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  • 1
    Online Resource
    Online Resource
    Feasibility and Costs of Phosphorus Application Limits on 39 U.S. Swine Operations
    Wiley ; 2004
    In:  Journal of Environmental Quality Vol. 33, No. 3 ( 2004-05), p. 1114-1123
    Details
    In: Journal of Environmental Quality, Wiley, Vol. 33, No. 3 ( 2004-05), p. 1114-1123
    Abstract: Concerns about manure P and water quality have prompted new regulations imposing P limits on land application of manure. Previous research established that P limits increase land needs for animal feeding operations. We evaluated the effect of N, annual P, and rotation P limits on the feasibility of manure management. A mechanistic model characterized manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Extensive information collected from each operation was used to determine effects of manure storage type, ownership structure, and application limits on attributes of manure management. Phosphorus limits had substantially greater effect on slurry operations, increasing land needs 250% (0.3 hectares per animal unit [AU]) and time for manure application 24% (2.5 min AU −1 ) for rotation P limits and 41% (4.4 min AU −1 ) for annual P limits. Annual P limits were infeasible for current land application equipment on two operations and had the greatest effect on time and costs because they required all but three slurry operations to reduce discharge rate. We recommend implementing rotation P limits (not to exceed crop N need) to minimize time effects, allow most farmers to use their current manure application methods, and allow manure to fulfill crop N and P needs in the year of application. Phosphorus limits increased potential manure value but would require slurry operations to recover at least 61% of manure value through manure sales. Phosphorus limits are likely to shape the U.S. swine industry through differential effects on the various sectors of the swine industry.
    Type of Medium: Online Resource
    ISSN: 0047-2425 , 1537-2537
    URL: Article
    DOI: 10.2134/jeq2004.1114
    Language: English
    Publisher: Wiley
    Publication Date: 2004
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    detail.hit.zdb_id: 2050469-X
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  • 2
    Online Resource
    Online Resource
    An Assessment of Nitrogen‐Based Manure Application Rates on 39 U.S. Swine Operations
    Wiley ; 2004
    In:  Journal of Environmental Quality Vol. 33, No. 3 ( 2004-05), p. 1106-1113
    Details
    In: Journal of Environmental Quality, Wiley, Vol. 33, No. 3 ( 2004-05), p. 1106-1113
    Abstract: Water quality concerns and revised regulations are changing how confined animal feeding operations manage manure. Devising acceptable and feasible changes in manure practices requires a full understanding of the forces shaping current manure management decisions. Previous theoretical models have shown that a wide range of factors influence the lowest cost solution for manure management. We used a mechanistic model to characterize the manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Information was collected from each operation about animal numbers, feed and water use, manure handling and storage characteristics, field locations, crop rotation, fertilizer need, and equipment inventory and usage. Collected data were used as input and to validate results from a mechanistic model that determined acres required for manure application, manure application rate, time required for manure application, value of manure, and costs of manure management. The 39 farms had a mean of 984 animal units (AU) per operation, 18.2 AU ha −1 (7.4 AU acre −1 ), and manure application costs of $10.49 AU −1 yr −1 Significant factors affecting manure management included operation size, manure handling system, state, and ownership structure. Larger operations had lower manure management costs ( r 2 = 0.32). Manure value potentially exceeded manure application costs on 58% of slurry and 15% of lagoon operations. But 38% of slurry operations needed to apply manure off the farm whereas all lagoon operations had sufficient land for N‐based manure management. Manure management was a higher percentage of gross income on contract operations compared with independents ( P 〈 0.01). This research emphasized the importance of site‐specific factors affecting manure management decisions and the economics of U.S. swine operations.
    Type of Medium: Online Resource
    ISSN: 0047-2425 , 1537-2537
    URL: Article
    DOI: 10.2134/jeq2004.1106
    Language: English
    Publisher: Wiley
    Publication Date: 2004
    detail.hit.zdb_id: 120525-0
    detail.hit.zdb_id: 2050469-X
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  • 3
    Online Resource
    Online Resource
    Calibrating Corn Color from Aerial Photographs to Predict Sidedress Nitrogen Need
    Wiley ; 2002
    In:  Agronomy Journal Vol. 94, No. 3 ( 2002-05), p. 397-404
    Details
    In: Agronomy Journal, Wiley, Vol. 94, No. 3 ( 2002-05), p. 397-404
    Abstract: Supplemental N need of corn ( Zea mays L.) and other crops can vary substantially within and among fields. Corn color is sensitive to N status and may provide a means to accurately match N fertilizer rates to spatially variable N needs. Our objective was to calibrate the relationship between corn color measured in aerial photographs and sidedress N need. Economic optimum N rate (EONR) at sidedress was determined in 18 yield response experiments located in production cornfields. Low‐altitude, high‐resolution aerial photographs were taken at growth stage V6 or V7 with two types of film: color positive and color infrared. The EONR ranged from 0 to 336 kg N ha −1 . For both types of film, corn color was a significant predictor of EONR at sidedress but only when expressed relative to the color of well‐fertilized corn in the same field and when no N had been applied at planting. Predictions were more accurate using color film than color‐infrared film. Removal of soil pixels from the true‐color aerial images greatly strengthened the relationship between measured color and EONR: R 2 values ranged from 0.27 to 0.31 for single colors measured from the entire image and from 0.60 to 0.79 after the removal of soil pixels. Our results demonstrate that corn color measured in aerial photographs can be used to predict sidedress N need. Obstacles to practical use in guiding variable‐rate sidedressing include: no N can be applied at planting, a high‐N reference strip is needed, and soil pixels must be removed from the image.
    Type of Medium: Online Resource
    ISSN: 0002-1962 , 1435-0645
    URL: Article
    DOI: 10.2134/agronj2002.3970
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1471598-3
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  • 4
    Online Resource
    Online Resource
    Corn Yield Response to Nitrogen Fertilizer Timing and Deficiency Level
    Wiley ; 2002
    In:  Agronomy Journal Vol. 94, No. 3 ( 2002-05), p. 435-441
    Details
    In: Agronomy Journal, Wiley, Vol. 94, No. 3 ( 2002-05), p. 435-441
    Abstract: Nitrogen fertilizer is typically applied to corn ( Zea mays L.) shortly before planting, but there are several reasons why later N applications may be of interest: to spread work away from the busy planting season, to avoid the frequent wet field conditions in spring, to reduce or remedy in‐season N loss in wet years, or to allow use of in‐season diagnostic tools. One of the obstacles to the use of later N applications is the fear that irreversible yield loss will occur due to N stress. Our objective was to evaluate the yield impact of delaying N applications until the late vegetative growth stages and as far as silking. We conducted a total of 28 experiments with timing of a single N application as the experimental treatment. We found little or no evidence of irreversible yield loss when N applications were delayed as late as stage V11, even when N stress was highly visible. There was weak evidence of minor yield loss (about 3%) when N applications were delayed until stage V12 to V16. Only 3 of the 28 experiments had N applications later than V16—all were at silking and relative yields were 0.71, 0.89, and 0.95. Though full yield was not achieved when N applications were delayed until silking, yield was still highly responsive to N application at this stage—yield response exceeded 2.2 Mg ha −1 in all three experiments.
    Type of Medium: Online Resource
    ISSN: 0002-1962 , 1435-0645
    URL: Article
    DOI: 10.2134/agronj2002.4350
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1471598-3
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  • 5
    Online Resource
    Online Resource
    The chaperone/usher pathways of Pseudomonas aeruginosa : Identification of fimbrial gene clusters ( cup ) and their involvement in biofilm formation
    Proceedings of the National Academy of Sciences ; 2001
    In:  Proceedings of the National Academy of Sciences Vol. 98, No. 12 ( 2001-06-05), p. 6911-6916
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 12 ( 2001-06-05), p. 6911-6916
    Abstract: Pseudomonas aeruginosa , an important opportunistic human pathogen, persists in certain tissues in the form of specialized bacterial communities, referred to as biofilm. The biofilm is formed through series of interactions between cells and adherence to surfaces, resulting in an organized structure. By screening a library of Tn 5 insertions in a nonpiliated P. aeruginosa strain, we identified genes involved in early stages of biofilm formation. One class of mutations identified in this study mapped in a cluster of genes specifying the components of a chaperone/usher pathway that is involved in assembly of fimbrial subunits in other microorganisms. These genes, not previously described in P. aeruginosa , were named cupA1–A5 . Additional chaperone/usher systems (CupB and CupC) have been also identified in the genome of P. aeruginosa PAO1; however, they do not appear to play a role in adhesion under the conditions where the CupA system is expressed and functions in surface adherence. The identification of these putative adhesins on the cell surface of P. aeruginosa suggests that this organism possess a wide range of factors that function in biofilm formation. These structures appear to be differentially regulated and may function at distinct stages of biofilm formation, or in specific environments colonized by this organism.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.111551898
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2001
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Calibrating Corn Color from Aerial Photographs to Predict Sidedress Nitrogen Need
    Wiley ; 2002
    In:  Agronomy Journal Vol. 94, No. 3 ( 2002), p. 397-
    Details
    In: Agronomy Journal, Wiley, Vol. 94, No. 3 ( 2002), p. 397-
    Type of Medium: Online Resource
    ISSN: 1435-0645
    URL: Article
    DOI: 10.2134/agronj2002.0397
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1471598-3
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  • 7
    Online Resource
    Online Resource
    Corn Yield Response to Nitrogen Fertilizer Timing and Deficiency Level
    Wiley ; 2002
    In:  Agronomy Journal Vol. 94, No. 3 ( 2002), p. 435-
    Details
    In: Agronomy Journal, Wiley, Vol. 94, No. 3 ( 2002), p. 435-
    Type of Medium: Online Resource
    ISSN: 1435-0645
    URL: Article
    DOI: 10.2134/agronj2002.0435
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1471598-3
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  • 8
    Online Resource
    Online Resource
    Nitrogen response of no‐till corn in first and second years following conservation reserve program
    Informa UK Limited ; 2000
    In:  Communications in Soil Science and Plant Analysis Vol. 31, No. 15-16 ( 2000-09), p. 2501-2508
    Details
    In: Communications in Soil Science and Plant Analysis, Informa UK Limited, Vol. 31, No. 15-16 ( 2000-09), p. 2501-2508
    Type of Medium: Online Resource
    ISSN: 0010-3624 , 1532-2416
    URL: Article
    DOI: 10.1080/00103620009370604
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2000
    detail.hit.zdb_id: 2053897-2
    SSG: 12
    SSG: 13
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