Brief Summary of Minutes of Annual Meeting

Nov. 12 (13:00 – 17:00):

Ken Shackel – 2015 Committee Chair, presiding

(Kelly Morgan – 2015 Vice Chair, only present on Nov. 13)

Pete Jacoby – 2015 Secretary, recording

Registration, Introductions

Agenda review and changes to agenda

• No changes

Business meeting

• 2016 meeting location be determined by the 2016 Committee Chair (Kelly Morgan)

1. Possible meeting locations could be Florida, Virgin Islands, or Phoenix (at end of ASA,CSSA,SSSA meeting during first week of November)

• Secretary (Johnny Ferrarezi) – elected with term beginning at 2016 meeting
• Webinar – clogging and remediation of micro-irrigation systems

1. Beta test with a small group
2. Prepare and present archival webinar
3. W3128 group should submit ideas for subject matter
4. Money needs to be spent - $13.4 k – ($10 k for webinar and $3.4 k for tour at next meeting) - Ken will check with Steve Lohring about using the residual funds for the tour at the next meeting after the webinar costs are covered

Overview of W3128 multi-state project (Brad Rein – USDA NIFA)

• Experiment Station directors approve new projects (over 200 multi-state projects currently)
• Report is usually submitted for each project by each state Experiment Station director
• Focus on objectives – listed on back of meeting agenda

Updates from NIFA (Brad Rein)

• Operating on continuing resolution (cannot obligate funds, except 1^st quarter)
• 2016 AFRI – has provision to consider priorities established by commodity boards that align with those of NIFA
• Water for Agriculture – RFA

Shortage of Water (Irrigation) Engineering Faculty positions (Brad Rein)

• Meeting between Sonny Ramaswamy and Ag. Engineering Dept. Chairs from Land Grant universities to discuss situation
• AFRI funding is phased to assist new faculty applications (considered “new” if faculty member has not received a grant from AFRI)

State Project Updates and visitor reports (Nov 12 and 13)

A number of attendees presented a state project update by PowerPoint or oral update on research and education activities being performed to advance use of subsurface micro-irrigation for better water conservation and crop production. On Thursday afternoon, Freddie Lamb (KS) summarized findings from a recent review of 150 published works on SDI. Seleh Taghvaeian (OK) discussed work on more effective irrigation scheduling using the OK MesoNet and HYDRUS 2D/3D modeling. Jim Bordovsky (TX) reviewed his work on SDI on cotton production in the southern high plains near Lubbock. Zhu Delan presented her work on use of porous ceramic emitters in China. Jiri Simunek discussed irrigation applications of HYDRUS. On Friday, state presentations continued, led off by a presentation by Freddie Lamm on corn production with SDI. Kelly Morgan (FL) briefed the attendees about impacts of HLB (greening disease) on the Florida citrus industry. Suat Irmak (NE) discussed the development and studies associated with a comprehensive field scale site to perform research on use of SDI on a variety of crops. Pete Jacoby (WA) discussed use of SDI delivered through hard PVC delivery tubes in vineyards. Claude Corcos (TORO) brought an industry perspective to the group, indicating that 5 million acres are under SDI and a number of crops respond very favorably to SDI. Problems with gopher damage and emitter clogging continue to plague some users, so both education and training are important factors in maintaining and designing systems. System design issues address on-farm efficiency and basic hydrology. Elin Roman Paoh discussed the use of low-pressure bubblers in Egypt. Clint Shock (OR) updated the group on SDI for production of steevia and issues of nutrient balance and scheduling in wheat. Johnny Ferrarezi (VI) reported on his research using the Arduino micro-controller with sensors. Paul Colaizzi discussed issues of overwatering based on certain crop coefficients and reduction of evaporation with SDI. Ken Shackel (CA) discussed use of stem water potential as a baseline by which to schedule irrigation.

Webinar Discussion

Ken Shackel led a group discussion about the educational webinar to be conducted prior to the 2016 meeting. It is envisioned to be preceded by a “dry run” to help refine the programmatic content. Comments from the group included the following considerations:

• Real life examples
• Non proprietary
• Geographical representation – different areas have different problems
• Focused central topics
• Types of plugging (internal and external)
• Filtration – both for particulates and biotic material
• Water quality issues
• Preliminary considerations prior to purchase and installation of a system, including maintenance
• Placement of injector in relation to filtration system – issues of back-flushing chemicals
• Utilize Grange network
• Develop the product, then consider the marketing

W3128 Objectives

1. Develop robust and appropriately-scaled methods of irrigation scheduling using one or more soil-, plant- or weather-based approaches.
   1. Development and Evaluation of Soil-Based Irrigation Scheduling
   2. Development and Evaluation of Weather-Based Irrigation Scheduling
   3. Development and Evaluation of Plant-Based Irrigation Scheduling
   4. Software Development and Comparison of Multiple or Combined Irrigation Scheduling Methods
2. Develop microirrigation designs and management practices that can be appropriately scaled to site-specific characteristics and end-user capabilities.
   1. Improved Management for Soil Salinity and Source Water Quality Concerns
   2. Improved Efficiency of Water and Nutrients
   3. Improved Designs and Performance of Microirrigation Systems
3. Develop technology transfer products for a diversity of stakeholders to promote adoption of microirrigation.
   1. Development and expansion of internet-based resources, decision tools and applications
   2. Development of print and multimedia content
   3. Coordination of Educational Events
   4. Advancement and Promotion of Microirrigation through Public-Private Partnerships

Milestones (2015):

Laboratory and field studies to select, develop, calibrate, adapt, and evaluate soil water sensors begin.

Software development/adaptation/modification and field studies involving weather-based irrigation scheduling begin.

Plant-based sensor development/modification and their evaluation in field studies begin.

Field studies to evaluate single, multiple, or combined irrigation scheduling techniques begins.

Modeling, field, and educational efforts to address soil salinity and poor source water quality begin.

Field studies will be initiated to determine optimal DI and SDI water and nutrient management for various crops.

Initial discussions and outlines will be developed for both publications and software being jointly developed or adapted to a new locale.

Tours, field days and educational events will be held at the local and regional level to promote microirrigation.

Outline of needs for small holder systems will be developed in cooperation with USDA-NRCS.

Conduct roundtable discussions with industry partners to identify needs and possible areas of cooperation.

Initiate a pilot joint activity with industry to gage opportunities and challenges of such activities.

1. Develop robust and appropriately-scaled methods of irrigation scheduling using one or more soil-, plant- or weather-based approaches.

(AL) Continued using replicated SDI fertigation plots (cotton) in northern Alabama with capability to manually adjust timing of nutrient injection throughout the season. Eight years of subsurface drip irrigation with corresponding cotton yield and daily weather data collection has been completed with replicated research plot study. Results currently being compiled for publication with Biosystems Engineering graduate student.

(AZ) Field data that was collected for two seasons at the University of Arizona’s Campus Agricultural Center in Tucson, AZ, was analyzed to determine heat-unit based crop evapotranspiration (ETc) for field corn. The volume balance approach was used to determine the actual crop evapotranspiration.   The reference evapotranspiration (ET0) that was used to determine the crop coefficient was taken from the Arizona Meteorological Network (AZMET). The resulting crop coefficient was plotted as a function of the heat unit i.e., growing degree days for the period the crop coefficient was developed. The result fit very well with crop coefficient developed by other researchers. In Tucson, Arizona, USA, two planting dates, May 5th and June 15^th and four sweet sorghum varieties (M81E, ST, SM and A4) were evaluated to estimate crop coefficients (kc) based on the heat unit accumulation concept (GDD). One irrigation level at 50% depletion of available water capacity prior to irrigation and its effect on juice, biomass and ethanol yields was evaluated. Results show that it was possible to develop heat unit based kc´s for two day-neutral varieties (ST and SM) and that they required 25% less water than the photo-sensitive varieties. Peak crop coefficients were determined as 1.13, 1.05, 1.16 and 1.22 for M81E, ST, SM and A4. Results also showed that Growing Degree Days accumulated to flowering were 2226 and 1759 GDD for ST and SM respectively. At a P-value of 5% there were differences in crop water use, juice yields and bagasse production among treatments. For the May planting there was a slight effect on ethanol yields but no effect for the June planting showing that regardless of the planting date and variety they are more likely to be similar.

(CA) An alternative tensiometer design was developed that eliminates temperature-induced diurnal tensiometer fluctuations and removes the limitation of depth of installation. The new tensiometer is especially suited for deep soil monitoring of soil water potential gradients as required for water and nutrient leaching in irrigated systems.   A dual-probe heat pulse sensor (DPHP) was developed for improved soil moisture measurements, and exhibited a root mean square error of 1.4 % volumetric water content. The DPHP method is largely advantageous of other available soil moisture measurements, is generally soil-independent, and is especially suitable for field soil water content monitoring because of its robust design with rigid probes. Because of its simplicity and measurements being independent of soil type, we propose the presented DPHP method as an excellent alternative to other available measurement techniques for soil water content. The plant-based technique of midday stem water potential (SWP) was used in a number of industry funded irrigation scheduling projects in commercial walnut and almond orchards. In walnuts, the start of irrigation in the spring was delayed compared to the grower practice until a threshold SWP was reached (1, 2, 3, or 4 bars below baseline). In 2014, grower practice corresponded to the 1 bar treatment, but for the rest of the treatments a substantial delay of 4 to 7 weeks (depending on the block and threshold) was possible, and allowed a water savings of 15-30%, with a 10% reduction in yield only for the highest (4 bar) threshold but no effect on nut quality. The 2 bar treatment had a minimal effect on yield and nut size, but allowed a substantial delay in the start of irrigation and may result in improved tree health in the long term. Novel plant-based measures of stress (in-situ psychrometry, dendrometry, sap flow) are being tested on walnuts in the greenhouse. In almonds, yield, applied water, and SWP are being measured for a range of irrigation amounts at each of three sites. The reduction in crop yield for a 40% difference in orchard water use (applied + soil water used), ranged from 0 to 40% depending on the site. The site with the highest yields was not the site with the highest water application, indicating that the water production function may depend on site effects. A lysimeter was planted to almonds in order to determine the level of stress required to reduce orchard transpiration.

(FL) Citrus greening or Huanglongbing (HLB) is the most fatal and epidemic citrus disease caused by Candidatus Liberibacter, and there is an urgent need for strategies to sustain production of citrus trees affected by HLB without depletion to our resources including water. Understanding the role of evapotranspiration (ET) in HLB affected trees is critical for determining if changes in water management of commercial citrus orchards are necessary. A study was initiated in March, 2013 on five-year-old sweet orange (Citrus x sinensis (L.) Osbeck) trees located in three commercial groves at Avon Park on the central Florida ridge; and near Arcadia, and Immokalee in flatwood soils in southwest Florida. Each grove had three irrigation regimes including daily, IFAS (Institute of Food and Agricultural Sciences) recommendation and intermediate irrigation schedules. All groves received approximately the same volume of water per week based on evapotranspiration. Sap flow measurements were taken three times per year on three trees per treatment with three sensors per tree. Volumetric soil water content (VWC) was measured continually using data logger EM 50 (Decagon Devices, Pullman, WA, USA) at incremental soil depths of 0-6, 6-12, and 12-18 in. Results showed significantly greater average daily sap flow, leaf area index, leaf water potentials, and soil moisture measurements for the daily irrigation treatment. Average soil volumetric water content (VWC) measured in daily schedule was estimated to be 0.08 cm³ cm^-3, 17% and 41% higher than that measured under IFAS or intermediate, respectively. A second study estimated water use and crop coefficients (Kc) as affected by ET and HLB. Two orange varieties (Hamlin and Valencia) with twelve weighing lysimeters per variety (6-HLB infected and 6-non-infected trees) were used to determine daily water use. Crop coefficients (Ks) were estimated by comparing daily water use to daily ET calculated as described by Penman-Monteith (FAO-56 Method). Results showed significant reduction in water use and Kc for infected trees when compared to non-infected ones (control). Citrus water use values under HLB diseased trees averaged almost 25 percent lower than that under healthy trees during the two year study. Therefore, crop coefficients under diseased trees were less than those of healthy Hamlin and Valencia trees, respectively. This led to higher soil water content under HLB infected trees estimated to be 81% and 84% greater than that under healthy Hamlin and Valencia trees, respectively. In addition, leaf Ca declined by 31 and 41% while Mg declined by 20 and 33% in infected Hamlin and Valencia trees, respectively. In contrast, leaf Zn in healthy trees significantly increased by 396% and 360% when compared to infected Hamlin and Valencia trees, respectively.

(KS) An irrigation scheduling field study concerning usage of crop coefficients based on thermal units was continued at the KSU Northwest Research-Extension Center at Colby, Kansas. The field data for the 2015 season has been collected and will be analyzed during the winter months.

(NE) Several research projects, including investigation of irrigation frequency response to evapotranspiration and crop coefficients of corn; planting date and planting population density impact(s) on soybean evapotranspiration, and comparison of center pivot and SDI for evaporation, transpiration, evapotranspiration and crop water productivity parameters were conducted. Sweet corn and watermelon evapotranspiration and crop coefficients research projects have been initiated and the first year of data collection has been completed.

(NM) Three soil moisture content sensors (CS616, Hydra-probe, and 5TM. Both CS616 and Hydra probe) were calibrated and use to schedule irrigation for the partial rootzone drying experiments conducted in the greenhouse for NuMex Joe Parker chile. Experiments were conducted using saline water and sensor calibration and irrigation scheduling was done using Hydra sensors. A greenhouse was instrumented with meteorology sensors and reference ET was calculated using Priestley-Taylor (PT) and Penman-Monteith (PM) equation. PT equation slightly underestimated ETr compared to the PM equation possibly due to its reliance on the solar radiation and temperature only and its neglect of the aerodynamic term. Stem water potential was also measured to check the timing of irrigation, however, being a destructive method only three measurements were made during the growing season.

(NY) A trial was established at 5 different locations across NY state to manage soil water level according to the Cornell-irrigated irrigation model to minimize water stress while other trees were left unirrigated. Less stress was observed for Cornell-irrigated trees than unirrigated trees, however, these results were mainly important for Hudson Valley, where the recorded rainfall was not enough to compensate the ET. Significantly smaller fruits were also harvested in Hudson on the non-irrigated trees. No significant differences were observed for yield and number of fruits.

(OK) A total of seven demonstration sites were developed across the state, where different types of soil moisture sensors were used to train producers on different aspects of using sensor-based information to determine irrigation timing and amount. These sites included four cotton fields under subsurface drip irrigation, center pivot sprinkler, and flood irrigation systems, as well as a pecan orchard, a vineyard, and a commercial nursery. In addition, soil moisture and canopy temperature sensors were used research projects in Oklahoma Panhandle.

(OR) An initial irrigation scheduling trial for drip-irrigated stevia was conducted during 2015 with irrigation onset criteria of 10, 20, 40, 60, and 80 kPa. Water application amounts were kept small to minimize deep water percolation. Steviol glycosides are desired as natural non-caloric sweeteners. Stevia leaf and steviol glycoside production was greatest at the wettest irrigation criteria tested. The ratio of the individual steviol glycosides harvested in the leaves varied with the irrigation criteria. Twenty eight replicated irrigation trials were conducted in 2015 to help determine the irrigations water requirements for economically viable commercial production of native wildflower seed. By burying drip tapes at 12-inch depth and avoiding wetting the soil surface, we hoped to assure flowering and seed set without undue encouragement of weeds or opportunistic diseases. Each species received 0, 100, and 200 mm of irrigation water, and seed yields were measured. Species varied substantially in their needs for supplemental irrigation water, from 0 to 200 mm/yr. In 2014 and 2015 an IRROmesh™ system that used a SensMitWeb™ smartmesh radio platform was tested. The system read soil temperature and soil water tension using three Watermark™ soil moisture sensors in each of twelve fields planted to eight different crops. Real time soil data and graphs of soil water tension trends were easily accessible by smart phone. These preliminary trials using the sensor web showed that this technology holds potential for saving time, increasing accuracy of irrigation scheduling, and assuring yield.

(TX, A&M) A two-year project, “Higher Integration Networking, Texas High Plains Evapotranspiration Network,” sponsored by the Texas Water Development Board via Panhandle Regional Planning Commission was completed. This work supported a graduate student and provided public access to adapted and user-friendly packaged ET-based crop water use information and related agricultural meteorological data. End users of the information included agricultural irrigators; agricultural, environmental and other research programs; water resources managers/agencies; crop insurance companies and agencies; municipalities, turf managers, homeowners; environmental consultants and researchers; and educators. The “Extension Portal” supported through this project served as a public gateway to information available from the Texas High Plains Evapotranspiration (TXHPET) Network. Internet access to crop water use estimates, an online irrigation scheduling tool, information and educational resources were provided through this gateway. While the tools and resource materials were broadly applicable to a wide range of audiences and conditions, the crop water use data are regionally focused in the Texas High Plains (Panhandle and South Plains) where the majority of irrigation water in the state is used, as well as portions of the Rolling Plains and West Texas. The products of this effort support Regional Water Planning agricultural water conservation strategies. The project leveraged the Texas High Plains ET Network resources by 1) providing public access to agriculturally appropriate weather data and crop water use estimates; and 2) promoting proficient use of the data through educational programs. The Texas High Plains ET Network Water Management Website (Extension Portal) provided convenient access to timely, pertinent, summarized and interpreted weather data and crop water use estimates to support improved irrigation water management. Estimated potential water conservation resulting from this project are in the range of 0.5 -2.0 ac-inches/irrigated acre, depending upon level of adoption and well capacity and crops produced, with higher potential savings in areas with greater irrigation capacity such as in the Panhandle and Northern Texas High Plains.

(TX, USDA) Two TDR-type soil water sensors (CS-655 and Acclima TDR-315) were compared and TDR-315 sensors were more sensitive to soil water fluxes as compared with Campbell Scientific CS-655 soil water sensors when deployed in plots of irrigated sorghum. A wireless distributed network of soil water sensors (CS CR206X dataloggers, CS-655 and TDR-315 soil water sensors) were integrated with a plant sensing (infrared thermometry) and weather-based system for irrigation scheduling of grain sorghum. Acclima TDR-315 sensors indicated trends of soil water depletion, while CWSI calculations indicated no water stress during extended periods of cloud cover. Soil water measurements with the neutron probe also indicated significant soil water depletion in the root zone during this same period.

Commercial wireless infrared thermometers were deployed over corn to test reliability of wireless transmission over a 230 m range. Data was consistently captured from 90% of the wireless IRTs throughout the irrigation season. Percent packet reception was approximately 98% per sensor. Data was captured using a proprietary Windows-based graphical user interface. A plant feedback method using canopy temperature sensing and a CWSI threshold can be used for irrigation scheduling of cotton and provide lint yields similar to manual irrigation scheduling using a neutron moisture meter and replenishing soil water depletion to field capacity in a semi-arid area.

(VI) An automated system powered by solar energy was developed to monitor soil volumetric water content (VWC) and to control irrigation. The system was tested in the laboratory and at two independent experimental locations cultivated with kale (Brassica oleracea var. sabellica) and sweet pepper (Capsicum annuum) ‘Cubanelle’. A low-cost and open-source microcontroller (Mega; Arduino, Ivrea, Italy) with a logging shield (model 2.0; Adafruit, New York, NY) connected to twelve capacitance soil moisture sensors (10HS; Decagon Devices, Pullman, WA) was used. The system was powered by a 15-W solar panel connected to a 12/24VDC charge controller and two 12VDC 7.2 Ah batteries. The technology is accessible and relatively inexpensive (microcontroller and accessories cost $150 and each sensor cost $115). This system effectively monitored VWC over time. The irrigation controller required little maintenance over the course of both trials. The microcontroller can be used with latching 6 to 18-V direct current (DC) solenoid valves to control irrigation based on real-time readings. The low cost of this irrigation controller makes it useful in many applications, including both research and commercial production.

(WA) Subsurface irrigation research trials were conducted in the Yakima Valley vineyards to evaluate opportunities to conserve water, energy and pesticide use while producing superior quality grapes. At early veraison, the lowest rate of irrigation delivered subsurface exhibited more stress than the full irrigation rate delivered by surface drip, regardless of whether applied as pulse or constant rates. Cluster weights at mid-veraison were lower for all subsurface delivery (SSD) treatments applied at reduced amounts of water using pulsed application than were clusters sampled from the surface drip (SD) full commercial rate treatment. By contrast, cluster weights from SSD treatments applied at constant application were similar between SD and SDD treatments, regardless of water amount or depth of water delivery. Clusters from SSD treatments applied in pulses of water had lower numbers of berries per cluster than clusters from the SD treatment, but were more similar in number in the SDD treatments with 30 and 60 percent of water applied. By contrast, all SSD treatments were found to have greater numbers of berries per cluster than SD, regardless of amount of water applied or depth of water delivery. Individual berry weights were generally lower for the SDD treatments whether applied under pulse or constant delivery. At harvest, total fruit production was weighed from each vine. While production was greater from vines receiving commercial rates of irrigation, production from the subsurface treatments was possible under rates as low as 15 % of the commercial rate. A subsurface delivery system was installed within a 12-year old block of Concord grapes located on the Roza Unit of the WSU Prosser-Irrigated Agriculture Research and Extension Center near Prosser, WA during 2014 and date collection began during the 2015 growing season – one of the hottest and driest periods on record. Standard surface drip irrigation is compared to sub-surface drip irrigation delivered at 1-, 2-, 3- and 4-feet below the soil surface. The experimental design employs a split-plot sub-treatment with 3 replications to compare differences in plant response to full-rate irrigation (8 gallons per plant) and half-rate irrigation (4 gallons per plant) per irrigation date, as scheduled by estimated E/T rates and measured stem xylem pressure potential. Data collection in 2015 was terminated when water delivery was interrupted by the irrigation district as a result of water shortage and the fact that the site was located on a junior water right. The experiment will be repeated during the 2016 growing season.

2. Develop microirrigation designs and management practices that can be appropriately scaled to site-specific characteristics and end-user capabilities.

(AL) Developed 2 funded proposals on the use of UAV’s for real-time assessment and management of soil moisture.

(AZ) A field study to understand the effect of salinity on corn yield and development under subsurface drip irrigated field was conducted at the University of Arizona’s Campus Agricultural Center, Tucson, Arizona. Data on salinity and plant factors such as plant height, plant dry mass, root dry mass, tasseling, and silking, was collected and analyzed, and a salinity response function for field corn under arid conditions was developed. The result showed that corn yield, shoot growth, plant height and root development decreased with increased salt concentration. Silking and tasseling were also delayed at higher salt concentrations. The statistics showed significant difference between the four treatments during different growth stages. Although the highest concentration of salts was accumulated in the shallow layer, salinity greatly affected distribution of corn roots in the soil and this influenced the uptake of water and nutrients. During the vegetative stage of the plant, roots grew rapidly. After this stage root growth generally increased at a slower rate than shoot growth and after the reproductive stage root dry mass declined, which has been associated with the translocation of N in the roots to the developing ear.

The corresponding response function of yield to salinity was Y = 9.276 – 0.51(ECe – 1.32) for ECe > 1.32, and Y = 9.276 for EC< or = 1.32.

(CA) Subsurface monitoring capabilities for soil moisture, soil nitrate, salinity, and leaching of water and nitrate across various micro-irrigated agricultural fields, with most in tree crops (almond, pistachio, citrus, walnut) were installed. The soil water balance (WB) and Darcy law (DL) methods to estimate leaching were applied to assess field-scale leaching rates and their variations for an almond orchard, comparing drip and fanjet micro-irrigation systems. Evapotranspiration rates and unsaturated hydraulic conductivity values are the main sources of uncertainties for the WB and DL method, respectively. The Darcy law approach was found to be a more informative approach. It is suggested that in-situ measurements of soil water dynamics are coupled with numerical simulation modeling to obtain improved field-scale estimates of the soil hydraulic properties, using the inverse modeling approach.

(CO) In 2015, a study was conducted to study water use and salt distribution patterns in the soil profile for muskmelon grown with drip irrigation. The electrical conductivity (EC) of the ground water source was 2.8 ds.m^-1. The timing and amounts of irrigations were based on data collected from a nearby weather station. Seasonal changes in soil moisture and salinity distribution were monitored via data loggers/soil probes and a neutron moisture meter. During the growing season, a total of 9.8 acre-inches of water was applied through the drip system. An additional 1.9 acre-inches was added via precipitation. Muskmelons grown with a saline water source had comparable yields and qualities to those grown with higher quality water. Post-season soil samples were collected and salt distribution patterns in the soil profile were also assessed. The overall water use efficiency and salt distribution patterns will be determined and reported in a subsequent report.

(KS) Two field studies were initiated at NWREC to evaluate in-season fertigation with macronutrients (N and P) and microelements (primarily Zinc) for field corn production. A field study examining precision mobile drip irrigation (PMDI) where driplines are attached to a moving center pivot platform was initiated at the KSU Southwest Research-Extension Center at Garden City, Kansas. A preliminary exploratory study was conducted at NWREC to evaluate the potential for narrow row spacing of corn when grown with subsurface drip irrigation (SDI). This latter study is laying groundwork for future collaboration with Chinese Agricultural University, Beijing China. The field data for the 2015 season for all these studies has been collected and will be analyzed during the winter months. A review of subsurface drip irrigation for 4 crops (tomato, cotton, corn and onion) was presented at an international symposium in November 2015 and has been accepted for publication in a refereed journal in 2016. A small international conference was coordinated with Chinese Agricultural University and a presentation on usage of on SDI under varying constraints was presented.

(OK) A research project was initiated in 2014 at the OSU Panhandle Research and Extension Center near Goodwell, OK on “Developing Management Strategies for Subsurface Drip Irrigation in the Oklahoma Panhandle.” The objective of this project was to evaluate how crop row placement will influence corn and grain sorghum yield response at irrigation regimes of 50, 75, and 100% of full irrigation. This project continued in 2015 growing season and will be repeated in 2016 as well.

(OR) Various N, P, and K applications strategies have been compared from 2013 - 2015 in replicated yield trials based on information collected by soil analysis, plant tissue analysis, and soil solution sampling. Soil solution sampling seems to provide the fewest positive feedback signals for fertilization, yet results in production without yield reductions. Work in 2014 and 2015 has explored rates and timings of applying Outlook herbicide through drip irrigation for yellow nutsedge control. This method of application shows promise for yellow nutsedge control but is not currently labeled. Tests in 2014 and 2015 have examined options to manage soil borne diseases via the application of fungicides through the drip irrigation system. These application methods are not yet labeled, so they are not being promoted. . In 2013- 2015 furrow irrigation using canal water with moderate or high levels of E. coli contamination and drip irrigation using canal water and well water free of E. coli were tested. Water was sampled hourly for E. coli and the lateral movement of E. coli in the soil solution was measured at the end of irrigations. Onions were sampled for E. coli contamination. Under furrow irrigation, the soil filtered out most of the E. coli between the edge of the water and the soil immediately adjacent to the onion bulbs. E. coli movement under drip irrigation was mostly confined to near the drip tape, with relatively little reaching the proximity of the onion bulbs. Chlorine dioxide at 1 and 3 ppm through drip irrigation was tested to reduce generic E. coli in water delivered to commercial onion fields in 2014 and 2015. Chlorine dioxide substantially reduced E. coli counts at all sampled locations and concentrations.

(PR) A citrus orchard (lemon cv. ‘Meyer’) was planted in May 2014 in a soil classified as Vertisol including factoral treatments of bed type (plastic mulch vs. bare beds [conventional]) and fertility (fertigation vs foliar spray vs combined). To improve comparison statistical strength two checks were established (first, granular fertilizer recommendations and second is the absolute control (no fertilizer and drip irrigation applications). Variables being measured are: canopy volume, trunk diameter, and nutrient content in the foliar tissue, soil moisture, and water applied. Also, trees were sampled for HLB and vector population. One year after planting HLB samplings indicate that trees submitted to five of the eight treatments were positive for HLB. All other variables still under collection and need further analysis. An experiment was performed to correlate soil moisture reading (soil water tension) with leaf water potential (pressure chamber) in fourteen-year old avocado trees. A significant correlation of r = 0.52 was obtained between soil water tensions and leaf water potential. Soil water tensions values greater than 70 kPa were correlated with leaf water potential values less than 900 kPa, indicating that trees were not necessarily in water stress. The analysis also showed that avocado trees submitted to low soil water tensions significantly produced lower yields. Published data from the same orchard indicate that avocado trees submitted to soil water tension of 40 to 45 KPa significantly increased trees growth and productivity. A trial was established to determine the effect of various management systems on tanier (Xanthosoma spp.) production in the south coast of Puerto Rico. Three factors were evaluated; drip irrigation system vs subsurface drip irrigation (SDI), plant densities (7,050 vs. 9,401 plants per acre); and two varieties (Estela and Nazareno ). Among the collected data is main corm weight, percentage of damage caused by dry root rot syndrome, commercial corm number and weight. Another malanga Lila (Colocasia esculenta) experiment was established proving subsurface drip irrigation management systems to assess two planting densities (10,560 and 14,100 plants per acre). It is planned to eliminate the use of beds for malanga lila production in the south coast of Puerto Rico. In this new system, plastic mulch and drip irrigation lines are installed right after land preparation. A project was established to validate /calibrate remotely sensed solar radiation, which forms the basis of ET calculations, and to automate the entire system via a public website for PR, USVI, Hispaniola, Jamaica and Cuba (http://pragwater.com).

(TX) An SDI system was installed on a 1-ha area to optimize management for cotton germination, with the field experiment beginning in 2013 and continuing for the third year in 2015. The factors considered are SDI lateral/row position and planting date. 2013 results showed highest yield in early planted treatments, and 2014 results showed relatively small differences in yield due to planting date or row/lateral arrangement due to higher than average season rain. 2015 harvest results were non-conclusive due to a severe hail event on August 28. This experiment will ultimately provide economic comparisons of water value (crop yield) relative to initial irrigation system cost and management.

3. Develop technology transfer products for a diversity of stakeholders to promote adoption of microirrigation.

(AZ) A computer program that was developed for designing low-head bubbler irrigation system was rewritten in HTML format to be available on the World Wide Web.

(CO) In 2015, the website, www.coloradoproduce.org, was further developed and promoted as a delivery mechanism for research-based information to Colorado specialty crop growers.

(KS) Presentations have been made at a regional irrigation meeting and the SWREC Field Day for irrigators and nationally for scientists and engineers at the technical conference of the Irrigation Association.

(NY) A web-based apple transpiration model, which allows NY State apple growers to estimate irrigation requirements for NY apple orchards of various ages was developed. The interface links the model with three data input sources: (1) Grower supplied orchard-specific parameters, including tree density, orchard age and green tip date; (2) Hourly meteorological data for the previous seven days accessed from the Applied Climate Information System (ACIS). Temperature, humidity, wind speed and solar radiation are the necessary variables that are used and are supplied from either grower-operated weather stations or, in some cases, existing federally supported weather networks. Data from both sources are accessible via ACIS. (3) Forecast weather data for the location of the orchard are extracted from the National Digital Forecast Database (NDFD). The NDFD is a gridded product created by the National Weather Service that provides forecast information for up to seven days into the future on a 5 km x 5 km grid. Solar radiation forecasts are not provided directly by NDFD, but are estimated based on forecast sky cover data from NDFD using a solar radiation model developed by the Northeast Regional Climate Center.

(OK) Information on science-based irrigation scheduling was presented at five national conferences, four regional meetings and in-service trainings, and five field days and crop tours. The 2nd Oklahoma Irrigation Conference was held in August, with invited irrigation specialists from Oklahoma, Kansas, and Texas to train Oklahoma producers on improving irrigation management. Three presentations were on the specific topic of implementing ET-based and sensor-based irrigation scheduling. Eighty eight people attended this one-day conference.

(TX) A team of scientists from Texas A&M AgriLife Research and Extension and a group of computer programmers from the Texas A&M Center for Applied Technology (TCAT) has developed prototype software and recently conducted the first software review by external users for a web-based cotton irrigation management software called DIEM - dashboard for irrigation efficiency management. Members of the team have also conducted additional field scale evaluations on producer's fields to validate the original research findings. The High Plains Irrigation Conference in Amarillo, Texas in January 2015 addressed topics of interest to agricultural producers, irrigation professionals, landowners and federal and state agency personnel participated in this one-day event that offered CEUs for Irrigation Association Certified Irrigation Professionals (Certified Irrigation Designers and Certified Agricultural Irrigation Specialists) and Agronomy Society Certified Crop Advisers. Of the survey respondents, 90% indicated increased understanding of regional and state water issues, planning and programs; 69% indicated increased understanding of risk management considerations and tools; 72% indicated increased understanding of crop-specific water management considerations; 83% indicated increased understanding of information resources, research programs and expertise available; 64% indicated increased understanding of efficient irrigation strategies and technologies; and 61% indicated increased understanding of irrigation products and services available. All (100%) of respondents indicated that the information provided in the program would be helpful in their irrigation decisions. Several indicated specific technologies and/or practices they would implement as a result of what they learned in the program. Extensive local radio and television media coverage promoted highlights of the event throughout the region. One local radio station broadcast the entire event live and re-broadcast portions of the event at later dates.

(VI) Two independent systems were developed using soil moisture and EC sensors to control irrigation and fertigation in geranium (Pelargonium ×hortorum Bailey) ‘Maverick Violet’ grown in 6-inch pots with peat:perlite substrate. Pore water electrical conductivity (EC), temperature, and volumetric water content (VWC) data were collected, added to a database, and made available online. A web application using twitter/BootStrap was written to query the databases and provided graphs online. The system did not control irrigation and fertigation properly. The connection with the database was unstable due to the authentication protocol used by the network and the communication between sensors and microcontrollers was problematic, resulting in random loss of data and storage of unrealistic values. As a result, valves opened at the wrong times, not allowing a precise control. More studies are needed before these microcontrollers can be recommended for agricultural applications.

Aguilar, J., D. H. Rogers, I. Kisekka, and F. R. Lamm. 2015. SDI applications in Kansas and the US. In: Proc. 27th annual Central Plains Irrigation Conference, Feb. 17-18, 2015, Colby, Kansas. Available from CPIA, 760 N. Thompson, Colby, Kansas. pp. 71-82.

Agnello, A.M., Cox, K.D., Dominguez, L., Francescatto, P., Lordan, J., and Robinson, T.L., 2015a. An insect, disease and weed management program for New York organic apples. New York Fruit Quarterly 23.

Agnello, A.M., Landers, A., Rosenberger, D.A., Robinson, T.L., Carroll, J.E., Cheng, L., Curtis, P.D., Breth, D.I., and Hoying, S., 2015b. Pest management guidelines for commercial tree-fruit production 2015, p. 252. Cornell University, Ithaca, NY, USA.

Bartolo, M.E., K. Tanabe, J. Davidson, and L. Simmons. 2015. Arkansas Valley Research Center Reports, CSU Ag. Expt. Station Technical Report TR15-11.

Bhattarai, N., Quackenbush L.J., Dougherty, M., Marzen L.J. 2014. A simple Landsat-MODIS fusion approach to monitor seasonal evapotranspiration at 30 m spatial resolution. International Journal of Remote Sensing 36: 115-143. (doi: 10.1080/01431161.2014.990645).

Dobbs, N.A., K.W. Migliaccio, Y.C. Li, M.D. Dukes and K.T. Morgan. 2014. Evaluating irrigation applied and nitrogen leached using different smart irrigation technologies on bahiagrass (Paspalum notatum). Irrigation Science 32:193-203.

Dominguez, L.I. and Robinson, T.L., 2015. Strategies to improve early growth and yield of Tall Spindle apple plantings. New York Fruit Quarterly 23:5-10.

Fazio, G., Cheng, L., Grusak, M.A., and Robinson, T.L., 2015. Apple rootstocks influence mineral nutrient concentration of leaves and fruit. New York Fruit Quarterly 23:11-15.

Felix, J., C.C. Shock, J. Ishida, E.B.G. Feibert, L.D. Saunders. 2015. Irrigation criteria and sweetpotato cultivar performance in the Treasure Valley of Eastern Oregon. HortScience 50(7):1011-1017.

Gowda, Prasanna H., Terry A. Howell, José L. Chávez, George Paul, Jerry E. Moorhead, Daniel Holman, Thomas H. Marek, Dana O. Porter, Gary H. Marek, Paul D. Colaizzi, Steve R. Evett, and David K. Brauer. 2015. A Decade of Remote Sensing and Evapotranspiration Research at USDA-ARS Conservation and Production Research Laboratory. ASABE Paper Number 2143458. ASABE / IA Irrigation Symposium, “Emerging Technologies for Sustainable Irrigation”, Long Beach, California, November 10 – 12, 2015.

Harmsen, E. 2015. Irrigation Scheduling Methods Applicable to the Southern Coast of Puerto Rico, Nov 10, 2015, Irrigation Scheduling Workshop, Salinas, Puerto Rico, Nov 10, 2015.

Harmsen, E. 2015. Irrigation Requirements in a Changing Climate YouTube Video.

Harmsen, E.W., P. Tosado and J. Mecikalski, 2014. Calibration of Selected Pyranometers and Satellite Derived Solar Radiation in Puerto Rico. Int. J. Renewable Energy Technology, 5(1):43-54.

Irmak, S., J.E. Specht, L.O. Odhiambo, J.M. Rees, and K.G. Cassman 2015. Soybean yield, water productivity, evapotranspiration and soil-water extraction response to subsurface drip irrigation. Transactions of the ASABE 57(3):729-748. DOI 10.13031/trans.57.10085.

Kadyampakeni, D.M., and K.T. Morgan. 2014. Nutrient management options for Florida citrus: a review of N,P, and K application and analytical methods. J. Plant Nutrition http://dx.doi.org/10.1080/01904167.2014.934470

Kadyampakeni, D.M., K.T. Morgan, A.W. Schumann, P. Nkedi-Kizza. 2014. Effect of irrigation pattern and timing on root density of young citrus trees infected with Huanglongbing disease. HortTechnology 24(2):209-221.

Kadyampakeni, D.M., K.T. Morgan, A.W. Schumann, P. Nkedi-Kizza. 2014. Effect of irrigation pattern and timing on root density of young citrus trees infected with Huanglongbing disease. HortTechnology 24(2):209-221.

Kadyampakeni, D.M., K.T. Morgan, A.W. Schumann, P. Nkedi-Kizza, and T.A. Obreza. 2014. Water use in drip and microsprinkler irrigated citrus trees as a function of tree size, soil characteristics and Huanglongbing infection. Soil Sci. Soc. Am. J. DOI:10.2136/sssj2014.02.005.

2015. Kandelous, B.A. Moradi and J.W. Hopmans. 2015. An alternative tensiometer design for deep vadose zone monitoring. Soil Sci. Soc. Amer. J.   79:1293-1296. DOI:10.2136/sssaj2015.03.0121

Kamai, T., G.J. Kluitenberg, and J.W. Hopmans. 2015. A Dual-Probe Heat-Pulse Sensor with Rigid Probes for Improved Soil Water Content Measurements. Soil Sci. Soc. Amer. J. doi:10.1029/2015.

Lakso, A.N. and Robinson, T.L., 2015. Decision support for apple thinning based on carbon balance modeling. Acta Hort. 1068:235-242.

Lamm, F. R. and D. H. Rogers. 2014. SDI for corn production -A brief review of 25 years of KSU research. In: Proc. 2014 Irrigation Association Technical Conference, Nov. 19-20, Phoenix, AZ. CD-Rom. 12 pp.

Lamm, F. R., D. H. Rogers, I. Kisekka, and J.P. Aguilar. 2014. Successful SDI - Addressing the essential issues. In: Proc. 2014 Irrigation Association Technical Conference, Nov. 19-20, Phoenix, AZ. CD-Rom. 15 pp.

Lamm, F. R. and D. H. Rogers. 2014. SDI for corn production -A brief review of 25 years of KSU research. In: Proc. 4th Reunion Internacional de Riego – Uso eficiente del agua para riego. October 15-16, Manfredi, Cordoba Argentina. pp. 86-97.

Lamm, F. R. and D. H. Rogers. 2015. Frequently and not-so-frequently asked questions about subsurface drip irrigation. In: Proc. 27th annual Central Plains Irrigation Conference, Feb. 17-18, 2015, Colby, Kansas. Available from CPIA, 760 N. Thompson, Colby, Kansas. pp. 96-107.

Lamm, F. R., D. M. O’Brien, and D. H. Rogers. 2015. Using the K-State center pivot sprinkler and SDI economic comparison spreadsheet – 2015. In: Proc. 27th annual Central Plains Irrigation Conference, Feb. 17-18, 2015, Colby, Kansas. Available from CPIA, 760 N. Thompson, Colby, Kansas. pp. 108-116.

Marek, Thomas and Dana Porter. 2015. Extension Portal for Higher Integration Networking for Coordination of Training, Information and Research. Final report for Texas Water Development Board Contract Number 1213581481. Texas A&M AgriLife Research and Texas A&M AgriLife Extension Service. Texas A&M University System, College Station, Texas.

Martínez-Cruz T. E., Slack D. C., Ogden K. L., and Ottman M. (2014) THE WATER USE OF SWEET SORGHUM AND DEVELOPMENT OF CROP COEFFICIENTS, Irrig. and Drain., doi:10.1002/ird.1882.

Miranda Sazo, M. and Robinson, T.L., 2015. Measuring and extending the benefits of orchard mechanization in high density orchards in Western NY. New York Fruit Quarterly 23:25-29.

Morgan, K.T., S. Barkataky, D. Kadyampekeni, R. Ebel, and F. Roka. 2014. Effects of short-term drought stress and mechanical harvesting on sweet orange tree health, water uptake, and yield. HortScience 49(6):835-842.

Moorhead, Jerry, Prasanna Gowda, Mike Hobbins, Gabriel Senay, George Paul, Thomas Marek, and Dana Porter, 2015. Accuracy Assessment of NOAA Gridded Daily Reference Evapotranspiration for the Texas High Plains. Journal of the American Water Resources Association (JAWRA) 51(5): 1262-1271. DOI: 10.1111/1752-1688.12303.

Moser, Kendra, Paul Baumann, Guy Fipps, Clark Neely, Dana Porter and M.O. Way. 2015. Texas Best Management Practices Guide. Texas Soybean Board.

Nouiri, I. , M. Yitayew, J. Maßmann, J. Tarhouni. 2015. Multi-objective Optimization Tool for Integrated Groundwater Management. Journal of Water Resources Mangement, Volume 29, Issue 14, pp5353-5375

O’Shaughnessy, S.A., Evett, S.R., Andrade A., Workneh, F., Price, J.A. and Rush, C.M. Site-Specific Variable Rate Irrigation as a Means to Enhance Water Use Efficiency. In Proceedings, 2015 ASABE/IA Irrigation Symposium. Nov 10-12, 2015. Long Beach, Calif. (doi: 10.13031/irrig.2015214448).

O'Shaughnessy, S.A., Evett, S.R., and Colaizzi, P.D. Dynamic Prescription Maps for Site-specific Variable Rate Irrigation of Cotton. Agric. Water Manage. 159: 123-138.

Odhiambo, L., and S. Irmak. 2015. Relative evaporative losses and water balance in subsurface drip- and center pivot-irrigated soybean fields. J. Irrigation and Drainage Engineering, ASCE 141(11):1-17. 04015020.

Porter, Dana. 2015. Advances in Managing Limited Irrigation Water. Invited presentation in Efficient Resource Utilization for Improving Crop Productivity and Environmental Stewardship Symposium. ASA-CSSA-SSSA Annual Meeting, Minneapolis, MN. November 16, 2015.

Porter, Dana, Danny Rogers, David Brauer, Thomas Marek, Prasanna Gowda, Freddie Lamm, James Bordovsky, Bridget Guerrero, and Paul Colaizzi. 2015. Promoting OAP Research through Technology

Transfer. 2015 Annual Meeting of the USDA-ARS Ogallala Aquifer Program.

Porter, Dana, Prasanna Gowda, Thomas Marek, and Jerry Moorhead. 2015. Considerations in Recommending Alternatives to Agriculturally-Based Weather Station Networks for Irrigation Scheduling. (Abstract). 2015 World Environmental and Water Resources Congress. American Society of Civil Engineers Environmental and Water Resources Institute, Austin, TX, May 17-21, 2015.

Porter, Dana O., Danny Rogers, David Brauer, Thomas H. Marek, Prasanna H. Gowda, Freddie Lamm, James Bordovsky, Terry A. Howell, Sr. 2015. Promoting Efficient Water Management through Effective Outreach Education in the High Plains and Beyond: Role of the Ogallala Aquifer Program. ASABE Paper Number 2143456. ASABE / IA Irrigation Symposium, “Emerging Technologies for Sustainable Irrigation”, Long Beach, California, November 10 – 12, 2015.

Prado, J. V., E. Román-Paoli, R. Tirado-Corbalá^. 2015. Estudio del comportamiento hídrico en aguacate (Persea americana cv. “Simmond”) mediante la evaluación y relación del potencial hídrico del suelo y foliar. Puerto Rican Society of Agricultural Sciences’ Annual Meeting, November 13, 2015 Coamo. Puerto Rico.

Robinson, T.L. and Dominguez, L.I., 2015. Precision pruning to help maximize crop value. New York Fruit Quarterly 23:29-32.

Robinson, T.L., Fazio, G., Black, B., and Parra, R., 2015a. Cornell-Geneva apple rootstocks for weak growing scion cultivars. New York Fruit Quarterly 23:21-24.

Sadeghi, S. H., R. T. Peters; and F. R. Lamm. 2015. Design of zero slope microirrigation laterals: Effect of the friction factor variation. J. Irrig. Drain Eng. ASCE, ISSN 0733-9437/04015012(9)

Sharma P., M.K. Shukla, P. Bosland and R. Steiner. 2015. Physiological responses of greenhouse-grown drip irrigated Chile Pepper under partial root zone drying. Hort. Science. 50 (8): 1224-1229.

Shock, C.C., E.B.G. Feibert, N.L. Shaw, M.P. Shock, L.D. Saunders. 2015. Irrigation to enhance native seed production for great basin restoration. Natural Areas Journal 35(1):74-82.

Shock, C.C., E.B.G. Feibert, A. Rivera, L.D. Saunders. 2015. Response of onion yield, grade, and financial return to plant population and irrigation system. HortScience 50(9):1312-1318.

Shukla M.K. 2015. Water resource management for semi-arid areas: status, problems and opportunities. 27th International Agronomy Week, Sept. 7-11, Durango, Mexico (Key-note speaker).

Shukla M.K. and H. Sharma. 2014. Water balance analysis and development of crop coefficient for drip irrigated chile. Soil Science Society America conference, Long Beach, CA, Nov. 2-5.

Teegerstrom, T., P. Livingston and D. Slack. 2015. Sweet Sorghum to Ethanol: A Guidance Manual for the Grower. Proceedings of the 8th International Conference of TSAE. Thai Society of Agricultural Engineers. March 17-19, Bangkok, Thailand

Waller, P. and M. Yitayew. 2015. Irrigation and Drainage Engineering. Springer Cham Heidelberg, New York, Dordecht, London. ISBN 978-3-319-05698-2.

Yitayew, M., and A. Barreto. 2015 http://cals.arizona.edu/research/bubbler/   BUBBLER Design of Low-Head Gravity-Flow Bubbler Irrigation Systems for Trees, Vines and Orchard Crops.