    detail on the conceptual framework of this system can be

    found in Kang et al.(2006). Thispaper presents detailed imple-

    mentation of PLDSS in ArcGIS using ArcObjects, VBA, and

    Network Analyst.

    2.1. CNMP Decision Module

    The CNMPDecision Moduleof the PLDSS wasdeveloped basedon the methodology proposed by the Alabama Cooperative

    Extension System (ACES; Mitchell and Tyson, 2001). The ACES

    plan is composed of five steps: (1) estimate poultry litter and

    compost produced; (2) determine the nutrient value of the

    poultry litter and compost based on quantity and availability

    of nutrients in the litter; (3) map and calculate the spreadable

    land area available for application; (4) determine the target

    crop and nutrient needs, including whether poultry litter is

    applied based on a nitrogen limit or on phosphorus removal

    by the crop; and (5) determine uses for excess litter that can-

    not be used on thefarmwhere it is produced and CAWV needs

    (Miles and Bock, 2006; Kang et al., 2006).

    The CNMP Decision Module of the PLDSS consists of threesub-modules: (1) Farm Operation, a sub-module containing

    general information regarding the AFOs that calculates total

    litter produced and the total nutrient value of produced lit-

    ter; (2) Fields, a sub-module that calculates the P-Index and

    nutrient needs of a cropland/hay/pasture field; and (3) CNMP

    Application, a sub-module that determines the amount of lit-

    ter to be applied to the field and the excess litter (Fig. 1). All

    of the data calculated and generated by the CNMP Module

    are stored and managed in PLDSSs database, named PLDBMS

    (discussed later).

    2.1.1. Comprehensive nutrient management plan (CNMP)

    The United States Department of Agriculture (USDA) and theUnited States Environmental Protection Agency (EPA) have

    released a Unified National Strategy for AFOs. This strat-

    egy represents the USDAs and EPAs plan for addressing

    the water quality and public health concerns arising from

    AFOs. The cornerstone of the strategy is the expectation

    that all AFOs will develop and implement a site-specific

    CNMP.

    Due to the limited technical staff available, the states

    County Conservation District staffs are only able to develop

    CNMPs/P-Index for CAFOs. The owners/operators of the more

    than 4000 AFOs in Alabama receive little assistance. Since

    AFOs are not required by law to have a CNMP in place,

    CAWVs and AFO owners/operators are often not interested ina comprehensive plan, but prefer a simple plan that works.

    In an attempt to address this problem, the CNMP Decision

    Module will simplify development of CNMP and P-Index for

    County Conservation District staff. Further, this will allow

    CAWVs to develop CNMP and P-Index themselves with assis-

    tance from County Conservation District staff. Note that in

    Alabama only CAWVs are certified to transport poultry litter

    in accordance with the Alabama Department of Environmen-

    tal Managements (ADEM) AFOs/CAFOs rules. AFOs are small

    operations, while CAFOs are big animal feeding operations.

    CAFOs are AFOs with 1000 animal (feed cattle) unit equiv-

    alency or more. For poultry (broiler) production this means

    about 100,000 chickens. Federal regulations require CAFOs to

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    c o m p u t e r s a n d e l e c t r o n i c s i n a g r i c u l t u r e 6 4 ( 2 0 0 8 ) 212224 215

    Fig. 1 Overall conceptual architecture of the poultry litter decision support system (PLDSS).

    carry a permit and to develop detailed nutrient management

    plans designed to keep animal waste from contaminating sur-

    face and groundwater.

    2.1.2. Estimation of poultry litter produced and nutrient

    value

    Annual production estimates for poultry litter and compost

    are calculated by multiplying the market weight of birds pro-

    duced each year by the production rate, which is estimated to

    be about 0.5 pounds of poultry litter per market weight pound

    of bird produced, as suggested by Auburn University Biosys-

    tems Engineering and the Alabama poultry industry (Mitchell

    and Tyson, 2001).The nutrient values of poultry litter and compost used

    in this study were the average values for litter and com-

    posted dead birds and were estimates of the plant available

    nutrients during the first year under Alabama conditions,

    as reported by ACES (Mitchell and Tyson, 2001). Avail-

    able nutrients from surface-applied litter and compost were

    475845 and 425845 pounds of NP2O5K2O per ton,

    respectively. Note that in the case of surface-applied lit-

    ter, the N value should be multiplied by 0.84 to account

    for N volatilization (Mitchell and Tyson, 2001). The nutrient

    removal for the targeted crop (Bermuda grass pasture) was

    501243 pounds NP2O5K2O per tons (Mitchell and Tyson,

    2001).

    2.1.3. Determination of crop and nutrient needs for each

    field

    Calculating thecorrect rate of nutrient needs to applyis impor-

    tant to prevent the buildup of excess phosphorus in soil and

    the contamination of ground and surface waters. Crop and

    nutrient needs in the PLDSS were determined based on the

    methodology (described earlier) proposed by ACES (Mitchell

    and Tyson, 2001).

    To identify fields for litter and compost spreading and to

    calculate spreadable acreage, the land cover classificationdata

    provided by the United States Geological Survey (USGS) were

    used in thissystem. Spreadable land area in the PLDSS was the

    total land area in fields receiving litter minus required buffersfor property lines (see Mitchell and Tyson, 2001, for example,

    determination of spreadable land area). Nutrient needs were

    determined based on N limit or on P removal by the crop to

    which poultry litter was applied. P application in excess of

    that recommended by soil test is based on a P-Index of field

    vulnerability for P runoff into surface waters.

    2.1.4. Phosphorus (P)-Index

    Non-point sources of agricultural P have a considerableimpact

    on water quality at a watershed-scale (McDowell et al.,

    2001). Out of the three management scenarios examined by

    McDowell et al. (2001), the P-Index seems to be the most use-

    ful. Consequently, in many states the P-Index risk rating of an

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    agricultural field plays a major role in the development of a

    nutrient management plan (De et al., 2004).

    TheP-Indexis a toolthatis usedto assess thesite and man-

    agement practices with regard to the potential risk posed by

    P movement to water bodies (USDA-NRCS, 2001). The P-Index

    rating indicates the specified areas (e.g., pastures) that should

    benefitand thepoultry litterratesthat shouldbe applied (Kang

    et al., 2006). Nutrients are applied based on two options andare modified based on theP-Index: (1) N limitbased on soil test

    recommendations fromAuburn Universitys Soil Testing Labo-

    ratory (http://www.ag.auburn.edu/agrn//croprecs/index.html)

    and (2) anticipated crop P removal, namely, at the N rate, 3 P

    removal by crop, 2P removal by crop, 1P removal by crop,

    andno P applicationfor verylow/low, medium,high,veryhigh,

    and extremely high vulnerability ratings, respectively. More

    information about Alabamas P-Index has been provided by

    Kang et al. (2006), USDA-NRCS (2001) and Mitchell and Tyson

    (2001).

    2.1.5. Determination of excess litter

    Once the previous determinations are completed, the poultrylitter orcompost can belandapplied. Note that dead birdcom-

    post was not considered for offsite transport because farmers

    are required to usethe dead birdcompost on thefarmwhere it

    is generated before spreading any litter. Because of the human

    health issues, dead bird compost cannot be transported with-

    out a special permit from the state veterinarians office of the

    Alabama Department of Agriculture and Industries (ADAI). In

    PLDSS, dead bird compost wasnot considered for offsitetrans-

    port.

    The excess litter produced is determined based on how

    much litter can be reasonably applied to each field, and thus

    whether the poultry farm operation can effectively use all

    the nutrients in the litter in an environmentally sound man-ner. If more litter is produced than can be used, it should

    be consigned to an Alabama CAWV. The assigned CAWV can

    utilize the Transportation Analysis Module to find the opti-

    mum way to transport litter to nutrient deficient areas in the

    Appalachian Plateau or Black Belt regions of the state.

    2.2. Transportation Analysis Module

    The Transportation Analysis Module allows CAWVs to find

    the best route to transport litter from production areas to

    application areas by examining factors such as the best route,

    the closest route to fields within a certain distance, and

    OriginDestination matrix created using NetworkModel tool-box in ArcGIS 9.1. The workflow used by Network Analyst in

    the model is the same as the workflow for Network Analyst

    in ArcMap. More detail on conceptual workflow for modeling

    various transportation network analyses usingthe ArcGIS Net-

    workModel can be found in Kang et al.(2006). This module was

    developed using VBA in conjunction with ArcObjects in ArcGIS

    environment.

    Currently, CAWVs are reluctant to risk transporting litter

    very far from the source. Some of the reasons given for this

    include cost of transportation, low value of litter, unable to

    load/reload litter, storage problems, and inability to spread

    litter. As mentioned earlier, this study focuses on many of

    these issues because there is consensus among researchers

    and practitioners that transportation of litter within the pro-

    duction areas (for proper distribution and land application)

    and from production areas to Black Belt and Tennessee Valley

    regions is a possible solution to alleviate excess litter problem

    in the Appalachian Plateau region.

    2.3. CNMP Assessment Module

    An important component of PLDSS is the CNMP Assessment

    Module, which is composed of two sub-modules, namely, On-

    Farm Application and Offsite Application. These sub-modules

    are used to determine optimal uses for excess litter that can-

    not be used on the farm where it is produced. Based on

    all previous modules, this module determines optimal land

    application, the value of poultry litter as a fertilizer, and

    the transport cost including a cleanout cost. It is economi-

    cally most effective to transport excess litter from a farm to

    offsite based on the rank considering travel distance using

    OD matrix. The results of these sub-modules are linked

    and managed by the PLDBMS. According to Miles and Bock

    (2006), a recent inquiryindicates thatcurrently north Alabamavendors are typically receiving about $10 per ton for land

    application of litter. Thus, they assume as our base case that

    vendors could deliver poultry litter for a cleanout cost of $4

    per ton plus $6 per ton for hauling an average of 40 miles at

    $0.15/ton-mile. These values were used to calculate transport

    cost.

    2.4. PLDBMS and Geodatabase Modules

    A critical issue when coupling the GIS software with CNMP

    and network analysis is the database that is integrated into

    the spatial-temporal database model. The PLDSS procedure

    generates a large volume of CNMP and GIS data. Ineffectivedata management will result in a computational bottleneck

    that can seriously degrade the performance of the system.

    The PLDSS offers data input, data search, data management,

    analytical and geographic visualization capabilities that can

    provide effective decision support. The PLDSS incorporates

    two database modules, PLDBMS and Geodatabase. The unique

    spatial object IDs (i.e., operation ID and field ID) from Geo-

    database are used to connect the PLDBMS with Geodatabase

    and models (Fig. 2).

    The PLDBMS was developed for the efficient management

    of datarelatedto poultry litter. Thissystem was created bypro-

    gramming MySQL, a relational database management system,

    and VBA in ArcGIS. The data collected by CNMP from the userare stored and managed in a database server called MySQL

    (MySQL AB, 2006). To access information from the database

    server and open database connectivity (ODBC), a driver called

    MySQL ODBC was used. The PLDBMS and MySQL database

    server were used for pre- and post-processing the CNMP data.

    PLDBMS consists of Data Management and Data Search

    sub-modules. These sub-modules facilitate basic functions

    for efficient data searches, storage, updates and export. The

    Data Management sub-module includes an Excel-based cus-

    tom record keeping tool that may meet users needs for farm

    and field information, litter application, and excess litter to

    CAWV. The Data Search sub-module has a function that can

    search data regarding all CNMP implementation.

    http://www.ag.auburn.edu/agrn//croprecs/index.htmlhttp://www.ag.auburn.edu/agrn//croprecs/index.html
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    c o m p u t e r s a n d e l e c t r o n i c s i n a g r i c u l t u r e 6 4 ( 2 0 0 8 ) 212224 217

    Fig. 2 Overall structure of PLDBMS and Geodatabase.

    The data sets were organized into a geodatabase of ArcGIS

    as separate feature classes. The geodatabase is the heart of

    a spatial and operational information system and provides

    the central storage system that allows communication and

    intermediate storage among the various subsystems (Kang

    et al., 2006). This geodatabase, which is similar to the cov-

    erage model, supports a model of topologically integrated

    feature classes. It also extends the coverage model to supportcomplex networks, topologies, relationships among feature

    classes, and other object-oriented features. Each separate fea-

    ture class represents either a factor or a constraint to be used

    within the PLDSS analysis. Additional attributes have been

    included in some feature classes to more effectively support

    the analysis.

    3. Implementation of the PLDSS

    3.1. Study area and geodata

    Alabama is a major sink for nutrients because over 95% ofthe grain fed to Alabamas farm animals is imported (Kingery

    et al., 1994). The eight leading poultry producing counties in

    the state produce more than 100% of each countys P needs

    in the form of poultry litter. Cullman was the leading poultry

    producing county in the state, followed by DeKalb, Marshall,

    and Blount during the 2003 and 2004 marketing years. The

    Black Belt region was selected as the pasture area to which

    the excess poultry litter should be transported. All poultry

    houses, pastures, and local road information in the study area

    are visible at a zoom factor of 1:800,000.

    In order to identify the amount of poultry litter produced,

    the broiler data for each county were obtained from the

    National Agricultural Statistics Service (USDA-NASS, 2005;

    Kang et al., 2006). Users can easily add and use the poultry

    farm layer in the PLDSS if they have real data on location

    of poultry farms. The PLDSS can easily be extended to work

    with other real data due to its generic form and structure.

    Forage pastures were selected for poultry litter application in

    the study area, although using the CNMP the procedure can

    be easily extended to other crops. The pasture polygons were

    converted to a point type geodatabase for Network Analysis.The attributes such as ID number, coordinates of latitude and

    longitude, and pasture area for each pasture polygon were

    then calculated and added to the database table associated

    with the point pasture theme.

    To create the pasture data set, the land cover classification

    data provided by the United States Geological Survey (USGS)

    were used to reclassify pasture/hay from Landsat TM images

    of the study area. The land cover data are in the form of a sin-

    gle band raster image. Pasture/Hay in this study was defined

    as areas of grass, legumes, or grasslegume mixtures planted

    for livestock grazing or the production of seed or hay crops.

    The hydrologic soil group and field slope for the calculation

    of the P-Index were extracted from the soil map and digitalelevation model, respectively. To identify fields for litter and

    compostspreadingand to calculate spreadablearea, a detailed

    farm map such as an aerial photo of the fields to scale will

    be needed. The pasture polygons were used to obtained field

    boundary and spreadable area in this DSS because it is not

    easy to use numerous aerial photos of each field for the whole

    study area.

    A geodatabase network dataset must be created to con-

    duct various network analyses. A geodatabase-based network

    dataset was created using the streets feature class for

    Alabama. This work is conducted using ArcCatalog in ArcGIS.

    More detail on the procedure of creating a geodatabase net-

    work dataset can be found in ESRI (2005).

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    3.2. CNMP Decision Module

    Users will be able to accurately identify the spatial location

    where the litter is being generated and the location of the

    application fields. We now give a hypothetical example that

    demonstrates the utility of the CNMP Decision Module.

    Suppose a farmer with three poultry houses cleans his

    chicken houses producing X amount of poultry litter. He alsohas some fields where he can apply some of the litter. He,

    therefore, contacts a CAWV to handle his litter. The CAWV,

    whois trained in theuse of PLDSS,locates thefarmers chicken

    houses and available fields. The CAWV and users can locate

    thefarms using thesubmenu to retrievean address or it is pos-

    sible to select directly them on the GIS data in the PLDSS. He

    then determines if the farmer already has a nutrient manage-

    ment plan. If not, the CAWV uses the CNMP Decision Module

    and creates a simple but effective nutrient management plan

    for the farmers land. Once developed, the CAWV determines

    the amount of litter that can be applied on the farmers fields

    (assume this amount is Y, where Y< X). The CAWV then takes

    a look at the CNMP and locates farmers that require litter.He then uses the Transportation Analysis Module to deter-

    mine thecost associatedwith haulinglitter to various farmers

    fields that could benefit from the litter. He evaluates various

    alternatives and makes arrangements to haul the litter. Before

    applying litter, the CAWV uses the P-Index/CNMP Module to

    develop a nutrient management plan if the farmer (to whose

    farm excess litter will be applied) does not already have one.

    Once fully developed and implemented, this simple to use

    PLDSS will provide numerous options for both the farmers

    interested in disposing of their litter and those requiring litter.

    CAWVs will also be able to perform their task much more effi-

    ciently and effectively and keep an electronic record of their

    activities.To demonstrate how the PLDSS can be used to help the

    user efficiently develop nutrient management plans in the

    concentrated poultry litter production areas for on-farm uti-

    lization, the PLDSS was applied to Cullman county. To assess

    the applicability of this systems CNMP, on-farm application

    of the CNMP and a transportation analysis was carried out on

    selected farms in the county (see Kang et al., 2006).

    3.2.1. Farm Operation sub-module

    The Farm Operation sub-module has three dialog boxes,

    namely, General Information, Total Litter Produced, and Total

    Nutrient Value.

    3.2.1.1. General Information Dialog Box. The General Infor-

    mation Dialog Box (Fig. 3) allows users to enter general

    information regarding the CAFO/AFO owner/operator and

    CAWV for which the CNMP is being prepared, including the

    farm ID and contact information. All the information entered

    for the selected farm is saved into the systems database. The

    ID of the poultry farm randomly selected to assess the appli-

    cability of this system was 161.

    3.2.1.2. Total Litter Produced and Nutrient Value Dialog Boxes.

    The Total Litter Produced Dialog Box (Fig. 4) allows the user

    to estimate the amount of poultry litter and compost pro-

    duced by the farm selected from the General Information

    Dialog Box. The corresponding Total Nutrient Value Dialog

    Box calculates the total nutrient value of litter. In reaching

    this figure, about 20% weight loss during the composting pro-

    cess and about 5% mortality were assumed. Total poultry

    litter and compost produced by the selected farm were 712.5

    and 89.6 ton, respectively. As shown in Fig. 5, available nutri-

    ents in poultry litter and compost were 33,51741,32632,063

    (NP2O5K2O, ton) and 376451984033 (NP2O5K2O, ton),respectively.

    3.2.2. Fields sub-module

    3.2.2.1. P-Index Dialog Box. The P-Index Dialog Box (Fig. 5)

    allows users to select a field and determine the distance for

    buffer zones in order to properly determine the amount of

    land application with respect to the nutrient needs and vul-

    nerability of P runoff. It then extracts the field attributes such

    as the applicable field ID, hydrologic soil group, field slope

    and spreadable area, etc., and calculates the P-Index. A good

    example of the use of the P-Index Dialog Box is shown in the

    P-Index worksheet for Alabama presented in Agronomy Tech-

    nical Note AL-72 (USDA-NRCS, 2001). The P-Index worksheet

    is a matrix with 11 field characteristics and five value factors.

    Each field characteristic has a weighting factor that is mul-

    tiplied by a value factor. The hydrologic soil group and field

    slope (%) among 11 field characteristics were automatically

    extracted from geodatabase of the PLDSS. The sum of these

    values gives the P-Index result. The P-Index Dialog Box exam-

    ines one field at a time, calculating the P-Index by the method

    described above.

    The P-Index calculation resulted in a value of 14 for the

    selected field ID of 2281, with an area of 7.88ha and the P-

    Index was Very low/Low (Fig. 5). The distance to calculate

    the buffer zone was 25 ft recommended by buffer width for

    property line.

    3.2.2.2. Nutrient Needs Dialog Box. The Nutrient Needs Dialog

    Box (Fig. 6(A)) allows the user to select a crop and then deter-

    mine the amount of nutrient needed for each field based on

    the results received from the P-Index Dialog Box. The execu-

    tion of this module for nutrient needs resulted in 19.6 ton for

    poultry litter type and 21.9 ton for compost type, respectively.

    3.2.3. CNMP Application sub-module

    Based on the results produced by running the Total Lit-

    ter Produced and Total Nutrient Value Dialog Boxes (Farm

    Operation sub-module) for the poultry farm selected andthe field selected by the P-Index and Nutrient Needs Dialog

    Boxes (Fields sub-module), the CNMP Application sub-module

    (Fig. 6(B and C)) enables the user to determine the land appli-

    cation rate and calculates excess litter and compost.

    The results of carrying out the CNMP Decision sub-

    module for on-farm utilization were as follows: the amount of

    land application showed 21.9 ton in compost. Consequently,

    the excess litter and excess compost by the selected farm

    were 712.5 and 67.7 ton, respectively. This means that the

    Transportation Analysis module should be implemented to

    optimize the transportation of the excess litterto a region with

    a poor soil fertility problem, such as the Black Belt region of

    the state.

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    Fig. 3 The General Information Dialog Box showing the general information for the selected farm.

    Fig. 4 The Total Litter Produced And Total Nutrient Value Dialog Boxes showing the total poultry litter produced from the

    selected farm and the results that calculates its total nutrient value.

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    Fig. 5 The P-Index Dialog Box showing the procedure that calculates the P-Index and determines the buffer zone from the

    selected field and the results that calculates its P-Index.

    Fig. 6 The Nutrient Needs Dialog Box (A) showing its results about calculating the nutrient needs for the selected field and

    the CNMP application sub-modules showing their results about calculating the amount of land application (B) and excess

    litter (C).

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    Fig. 7 The result of the available area polygons within the 1.0 mile cut off and conceptual workflow for its modeling (A)

    and the result of the origindestination matrix with a cut off value of 1.0 mile and default number of 10 to find destinations

    (fields) and conceptual workflow for its modeling (B).

    3.3. Transportation Analysis

    For the CNMPs offsite utilization of excess litter, this module

    suggests alternatives to the selected farm and field to make

    it possible to determine the optimal transportation. Once

    the user selects a farm, this module automatically carries out

    the transportation analysis. Once a farm has been selected by

    the CNMP module, unless the user changes the selection, the

    information for that farm is used to create a link to obtain the

    CNMP calculationresults.This module finds thebest routesfor

    a given order of stops based on travel distance that is the least

    costly path (distance cost) from a farm to fields. The Direc-

    tions Window can also be displayed with turn-by-turn maps

    that can be shown by clicking on the Show Map sub-module.

    This modules applicability assessment was conducted by

    making use of a randomly selected farm and carrying out

    Fig. 8 The CNMP Assessment modules for on-farm (A) and offsite (B) application.

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    Fig. 9 PLDBSS: (A) the data management sub-module for the CNMP data record form; (B) the CNMP data record form

    exported to MS-Excel file format; and (C) the data search sub-module in the PLDBMS.

    a transportation analysis within the county by running the

    CNMP. The excess litter calculated by the CNMP Decision

    module is then available for transport to the offsite, and theoutcome predicted. Fig. 7(A) shows the results based on cal-

    culation of 0.3, 0.5, and 1.0 miles feasible area for the selected

    farms, which can reveal how many land application locations

    (fields) lie within each of these areas. This can also be used

    to determine how best to relocate the least accessible farms

    or place new ones to facilitate land application of the poultry

    litter produced (Kang et al., 2006).

    An OriginDestination (OD) cost matrix (Fig. 7(B)) is also

    created to illustrate deliveries from the chicken houses to each

    pasture. The results of this matrix can be used to identify the

    land application areas that will be serviced by each chicken

    house within a specific travel distance. Also, it determines

    the total travel distance from each chicken house to its landapplication pastures.

    3.4. CNMP Assessment Module

    In order to perform an optimal poultry litter management

    process, CNMP for on-farm utilization within the selected

    county and transportation analysis for on-farm utilization in

    the Black Belt region was conducted. The CNMP was applied

    to all the fields from all the farms within Cullman County and

    an OD matrix analysis was carried out for the excess litter.

    Network analysis of the On-Farm Application and Offsite

    Application sub-modules are similar to the Transportation

    Analysis Module. These sub-modules enablethe user to deter-

    mine the land application area and the ranking according to

    travel distance from each of the farm to fields within a cer-

    tain distance (1.0 mile for this example) (Fig. 8). This modulehelps theuser to selectthe optimal nutrient management plan

    based on destination rank.

    These sub-modules carried out optimal poultry litter man-

    agement to transport the excess litter or compost from the

    selected farm (chicken house) to the feasible area within

    distance less than 1.0 mile for the On-Farm Application sub-

    module and the Black Belt region for the Offsite Application

    sub-module.

    3.5. Implementation of the PLDBMS

    The results of all previous modules are linked to the systems

    database,named PLDBMS, which allows data storage, revision,and searches to be conducted through the Data Management

    and Data Search sub-modules.

    A summary worksheet (for record keeping) is generated

    that contains general information, poultry litter informa-

    tion, field information, land application, excess litter, etc.,

    needed for the development of the CNMP on the selected

    farm (Fig. 9(A)). This summary CNMP worksheet can then

    be uploaded and exported as an Excel spreadsheet file

    through the Data Management sub-module (Fig. 9(B)). Prior

    to running each sub-module, the user can examine and

    confirm the farm and field data that are used to calcu-

    late the applied CNMP through the Data Search sub-module

    (Fig. 9(C)).

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    4. Conclusions

    This study focused on the development and implementa-

    tion of a GIS-integrated poultry litter decision support system

    (PLDSS) for on- and off-farm applications of poultry lit-

    ter in the Appalachian Plateau and Black Belt regions of

    Alabama. Development of this DSS was initiated because offour main reasons. First, the poultry industry in Alabama

    is mostly concentrated in the Appalachian Plateau region,

    and improper distribution and over-application of litter for

    more than 25 years in this region has resulted in buildup

    of phosphorus in many pasture fields, which threatens

    surface water quality. Second, currently available DSS for

    land application of poultry litter do not support transporta-

    tion analysis. Third, available DSS are difficult to use. And,

    fourth, record keeping required by Alabama Department of

    Environmental Management (to show compliance with reg-

    ulations) is not supported by many of the currently available

    DSSs.

    Various modules provided in the PLDSS addressed many ofthese issues. For example, the CNMP module allows users to

    develop a quick nutrient management plan and phosphorus-

    Index, the transportation analysis module allows them to

    minimize transportation cost, and the database manage-

    ment module allows them to keep record of their activities.

    We envision this system to be used by County Conserva-

    tion District staff and/or the CAWVs in cooperation with the

    County Conservation District staff. Once fully implemented,

    the system will allow increased use of nutrient manage-

    ment planning and P-Index, thus reducing over-application

    of poultry litter. The transportation analysis will help dis-

    tribute excess litter within the Appalachian Plateau region

    or the Black Belt region. The transportation analysis willalso help minimize transportation cost. Thus proper use of

    the PLDSS will help simultaneously minimize water qual-

    ity impairment of water bodies and transportation cost,

    thus providing optimal management of poultry litter in

    Alabama.

    The PLDSS will allow optimal land application and trans-

    portation of litter first in the Appalachian Plateau region

    and then transportation and land application in the Black

    Belt region. This will ensure that the litter application pro-

    tects the water quality in the Appalachian Plateau region,

    minimizes transportation costs, and improves soil fertility

    in the Black Belt region. Hence, this study will help alle-

    viate water quality problems in the Appalachian Plateauregion and poor soil fertility problems in the Black Belt

    region.

    There are several benefits and implications of the PLDSS.

    For example, if used for a long time, the PLDSS will supply

    a detailed database of poultry litter applications. Using this

    database, researchers will be able to study the hydrologic,

    geomorphic, and ecological characteristics that control NPS

    pollution in animal waste applied watershed. Further, this

    database will provide a complete picture of theextent of poul-

    try litter management problem in the Appalachian Plateau

    region andthe accurate locationof thearea(within thisregion)

    where poultry production is concentration. A company inter-

    ested in developing value-added products from poultry litter

    will then be able to identify hot spots of excess poultry litter.

    Further, we will be able to accurately determine the potential

    of expansion of poultry industry in the Appalachian Plateau

    region.

    As mentioned earlier, this system was designed for use

    by County Conservation District staff and/or CAWVs, because

    they have traditionally developed nutrient management plans

    and P-Index for CAFOs and AFOs. Further, County Conserva-tion District staffs are trained in the use of ArcGIS system.

    However, often County Conservation District staffs are unable

    to assist all the poultry producers because of their concen-

    tration in a few counties. The authors envision that to fully

    optimize litter management (i.e., environmentally sustainable

    application and proper distribution with minimum trans-

    portation cost), in future, the litter management will need to

    transferred directly in the hands of CAWVs, poultry produc-

    ers, and farmers. With the increased useof web-based system,

    a webGIS-based system with all the functionalities provided

    in the PLDSS will be ideal. This will shift the task of proper

    land application of litter and transportation of excess litter

    in the hands of CAWVs, producers, and farmers. The trickwould be to develop this system in such a user-friendly man-

    ner that a person with litter knowledge of computers is able to

    use it.

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