Education

Research Description

Irrigation systems for wastewater, agricultural lands and turfgrass, irrigation water management

Honors and Awards

• Carolinas Irrigation Association (CIA) Ron Sneed Award, 2016
• NC Irrigation Award, 2013
• NC State Grange Search for Excellence Award from NC Extension, 2011

Publications

Discussion of "Cylindrical Central Baffle Flume for Flow Measurement in Open Channels" by Aniruddha D. Ghare, Ankur Kapoor, and Avinash M. Badar

Grabow, G. (2021, July 1), JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, Vol. 147. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001582

Color, Transfer, and Application Parameters of Turfgrass Colorants

Pinnix, G. D., Miller, G. L., Bowman, D. C., & Grabow, G. L. (2018), AGRONOMY JOURNAL, 110(1), 66–76. https://doi.org/10.2134/agronj2017.03.0164

Water Conservation Potential of Smart Irrigation Technologies in the Catawba-Wateree River Basin

Vick, R. L., Grabow, G. L., Miller, G. L., & Huffman, R. L. (2017), JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, 143(2). https://doi.org/10.1061/(asce)ir.1943-4774.0001130

Influence of Drawdown Period on Overflow Volume and Pollutant Treatment for Detention-Based Stormwater Control Measures in Raleigh, North Carolina

Smolek, A. P., Hunt, W. F., III, & Grabow, G. L. (2015), Journal of Sustainable Water in the Built Environment, 1(2), 05015001. https://doi.org/10.1061/JSWBAY.0000798

Residential Irrigation Water Use in the Central Piedmont of North Carolina. I: Measured Use and Water Requirements

Nautiyal, M., Grabow, G. L., Huffman, R. L., Miller, G. L., & Bowman, D. (2015), JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, 141(4). https://doi.org/10.1061/(asce)ir.1943-4774.0000819

Residential Irrigation Water Use in the Central Piedmont of North Carolina. II: Evaluation of Smart Irrigation Technologies

Nautiyal, M., Grabow, G. L., Huffman, R. L., Miller, G. L., & Bowman, D. (2015), JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, 141(4). https://doi.org/10.1061/(asce)ir.1943-4774.0000820

Corn, cotton, and peanut response to tillage and subsurface drip irrigation in north carolina

Jordan, D. L., Johnson, P. D., Grabow, G. L., & Corbett, T. (2014), Agronomy Journal, 106(3), 962–967. https://doi.org/10.2134/agronj13.0486

GROUNDWATER NITRATE CONCENTRATION REDUCTIONS IN A RIPARIAN BUFFER ENROLLED IN THE NC CONSERVATION RESERVE ENHANCEMENT PROGRAM

Wiseman, J. D., Burchell, M. R., Grabow, G. L., Osmond, D. L., & Messer, T. L. (2014), JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, 50(3), 653–664. https://doi.org/10.1111/jawr.12209

Water Application Efficiency and Adequacy of ET-Based and Soil Moisture-Based Irrigation Controllers for Turfgrass Irrigation

Grabow, G. L., Ghali, I. E., Huffman, R. L., Miller, G. L., Bowman, D., & Vasanth, A. (2013), JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, 139(2), 113–123. https://doi.org/10.1061/(asce)ir.1943-4774.0000528

Factors affecting uniformity of irrigation-type manure application systems

Liu, Z., Grabow, G. L., Huffman, R. L., Osborne, J., & Evans, R. O. (2012), Applied Engineering in Agriculture, 28(1), 43–56. https://doi.org/10.13031/2013.41285

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Grants

Development and Field Validation of New Sensor Technology for Characterizing Maize Yield Components

Syngenta Crop Protection, LLC(7/15/15 - 12/31/17)

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Development and Field Validation of New Sensor Technology for Characterizing Maize Yield Components

Sponsor: Syngenta Crop Protection, LLC

Start Date: 7/15/15

End Date: 12/31/17

Abstract

Improving plant genetics has demonstrated to be one of the greatest ways to increase agricultural production. Accurate, robust, and reliable phenotyping and quantification of crop yield components are critical for identifying yield traits, understanding their response to environmental conditions, incorporating these traits into adapted genotypes, and developing in-season management decisions. In addition, longitudinal phenotyping provides data needed to develop the next generation of crop growth models and crop management decision aids. We propose research to apply new and existing sensor technologies to plant phenotyping and to validate these technologies on a highly monitored field site. One ultimate goal is to generate a unique remote sensing-based crop phenotyping database as an initial step toward developing a “spectral library” of crop/canopy characteristics to facilitate rapid phenotyping. The specific objectives are: 1) Collect detailed plant phenotypic information on two maize genotypes grown under two different nutrient management strategies on a highly monitored, intensively managed field site; 2) Use spectral and non-spectral remote sensing to collect information on canopy reflectance, structure, and temperature throughout the growing season; 3) Develop new sensor-based phenotyping technologies based on identification of sensor measurements that can be related to genotypic yield responses; 4) Generate a unique dataset combining sensor, yield, and management information with extensive season-long monitoring of soil, meteorology, and plant growth and nutrient status; and 5) Use these data to calibrate and test an existing crop growth model and a hybrid crop growth-soil drainage-nitrogen dynamics model.

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Evaluation of Selected Consumer Lawn Tractors for Turf Mowing Characteristics

Deere & Company(10/15/13 - 10/14/14)

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Evaluation of Selected Consumer Lawn Tractors for Turf Mowing Characteristics

Sponsor: Deere & Company

Start Date: 10/15/13

End Date: 10/14/14

Abstract

Consumer Reports annually reviews Lawn Tractors for turfgrass mowing performance (and other user-criteria) before ranking them. John Deere would like a third-party to evaluate their new mower decks in comparison to their competition as identified by Consumer Reports. This evaluation should include techniques that emulate Consumer Reports methodology as well as any techniques that may be viewed is improvements, since the goal is to determine the best performing Lawn Tractor by scientifically sound and reproducible methodologies. This study will be conducted under a “Non-Disclosure Agreement”.

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Comparison of Irrigation Water Management Strategies Under Limited Water Conditions

Corn Growers Association of NC, Inc.(2/01/14 - 1/31/16)

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Comparison of Irrigation Water Management Strategies Under Limited Water Conditions

Sponsor: Corn Growers Association of NC, Inc.

Start Date: 2/01/14

End Date: 1/31/16

Abstract

Because of frequent dry periods during growing seasons, producers in the U.S. Southeastern Atlantic Coastal Plain, including North Carolina, are increasingly installing irrigation systems to provide supplemental water. However, water supplies during droughts oftentimes do not meet the full water requirement of crops and therefore, careful use of available irrigation water supplies is required to optimize yield under water limiting conditions. As field studies only produce yield results for one particular year of weather and a specific soil type, simulation modeling is an obvious choice to investigate the impact of irrigation water management strategies on corn yield for different soils and climatic conditions and to develop probabilities of relative corn yield from these strategies. The goal of this proposal is to conduct a modeling study to optimize irrigation water use and maximize corn yield. This project will identify irrigation water management strategies that can conserve limited water resources while increasing corn yield. Irrigation water management strategies will be simulated for their effect on corn yield using DRAINMOD-DSSAT, a water management model (DRAINMOD) coupled to a crop model (DSSAT). Simulations will be performed for multiple locations in North Carolina where corn production is concentrated using historic weather data and multiple soils varying in texture and drainage class. Identification of strategies that maximize yield under water limited conditions will be identified by relative yields (ratios of deficit irrigated yields to fully irrigated yields) and irrigation water use efficiency (incremental yield due to irrigation over rainfed yield to amount of irrigation water applied).

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Increasing Water Use Efficiency in High Population Corn Systems Grown Under Irrigation

Corn Growers Association of NC, Inc.(2/01/13 - 1/31/16)

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Increasing Water Use Efficiency in High Population Corn Systems Grown Under Irrigation

Sponsor: Corn Growers Association of NC, Inc.

Start Date: 2/01/13

End Date: 1/31/16

Abstract

The overall scope of this project is to improve water use efficiency in irrigated corn production systems. Specific objectives are: 1) To determine how tillage and high plant populations affect soil water content and water stress in corn grown using irrigation, 2) to determine the impact of drought tolerant hybrids on water use efficiency in irrigated production systems, and 3) to identify the best methods and equipment for sensing soil moisture levels to determine when to apply water and how much water to apply.

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Irrigation System and Water Management Training to Conserve Water and Reduce Nutrient Losses

Environmental Defense Fund(10/01/12 - 6/30/14)

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Irrigation System and Water Management Training to Conserve Water and Reduce Nutrient Losses

Sponsor: Environmental Defense Fund

Start Date: 10/01/12

End Date: 6/30/14

Abstract

Irrigation water management plays an important part in efficiently managing water resources and preventing leaching and transport of fertilizers to ground and surface waters. In order to assist farmers with irrigation water management, a training workshop will be developed and delivered. Specific training topics include irrigation systems to include emerging technologies, irrigation scheduling, and fertigation. Focus will be on systems applicable to field crops (corn, winter wheat, sorghum, soybeans, etc.) although brief coverage of row crops (vegetable) will be included. Key extension field faculty will be invited to the training to provide additional local and technical knowledge. Irrigation dealers will be contacted and invited to share recent technology related to water efficiency and fertigation. The training as proposed here could be repeated at different times and/or locations.

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Soil Moisture Management in Drip Irrigated Sweetpotatoes and its Effect on Root Yields and Quality

NC Sweet Potato Commission(3/01/12 - 2/28/13)

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Soil Moisture Management in Drip Irrigated Sweetpotatoes and its Effect on Root Yields and Quality

Sponsor: NC Sweet Potato Commission

Start Date: 3/01/12

End Date: 2/28/13

Abstract

Most sweetpotato production fields are not irrigated in North Carolina since sweetpotatoes can tolerate dry periods and typically there is an adequate amount of rainfall during the production season resulting in reasonable yields. However, the use of drip irrigation in growing a sweetpotato crop may confer some advantages ; yield, earliness, improved root shape, etc. Irrigated acreage for the entire North Carolina sweetpotato crop is less than 5% of the total production acreage. There is increasing interest in drip irrigation by growers in North Carolina. However, there are many challenges that need to be overcome before significantly more drip irrigated acreage is grown in North Carolina. Some key impediments to growing sweetpotatoes with drip irrigation are; where and when to place the drip tape in relation to the planted row of sweetpotatoes, and how to pick up the drip tape from the field. Many basic management questions exist in optimizing the growing of sweetpotatoes with drip irrigation. Some of these questions are; when should I irrigate?, how much should I irrigate?, how much water will I use?, when do I start fertigating, how much fertilizer do I apply through the irrigation system at a given time and over the season?, etc. Obviously, we cannot answer all of these questions. However, the research we propose should begin to help answer questions regarding when and how much irrigation to apply by comparing three irrigation systems, and allow us to begin to understand how the various management systems affects various yield and quality aspects of the sweetpotato crop. In addition, we also want to quantify how much irrigation water is used to produce a crop using the two drip irrigation systems. We propose to compare three growing/management systems. The first system or treatment would be the standard growing practiced by the industry in which no irrigation is applied; in other words the crop would be exposed to ambient (rainfed) growing conditions. Fertilizer would be applied two times and rates would be similar to recommended production practices for ?Covington?. A second system or treatment would be drip irrigation application which generally has a prescribed schedule to mimic current used commercial grower practices. Fertilizer in the drip would be applied beginning near layby and rates used would be comparable to those used in the standard growing practice system. At third system or treatment would be the Smart Irrigation system in which drip irrigation would only be applied when soil moisture reached a ?management allowable depletion? level or percentage yet to be determined that is between field capacity and the permanent wilting point. The percentage soil moisture used to determine when to drip irrigate will depend on soil texture in which the test is located. We would conduct this test on one of the research stations, Clinton or Kinston. In addition to relating the effects of management system to root yield and quality, we will also quantify the amount of water used in the two drip irrigation systems by installing a flow meter for each drip irrigation system. Lastly, we propose to set up some moisture monitoring equipment on commercially grown drip irrigated sweetpotatoes. This will provide a real example of a commercial grown, drip irrigated sweetpotato crop. We propose to sample the commercially drip irrigated field and obtain yield and quality measures that can then be compared with the data collected on the research station. We hope to learn what potential benefits can be gained when using each of the irrigation management systems by comparing it with standard North Carolina sweetpotato production grown without irrigation.

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Preliminary Evaluation of Using Drip Irrigation for Production of Sweetpotatoes in North Carolina

NC Sweet Potato Commission(3/01/11 - 2/29/12)

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Preliminary Evaluation of Using Drip Irrigation for Production of Sweetpotatoes in North Carolina

Sponsor: NC Sweet Potato Commission

Start Date: 3/01/11

End Date: 2/29/12

Abstract

Most sweetpotato production fields are not irrigated in North Carolina. In California, the opposite is the case as nearly all of the sweetpotato crop is irrigated, with over 90% of the state?s crop being drip irrigated. Sources from California indicate that yields were increased 10% with the use of drip irrigation rather than furrow irrigation. Louisiana growers commonly use irrigation and use either furrow or overhead irrigation. Weather conditions can vary considerably over the growing season and extremes are many times experienced in which environmental conditions are too wet or dry. It is not uncommon in North Carolina to experience periods of drought throughout the growing season. Untimely drought conditions can be experienced during planting resulting in plant stand reduction, or during the season inhibiting storage root enlargement and resulting in reduced yields. By having drip irrigation in place, a producer could supply water when needed directly where the plant needs it. Additionally, yields could potentially be increased by maintaining soil moisture at levels that are optimum during critical times of plant development. Furthermore, irrigation might potentially lead to earlier yields potentially reducing the time that the crop is at risk to environmental extremes. Water use efficiencies would be increased using drip rather than overhead irrigation, and fertilizer application could be made through the drip tube potentially reducing the number of times equipment traverses the field. With these potential advantages and others, we propose that a drip irrigation feasibility study be conducted.

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Water Use Efficiency of Soil-Water-Sensor-Controlled Irrigation with a Subsurface Drip Irrigation System Contrasted with Center Pivot Irrigation in a Corn-Wheat-Soybean Crop Rotation

NC Soybean Producers Association, Inc.(3/01/11 - 11/30/14)

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Water Use Efficiency of Soil-Water-Sensor-Controlled Irrigation with a Subsurface Drip Irrigation System Contrasted with Center Pivot Irrigation in a Corn-Wheat-Soybean Crop Rotation

Sponsor: NC Soybean Producers Association, Inc.

Start Date: 3/01/11

End Date: 11/30/14

Abstract

Recurring drought in North Carolina has resulted in a need to increase water use efficiency in irrigated agriculture. The goals of the proposed research are to evaluate how well a commercially installed SDI system performs in a corn-winter wheat- soybean crop rotation, and to compare its relative performance to a center pivot system and a dryfarmed system. The objectives of the research to accomplish this goal are to: ? Compare crop yields in the two irrigation systems (SDI and pivot) ? Compare applied water and irrigation water use efficiencies of the two irrigation systems ? Implement and evaluate sensor-controlled irrigation in an SDI system ? Compare sensor-controlled scheduling to typical scheduling in terms of applied water and crop yield in an SDI irrigation system. ? Measure soil-water distribution from SDI driplines in a sandy loam soil to infer potential alternative dripline spacings An SDI system will be installed this fall or winter in Robeson County, North Carolina, using funds received from a conservation innovation grant (CIG). The soils located in the fields proposed for research include Nahunta very fine sandy loam, Trebloc loam, Aycock very fine sandy loam, and Exum very fine sandy loam. The production system is no-till with a corn-winter wheat-soybean crop rotation. A center pivot irrigation system was recently installed on the farm and the SDI system will be installed on land immediately adjacent to the pivot-irrigated land. The SDI system will irrigate approximately 25 acres immediately adjacent to the existing center pivot irrigation system, and both SDI and center pivots fields will be planted to the same crop. Corn will be planted in spring 2011, followed by wheat planted behind corn in September and harvested in May 2012. Soybeans will be planted in June 2012 and harvested in December 2012, and corn planting would follow in spring 2013. Funds received for research proposed herein will be used to monitor and control the SDI system, monitor soil water in the SDI, pivot and unirrigated fields, and to compare all three systems (SDI, pivot, unirrigated) with respect to crop yield, irrigation water use, and water use efficiency. Two irrigation water management strategies will be compared in the SDI system. One zone will be scheduled to apply 0.20 inch of water daily, but will use feedback from soil-moisture sensors to override the scheduled irrigation if soil moisture is sufficient. The other SDI system zone will be scheduled to apply the gross long-term irrigation requirements by crop growth stage. The center pivot system will also be scheduled to apply the long-term irrigation requirement by crop growth stage and will differ in applied water from the similarly scheduled SDI zone only by the difference in irrigation system efficiency. Weekly applied water will be compared between both SDI zones (irrigation treatments) and the center pivot. Fertilizer will be injected in both the drip and pivot systems at rates according to realistic yield expectations for the particular crop irrigated and soil type. Soil-moisture sensors will be used not only to control irrigation in one SDI zone, but to monitor soil-moisture in the other SDI zone, on the pivot irrigated field, and in the unirrigated field. In the SDI field, sensors will be placed at various distances and depths from the drip line to characterize water distribution from an SDI dripline in a fine sandy loam soil.

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Heath Dairy Livestock Exclusion and Stream Restoration

US Environmental Protection Agency (EPA)(1/01/11 - 9/30/14)

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Heath Dairy Livestock Exclusion and Stream Restoration

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 1/01/11

End Date: 9/30/14

Abstract

The NC Ecosystem Enhancement Program (NC EEP) has developed a plan for the restoration of Back Creek (main tributary to Back Creek/Lucas Lake northwest of Asheboro), which it plans to implement beginning in November, 2010. The plan includes livestock exclusion and stream restoration/enhancement of a >1,000ft section of Back Creek that flows through a dairy cow pasture of Heath Dairy. The stream restoration includes priority I and II activities including construction of a new pattern and profile for the stream channel. Pre- exclusion and stream restoration monitoring including both stormwater and baseflow sampling was conducted by NCSU and DWQ personnel from June 2007 to March 2009 with direction and funding from the NC EEP; however, due to changes in the program and budget restrictions, funding similar monitoring during the post-restoration period is unlikely. Thus, the purpose of this project is to reinstall the monitoring stations and conduct water quality monitoring upstream and downstream of the same stream reaches for 2 years (March, 2011 to March 2013) following the restoration effort. These data will then be statistically compared to the pre-exclusion and restoration monitoring data that was previously collected to assess the effectiveness of the restoration effort. In addition, these data will be compared to monitoring data for a pasture where only livestock exclusion fencing (no stream restoration) was installed in an attempt to assess the additional benefits of stream channel restoration in combination with livestock exclusion.

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Catawba River Basin Residential Irrigation Water Conservation Study

Duke Energy Carolinas, LLC (Duke Power)(2/10/09 - 3/31/12)

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Catawba River Basin Residential Irrigation Water Conservation Study

Sponsor: Duke Energy Carolinas, LLC (Duke Power)

Start Date: 2/10/09

End Date: 3/31/12

Abstract

NC State University is proposing to lead a water use study on Duke Energy lakes in the Catawba River Basin. The study will establish an estimate of water withdrawals by homeowners bordering the lake through installation of water meters at 36 properties during phase I of the study. Additional information about water use practices will be obtained through a survey instrument designed by NC State. Long-term estimates of irrigation water requirements will be generated using existing long-term data from local weather stations, and weather stations will be deployed at project lakes to estimate irrigation water requirements over the course of the study. During Phase II, two groups of cooperating homeowners will receive two types of ?smart? irrigation control technologies. One type of technology is weather based and the other is soil-moisture sensor based. A third group of homeowners will receive educational material and guidance on programming their existing irrigation controller and a fourth group will receives no intervention other than water use monitoring. Soil moisture will be recorded in all homes that receive the smart technologies. Weekly and seasonal water use of all groups will be compared between all four groups. Water use of the four groups will all be compared against irrigation requirements as estimated from the weather stations deployed at the Duke Energy lakes. Study results will be used to quantify the potential reduction of water withdrawals from the use of smart irrigation technologies, and an educational campaign aimed at property owners along Duke Energy lakes. Typical water withdrawal patterns (both current patterns and patterns associated with efficient irrigation management) will be used to evaluate the potential water savings.

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