Brief Summary of Minutes of Annual Meeting

Minutes of NCERA-180 (Site-Specific Management) Kissimmee, Florida January 4-6, 2007 Hosts: John Schueller and Wonsuk Daniel Lee Members of the Committee spent January 4 touring a tangerine juice processing plant, the University of Florida Citrus Research and Education Center, a citrus grove with automated harvest equipment, and a supermarket food distribution warehouse. The remaining time, from January 5-6, was spent by committee members in technical and business meetings discussing Site-Specific Management activities. Friday, January 5, 2007 John Schueller and Daniel Lee opened the meeting and described the agenda. Jeff Willers (USDA-ARS, Mississippi) presented his research on Spatial Information and the Design and Analysis of Site-Specific Experiments in Commercial Cotton Fields. He introduced methods for testing the efficiency of Site-Specific Management (SSM) in commercial fields using remote sensing, GIS and topological relationships between spatial data layers. Experimental units for analysis were delineated by the intersection of rate of cotton plant growth regulator applied and management zones. A statistical model was developed to model yield as a function of treatment effects, spray path, planter path, harvester path, and topography. Jim Jones (University of Florida) presented his thoughts on the application of crop simulation modeling to Site-Specific Management (SSM). There have been few papers published on the use of crop simulation models in SSM. Batchelor and Paz (1999) calibrated a CERES model to soil moisture for an Iowa field and used it to predict soybean yield along a transect. Basso et al. (2001) used remote sensing to identify management zones and used crop simulation modeling to predict yield in each zone. Batchelor and Paz (2000) used inverse modeling to estimate spatial variability in input factors for a model of soybean yield. Fraisse et al. (2001) used the CERES model to study variations in yield as a function of topsoil depth in claypan soils of Missouri. Miao et al. (2006) used crop simulation modeling to evaluate nitrogen fertilizer management strategies for management zones in Illinois. New approaches were discussed for obtaining spatially variable model inputs, including remote sensing, inverse modeling, sensors, geostatistics, Kalman filtering and principal components analysis. K. C. Ting (University of Illinois) gave the Administrators Report. NCERA-180 was renewed for another 5 years (2006-2011), and is set up to integrate education, research and teaching. Within 60 days of meeting (March 7) the SAES-442 form must be submitted to the NIMSS online system. Committee participants can be contacted using the NIMSS website: http://www.nimss.umd.edu David Mulla (University of Minnesota) and Raj Khosla (Colorado State University) discussed the upcoming 2008 International Conference on Precision Agriculture (ICPA). The venue for the conference is being changed to Colorado for at least 2008 and 2010 (probably Denver). David Mulla discussed the rationale for moving the conference. The NCERA-180 committee was asked to make suggestions for improving the conference. It was felt that the A to Z portion of the conference was weaker than the rest of the program. The strength of the conference is in multidisciplinary technical papers, but there is a need to attract a wider diversity of scientists and limit the number of concurrent sessions. It was felt that the conference should meet at a time which doesnt conflict with ASABE or SWCS. It was felt that NCERA-180 could assist the process of putting on the ICPA by developing a conference planning committee. Don Bullock (University of Illinois) talked about Residuals and the Year to Year Variable in Precision Agriculture Research. He asked the question: How long do we need to run an experiment? More specifically: How does uncertainty in true nitrogen (N) fertilizer rate change over time?, and What is the cost of not knowing the true N fertilizer rate? To answer these questions he analyzed data from 21 years of small plot fertilizer rate trials in continuous corn conducted in Monmouth, IL. Using all the data, the mean optimum N rate was 173 kg/ha, with a standard deviation of 86 kg/ha. Monte Carlo simulation was used to pick 2, 4, or 12 years of data at random. Results showed that standard deviations of optimum N rate decreased as the number of years increased. Roughly five years of data were needed to adequately estimate the uncertainty in optimum N rate. Don Bullock also talked about the importance of compensating for spatial correlation of residuals from field trials. He compared ordinary least squares (OLS), nearest-neighbor (NN), spatial auto-regressive (SAR) approaches (lag vs queen), and SAS PROC MIXED models. OLS failed to adequately compensate for spatial correlation of residuals based on semivariograms of residuals. NN methods were better at compensating for spatially correlated errors. SAR lag and queen models were better than NN methods. Richard Ferguson (University of Nebraska) talked about Management Zone Delineation using example datasets for iron chlorosis in Nebraska soybean fields. He described four experiments where Pioneer cultivar 33V08 was tested for its resistance to iron chlorosis. Normalized Difference Vegetative Indices (NDVI), electrical conductivity (EC), soil pH and historical yield were best at delineating zones susceptible to iron chlorosis. It was difficult to separate the effects of water stress from iron chlorosis. There were few differences in yield between susceptible and tolerant varieties. Eric Lund (Veris Tech) talked about a Near Infrared (NIR) spectrophotometer that collects data in 8 nm bands from 500-900 nm and from 1100-2200 nm. Light and dark references are collected automatically. NIR is used to estimate soil organic carbon, N, C/N, pH, Ca, Mg, P, K, CEC and moisture. It is best at measuring C, but is not as accurate for P and K. William Rudolph (TeeJet Tech) talked about Centerline Guidance Devices and Field Pilot Automatic Steering Systems. He also talked about Swath Manager to turn on and off boom sections depending on whether the area was previously sprayed. TeeJet is developing a controller area network (CAN) based on ISO BUS ISO 11783 open standard to control all these devices. Tony DiPollina (GeoAgro) talked about GIS software for precision agriculture in Brazil and Argentina. The software allows Word or Excel documents to be georeferenced by polygons on a map. The software allows GPS data to be displayed and stored. They also have a Conservation Planner designed to access NRCS conservation data from any wireless location. Nyle Wollenhaupt (AGCO Global Tech) talked about ISO BUS standardized hardware (plugs and cables) and software (type and method of data exchange) protocols. AGCO is developing virtual terminals, ISO connectors, CAN BUS (ISO 11783), tractor electronic control unit (ECU), and task controller (defines how data moves). They also have an implement BUS which is used to compile fuel consumption and wheel slip. Harold Reetz (Foundation for Agronomic Research) talked about the reorganization of PPI into the International Plant Nutrition Institute. IPNI has 17 charter members and covers N, P, K and all other plant nutrients. FAR provides funding for IPNI, and works with universities on multi-state research, special initiatives and corporate directed projects. It also is involved in educational conferences, computer training, tours and the Info Ag conference. FAR is seeking cooperators and partnerships with universities, to help build research teams, coordinate research and leverage contributions. FAR currently has a NRCS-CIG project on fertilizer BMPs with N. Dakota, Illinois, New York, Kansas, Idaho and Arkansas. FAR is trying to raise funds to support agronomic research. Newell Kitchen (USDA-ARS, Missouri) talked about Division A-8 Integrated Ag Systems as a venue for symposia and papers on precision agriculture at the annual meetings of the Agronomy Society of America (ASA). Div. A-8 (David Clay- S. Dakota) is organizing a symposium on precision agriculture at the upcoming ASA meetings in New Orleans Nov 4-8, 2007. Tim Stombaugh (University of Kentucky) talked about the PM-54 committee of ASABE, which usually has 75 papers on precision agriculture. The next meeting of ASABE is June 17-20, 2007 in Minneapolis. They have worked on new standards, including yield monitor test protocols for the laboratory and field. They are also working on a GPS position accuracy standard for moving units, as well as standards for autosteer accuracy. Saturday, January 6, 2007 John Schueller (University of Florida) led a group discussion on the mission of NCERA-180. He raised several questions: Why is the adoption of Site-Specific Management (SSM) so slow? How can we provide better leadership in SSM? What synergistic activities in SSM are possible? Reactions to these questions included: We have too much data, how can we make it more useable and cheaper? The science of SSM is lagging technology. Farmers are asking what time it is, but were telling them how a clock works. Funding for SSM research (USDA-IFAFS) has declined. There was concern that conservation programs and practice standards at USDA-NRCS doesnt support precision agriculture as a BMP. It was suggested that a representative from NRCS should be invited to attend the NCERA-180 meeting to address this issue. Keith Morris (Louisiana) said that their state conservationist approved cost-sharing for grid sampling and yield monitoring. A two page proposal was developed for a new 590 practice standard. Newell Kitchen (Missouri) said that their state provides $20/ac for EM38, management zones and variable rate N management. Recommendations to improve the functioning of NCERA-180 were discussed. It was felt that NCERA-180 members could write a how-to-manual for data analysis in precision agriculture, develop science statements or white papers on precision ag in the same fashion as CAST, and could develop a high profile web site coupled to the CropLife Precision Ag Institute and a monthly newsletter produced by Bruce Erickson (Purdue University). One of the recommendations concerned the annual turnover in NCERA-180 leadership. It was felt that the productivity of NCERA-180 could be improved by developing sub-committees with long-term membership to work on various research, education and outreach tasks. The Chair of the overall committee would continue to rotate, with a primary function of organizing the annual meetings, but membership on sub-committees would continue for 3-5 years. Five major sub-committees and their initial membership were recommended during the discussion. These include: Visioning National Strategy Committee (Raj Khosla, John Schueller, David Mulla) Research RFPs (Fran Pierce, Shrini Upadhyaya) Evaluation and Promotion of Precision Ag Technologies (David Franzen, Don Bullock, Balaji Sethuramasamyraja, Jeff Willers, Ronnie Heiniger, Dennis Francis) Collaborative Arrangements Precision Ag Associations (Sid Parks, John Shanahan) NRCS (Keith Morris, Raj Khosla, Eugene Burris, Eric Lund, Fran Pierce) Communications and Outreach Web site (Bruce Erickson, Wonsuk Lee, David Franzen, William Rudolph, Tim Stombaugh, Ronnie Heiniger, Nathan Watermeier, Jill Stanford, Lei Tian) Books (David Clay, Ken Sudduth, Fran Pierce, David Franzen) Training (Nathan Watermeier, Bruce Erickson) Meetings NCERA (Ronnie Heiniger, John Schueller) International Precision Ag Conference (David Mulla, Raj Khosla) ASA (David Clay, Kurt Thelen) ASABE (Shrini Upadhyaya, Ken Sudduth, Tim Stombaugh, Balaji Sethuramasamyraja, William Rudolph) David Mulla (University of Minnesota) led a discussion about plans for the annual meeting of NCERA-180 during January 2008. After some discussion about conflicts with other meetings, it was decided to hold the 2008 meeting of NCERA-180 from Jan 9-11 in Minneapolis, MN. The program would be focused on sub-committee activities (see previous section) and progress during 2007. An interim steering committee consisting of John Schueller, David Mulla and Ronnie Heiniger was selected to oversee the initial development and establishment of action sub-committees. It was agreed that there would not be any state reports at the 2008 meeting. There will be a few technical sessions on applications of precision agriculture in biofuel production. A tour to an ethanol production facility will be organized. An election was held to select the Chair for the 2009 NCERA-180 meeting. Ronnie Heiniger of North Carolina State University was unanimously elected, and agreed to hold the 2009 meeting of NCERA-180 in Raleigh, NC. Newell Kitchen (USDA-ARS Missouri) led a discussion on the relationship between NCERA-180 and the International Conference on Precision Agriculture (ICPA). There is a critical need for dissemination of Precision Ag science and technology. ICPA has been very effective at fulfilling this need. Since David Mulla at the University of Minnesota has asked Raj Khosla at Colorado State University to organize the next ICPA, what role can NCERA-180 play in helping make this transition? It was agreed to establish a committee from NCERA-180 (Newell Kitchen, David Mulla, Raj Khosla, Dwayne Westfall, John Schueller, and Ronnie Heiniger) to work out the details for how NCERA-180 can help sponsor and organize ICPA. The committee was asked to consider issues such as location, timing, organization, and audience for ICPA. Fran Pierce (Washington State University) finished editing the publication on GIS in Precision Agriculture by CRC Press. This is the first in a series of books on GIS in agriculture. It is envisioned to have 1-2 volumes each year, on topics such as invasive species, IPM, precision conservation, agribusiness, etc. He asked whether there was interest in updating the book State of Site-Specific Management which appeared 10 years ago. Perhaps it could be updated by having symposia on precision ag at ICPA, ASA and ASABE in 2008. Fran described several new funding initiatives coming out of CSREES, one on vegetable crops and another on robotics. David Clay (South Dakota State University) presented research on Carbon Maintenance Rates in South Dakota. It is difficult to predict carbon storage at different landscape positions. A graphical technique was illustrated in which additions of organic carbon were related to the rate of change in soil organic carbon. The intercept on the graph could be used to estimate maintenance rates of soil organic carbon (no net change in carbon). Two factors control maintenance rates: 1) root/shoot ratios which vary across the landscape and 2) how much carbon is being added (measured with yield monitor and harvest index). David Mulla (University of Minnesota) talked about Hyperspectral Remote Sensing for N Deficiencies in Corn. Small plot research was conducted in a corn-corn and a corn-soybean rotation with 18 different nitrogen management strategies. These included several rates of pre-plant application, and several methods and rates for in-season application of nitrogen. Hyperspectral imagery collected from an airplane at V-9 were compared with in-field data collected using SPAD meter, Green Seeker and Crop Circle sensors. Several promising hyperspectral indices based on red edge effects were identified that accurately identified N deficiencies in the corn-corn rotation. Identification of N deficiencies in the corn-soybean rotation was more difficult due to carryover of fixed N from the soybean crop. Janos-Kriston-Vizi (Kyoto University) talked about Multi-spectral Reflectance Data for Leaf Water Potential in Mandarin Fruit Tree Orchards. There is a relationship between sugar accumulation and water stress in Mandarin fruits. A multi-spectral camera was used to collect data from fruit tree orchards. Reflectance and leaf water potential data were compared statistically. Green reflectance was higher from water stressed trees than un-stressed trees. Infrared thermography of fruit tree canopies was used to show a 2.8 C difference between water stressed and un-stressed trees, and a 0.48 MPa difference in water potential. Hyperspectral imaging from 400-1000 nm showed that water stress effects showed up best at 560 nm. John Schueller (University of Florida) officially adjourned the 2007 annual meeting of NCERA-180.

Activities and Outputs: 1. A significant number of NCERA-180 participants studied nitrogen fertilizer requirements using remote sensing techniques or sensor technologies (MN, SD, MO, IN, CO, CA, FL, NC, AR). This research is motivated in part by the rising cost of N fertilizers as oil and gas prices continued upward over the last two years. It is also motivated by concern over excess nitrate-N carried to the Gulf of Mexico from the Mississippi River. There is a critical need to improve the efficiency of nitrogen use in agricultural crops within the Mississippi River Basin to reduce water quality impacts. Remote sensing techniques studied by NCERA-180 participants show great promise for detecting leaf N deficiencies in spring for sidedress applications of N fertilizer. Remote sensing techniques also show promise for estimating spatial variability in soil properties that influence N requirements, and in helping to delineate fertilizer management zones. Publications resulting from these studies are listed below: Bajwa, S. G. 2006. Modeling rice plant nitrogen effect on canopy reflectance with partial least square regression. Transactions of the ASAE 49(1): 229-237. Bajwa, S. G., and M. Mozaffari. 2006. Response of cotton canopy reflectance to nitrogen fertilization. In. N. A. Slaton (Ed.) Wayne E. Sabbe Arkansas Soil Fertility Studies 2005, p.18-21, Research Series 525, Arkansas Agricultural Experiment Station, Division of Agriculture, Fayetteville, AR. Balasundram, S. K., P. C. Robert, and D. J. Mulla. 2006. Relationship between oil content and fruit surface color in oil palm (Elaeis guineensis Jacq.). Journal of Plant Sciences. 1(3):217-227. Clay, D.E. K. Kim, J. Chang, S.A. Clay, and K. Dalsted. 2006. Characterizing water and nitrogen stress in corn using remote sensing. Agron. J. 98:579-587. Hornung, A. Khosla, R. Reich, R. Inman, D. Westfall, D.G. 2006. Comparison of site-specific management zones: soil-color-based and yield-based. Agronomy Journal. 98(2): 407-415. Humburg, D. S., P. Thanapura, C. Ren, and D.E. Clay. 2006. Sugarbeet quality correlation to Landsat canopy data from a large GIS database. Transactions of the ASABE. 49(3) 775-782. Jahn, B. R. and Upadhyaya, S. K. 2006. Development of mid-infrared-based calibration equations for predicting soil nitrate, phosphate, and organic matter concentrations. American Society of Agricultural and Biological Engineers Paper No. 06-1058, St. Joseph, MI 49085. Kane, K. E., W. S. Lee. 2006. Spectral sensing of different citrus varieties for precision agriculture. ASAE Paper No. 061065. St. Joseph, Mich.: ASAE. Kim, H.J., Sudduth, K.A., and Hummel, J.W. 2006. Sensing nitrate and potassium ions in soil extracts using ion-selective electrodes. Journal of Biosystems Engineering 31(6):463-473. Mercuri P. A., B.A. Engel and C. J. Johannsen. 2006. Evaluation and Accuracy Assessment of High-Resolution IFSAR DEMs in Low-Relief Areas. International Journal of Remote Sensing. 27 (13): 2767-2786. Miao, Y., D. J. Mulla, P. C. Robert and J. A. Hernandez. 2006. Within-Field Variation in Corn Yield and Grain Quality Responses to N Fertilization and Hybrid Selection. Agron. J. 98:129-140. Min, M., W. S. Lee, Y. H. Kim, and R. A. Bucklin. 2006. Nondestructive detection of nitrogen in Chinese cabbage leaves using VIS-NIR spectroscopy. HortScience 41(1): 162-166. Min, M., and W. S. Lee. 2006. Design of a hyperspectral nitrogen sensing system for citrus. ASAE Paper No. 061061. St. Joseph, Mich.: ASAE. Roberts, D.R., Kitchen, N.R., Scharf, P.C., and Sudduth, K.A. An environmental assessment of sensor-based variable-rate nitrogen management in corn. In Proc. North Central Extension-Industry Soil Fertility Conf., Des Moines, IA, Nov. 7-8, 2006. Potash and Phosphate Institute, Brookings, SD. 2006. Scharf, P.C., S.M. Brouder, and R.G. Hoeft. 2006. Chlorophyll meter readings can predict nitrogen need and yield response of corn in the North-Central USA. Agron. J. 98:655-665. Sripada, R.P., R.W. Heiniger, J.G. White, and A.D. Meijer. 2006. Aerial color infrared photography for determining early in-season nitrogen requirements for corn. Agron. J. 98:968-977. 2. NCERA-180 participants are very active in helping to organize or participate in International, National and Regional Conferences on Precision Agriculture. These Conferences reach large numbers of scientists, ag industry professionals and producers, and help disseminate the latest advances in Precision Agriculture, thereby accelerating the adoption of Precision Agriculture. A partial listing of these Conferences is given below: Organized the 2006 International Conference on Precision Agriculture in Minneapolis, MN. Conference was attended by 400 scientists and practitioners from 30 countries, and nearly 300 papers were presented on a wide array of Precision Agriculture topics. Organized Precision Agriculture technical sessions for the 2007 International Meeting of the American Society of Agricultural and Biological Engineers in Minneapolis, MN. Technical sessions include roughly 75 papers on soil sensors, automated guidance, remote sensing and GIS and spatial technologies. Organized a special symposium on Precision Agriculture at the 2007 Annual Meeting of the American Society of Agronomy through Division S-8. Approximately 50-60 papers on Precision Agriculture are presented at this Symposium. Organized the Info-Ag Conference on Precision Agriculture for over 500 producers and ag industry professionals during July, 2007 in Springfield, IL. Organized the 2007 Precision Agriculture Data Management, Analysis and Decision Making Workshops in Ohio. 3. Future activities of NCERA-180 participants will focus on on five major areas. The first is visioning. NCERA-180 members will meet with agricultural and environmental agency leaders to help identify priority topics for Precision Agriculture research and education. The second is evaluation of Precision Agriculture technologies. NCERA-180 members will form teams to write white papers on emerging technologies used in Precision Agriculture. The third is networking with conservation agencies. NCERA-180 members will work with USDA-NRCS staff to help write 590 Practice Standards for cost-sharing of conservation practices that involve Precision Agriculture (for example, grid sampling for soil nutrients). Fourth is communications and outreach. NCERA-180 members will partner with the ag industry and work to enhance the dissemination of Precision Agriculture research results through extension newsletters, web sites, and training sessions. Fifth is conferences and workshops. NCERA-180 members will continue to be involved in planning and organization of major conferences, symposia and workshops on Precision Agriculture through a variety of Professional Societies and venues.

Journal Publications Adamchuk, V.I., M.T. Morgan, and S.M. Brouder. 2006. Analysis of variability in automated soil pH measurements. Trans. ASAE. 22(3): 335-344. Bajwa, S. G. 2006. Modeling rice plant nitrogen effect on canopy reflectance with partial least square regression. Transactions of the ASAE 49(1): 229-237. Bajwa, S. G., and E. Vories. 2007. Spatial analysis of cotton (Gossypium hirsutum L.) canopy responses to irrigation in a moderately humid area. Irrigation Science DOI# 10.1007/s00271-006-0058-4 (Online First). Bajwa, S. G., and M. Mozaffari. 2006. Response of cotton canopy reflectance to nitrogen fertilization. In. N. A. Slaton (Ed.) Wayne E. Sabbe Arkansas Soil Fertility Studies 2005, p.18-21, Research Series 525, Arkansas Agricultural Experiment Station, Division of Agriculture, Fayetteville, AR. Balasundram, S. K., P. C. Robert, and D. J. Mulla. 2006. Relationship between oil content and fruit surface color in oil palm (Elaeis guineensis Jacq.). Journal of Plant Sciences. 1(3):217-227. Balasundram, S. K., P. C. Robert, D. J. Mulla and D. L. Allan. 2006. Relationship between oil palm yield and soil fertility as affected by topography in an Indonesian plantation. Communications in Soil and Plant Analysis. 37(9-10):1321-1337. Balasundram, S. K., P. C. Robert, D. J. Mulla and D. L. Allan. 2006. Spatial variability of soil fertility variables influencing yield in oil palm (Elaeis guineensis Jacq.). Asian Journal of Plant Sciences. 5(2):389-400. Balasundram, S. K., D. J. Mulla, P. C. Robert and D. L. Allan. 2006. Accounting for spatial variability in a short-term fertilizer trial for oil palm. Int. J. Soil Sci. 1(3): 184-195. Bogrekci, I., and W. S. Lee. 2006. Effects of soil moisture content on absorbance spectra of sandy soils in sensing phosphorus concentrations using UV-VIS-NIR spectroscopy. Trans. ASABE 49(4): 1175-1180. Cabot, P.E. Pierce, F.J. Nowak, P. Karthikeyan, K.G. 2006. Monitoring and predicting manure application rates using precision conservation technology. Journal of Soil and Water Conservation. 61(5):282-292. Chung, S.O., and Sudduth, K.A. 2006. Soil failure models for vertically operating and horizontally operating strength sensors. Transactions of the ASABE 49(4):851-863. Chung, S.O., Sudduth, K.A., and Hummel, J.W. 2006. Design and validation of an on-the-go soil strength profile sensor. Transactions of the ASABE 49(1):5-14. Clay, D.E., C.G. Carlson, S.A. Clay, C. Reese, Z. Liu, and M.M. Ellsbury. 2006. Theoretical derivation of new stable and non-isotopic approaches for assessing soil organic C turnover. Agron. J. 98:443-450. Clay, D.E. K. Kim, J. Chang, S.A. Clay, and K. Dalsted. 2006. Characterizing water and nitrogen stress in corn using remote sensing. Agron. J. 98:579-587. Clay, S.A., B. Kruetner, D.E. Clay, C. Reese, J. Kleinjan. 2006. Spatial distribution, temporal stability, and yield loss estimates for annual grasses and common ragweed in corn/soybean production field over nine years. Weed Sci. 54:380-390. Clay, S.A., K. Banken, M.M. Ellsbury, and F. Forcella. 2006. Influence of yellow foxtail on corn growth and yield. Comm. Soil Plant Anal. 37:1421-1435. Gandonou, J., C.R. Dillon, S.A. Shearer, and T. Stombaugh. 2006. Precision Agriculture Equipment Ownership versus Custom Hire: A Break-even Land Area Analysis. Journal of the American Society of Farm Managers and Rural Appraisers 69(1):106-116. Hong, N., Scharf, P.C., Davis, J.G., Kitchen, N.R., and Sudduth, K.A. 2006. Economically optimal nitrogen rate reduces soil residual nitrate. Journal of Environmental Quality 36: 354-362. Hornung, A. Khosla, R. Reich, R. Inman, D. Westfall, D.G. 2006. Comparison of site-specific management zones: soil-color-based and yield-based. Agronomy Journal. 98(2): 407-415. Humburg, D. S., P. Thanapura, C. Ren, and D.E. Clay. 2006. Sugarbeet quality correlation to Landsat canopy data from a large GIS database. Transactions of the ASABE. 49(3) 775-782. Iqbal, J., P. Owens, and I Ali. 2006. Application of Remote Sensing Data to Assess Weed Infestation in Cotton. Agricultural Journal 1(4): 186-191. Jahn, B. R., Linker, R., Upadhyaya, S. K., Shavis, A., Slaughter, D. C. and Shmulevi, I. 2006. Mid-infrared spectroscopic determination of soil nitrate content. Biosystems Engineering 94(4):505-515. Jang, G.S., Sudduth, K.A., Hong, S.Y., Kitchen, N.R., and Palm, H.L. 2006. Relating hyperspectral image bands and vegetation indices to corn and soybean yield. Korean Journal of Remote Sensing 22(3):183-197. Jiang, P., Anderson, S.H., Kitchen, N.R., Sadler, E.J., and Sudduth, K.A. 2006. Landscape and conservation management effects on hydraulic properties on a claypan-soil toposequence. Soil Science Society of America Journal. Accepted. Jung, W.K., Kitchen, N.R., and Sudduth, K.A. 2006. Relationship of soil profile strength and apparent soil electrical conductivity to crop yield. Korean Journal of Soil Science and Fertilizer 39(2):109-115. Jung, W.K., Kitchen, N.R., Sudduth, K.A., and Anderson, S.H. 2006. Spatial characteristics of claypan soil properties in an agricultural field. Soil Science Society of America Journal 70: 1387-1397. Khosla, R. Westfall, D. Reich, R. Inman, D. 2006. Temporal and Spatial Stability of Soil Test Parameters Used in Precision Agriculture. Communications in Soil Science and Plant Analysis. 37(15-20): 127-2136. Kim, H.J., Sudduth, K.A., and Hummel, J.W. 2006. Sensing nitrate and potassium ions in soil extracts using ion-selective electrodes. Journal of Biosystems Engineering 31(6):463-473. Lambert, Dayton, J. Lowenberg-DeBoer and Gary Malzer. (2006). Economic Analysis of Spatial-Temporal Patterns in Corn and Soybean Response to Nitrogen and Phosphorous. Agronomy Journal 98:43-54. Liu, Y., S. M. Swinton, and N. R. Miller. 2006. Is Site-specific Yield Response Consistent over Time? Does it Pay? American Journal of Agricultural Economics 88(2):471-483. Martin, N., Bollero, G., Kitchen, N.R., Kravchenko, A.N., Sudduth, K.A., Wiebold, W.J., Bullock, D. 2006. Two classification methods for developing and interpreting productivity zones using site properties. Plant Soil 288: 357-371. Mercuri P. A., B.A. Engel and C. J. Johannsen. 2006. Evaluation and Accuracy Assessment of High-Resolution IFSAR DEMs in Low-Relief Areas. International Journal of Remote Sensing. 27 (13): 2767-2786. Miao, Y., D. J. Mulla, P. C. Robert and J. A. Hernandez. 2006. Within-Field Variation in Corn Yield and Grain Quality Responses to N Fertilization and Hybrid Selection. Agron. J. 98:129-140. Miao, Y., D. J. Mulla and P. C. Robert. 2006. Spatial Variability of Soil Properties, Corn Quality and Yield in Two Illinois, USA Fields: Implications for Precision Corn Management. Prec. Agric. 7:5-20. Miao, Y., D. J. Mulla, W. D. Batchelor, J. O. Paz, P. C. Robert and M. Wiebers. 2006. Evaluating Management Zone Specific Optimal N Rates with a Crop Growth Model. Agron. J. 98:545-553.. Miao, Y., D. J. Mulla and P. C. Robert. 2006. Identifying Important Factors Influencing Corn Yield and Grain Quality Variability using Artificial Neural Networks. Prec. Agric. 7(2):117-136. Min, M., W. S. Lee, Y. H. Kim, and R. A. Bucklin. 2006. Nondestructive detection of nitrogen in Chinese cabbage leaves using VIS-NIR spectroscopy. HortScience 41(1): 162-166. Myers, D.B., Kitchen, N.R., Sudduth, K.A., Miles, R.J., and Sharp, R.E. Soybean root distribution related to claypan soil properties and apparent soil electrical conductivity. Crop Science. (accepted) Omonode, R.A., and T. Vyn. 2006. Spatial dependence and relationships of electrical conductivity to soil organic matter, phosphorus, and potassium. Soil Science 171(3):223-238. Papiernik, S.K., W.C. Koskinen, L. Cox, P.J. Rice, S.A. Clay, N.R. Werdin-Pfisterer, and K.A. Nordberg. 2006. Sorption-desorption of imidacloprid and its metabolites in soil and vadose zone materials. J. Agric. Food Chem. 54:863-870. Pena-Yewtukhiw, E.M., G.J. Schwab and L.W. Murdock. 2006. Univariate Distribution Analysis to Evaluate Variable Rate Fertilization. Agron J. 98:554-561. Pydipati, R., T. F. Burks, and W. S. Lee. 2006. Identification of citrus disease using color texture features and discriminant analysis. Computers and Electronics in Agriculture 52(1): 49-59. Roel, A., H. Firpo and R.E. Plant. Why Do Some Farmers Get Higher Yields? Multivariate Analysis of a Group of Uruguayan Rice Farmers. Computers and Electronics in Agriculture. In press. Scharf, P.C. Kitchen, N.R., Sudduth, K.A., and Davis, J.G. 2006. Spatially variable corn yield is a weak predictor of optimal nitrogen rate. Soil Science Society of America Journal 70:2154-2160. Scharf, P.C., S.M. Brouder, and R.G. Hoeft. 2006. Chlorophyll meter readings can predict nitrogen need and yield response of corn in the North-Central USA. Agron. J. 98:655-665. Souza, E., Scharf, P., Sudduth, K.A., and Hipple, J.D. 2006. Using a field radiometer to estimate instantaneous sky clearness. Brazilian Journal of Agricultural and Environmental Engineering 10(2):369-373. Sripada, R.P., R.W. Heiniger, J.G. White, and A.D. Meijer. 2006. Aerial color infrared photography for determining early in-season nitrogen requirements for corn. Agron. J. 98:968-977. Sudduth, K.A., Chung, S.O., Andrade-Sanchez, P., and Upadhyaya, S.K. Field comparison of two prototype soil strength profile sensors. Computers and Electronics in Agriculture. (accepted). Thomson, S.J., L.A. Smith, and J.E. Hanks. 2007. An Instrumentation Platform and GPS Position Latency Issues for Remote Sensing on Agricultural Aircraft. Transactions of the ASABE. 50(1): 13-21. Books Clay, D.E., N. Kitchen, C.G. Carlson, J. Kleinjan, and J. Chang. 2007. Using historical management to reduce soil sampling errors. Pg 49-64. In: Pierce, F. and D.E. Clay (eds). GIS Applications in Agriculture. CRC Press, Boca Raton, FL. Clay, D.E., S.A. Clay, and C.G. Carlson. 2006. Site-specific management from a cropping systems perspective. Pg. 431-462. In Srinivasan, A. (ed) Precision farming  A global perspective. Haworth Press, Inc. Johannsen, C.J. 2006. Land Remote Sensing Applications for Human Welfare Support: Food Security. Contributions of Remote Sensing for Decisions about Human Welfare Workshop, National Research Council, Washington, DC. Appendix A 4 pp. Kitchen, N.R., Goulding, K.W.T., and Shanahan, J.F. Proven practices and innovative technologies for on-farm crop nitrogen management. In Nitrogen in the Environment. Elsevier Science, Amsterdam, Netherlands. (accepted) Kleinjan, J., D.E. Clay, C.G. Carlson, and S.A. Clay. 2007. Developing productivity zones from multiple years of yield monitor data. Pg. 65-80. In: Pierce, F. and D.E. Clay (eds). GIS Applications in Agriculture. CRC Press, Boca Raton, FL. Pierce, F. and D.E. Clay (editors). 2007. GIS Applications in Agriculture. CRC Press, Boca Raton, FL. 203 pg. Roel, A., G.S. Pettygrove, and R.E. Plant. 2006. Site-specific rice management. Handbook of Precision Agriculture, Principles and Applications. A. Srivivasan, ed. Haworth Press, New York, NY, 319-340. In press. Proceedings Adamchuk, V.I., Sudduth, K.A., Ingram, T.J., and Chung, S.O. 2006. Comparison of two alternative methods to map soil mechanical resistance on-the-go. Paper No. 061057. In: ASAE Annual Intl. Meeting Technical Papers. ASAE, St. Joseph, MI (available at: http://asae.frymulti.com/request.asp?JID=5&AID=20587&CID=por2006&T=2). Bajwa, S. G., and M. Mozaffari. 2006. Effect of petiole nutrients in cotton on vegetative indices. ASAE Paper No. 061170. St. Joseph, MI: ASAE. Bajwa, S. G., and E.D. Vories. 2006. Spectral response of cotton canopy to water stress. ASAE Paper No. 061064. St. Joseph, MI: ASAE. Bajwa, S. G., and M. Mozaffari. 2006. Correlating vegetative index with nitrogen treatments in cotton. Summaries of Arkansas Cotton Research 2005, Research Series. 533, p. xx. Arkansas Agricultural Experiment Station, Division of Agriculture, Fayetteville, AR. Bogrekci, I., and W. S. Lee. 2006. The effect of particle size on sensing phosphorus by Raman spectroscopy. ASAE Paper No. 063048. St. Joseph, Mich.: ASAE. Chinchuluun, R., and W. S. Lee. 2006. Citrus yield mapping system in natural outdoor scenes using the Watershed transform. ASAE Paper No. 063010. St. Joseph, Mich.: ASAE. Chung, S.O., Sudduth, K.A., Lee, K.S., and Motavalli, P.P. 2006. Characterization of cone index to define compaction management parameters. In: Proc. ISTRO 17th Triennial Conf., p. 395-400. Kiel, Germany, August 28  September 3, 2006. Clay, S.A. 2006. Use of remote sensing for weed management. Eighth International Precision Ag. Conference. A to Z Session. Minneapolis, MN July 2006. Clay, S.A. 2006. Developing weed management zones for site specific farming application. Eighth International Precision Ag. Conference. A to Z Session. Minneapolis, MN July 2006. Clay, S.A., J. Kleinjan, and D.E. Clay. 2006. Weed emergence by landscape position. International Precision Ag. Conference. Minneapolis, MN July 2006. Conrad, E., C.R. Dillon and J. Gandonou. Variable Rate Fertilization Profitability on High-Oil Corn Production. Paper presented at the 8th International Conference on Precision Agriculture, Minneapolis, Minnesota, July 23-26, 2006. Dillon C., J. Gandonou, B. Koostra, T. Stombaugh, T. Mueller. Evaluating the Economic Impact of Field Area Measurements. Poster presented at the 8th International Conference on Precision Agriculture, Minneapolis, Minnesota, July 23-26, 2006. Erickson, B., and J. Lowenberg DeBoer. Will Higher Fertilizer Prices Drive Adoption of Precision Fertilizer Management? Purdue Agricultural Economics Report, April, 2006. http://www.agecon.purdue.edu/extension/pubs/paer/2006/april/paer0406.pdf Erickson, Bruce. Economics of Precision Agriculture: Implications for Sugar Cane Production, presented at the Colombian Association of Sugar Cane Technologists National Conference, Cali, Colombia, September 2006. Gandonou, J. and C.R. Dillon. Precision Timing and Spatial Allocation of Economic Fertilizer Application. Paper presented at the 8th International Conference on Precision Agriculture, Minneapolis, Minnesota, July 23-26, 2006. Griffin, Terry, J. Lowenberg-DeBoer and R.J.G.M. Florax, Improving Farm Management Decision Making: Experiences from Spatial Analysis of Yield Monitor Data from Field Scale On-Farm Trials, Paper presented at the 8th International Precision Agriculture Conference, Minneapolis, MN, July, 2006. Griffin, T.W., J.M. Lowenberg-DeBoer and R.J.G.M. Florax, "Improving Farm Management Decision Making: Experience from Spatial Analysis of Yield Monitor Data from Field-Scale On-Farm Trials," presented at the 8th International Precision Agriculture Conference, Minneapolis, MN, July 23-26, 2006. Humburg, D. S. 2006. Correlation of sugarbeet quality to canopy and field variables using Landsat data and a large GIS database. In Proceedings of the 8th International Conference on Precision Agriculture. July 23-26, 2006. Minneapolis, MN. Jahn, B. R. and Upadhyaya, S. K. 2006. Development of mid-infrared-based calibration equations for predicting soil nitrate, phosphate, and organic matter concentrations. American Society of Agricultural and Biological Engineers Paper No. 06-1058, St. Joseph, MI 49085. Jang, G., Sudduth, K.A., Hong, S.Y., Kitchen, N.R., and Palm, H.L. Relating image-derived vetetation indices to crop yield. In: Proc. 20th Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment (unpaginated cd-rom). Am. Soc. for Photogrammetry and Remote Sensing, Bethesda, MD. 2006. Kane, K. E., W. S. Lee. 2006. Spectral sensing of different citrus varieties for precision agriculture. ASAE Paper No. 061065. St. Joseph, Mich.: ASAE. Lambert, Dayton M., R.J.G.M. Florax, and Kevin McNamara.. Multiplicative Heteroskedastic-Spatial Process Models: Monte Carlo Experiments and an Empirical Example, proceedings of the 53rd Annual North American Meetings of the Regional Science Association, November 16-18, 2006, Toronto, Canada. Lowenberg-DeBoer, J., Terry Griffin, R.J.G.M. Florax, Use of Cross Regression to Model Local Spatial Autocorrelation in Precision Agriculture, Paper presented at the 8th International Precision Agriculture Conference, Minneapolis, MN, July, 2006. Lowenberg-DeBoer, J., and B. Erickson. Economics of Innovative Technologies in Precision Agriculture Nutrient Management, presented at the American Society of Agronomy International Meetings, November, 2006. Min, M., and W. S. Lee. 2006. Design of a hyperspectral nitrogen sensing system for citrus. ASAE Paper No. 061061. St. Joseph, Mich.: ASAE. Nistor, Adela, Jason Brown, Raymond Florax, and Jess Lowenberg-DeBoer. Spatial Modeling of Yield Monitor Data: Implications for Crop Yields with Drainage Water Management, proceedings of the 53rd Annual North American Meetings of the Regional Science Association, November 16-18, 2006, Toronto, Canada. Reese, C. L., D. E. Clay, D. Beck, J. Kleinjan, C. G. Carlson and S. Clay. Lessons learned from implementing management zones and participatory research in production fields. Eighth International Conference on Precision Agriculture. 23  26 July 2006. Marriott Hotel, Minneapolis, Minnesota. Roberts, D.R., Kitchen, N.R., Scharf, P.C., and Sudduth, K.A. An environmental assessment of sensor-based variable-rate nitrogen management in corn. In Proc. North Central Extension-Industry Soil Fertility Conf., Des Moines, IA, Nov. 7-8, 2006. Potash and Phosphate Institute, Brookings, SD. 2006. Salim, J., C. Dillon, and J. Gandonou. (2006). Profit maximization under risk reducing behavior using variable cutting timings for Kentucky alfalfa. Paper presented at the 2006 Precision Agriculture Conference in July 23-26, 2006, Minneapolis, MN. Shockley, J., S.Saghaian, C. Dillon, and L.Maynard. A Logit Analysis of Precision Agriculture Adoption in Kentucky. Paper presented at the 8th International Conference on Precision Agriculture. Minneapolis, Minnesota. July 23-26, 2006. Smith, L.A. and S.J. Thomson. 2006. Performance of an Aerial Variable-Rate Application System With a Hydraulically Powered Chemical Pump and Spray Valve. NAAA/ASAE Paper No. AA05-009, National Agricultural Aviation Association, Washington, D.C. Sudduth, K.A., and Kitchen, N.R. Increasing information with multiple soil electrical conductivity datasets. Paper No. 061055. In: ASABE Annual Intl. Meeting Technical Papers. ASABE, St. Joseph, MI (available at: http://asae.frymulti.com/request.asp? JID=5&AID=21088&CID=por2006&T=2). 2006. Sudduth, K.A., Chung, S.O., Drummond, S.T., and Kitchen, N.R. Relating spatial variations in soil compaction to soil physical properties and crop yield. In Proc. 8th Intl. Conf. on Precision Agriculture, Minneapolis, MN, July 23-26, 2006 (in press). 2006. Sudduth, K.A., Chung, S.O., Drummond, S.T., and Kitchen, N.R. Relating spatial variations in soil compaction to soil physical properties and crop yield. In Proc. 8th Intl. Conf. on Precision Agriculture, Minneapolis, MN, July 23-26, 2006 (in press). 2006. Sudduth, K.A., Jang, G., Lerch, R.N., and Sadler, E.J. Hyperspectral reflectance sensing of reservoir water quality. In: Proc. 20th Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment (unpaginated cd-rom). Am. Soc. for Photogrammetry and Remote Sensing, Bethesda, MD. 2006. Thompson, J.A., E.M. Pena-Yewtukhiw and J.H. Grove. 2006. Soil-landscape modeling across a physiographic region: Topographic patterns and model transportability. Geoderma. 133:57-70. Thomson, S.J. and L.A. Smith. 2006. Dynamic testing of GPS on agricultural aircraft for remote sensing and variable rate aerial application. In Proceedings of the IEEE/ION Position, Location and Navigation Symposium (PLANS 2006). CD-ROM: 1067- 1070. Thomson, S.J. and P.V. Zimba. 2006. Application of hyperspectral imagery and digital videography to manage algal blooms in aquaculture systems: Current status. Proceedings of the 20th Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment. CD-ROM. American Society of Photogrammetry and Remote Sensing (ASPRS), Bethesda, MD. Upadhyaya, S. K., Shafii, M. S. and Garciano, L. O. 2006. Development of an impact type electronic weighing system for processing tomatoes. American Society of Agricultural and Biological Engineers Paper No. 06-1190, St. Joseph, MI 49085. Extension Publications Armstrong, S., and P. Owens. Spatial Variability of Nutrients in Soils Following Long-Term Poultry Litter Applications. SSMC Newsletter, December, 2006. Kleinjan, J., D.E. Clay, C.G. Carlson, and S.A. Clay. 2006. Developing productivity zones from multiple years of yield monitor data. Site Specific Management Guidelines. 45. Published by Potash and Phosphate Institute. Erickson, B., and J. Lowenberg-DeBoer. Will Higher Fertilizer Prices Drive Adoption of Precision Fertilizer Management? SSMC Newsletter, January, 2006. Erickson, B. The Use of Information Technology in Danish Agriculture. SSMC Newsletter, May 2006. Erickson, B. On-Farm Testing, Robotics, and Guidance Featured at the 2006 Top Farmer Crop Workshop. SSMC Newsletter, July, 2006. Erickson, B. Precision Agriculture in Colombian Sugar Cane. SSMC Newsletter, September, 2006. Erickson, B. A Comprehensive New Resource: Handbook of Precision Agriculture. SSMC Newsletter, October, 2006. Fulton, J.P., M.W. Veal and S.A. Shearer. Performance Assessment of Variable Rate Fertilizer Technology. SSMC Newsletter, April, 2006. Griffin, T., C. Dobbins, and J. Lowenberg-DeBoer. Whole Farm Profitability Impact from Implementing and Harvesting On-farm Trials: A Linear Programming Model. SSMC Newsletter, August, 2006. Lowenberg-DeBoer, J. and T. Griffin. Potential for Precision Agriculture Adoption In Brazil. SSMC Newsletter, June 2006. Lowenberg-DeBoer, J. Effect of Higher Energy and Fertilizer Prices on Precision Ag Adoption. SSMC Newsletter, February, 2006. Owens, P.R., J. Iqbal and D.M. Miles. Using Geostatistics to Determine Spatial Variability of Nutrients Within a Poultry House. SSMC Newsletter, March, 2006. Sripada, R.P., R.W. Heiniger, J.G. White, C.R. Crozier, and A.D. Meijer. 2006. Attempt to validate a remote sensing-based late-season corn nitrogen requirement prediction system. Online. Crop Management doi:10.1094/CM-2006-0405-01-RS. Struthers, R., and B. Erickson. The Modifiable Areal Unit Problem in Precision Agriculture. SSMC Newsletter, November, 2006. Staff Papers Whipker, Linda, and Jay Akridge, 2006 Precision Agricultural Services: Dealership Survey Results. Staff Paper No. 06-10, Center for Food and Agricultural Business, Department of Agricultural Economics, Purdue University, West Lafayette, IN, USA, August 2006. Trade Articles Erickson, B. Equipped to Succeed. CropLife, March 2006, pp 19-20. Erickson, B. Fertilizer and Precision, pp. 12-13 in 2006 Technology Tune-Up, supplement to February 2006 editions of CropLife, American Vegetable Grower, CottonGrower, and Western Fruit Grower. Whipker, Linda and Jay Akridge. A New Future, CropLife. June 2006, pp 10-15.