NUTRIENT AND WATER MANAGEMENT FOR SEMI-ARID AGROECOSYSTEMS IN CENTRAL AND WESTERN NEBRASKA

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0225215
• Project Start Date: Apr 1, 2011
• Project End Date: Mar 31, 2016
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583

Performing Department
West Central Res & Ext Center

Non Technical Summary
Water is the most limiting factor for agricultural production in the semi-arid environment of central and western Nebraska. While this region sits atop a vast quantity of ground water contained within the Ogallala Aquifer, the central and western part of the state itself is semi-arid and receives less than 500 mm (20 inches) of precipitation annually. Dry climate conditions combined with a large availability of ground water has led to crop production systems that are highly dependent on irrigation for maximum yields and sustainability. Elevated societal demand for water (quantity, as well as quality) has become increasingly important locally, regionally, nationally, and globally. This increased emphasis on the importance of water is forcing crop producers, regulatory agencies, and agronomic research entities to find new ways to protect water quality and increase the efficiency of water used for agriculture. Using more efficient nutrient management techniques that decrease the potential for nutrient leaching/runoff into water sources is one way water quality issues can be addressed. This can be accomplished through the use of precision agriculture technologies such as crop canopy sensors. These sensors can provide important information for mitigating potential water quality issues that can arise from the over-application of nutrients. Crop canopy sensors are already being used to determine the temporal and spatial nitrogen (N) requirements of irrigated corn, thereby increasing the efficiency of N and limiting potential environmental degradation. However, crop canopy sensor use has not been adequately explored in semi-arid climates where an array of water management techniques are practiced. The development of algorithms that are appropriate to environments with a range of climatic stresses is important as differences in climatic moisture regimes may affect the performance of crop canopy sensors. Crop canopy sensors may also have the potential to determine water stress in crops. If this potential can be realized, an effective, non-invasive way to determine the water requirement of crops could be developed that may lead to decreased applications of water for crop growth. The semi-arid, highly irrigated region of western Nebraska provides ideal conditions to investigate this potential due to our ability to vary moisture conditions. This research is technically feasible as it builds upon previous research using equipment found to be reliable and accurate in the determination of in-field crop variability. This research addresses stakeholder priorities by addressing water quality, quantity, and crop nutrient use issues related to corn production in semi-arid central and western Nebraska. By increasing the efficiency of both water and nutrients for crop growth the over-use of water and fertilizers may be greatly curtailed aiding in the profitability and sustainability of producers and rural communities. Increasing the efficiency of crop production inputs also enhances environmental stewardship and the sustainability of production agriculture.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	1070	80%
111	0110	1070	20%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0110 - Soil;

Field Of Science
1070 - Ecology;

Keywords

crop canopy sensors

nitrogen use efficiency

water use efficiency

precision agriculture

soil physical properties

crop residue management

agroecosystems

semi-arid environments

nebraska agriculture

nutrient management

water management

limited irrigation

Goals / Objectives
The goals and objectives of this project are: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Results of all stated objectives will be developed for publication in scientific journals such as the Soil Science Society of America Journal, The Agronomy Journal, and The Journal of Precision Agriculture. The outcomes of objectives 1 and 2 will be N and water application recommendation algorithms that farmers in the semi-arid environment of central and western Nebraska can use to maximize N and water use efficiency. The outcome of objective 3 will be increased knowledge about the impacts that residue removal can have on soil properties that are directly related to crop productivity and yield. The outcome of objective 4 will help farmers decide if adopting new precision technologies is economically feasible for their operation.

Project Methods
Two permanent study sites in central and western Nebraska will be used for the development of a regional semi-arid sensor based N application algorithm. These sites include North Platte, NE. located at the University of Nebraska-Lincoln West Central Research and Extension Center (WCREC) and Brule, NE. located at the University of Nebraska-Lincoln West Central Water Laboratory. Nitrogen application plots/strips will be placed at North Platte and Brule using established replicated statistical designs. The N rates used will vary from highly deficient (check, no N applied) to excessive (based on soil tests for residual N) with several rates in-between. Plots/strips will be divided into pre-plant and side-dress (at specific growth stages) application treatments. This will allow for the creation of plant N response gradients from which correlation and calibration data can be collected. We can then use the crop canopy sensors to read the plots and determine the relative N differences in the corn as well as plant N response from side-dress applications. Sensor readings will be recorded on a weekly basis beginning at the V6 growth stage and continuing through the V16 growth stage just before tasseling. This will allow for the determination of what growth stage best expresses the variability due to N that is present in the corn. Determining the potential for crop canopy sensors to quantify crop water stress will be conducted in conjunction with the N algorithm development study. This will be accomplished by incorporating water application treatments with the N application plots/strips at the North Platte and Brule study sites. Crop canopy sensor readings using a Holland Scientific Crop Circle model 430 will be collected on a weekly basis across all water and N treatments from the V6 to the R6 growth stage to determine if there is a relationship between sensor data and crop water stress. Soil physical property research will be conducted at Brule Nebraska at the aforementioned water laboratory and will utilize one full center pivot under continuous corn management. Crop residue management may affect soil fertility, nutrient cycling, and carbon sequestration. Soil samples will be collected on an annual basis across all treatments in depth increments of 0-8", 8-24", 24-36", and 36-48". This will allow us to determine the effect that removing crop residue has on nutrient cycling and carbon sequestration characteristics. Soil cores will be collected across all treatments annually across depths of 0-2", 2-4" and 4-8" to determine soil bulk density. Soil samples will also be collected and analyzed for water stable aggregate stability across depths of 0-2", 2-4" and 4-8". The benefits of precision agriculture technology often include reducing inputs such as N and water. However, new technologies are often expensive for farmers to adopt. As the precision agriculture research outlined above is being conducted I will work with the Agricultural Economist at the WCREC to analyze the costs of implementing this technology as well as the income generated from its use to determine economic feasibility.

Progress 04/01/11 to 03/31/16

Outputs
Target Audience:Farmers, Ranchers, Agricultural Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Changes/Problems:One of the primary goals of this study was to determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. Results of the study suggest that crop canopy sensors can determine water stress in crops. However, the practical application is limited at this time as the sensors are not designed for this function. It is very difficult to quantify the level of water stress and apply this information. It is believed that other sensor technologies are more practical for managing water stress such as soil moisture sensors, thermal sensors, and ET gauges. Once this was determined the study of crop canopy for use in crop water stress was halted. What opportunities for training and professional development has the project provided?Opportunities for training and professional development were provided through numerous extension activities including: -University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. -University of Nebraska-Lincoln Youth Science Field Days. -University of Nebraska-Lincoln Crop Production Clinics. -University of Nebraska-Lincoln Soils School. -Central Nebraska Public Power and Irrigation Tour. -Nebraska Independent Crop Consultants Meeting. -Nebraska Little Blue Natural Resource District Farmer Training. -Nebraska Water Balance Alliance Soil Moisture Probe Training. -Nebraska Water Balance Alliance Field Day. -UNL Crop and Cattle Short Course. How have the results been disseminated to communities of interest?Study results have been disseminated to the communities of interest through; -University of Nebraska-Lincoln Extension Circulars and NebGuides (See Publications List) -Peer Reviewed Journal Articles (See Publications List) -Producer Field Day Demonstrations and Presentations (UNL-WCREC Water Field Days 2010-2016, North Platte NE, Brule NE) -Youth Science Field Day Demonstrations and Presentations (North Platte NE, Kearney NE, Lexington NE, Hastings NE; 2010-2016) -Regional, national, and international conference presentations (American Society of Agronomy, 2010-2014, 2016; Great Plains Soil Fertility Conference, 2010, 2012, 2014, 2016; European Conference on Precision Agriculture, 2013) -UNL Crop Production Clinics (North Platte NE, Kearney, NE 2010-2016) -UNL WCREC Crops and Cattle Short Course (North Platte NE, 2011; Brule NE 2013) -Nebraska natural resource district seminars -University of Nebraska-Lincoln Soils School (2012-2014). -Nebraska Independent Crop Consultants Meeting (2015). -Nebraska Little Blue Natural Resource District Farmer Training (2015). -Nebraska Water Balance Alliance Soil Moisture Probe Training (2015). -Nebraska Water Balance Alliance Field Day(2015). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Project Impact: The Nutrient Management Project at the University of Nebraska-Lincoln West Central Research and Extension Center has highly related research and extension components that focus on increasing nutrient and water use efficiency for crop production in the semi-arid environment of west-central Nebraska. Our program also examines the effects that current and potential future agronomic management practices have on soil properties related to nutrient cycling, water infiltration, and soil water availability. These efforts are being conducted collaboratively with UNL and USDA scientists representing all aspects of agronomic production utilizing state of the art technologies. The overall impact of this project increases input use efficiency while negating potential environment degradation thereby decreasing the impact of agriculture on important natural soil and water resources. Goals and Objectives: The goals and objectives of this project are: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Accomplishments: Goal: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. Major Activities: A five year Landscape Position Study was completed at the UNL Water Laboratory at Brule. This study was conducted in cooperation with various other UNL scientists at the West Central Research and Extension Center and in Lincoln. The final 3 years of this work was supported by a CIG grant and was replicated in Colorado and Oklahoma with the goal of educating producers on the use of crop canopy sensors. A three year study utilizing sensors to quantify manure N mineralization was completed. Results: Results to date (analysis is continuing) from our Landscape position study suggest that crop canopy sensor algorithms developed and used in the eastern portion of Nebraska function well in the western semi-arid portion of Nebraska. There is no need at this time to develop specific algorithms for eastern and western Nebraska. This is beneficial as it decreases possible confusion for Nebraska farmers. Study results indicate the by using crop canopy sensors the overall amount of N applied can be reduced by up to 50-75 lbs N/ac while maintaining yields. This has the benefit of reducing potential environmental issues as well as helping farmers economically. Algorithm development on manured systems continues with a Ph.D. student as this information does not currently exist. Key Outcomes: Four research papers and one extension paper related to the use of crop canopy sensors were published in peer reviewed journals (see publications list): Information on crop canopy sensors was disseminated to farmers at several training sessions including; -Producer Field Day Demonstrations and Presentations (UNL-WCREC Water Field Days, various other farmer field days) -Youth Science Field Day Demonstrations and Presentations -Regional, national, and international conference presentations (American Society of Agronomy, Great Plains Soil Fertility Conference, European Conference on Precision Agriculture) -UNL Crop Production Clinics -UNL WCREC Crops and Cattle Short Course -Nebraska natural resource district seminars -University of Nebraska-Lincoln Soils School -Nebraska Independent Crop Consultants Meeting -Nebraska Little Blue Natural Resource District Farmer Training -Nebraska Water Balance Alliance Field Day Goal: 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. Major Activities: The final year of the Landscape Position Study was completed at the UNL Water Laboratory at Brule. This study was conducted in cooperation with various other UNL scientists at the West Central Research and Extension Center and in Lincoln. This work was also supported by a CIG grant and is being replicated in Colorado and Oklahoma with the goal of educating producers on the use of crop canopy sensors. Results: Results suggest that crop canopy sensors can determine water stress in crops. However, the practical application is limited at this time. It is believed that other sensor technologies are more practical for managing water stress such as soil moisture sensors, thermal sensors, and ET gauges. Key Outcomes: While not directly related to crop canopy sensors, two extension circulars were published relating to variable rate irrigation and irrigation and nitrogen management (see publications list). Information on crop canopy and soil moisture sensors was disseminated to farmers at several training sessions including; -Producer Field Day Demonstrations and Presentations (UNL-WCREC Water Field Days, various other farmer field days) -Youth Science Field Day Demonstrations and Presentations -Regional, national, and international conference presentations (American Society of Agronomy, Great Plains Soil Fertility Conference, European Conference on Precision Agriculture) -UNL Crop Production Clinics -UNL WCREC Crops and Cattle Short Course -Nebraska natural resource district seminars -University of Nebraska-Lincoln Soils School -Nebraska Independent Crop Consultants Meeting -Nebraska Little Blue Natural Resource District Farmer Training -Nebraska Water Balance Alliance Field Day -Nebraska Water Balance Alliance Soil Moisture Probe Training Goal: 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. Major Activities: The final soil sampling was conducted on the Corn Stalk Grazing and Baling study at Brule. Additional sampling was conducted to determine soil erosion characteristics and water run off characteristics related to residue grazing and baling management practices. Results: Research findings on the effects of cattle grazing of corn stalks suggest that compaction is not adversely affected if stocking rates are kept within university recommendations. Results also suggest that baling of residues can affect soil aggregation as well as erosion and run off adversely. Key Outcomes: Seven research papers and two extension papers related to corn stalk baling and grazing and/or soil physical properties were published in peer reviewed journals (see publications list). Information related to residue removal effects on soil properties were disseminated to several audiences including; -Producer Field Day Demonstrations and Presentations (UNL-WCREC Water Field Days, various other farmer field days) -Youth Science Field Day Demonstrations and Presentations -Regional, national, and international conference presentations (American Society of Agronomy, Great Plains Soil Fertility Conference, European Conference on Precision Agriculture) -UNL Crop Production Clinics -UNL WCREC Crops and Cattle Short Course -Nebraska natural resource district seminars -University of Nebraska-Lincoln Soils School Goal: 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Key Outcomes: I was a co-author on a peer reviewed journal article regarding this topic (see publications list):

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Ward, N., R.B. Ferguson, T.M. Shaver, S. Irmak, and D. Rudnik. 2013. Relationships between soil water status and crop canopy measurements of water and nitrogen stress. ASA, CSSA, and SSSA 2013 International Meetings.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Shaver, T.M., A. Stalker, S. van Donk, and H. Blanco. 2013. Corn Residue Grazing and Baling Effects on Soil Compaction. ASA, CSSA, and SSSA 2013 International Meetings.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Shaver, T.M., R. Khosla, and D.G. Westfall. 2014. Evaluation of two crop canopy sensors for nitrogen recommendations in irrigated maize. Journal of Plant Nutrition. Vol 37:406-419.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: van Donk, S.J., T.M. Shaver, J.L. Petersen, and D.R. Davidson. 2012. Effects of Crop Residue Removal on Soil Water Content and Yield Deficit-Irrigated Soybean. Transactions of the ASABE. Vol 55, no.1 pp. 149-157.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Shaver, T.M., G.A. Peterson, L. R. Ahuja, and D.G. Westfall. 2013. Soil sorptivity enhancement with crop residue accumulation in semiarid dryland no-till agroecosystems. Geoderma. Vol 192, pp. 254-258.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: R. Ferguson, M. Schmer, T. Shaver, B. Weinhold, S. Van Donk, S. Irmak, D. Rudnik, N. Ward, V. Jin, D. Francis, A. Bereuter and L. Hendrickson. 2013. Variable rate irrigation and nitrogen fertilization of maize across landscape positions. In: Precision Agriculture '13. Wageningen Academic Publishers. Pgs. 729-736.
• Type: Other Status: Published Year Published: 2014 Citation: Shaver, T.M., R. Ferguson, G. Hergert, B. Krienke, C. Shapiro, C. Wortmann. 2014. Nutrient Management for Agronomic Crops in Nebraska. Extension Circular, University of Nebraska-Lincoln Extension EC155.
• Type: Other Status: Published Year Published: 2015 Citation: Kranz, W.L., B. Farmaha, P. Grassini, G.W. Hergert, T. Shaver, C.A. Shapiro, S. Irmak, D. Martin, C. Burr, A. Nygren, and G. Zoubek. 2014. Irrigation and Nitrogen Management: User Education/Certification Program. UNL EC2008. Extension Circular,University of Nebraska-Lincoln Extension EC2008. In Press.
• Type: Other Status: Published Year Published: 2014 Citation: Klein, R. N., C. Burr, M. Reiman, D.C. Mazour, T. Shaver, G. Kruger, and B. Olsen. 2014. Dryland Water Management Guide For Corn on the Great Plains. UNL-Extension and Monsanto (Joint Publication). Monsanto Water Utilization Learning Center. Gothenburg, NE.
• Type: Other Status: Published Year Published: 2014 Citation: Kranz, W.L., S. Irmak, D.L. Martin, T.M. Shaver, and S.J. van Donk. 2014. Variable rate application of irrigation water with center pivots. Extension Circular, University of Nebraska-Lincoln Extension EC2000.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T.M., M. Schmer, T. Klopfenstein, B. Weinhold, and H. Blanco. 2014. The effects of 20 years of grazing on Soil Physical and Chemical Properties. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Schmer, M., T. Shaver, R. Ferguson, and B. Wienhold. 2014. Yield response of irrigated corn to landscape position under variable nitrogen. 2014. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T.M., S. van Donk, and G.R. Kruger. 2014. Suitability of crop canopy sensors for determining irrigation differences in maize. 12th International Conference on Precision Agriculture, Sacramento, CA. July 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T., R. Ferguson, S. Irmak, S. van Donk, D. Rudnik, N. Ward, M. Schmer, B. Weinhold, V. Jin, D. Francis, A. Bereuter, and L. Hendrickson. 2014. Effects of landscape position, variable rate nitrogen, and variable rate irrigation on corn yield. In: Proceedings of the 2014 Great Plains Soil Fertility Conference.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: M. Liakat Ali, Jon Luetchens, Amritpal Singh, Timothy M. Shaver, Greg R. Kruger, and Aaron J. Lorenz. 2015. Greenhouse screening of maize genotypes for deep root mass and related root traits and their association with grain yield. Euphytica. DOI 10.1007/s10681-015-1533-x
• Type: Journal Articles Status: Published Year Published: 2015 Citation: M. Liakat Ali, Jon Luetchens, Josiel Nascimento,Timothy M. Shaver, Greg R. Kruger, & Aaron J. Lorenz. 2015. Genetic variation in seminal and nodal root angle and their association with grain yield of maize under water-stressed field conditions. Journal of Plant and Soil. DOI 10.1007/s11104-015-2554-x
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Stalker, L. A.; Blanco-Canqui, H.; Gigax, J. A.; McGee, A. L.; Shaver, T. M.; van Donk, S. J. 2015. Corn residue stocking rate affects cattle performance but not subsequent grain yield. Journal of Animal Science. Vol. 93 No. 10, p. 4977-4983.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Christopher Proctor, Roger Elmore, Humberto Blanco, Richard B. Ferguson, Charles A. Francis, Derek Heeren, Charles A. Shapiro, Tim M. Shaver, Matt Stockton and Katja Koehler-Cole. 2015. Implementation of Cover Crops in Nebraska Corn and Soybean Cropping Systems. In: Proceedings of the 2015 ASA, CSSA, and SSSA Annual Meetings. Minneapolis, MN Nov. 15-18, 2015.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Blanco-Canqui, Humberto; Shaver, Tim M.; Lindquist, John L.; Shapiro, Charles A.; Elmore, Roger W.; Francis, Charles A.; Hergert, Gary W.2015. Cover Crops and Ecosystem Services: Insights from Studies in Temperate Soils. Agronomy Journal. Vol. 107 No. 6, p. 2449-2474.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Zach P. Stewart, Charles S. Wortmann, Ellen T. Paparozzi, Tim M. Shaver, and Vicki L. Schlegel. 2015. Effect of Foliar Micronutrients (B, Mn, Fe, Zn), Applied at Different Rates and Timings, on Maize (Zea mays L.) Grain Yield, Grain Nutrient Density, and Micronutrient Uptake, Mobility, and Partitioning. In: Proceedings of the 2015 ASA, CSSA, and SSSA Annual Meetings. Minneapolis, MN Nov. 15-18, 2015.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Tim Shaver, Richard Ferguson, Gary Hergert, Brian Krienke, Charles Shapiro, and Charles Wortmann. 2015. Grazing and Bailing Effects on Soil Compaction. In: University of Nebraska 2015 Crop Production Clinics Proceedings. Pgs. 169-170.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Charles Shapiro, Brian Krienke, Tim Shaver, Richard Ferguson, Gary Hergert, and Charles Wortmann. 2015. Nutrient Management Update. In: University of Nebraska 2015 Crop Production Clinics Proceedings. Pgs. 169-170.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Blanco-Canqui, Humberto; Aaron L. Stalker; Rick Rasby; Tim M. Shaver; Mary E. Drewnoski; Simon van Donk; & Leonard Kibet. 2016. Does Cattle Grazing and Baling of Corn Residue Increase Water Erosion? Soil Science Society of America Journal. Vol. 80 No. 1, p. 168-177.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2016 Citation: Shaver, T.M., G.R. Kruger, and D.R. Rudnick. Crop Canopy Sensor Orientation for Late Season Nitrogen Determination in Corn. 2017. Journal of Plant Nutrition. In Press.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Daran R. Rudnick, Suat Irmak, Richard Ferguson, Tim Shaver, Koffi Djaman, Glen Slater, Aaron Bereuter, Nicholas Ward, Dennis Francis, Marty Schmer, Brian Wienhold, & Simon VanDonk. 2016. Economic Return vs Crop Water Productivity of Maize of Various Nitrogen Rates Under Full Irrigation, Limited Irrigation, and Rainfed Settings in South Central Nebraska. Journal of Irrigation and Drainage Engineering. 10.1061/(ASCE)IR.1943-4774.0001023.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Van Donk, Simon J. and Tim M Shaver. 2016. Effects of nitrogen application frequency via subsurface drip irrigation on corn development and grain yield. Journal of Plant Nutrition. Volume 39, Issue 13. Pgs. 1830-1839.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Blanco-Canqui, Humberto; John Tatarko; Aaron L Stalker; Tim M Shaver; Simon van Donk: Impacts of Corn Residue Grazing and Baling on Wind Erosion Potential in a Semiarid Environment. 2016. Soil Science Society of America Journal. Vol. 80 No. 4, p. 1027-1037.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Shaver, T.M., H. Blanco, M.R. Schmer, T. Klopfenstein, and B. Wienhold. 2016. The effects of 20 years of grazing on soil physical and chemical properties. In: Proceedings of the Great Plains Soil Fertility Conference. Denver CO. March 1-2, 2016.
• Type: Other Status: Published Year Published: 2012 Citation: Stalker, A., R. Klein, B. Liu, T. Shaver, M. Stockton, S. van Donk, and S. Young. 2012. Grazing Cornstalks  a decision support tool to evaluate economics. Extension Circular, University of Nebraska-Lincoln Extension EC290.
• Type: Other Status: Published Year Published: 2012 Citation: van Donk, S., R. Klein, B. Liu, T. Shaver, A. Stalker, M. Stockton, S. Young. 2012. Baling corn residue - a decision support tool for evaluating the economics. Extension Circular, University of Nebraska-Lincoln Extension EC711.
• Type: Journal Articles Status: Published Year Published: 2011 Citation: Shaver, T., R. Khosla, and D. Westfall. 2011. More research needed on remote sensing for nitrogen management. Fluid Fertilizer Journal. Vol.19, No.3, Issue 73, Pgs.9-11.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Farmers, Ranchers, Agricultural Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Opportunities for training and professional development were provided through numberous extension activities including: -University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. -University of Nebraska-Lincoln Youth Science Field Days. -University of Nebraska-Lincoln Crop Production Clinics. -University of Nebraska-Lincoln Soils School. -Central Nebraska Public Power and Irrigation Tour. -Nebraska Independant Crop Consultants Meeting. -Nebraska Little Blue Natural Resource District Farmer Training. -Nebraska Water Ballance Alliance Soil Moisture Probe Training. -Nebraska Water Ballance Alliance Field Day. How have the results been disseminated to communities of interest?Study results have been disseminated to the communiteis of interest through; -University of Nebraska-Lincoln Extension Circulars -Four Peer Reviewed Journal Articles: -Producer Field Day Demonstrations and Presentations -Youth Science Field Day Demonstrations and Presentations -Regional, national, and international conference presentations. -Nebraska natural resource district seminars What do you plan to do during the next reporting period to accomplish the goals?Plans during the next reporting period to accomplish goals: The fifth year of the Landscape Position Study was completed this year. Data collection and data analysis and interpretation to determine how N and water managment are affected across landscapes in relation to variable rate N and water managment will continue. Manuscripts will be prepared for submission for publicaiton in scientific journals. Data analysis and interpretation will continue and manuscripts will be developed for all studies. Scientific and extension conferences, meetings and field days will be attended and results from the all studies will be disseminated to appropriate audiences. The manure application and crop canopy sensor study will be continued at the UNL water lab in Brule NE. This study will continue to study the potential for producers who use manure as a nutrient source to use canopy sensors to increase the nitrogen use efficiency of manure applications. An extension demonstration project will be continued in conjunction with Colorado State University and Oklahoma State University to show the methodology and benefits of using crop canopy sensors for N management to increase nitrogen use efficiency.

Impacts
What was accomplished under these goals? Project Impact: The Nutrient Management Project at the University of Nebraska-Lincoln West Central Research and Extension Center has highly related research and extension components that focus on increasing nutrient and water use efficiency for crop production in the semi-arid environment of west-central Nebraska. Our program also examines the effects that current and potential future agronomic management practices have on soil properties related to nutrient cycling, water infiltration, and soil water availability. These efforts are being conducted collaboratively with UNL and USDA scientists representing all aspects of agronomic production utilizing state of the art technologies. The overall impact of this project increases input use efficiency while negating potential environment degradation thereby decreasing the impact of agriculture on important natural soil and water resources. Goals and Objectives: The goals and objectives of this project are: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Accomplishments: Goal: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. Major Activities: The fifth year of the Landscape Position Study was completed at the UNL Water Laboratory at Brule. This study is being conducted in cooperation with various other UNL scientists at the West Central Research and Extension Center and in Lincoln. This work is now also supported by a CIG grant and is being replicated in Colorado and Oklahoma with the goal of educating producers on the use of crop canopy sensors. The second year of a study utilizing sensors to quantify manure N mineralization was initiated. Results: Results to date from our Landscape position study suggest that crop canopy sensor algorithms developed and used in the eastern portion of Nebraska function well in the western semi-arid portion of Nebraska. There is no need at this time to develop specific algorithms for eastern and western Nebraka. This is beneficial as it decreases possible confusion for Nebraska farmers. Algorithm development on manured systems continues with a Ph.D. student as this information does not currently exist. Key Outcomes: Information on crop canopy sensors was deciminated to farmers at several training sessions including; -University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. -University of Nebraska-Lincoln Youth Science Field Days. -University of Nebraska-Lincoln Soils School. -Nebraska Independant Crop Consultants Meeting. -Nebraska Little Blue Natural Resource District Farmer Training. -Nebraska Water Ballance Alliance Soil Moisture Probe Training. -Nebraska Water Ballance Alliance Field Day. Goal: 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. Major Activities: The fifth year of the Landscape Position Study was completed at the UNL Water Laboratory at Brule. This study is being conducted in cooperation with various other UNL scientists at the West Central Research and Extension Center and in Lincoln. This work is now also supported by a CIG grant and is being replicated in Colorado and Oklahoma with the goal of educating producers on the use of crop canopy sensors. Results: Results suggest that crop canopy sensors can determine water stress in crops. However, the practical application is limited at this time. It is believed that other sensor technologies are more practical for managing water stress such as soil moisture sensors, thermal sensors, and ET gauges. Key Outcomes: Information on crop canopy and soil moisture sensors was deciminated to farmers at several training sessions including; -University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. -University of Nebraska-Lincoln Youth Science Field Days. -University of Nebraska-Lincoln Soils School. -Nebraska Independant Crop Consultants Meeting. -Nebraska Little Blue Natural Resource District Farmer Training. -Nebraska Water Ballance Alliance Soil Moisture Probe Training. -Nebraska Water Ballance Alliance Field Day. Goal: 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. Major Activities: The sixth soil sampling was conducted on the Corn Stalk Grazing and Baling study at Brule. Additional sampling was conducted to determine soil erosion characteristics and water run off characteristics related to residue grazing and baling management practices. Results: Research findings on the effects of cattle grazing of corn stalks suggest that compaction is not adversely affected if stocking rates are kept within university recommendations. Results also suggest that baling of residues can affect soil aggregation as well as erosion and run off adversely. Key Outcomes: Publications: Stalker, L. A.; Blanco-Canqui, H.; Gigax, J. A.; McGee, A. L.; Shaver, T. M.; van Donk, S. J. 2015. Corn residue stocking rate affects cattle performance but not subsequent grain yield. Journal of Animal Science. Vol. 93 No. 10, p. 4977-4983. Proceedings Publications: Tim Shaver, Richard Ferguson, Gary Hergert, Brian Krienke, Charles Shapiro, and Charles Wortmann. 2015. Grazing and Bailing Effects on Soil Compaction. In: University of Nebraska 2015 Crop Production Clinics Proceedings. Pgs. 169-170. Two research papers related to soil compaction and soil erosion and runoff were submitted to peer reviewed journals for consideration for publication. Information realted to residue removal effects on soil properties were deseminated to several audiences including; -University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. -University of Nebraska-Lincoln Crop Production Clinics. -University of Nebraska-Lincoln Soils School -Nebraska Independant Crop Consultants Meeting. -Nebraska Little Blue Natural Resource District Farmer Training. -Nebraska Water Ballance Alliance Field Day. Goal: 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Key Outcomes: I was a co-author on a peer reviewed journal article was accepted for publication regarding this topic: ECONOMIC RETURN VS CROP WATER PRODUCTIVITY OF VARIOUS NITROGEN RATES UNDER FULL IRRIGATION, LIMITED IRRIGATION, AND RAINFED SETTINGS IN SOUTH CENTRAL NEBRASKA'

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: M. Liakat Ali, Jon Luetchens, Amritpal Singh, Timothy M. Shaver, Greg R. Kruger, and Aaron J. Lorenz. 2015. Greenhouse screening of maize genotypes for deep root mass and related root traits and their association with grain yield. Euphytica. DOI 10.1007/s10681-015-1533-x under water-deficit conditions in the field
• Type: Journal Articles Status: Published Year Published: 2015 Citation: M. Liakat Ali, Jon Luetchens, Josiel Nascimento,Timothy M. Shaver, Greg R. Kruger, & Aaron J. Lorenz. 2015. Genetic variation in seminal and nodal root angle and their association with grain yield of maize under water-stressed field conditions. Journal of Plant and Soil. DOI 10.1007/s11104-015-2554-x
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Stalker, L. A.; Blanco-Canqui, H.; Gigax, J. A.; McGee, A. L.; Shaver, T. M.; van Donk, S. J. 2015. Corn residue stocking rate affects cattle performance but not subsequent grain yield. Journal of Animal Science. Vol. 93 No. 10, p. 4977-4983.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Blanco-Canqui, Humberto; Shaver, Tim M.; Lindquist, John L.; Shapiro, Charles A.; Elmore, Roger W.; Francis, Charles A.; Hergert, Gary W.2015. Cover Crops and Ecosystem Services: Insights from Studies in Temperate Soils. Agronomy Journal. Vol. 107 No. 6, p. 2449-2474.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Zach P. Stewart, Charles S. Wortmann, Ellen T. Paparozzi, Tim M. Shaver, and Vicki L. Schlegel. 2015. Effect of Foliar Micronutrients (B, Mn, Fe, Zn), Applied at Different Rates and Timings, on Maize (Zea mays L.) Grain Yield, Grain Nutrient Density, and Micronutrient Uptake, Mobility, and Partitioning. In: Proceedings of the 2015 ASA, CSSA, and SSSA Annual Meetings. Minneapolis, MN Nov. 15-18, 2015.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Christopher Proctor, Roger Elmore, Humberto Blanco, Richard B. Ferguson, Charles A. Francis, Derek Heeren, Charles A. Shapiro, Tim M. Shaver, Matt Stockton and Katja Koehler-Cole. 2015. Implementation of Cover Crops in Nebraska Corn and Soybean Cropping Systems. In: Proceedings of the 2015 ASA, CSSA, and SSSA Annual Meetings. Minneapolis, MN Nov. 15-18, 2015.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Tim Shaver, Richard Ferguson, Gary Hergert, Brian Krienke, Charles Shapiro, and Charles Wortmann. 2015. Grazing and Bailing Effects on Soil Compaction. In: University of Nebraska 2015 Crop Production Clinics Proceedings. Pgs. 169-170.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Charles Shapiro, Brian Krienke, Tim Shaver, Richard Ferguson, Gary Hergert, and Charles Wortmann. 2015. Nutrient Management Update. In: University of Nebraska 2015 Crop Production Clinics Proceedings. Pgs. 169-170.

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Farmers, Ranchers, Agricultural Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Opportunities for training and professional development were provided through numberous extension activities including: University of Nebraska Lincoln West Central Research and Extension Center Crops and Cattle Short Course. University of Nebraska Lincoln West Central Research and Extension Center Crops and Water Field Day. University of Nebraska-Lincoln Youth Science Field Days. University of Nebraska-Lincoln Crop Production Clinics. University of Nebraska Lincoln West Central Research and Extension Center Lawn and Landscape School. University of Nebraska-Lincoln Wheat Field Day. University of Nebraska-Lincoln Soils School. University of Nebraska-Lincoln Roads Scholar Tour. Colorado State University Crop Clinic. Sterling, CO. Middle Niobrara Natural Resources District's 3rd Annual Farm and Ranch Seminar. Valentine, NE. How have the results been disseminated to communities of interest? Study results have been disseminated to the communiteis of interest through; -University of Nebraska-Lincoln Extension Circulars -Journal Articles: SSSAJ; Journal of Plant Nutrition -Producer Field Day Demonstrations and Presentations -Youth Science Field Day Demonstrations and Presentations -Regional, national, and international conference presentations. -Nebraska natural resource district seminars What do you plan to do during the next reporting period to accomplish the goals? Plans during the next reporting period to accomplish goals: The fourth year of the Landscape Position Study was completed this year. Data collection and data analysis and interpretation to determine how N and water managment are affected across landscapes in relation to variable rate N and water managment will continue. Manuscripts will be prepared for submission for publicaiton in scientific journals. Data analysis and interpretation will continue and manuscripts will be developed for all studies. Scientific and extension conferences, meetings and field days will be attended and results from the all studies will be disseminated to appropriate audiences. A new study (manure application and crop canopy sensors) will be continued at the UNL water lab in Brule NE. This study will continue to study the potential for producers who use manure as a nutrient source to use canopy sensors to increase the nitrogen use efficiency of manure applications. An extension demonstration project will be continued in conjunction with Colorado State University and Oklahoma State University to show the methodology and benefits of using crop canopy sensors for N management to increase nitrogen use efficiency.

Impacts
What was accomplished under these goals? Project Impact: Increasing nutrient use efficiency for crop production would reduce the overall amount of fertilizers used by farmers. This is of primary importance both economically and environmentally as many of the nutrients used are potential environmental contaminants if exposed to streams, rivers, or ground water. This is especially important in western Nebraska due to the Ogallala Aquifer. One way increasing nutrient use efficiency may be accomplished is through variable rate nutrient applications (applying the exact amount needed at the correct time). A great deal of work has been conducted on variable rate nutrient applications to address these issues. In conjunction with variable rate nutrient applications, it is now technologically possible to variable apply irrigation water as well. Numerous nutrients (nitrogen especially) are water soluble and will move with water in the soil. As variable rate irrigation (VRI) systems become more prevalent (they will become especially prevalent in western Nebraska due to water allocations) the relationship between applied water and nitrogen will become more complex, possibly affecting input management and recommendations. Goals and Objectives: The goals and objectives of this project are: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Accomplishments: Goals: 1) Develop a crop canopy sensor based irrigated corn N application algorithm for use in semi-arid central and western Nebraska. 2) Determine the potential for crop canopy sensors to quantify crop water stress in irrigated corn and relate these values to available soil water. Note: Goals 1 and 2 are related and being researched concurrently. Therefore they have many of the same activities, results, and outcomes. Major Activities: The fourth year of the Landscape Position Study was completed at the UNL Water Laboratory at Brule. This study is being conducted in cooperation with various other UNL scientists at the West Central Research and Extension Center and in Lincoln. This work is now also supported by a CIG grant and is being replicated in Colorado and Oklahoma with the goal of educating producers on the use of crop canopy sensors. A new study utilizing sensors to quantify manure N mineralization was initiated. Three presentations on goals 1 and 2 were given at research conferences: Schmer, M., T. Shaver, R. Ferguson, and B. Wienhold. 2014. Yield response of irrigated corn to landscape position under variable nitrogen. 2014. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014. Shaver, T.M., S. van Donk, and G.R. Kruger. 2014. Suitability of crop canopy sensors for determining irrigation differences in maize. 12th International Conference on Precision Agriculture, Sacramento, CA. July 2014. Shaver, T., R. Ferguson, S. Irmak, S. van Donk, D. Rudnik, N. Ward, M. Schmer, B. Weinhold, V. Jin, D. Francis, A. Bereuter, and L. Hendrickson. 2014. Effects of landscape position, variable rate nitrogen, and variable rate irrigation on corn yield. In: Proceedings of the 2014 Great Plains Soil Fertility Conference. Results: Results to date have shown that increasing nutrient and water use efficiency through the use of crop canopy sensors can be effective but is highly site specific. In some cases it works well, and on some fields it does not work well. More work is required. Data Collected: Data analysis is being conducted by a Ph.D. graduate student on the use of crop canopy sensors for N applications and determining water stress under variable rate irrigation practices. Key Outcomes: Understanding of the practical application of variable rate irrigation (VRI) has been gained through this ongoing research. West Central Nebraska has approximately 3.3 million irrigated acres. By gaining a better understanding of what farmers will face when adopting VRI, a substantial number of acres may benefit from our findings. Four Extension publications were created related to these topics: Shaver, T.M., R. Ferguson, G. Hergert, B. Krienke, C. Shapiro, and C. Wortmann. 2014. Nutrient Management for Agronomic Crops in Nebraska. Extension Circular, University of Nebraska-Lincoln Extension EC155. Wortmann, C.S., J.A. Jansen, M.W. Van Liew, R.B. Ferguson, G.W. Hergert, C.A. Shapiro, and T.M. Shaver. 2014. Nitrogen Loss Assessment Toll (N-LAT) for Nebraska: Background and Users Guide. NebGuide, University of Nebraska-Lincoln Extension G2249. Klein, R. N., C. Burr, M. Reiman, D.C. Mazour, T. Shaver, G. Kruger, and B. Olsen. 2014. Dryland Water Management Guide For Corn on the Great Plains. UNL-Extension and Monsanto (Joint Publication). Monsanto Water Utilization Learning Center. Gothenburg, NE. Kranz, W.L., S. Irmak, D.L. Martin, T.M. Shaver, and S.J. van Donk. 2014. Variable rate application of irrigation water with center pivots. Extension Circular, University of Nebraska-Lincoln Extension EC2000. Goal: 3) Determine the effect of central and western Nebraska crop residue management practices (specifically corn-stalk grazing and baling) on soil physical properties that are related to nutrient cycling and water infiltration. Major Activities: The fifth soil sampling was conducted on the Corn Stalk Grazing and Baling study at Brule. Initial analysis shows that there may be an impact to soil physical properties in terms of soil compaction related to baling corn stalks. However, these affects do not appear great enough to affect crop production at this time. A research presentation on this topic was given at the American Society of Agronomy Meetings: Shaver, T.M., M. Schmer, T. Klopfenstein, B. Weinhold, and H. Blanco. 2014. The effects of 20 years of grazing on Soil Physical and Chemical Properties. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014. Results: Research findings on the effects of cattle grazing of corn stalks on soil physical properties (specifically compaction) show no adverse effects on crop production. Our results suggest that grazing of corn stalks, if done properly, is not a destructive process in terms of soil quality. Key Outcomes: Nebraska has approximately 6 million acres of irrigated corn production, currently only 25% are grazed and estimates are that ranchers can reduce feed costs by 50% by grazing corn stalks. This information could encourage more farmers and ranchers to graze corn stalks, more effectively utilizing this resource and increasing economic return. A peer reviewed paper has been accepted (with revisions) on this topic: Shaver, T.M., H. Blanco, A. Stalker, and S.J. van Donk. 2014. Corn Residue Grazing and Baling: Effects on Soil Compaction, Wind Erosion Potential, and Nitrogen Cycling. Soil Science Society of America Journal. Accepted Pending Revision. Goal: 4) Investigate the economic feasibility and implications of farmer adoption of precision agriculture technologies used for the purpose of increasing nutrient and water use efficiency. Major Activities: To date little progress have been made on the economics related to farmer adoption of precision agriculture technologies as data from the other listed goals is needed to accurately accomplish this goal. Work on this topic will begin in earnest in 2015.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: van Donk, S.J. and T.M. Shaver. Effects of Nitrogen Application Frequency via Subsurface Drip Irrigation on Corn Development and Grain Yield. 2014. Journal of Plant Nutrition. In Press.
• Type: Journal Articles Status: Under Review Year Published: 2014 Citation: Shaver, T.M., H. Blanco, A. Stalker, and S.J. van Donk. 2014. Corn Residue Grazing and Baling: Effects on Soil Compaction, Wind Erosion Potential, and Nitrogen Cycling. Soil Science Society of America Journal. Accepted Pending Revision.
• Type: Other Status: Published Year Published: 2014 Citation: Shaver, T.M., R. Ferguson, G. Hergert, B. Krienke, C. Shapiro, C. Wortmann. 2014. Nutrient Management for Agronomic Crops in Nebraska. Extension Circular, University of Nebraska-Lincoln Extension EC155.
• Type: Other Status: Awaiting Publication Year Published: 2015 Citation: Kranz, W.L., B. Farmaha, P. Grassini, G.W. Hergert, T. Shaver, C.A. Shapiro, S. Irmak, D. Martin, C. Burr, A. Nygren, and G. Zoubek. 2014. Irrigation and Nitrogen Management: User Education/Certification Program. UNL EC2008. Extension Circular,University of Nebraska-Lincoln Extension EC2008. In Press.
• Type: Other Status: Published Year Published: 2014 Citation: Klein, R. N., C. Burr, M. Reiman, D.C. Mazour, T. Shaver, G. Kruger, and B. Olsen. 2014. Dryland Water Management Guide For Corn on the Great Plains. UNL-Extension and Monsanto (Joint Publication). Monsanto Water Utilization Learning Center. Gothenburg, NE.
• Type: Other Status: Published Year Published: 2014 Citation: Kranz, W.L., S. Irmak, D.L. Martin, T.M. Shaver, and S.J. van Donk. 2014. Variable rate application of irrigation water with center pivots. Extension Circular, University of Nebraska-Lincoln Extension EC2000.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T.M., M. Schmer, T. Klopfenstein, B. Weinhold, and H. Blanco. 2014. The effects of 20 years of grazing on Soil Physical and Chemical Properties. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Schmer, M., T. Shaver, R. Ferguson, and B. Wienhold. 2014. Yield response of irrigated corn to landscape position under variable nitrogen. 2014. In Proceedings: ASA-CSSA-SSSA 2014 International Meetings, Long Beach, CA. November 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T.M., S. van Donk, and G.R. Kruger. 2014. Suitability of crop canopy sensors for determining irrigation differences in maize. 12th International Conference on Precision Agriculture, Sacramento, CA. July 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Shaver, T., R. Ferguson, S. Irmak, S. van Donk, D. Rudnik, N. Ward, M. Schmer, B. Weinhold, V. Jin, D. Francis, A. Bereuter, and L. Hendrickson. 2014. Effects of landscape position, variable rate nitrogen, and variable rate irrigation on corn yield. In: Proceedings of the 2014 Great Plains Soil Fertility Conference.

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Farmers, Ranchers, Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project provided professional development opportunites by allowing the PI to attend three conferences that resulted in increased knowledge in the area of nitrogen and water managment. These conferences included: the European Conference on Precision Agriculture , Heartland Water Quality Conference (Kansas City, KS), and the American Society of Agronomy meetings (Tampa, FL). Additionally one graduate student also recieved professional development by attending the American Society of Agronomy meetings (Tampa, FL). How have the results been disseminated to communities of interest? Results from the efforts of this project have been disseminated to communities of interest at field days during the summer of 2013 at North Platte and Brule NE. Farmers, business and industry professionals, natural resource district employees, college and high school students, and crop consultants were all represented at these field days. The primary goal of the field days was to inform participants about the research projects that have been initiated to address nitrogen and water related issues pertinent to the West-Central District of Nebraska. The field days also served the purpose of educating participants about the potential for crop canopy sensors to direct nitrogen applications and detect crop water stress (potentially increasing nutrient and water use efficiency) as well as nutrient recommendation tools available to farmers to accurately estimate nutrient needs. Research findings related to nutrient and water management, precision agriculture, and soil physical properties were presented at several national and international scientific meetings in 2013. These meetings included: the European Conference on Precision Agriculture , Heartland Water Quality Conference (Kansas City, KS), and the American Society of Agronomy meetings (Tampa, FL). Topics and research related to nitrogen and water use efficiency, precision agriculture technologies generally, and crop canopy sensors specifically were presented youth science field days at North Platte, Kearney, Hastings, and LexingtonNE. These field days targeted high school sophomores and juniors with an attendance of well over500 students in total. These topics were also presented to audiences at several UNL Extension/teaching programs including: Excellence in Ag sciences day (North Platte, NE); Crop production clinics (North Platte, Kearney, NE); and the Nebraska Soils School (Grand Island, NE). Additional presentations were given to the Nebraska and South Dakota Ag Business Associations. Several hundred farmers, ranchers, business and industry professionals, natural resource district employees, college and high school students, crop consultants, and UNL Extension educators were reached by these output efforts. What do you plan to do during the next reporting period to accomplish the goals? Plans during the next reporting period to accomplish goals: Thethird year of the Landscape Position Study was completed this year which may complete the funding cycle of the study. Focus will shift from data collection to data analysis and interpretation to determine how N and water managment are affected across landscapes in relation to variable rate N and water managment. Manuscripts will be prepared for submission for publicaiton in scientific journals. Thethird year of theCorn Hybrid x N x Water study will be conducted to determine the effects of corn hybrid genetics on N and water management. Data analysis and interpretationwill continue and manuscripts will be developed. Scientific and extension conferences, meetings and field days will be attended and results fromt he aforementioned studies will be disseminated to appropriate audiences. A new study (manure application and crop canopy sensors) will be initiated at the UNL water lab in Brule NE. This study will open up the potential for producers who use manure as a nutrient source to use canopy sensors to increase the nitrogen use efficiency of manure applications. An extension demonstration project will be initiated in conjunction with Colorado State University and Oklahoma State University to show the methodology and benefits of using crop canopy sensors for N management to increase nitrogen use efficiency.

Impacts
What was accomplished under these goals? Efforts to accomplish the goals include the following: Thethird year of the Landscape Position Study was completed at 4 locations throughout the state including the UNL Water Laboratory at Brule. This study is being conducted in cooperation with John Deere, various other UNL scientists at the WCREC and in Lincoln, and with the USDA-ARS in Lincoln. An effort to also include the USDA-ARS unit in Fort Collins CO on this project was also made and they have expressed interest in collaborating. The Fort Collins ARS unit has substantial modeling capabilities that will greatly enhance our efforts. Results to date indicate that this is a very complicated issue that will require much more study. The extreme variability of the Brule site is very challenging for this kind of work. The second year of theCorn Hybrid x N x Water study wascompleted at Brule in collaboration with Greg Kruger, Aaron Lorenz, Harkamal Walia, and Richard Ferguson. A Post-Doctoral employee was brought on to manage this project and he spent the field season at the WCREC. Results to date suggest there are differences in genetic lines related to water utilization. Collaborative Efforts with the Monsanto Water Utilization Center were maintained resulting in 6 studies related to N and water management being conducted at Gothenburg and Brule. Monsanto has funded a graduate student to conduct these studies. The Imperial NE Corn x Water x N study was completed resulting in two manuscripts to date being submitted to peer-reviewed journals. The results of this study show that crop canopy sensors have the ability to differentiate irrigation levels in corn. This research was an important first step for using remote sensing technologies to help improve water use efficiency. Thethird soil sampling was conducted on the Corn Stalk Grazing and Baling study at Brule. Initial analysis shows that there may be an impact to soil physical properties in terms of soil compaction related to baling corn stalks. However, these affects do not appear great enough to affect crop production at this time. Our results suggest that grazing of corn stalks, if done properly, is not a destructive process in terms of soil quality. Additional grant funding was secured in 2013 for several new studies related to nitrogen and water use efficiency. Support funding was secured for the purchase of a high clearance sprayer/applicator for use at Brule. This equipment will greatly enhance our ability to conduct all agricultural related research, especially nitrogen management. A manuscript on the effects of crop residue on soil sorptivity was published in Geoderma. Several research presentations on the topic of N and water management were given at international and regional conferences. Numerous extension presentations were given at various meetings, conferences and field days covering the topics of this project.

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: Shaver, T.M., G.A. Peterson, L. R. Ahuja, and D.G. Westfall. 2013. Soil sorptivity enhancement with crop residue accumulation in semiarid dryland no-till agroecosystems. Geoderma. Vol 192, pp. 254-258.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: R. Ferguson, M. Schmer, T. Shaver, B. Weinhold, S. Van Donk, S. Irmak, D. Rudnik, N. Ward, V. Jin, D. Francis, A. Bereuter and L. Hendrickson. 2013. Variable rate irrigation and nitrogen fertilization of maize across landscape positions. In: Precision Agriculture '13. Wageningen Academic Publishers. Pgs. 729-736.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Ward, N., R.B. Ferguson, T.M. Shaver, S. Irmak, and D. Rudnik. 2013. Relationships between soil water status and crop canopy measurements of water and nitrogen stress. ASA, CSSA, and SSSA 2013 International Meetings.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Shaver, T.M., A. Stalker, S. van Donk, and H. Blanco. 2013. Corn Residue Grazing and Baling Effects on Soil Compaction. ASA, CSSA, and SSSA 2013 International Meetings.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2013 Citation: Shaver, T.M., R. Khosla, and D.G. Westfall. 2013. Evaluation of two crop canopy sensors for nitrogen recommendations in irrigated maize. Journal of Plant Nutrition. In Press.

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Outputs to disseminate information related to the objectives of this project have so far included: Research dissemination field days were conducted during the summer of 2012 at North Platte and Brule NE. Farmers, business and industry professionals, natural resource district employees, college and high school students, and crop consultants were all represented at these field days. The primary goal of the field days was to inform participants about the research projects that have been initiated to address nitrogen and water related issues pertinent to the West-Central District of Nebraska. The field days also served the purpose of educating participants about the potential for crop canopy sensors to direct nitrogen applications and detect crop water stress (potentially increasing nutrient and water use efficiency) as well as nutrient recommendation tools available to farmers to accurately estimate nutrient needs. Research findings related to nutrient and water management, precision agriculture, and soil physical properties were presented at several national and international scientific meetings in 2012. These meetings included: Great Plains Soil Fertility Conference (Denver, CO); International Conference on Precision Agriculture (Indianapolis, IN); and the American Society of Agronomy meetings (Cincinnati, OH). Topics and research related to nitrogen and water use efficiency, precision agriculture technologies generally, and crop canopy sensors specifically were presented youth science field days at Whitman and North Platte NE. These field days targeted high school sophomores and juniors with an attendance of over 100 students in each program. These topics were also presented to audiences at several UNL Extension/teaching programs including: UNL late season crop diagnostic clinic (Mead, NE); Nebraska agricultural technology association (Kearney, NE); Excellence in Ag sciences day (North Platte, NE); Crop production clinics (North Platte, Kearney, Gering NE, Fort Collins CO); Nebraska Roads Scholar Tour (North Platte, NE); Spatial variability in soils course (Lincoln, NE); Soil management course (Lincoln, NE); and the Nebraska Soils School (Kearney, NE). Several hundred farmers, ranchers, business and industry professionals, natural resource district employees, college and high school students, crop consultants, and UNL Extension educators were reached by these output efforts. PARTICIPANTS: Individuals: Tim Shaver, UNL Nutrient Management Specialist (PI). Partner Organizations: USDA-ARS Lincoln, NE. John Deere, Monsanto, Nebraska Corn Board, Nebraska Wheat Board, International Plant Nutrition Institute. Collaborators: Simon van Donk, UNL Irrigation Specialist; Greg Kruger, UNL Cropping Systems Specialist; Richard Ferguson, UNL Soil Fertility Specialist; Suat Irmak, UNL Irrigation Specialist; Aaron Stalker, UNL Beef Nutrition Specialist; Aaron Lorenz, UNL Asst. Professor; Harkamal Walia, UNL Asst. Professor; Robert Tigner, UNL Extension Educator; Aaron Bereuter, USDA-ARS Research Technician; Dennis Francis, USDA-ARS Soil Scientist; Virginia Jin, USDA-ARS Research Scientist; Marty Schmer, USDA-ARS Research Agronomist; Brian Wienhold, USDA-ARS Soil Scientist; Nick Ward, UNL PhD Student. Training: Graduate Studies (PhD Student); UNL WCREC Crops and Cattle Short Course (Farmers, Ranchers, Consultants, Industry Professionals, etc.). TARGET AUDIENCES: Target Audience: Farmers, Ranchers, Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Efforts: Producer Field Days, Youth Science Field Days, Short Courses, Formal Classroom Instruction, Extension and Outreach. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Results from project efforts have impacted our knowledge in several ways in 2012. A study to determine the capability of crop canopy sensors to determine water stress in corn have shown that crop canopy sensors can differentiate water applied differences in corn at later growth stages (R3 and R5) when irrigation is usually critical in the semiarid Great Plains. This study has also shown that there is no clear benefit of using sensor orientations that remove the influence of the corn tassel on sensor readings. At the R3 corn growth stage using 45 degree and 90 degree off nadir sensor orientations the crop sensor red-edge normalized difference vegetation index (ReNDVI) values showed a definite decreasing trend in readings from corn irrigated at 100% field capacity (F.C.) to corn receiving no irrigation. Significant differences were observed with the 100% F.C. irrigation having higher ReNDVI readings than the 75% F.C., 50% F.C. and no irrigation treatments. Inter-row sensor orientation also showed significant differences; however, only the 75% F.C. and 50% F.C. treatments had higher readings than the no irrigation treatment with the 100% F.C. treatment not being significantly different from any other treatment. Also, the decreasing trend of ReNDVI with decreasing irrigation is not present in the inter-row orientation. The NDVI readings for corn growth stage R3 show trends for decreasing sensor readings with decreasing irrigation. However, none of the results were significantly different. At the R5 corn growth stage both the ReNDVI and normalized difference vegetation index (NDVI) showed decreasing sensor readings with decreasing amounts of irrigation. The trends were observed across all sensor orientations within both indices. There were significant differences observed from higher to lower irrigations using the 90 degree orientation with ReNDVI and using the 45 degree and inter-row orientations with NDVI. Generally the sensor could not differentiate the 100% and 75% F.C. treatments, or the 50% F.C. and no irrigation treatments at this growth stage. These results suggest that there was little difference in corn growth between the 100% and 75% F.C. treatments, or the 50% F.C. and no irrigation treatments at the R5 growth stage. As stated above, there was no clear benefit to sensor readings by changing sensor orientation to remove the influence of the corn tassel. Results show that the 90 degree and inter-row orientations worked equally well for the determination of irrigation effects on corn growth. This could be of great benefit for practical application purposes. If the sensor can be used above the canopy inter-row, this is beneficial from a mounting standpoint. Placing the sensor within the canopy (as with the other two sensor orientations tested) could be quite challenging if readings are taken in manners other than by hand. Overall, the results of this study suggest that crop canopy sensors can distinguish differences in corn related to water application and could possibly be adapted for use for irrigation scheduling and for increasing water use efficiency.

Publications

• Shaver, T.M., S.J. van Donk, G.R. Kruger, and R. Ferguson. 2012. Potential of Crop Canopy Sensors to Detect Different Irrigation Levels in Corn. Transactions of the ASABE. In Review.
• van Donk, S.J., T.M. Shaver, J.L. Petersen, and D.R. Davidson. 2012. Effects of Crop Residue Removal on Soil Water Content and Yield Deficit-Irrigated Soybean. Transactions of the ASABE. Vol 55, no.1 pp. 149-157.

Progress 04/01/11 to 11/30/11

Outputs
OUTPUTS: Research dissemination field days were conducted during the summer of 2011 in six locations in Central and Western Nebraska including; North Platte, Arapahoe, McCook, Curtis, Imperial, and Brule NE. Farmers, business and industry professionals, natural resource district employees, college and high school students, and crop consultants were all represented at these field days. The primary goal of the field days was to inform participants about the research projects that have been initiated to address nitrogen and water related issues pertinent to the West-Central District of Nebraska. The field days also served the purpose of educating participants about the potential for crop canopy sensors to direct nitrogen applications and detect crop water stress (potentially increasing nutrient and water use efficiency) as well nutrient recommendation tools available to farmers to accurately estimate nutrient needs. The economics of precision agriculture technologies was also discussed at several of the field days. Additionally, a University of Nebraska-Lincoln Extension practicum entitled "Cropping System and Beef Production Practicum" was initiated to aid producers in management decisions regarding crop and beef production. This is a seven session (seven days) practicum with nitrogen and water use efficiency being central topics of importance. Related to this are crop residue management practices (specifically corn-stalk grazing and baling) and the effects of residue management in terms of nutrient cycling and water infiltration/runoff are discussed at length. The potential for precision agriculture technologies to aid in nutrient and water management related decisions, as well as the economics and challenges involved with adoption of such technologies, are also important topics in the practicum. Farmers, ranchers, and UNL Extension personnel were represented in the first class of the practicum. Topics and research related to nitrogen and water use efficiency, precision agriculture technologies generally, and crop canopy sensors specifically were also presented at five youth science field days at Whitman, North Platte, Kearney, Lexington, and Holdredge NE. These field days targeted high school sophomores and juniors with an attendance of over 500 students over the five field days. PARTICIPANTS: Individuals: Tim Shaver, UNL Nutrient Management Specialist (PI). Partner Organizations: USDA-ARS Lincoln, NE. John Deere. Collaborators: Simon van Donk, UNL Irrigation Specialist; Richard Ferguson, UNL Soil Fertility Specialist; Suat Irmak, UNL Irrigation Specialist; Aaron Stalker, UNL Beef Nutrition Specialist; Jim Peterson, UNL Research Technologist; Aaron Bereuter, USDA-ARS Research Technician; Dennis Francis, USDA-ARS Soil Scientist; Virginia Jin, USDA-ARS Research Scientist; Marty Schmer, USDA-ARS Research Agronomist; Brian Wienhold, USDA-ARS Soil Scientist; Nick Ward, UNL PhD Student. Training: Graduate Studies (PhD Student); UNL Cropping System and Beef Production Practicum (Farmers, Ranchers, Consultants, Industry Professionals, etc.). TARGET AUDIENCES: Target Audience: Farmers, Ranchers, Business and Industry Professionals, Natural Resource District Employees, College and High School Students, Crop Consultants, UNL Extension Educators. Efforts: Producer Field Days, Youth Science Field Days, Practicums, Formal Classroom Instruction, Extension and Outreach. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Results from the project have impacted our knowledge in two primary areas thus far; crop canopy sensor plant water stress determination and soil compaction due to residue management. For crop canopy sensors preliminary results suggest that the sensors can detect differences in plant water stress in addition to plant nitrogen stress. Therefore, there may be potential for the sensors to be used to aid in irrigation management decisions. Preliminary results also show that there is no direct relationship between sensor detected crop stress and available soil water. These results are after only 1 field season and further study is required. Additionally we have learned that crop canopy sensors can be used quite effectively after corn tasseling. Corn tassels can refract the sensor produced light thereby making the reflectance values suspect. Results of a small study have shown that by moving the sensor to an inter-row orientation after tasseling (as opposed to directly over the row prior to tasseling) the sensor can effectively determine differences in crop color and growth due to nitrogen and water stresses. This is important because if the sensors could not be used effectively after corn tasseling their use for irrigation management would be significantly diminished. These results were of great value for the producer and youth science field days as well as the cropping system and beef production practicum listed in the output section as it provided the target audience with valuable information regarding nutrient and water management. The second change in knowledge impact is related to crop residue management and soil compaction. Measuring compaction, using a soil penetrometer, preliminary results suggest that baling corn residue and cattle grazing significantly affect soil compaction after a period of only 3 years. Compaction measurements were collected to a depth of 27.5cm in 2.5cm increments. Results show that in the 0-2.5cm depth compaction was greatest in the baling and heavy grazing treatments, intermediate in the light grazing treatment, and lowest in the control (no bailing or grazing) treatment. The relationship between residue removal treatment and compaction changes as we go deeper in the soil. At the 2.5-5.0cm depth both grazing treatments and the bailing treatment are similar, but higher than the control. At the 5.0-7.5cm depth the bailing treatment has the highest compaction, heavy and light grazing are intermediate, and the control is lowest. At the 7.5-10.0cm depth the grazing treatments come back in line with the control, and the bailing treatment is significantly higher than all other treatments. This relationship continues all the way to the 27.5cm depth. These results suggest that bailing causes soil compaction to a much greater depth than grazing, and that grazing cause's surface compaction. The extent of the compaction and how this may affect water infiltration and yield is yet to be determined.

Publications

• No publications reported this period