Brief Summary of Minutes of Annual Meeting

WERA 1022 – Accomplishments

October 1, 2018 – September 30, 2019

 
Objective 1.  Coordinate the documentation of crop coefficients used in irrigation scheduling.

Colorado: Hourly and daily crop evapotranspiration (ETC) rates of dry beans and grass hay were collected from two precision weighing lysimeters at the CSU Arkansas Valley Research Center in Southeast Colorado during 2019. The ETc data will be used in conjunction with ASCE Standardized reference ET to develop crop coefficients (Kc) of dry bean and grass hay. The seasonal soil water balance and daily actual ETc for grass hay were also calculated from lysimeter data collected in 2018. The 2018 grass hay ETc data will be combined with the 2019 data to develop a grass hay Kc curve appropriate for the semi-arid conditions of Southeast Colorado.

Minnesota:  This year in Minnesota, we started a new research project that evaluates the interaction effects of different irrigation strategies and different nitrogen (N) rates on grain yield, nitrate-N leaching, crop evapotranspiration, and N and water use efficiency in continuous maize. The goal of this study is to develop the best management system aimed at maximum maize production and minimum nitrate leaching. The other objective of this research is to develop crop coefficients (Kc) for maize, under various irrigation and nitrogen management practices in the central sands region of Minnesota. For now, ASCE manual 70 crop coefficients adjusted for Minnesota climate are being used for irrigation water management in the state. This year was exceptionally wet in Minnesota, resulted in limited irrigation requirements.

Utah:  We conducted a study comparing the ET of drip-irrigated onions to surface irrigated onions. ET was measured with a soil water budget and surface temperatures.  Three arrays of 10 Acclima TDR-15H were used in each of the drip and surface irrigated fields along with surface temperature infrared radiometers.  The soil moisture sensors were located under both the furrow and bed.  The amount of water applied with the drip system was less than 25 percent of surface irrigation.  The primary difference between the drip and surface irrigation was the soil water evaporation was much greater for surface irrigation.  We are still analyzing the data.

Washington: This year in Washington state we continued to tabulate and revise their tables of crop coefficients.  We created a database of these that we converted over to SQL and used these to create some online tools for estimating historical crop water use and create Woodruff charts and irrigation system design capacity estimator.  We plan to make the entire database of crop coefficients available online and provide a way to get feedback from the public to get revised and updated season dates and or accept data from users as to whether they have doubts about the existing crop coefficients.  In Washington we have a very large variety of crops and we don’t have good crop coefficients for most of them and these are estimated from other crops.  Our growers are also fairly educated and sophisticated.  Thus we are open to growers who might have more data that they would be willing to share that would better inform the estimates that we are forced to make for what these crop coefficients are.

Objective 2.  Coordinate efforts to promote adoption of improved irrigation scheduling technology, including computer models based on crop coefficients and ETref, remote sensing and instrumentation that will help producers more efficiently apply irrigation water.

Arkansas:  This year Arkansas hosted an Irrigation Yield Contest to promote the adoption of Irrigation Water Management Practices.  The three practices that are being adopted are surge irrigation, computerized hole selection for lay-flat pipe and soil moisture monitoring.  Fifty-nine irrigators have participated in this program which includes a large cash prize for winners in three the commodity categories of corn soybeans and rice.  The average rice yield attained by contestants in 2018 was 210.7 bpa with a water use efficiency of 5.17 bu/ac-in using 29.2 inches of irrigation. The winner achieved a yield of 229 bpa with a water use efficiency of 7.8 bu/ac-in using only 15.9 inches of irrigation. For reference, the average yield in the Rice Research and verification program was 186 bpa and the average depth of irrigation applied was 24.6 ac-in/ac.  This winner achieved a very good rice crop on 58% less water than the expected irrigation needs for rice.  This program is providing key data on water use, yields, and water use efficiency. The participants are demonstrating extremely high yields, low water use, and high water use efficacies.  Most importantly the contest demonstrates the full effect and results that can be achieved when irrigators apply highly managed crop production and irrigation management practices.  The program is demonstrating how a comprehensive approach to IWM can achieve sustainability. 

To support this program, Irrigation Schools have been developed.  74 participants attended surge schools and 81 attended the soil moisture schools for a total of 472 contact hours.  Schools are limited to 20 people per school and these are designed as intense learning environments, with an average of 2-5 contact hours.  Soil moisture sensor schools resulted in substantial learning, 95% reported substantial learning on how to assemble and install soil moisture sensors.  Using the mobile app to interpret sensors resulted in 85% of respondents reporting substantial learning about this key skill.  Participants were using sensors on 12% of their acres before the workshop and indicated that they could be used on over 60% of their acres. 

Mobile apps to help with rice irrigation design and soil moisture monitoring have been developed and are used by Arkansas irrigators. 

California: Two adjacent irrigation trials (a total of 144 landscape irrigation plots) were established in early 2019 at the University of California, Riverside Agricultural Experiment Station in Riverside, California to develop crop coefficient and irrigation management information for twelve groundcover species. The selected species are (a): Ice Plant (Ruschia lineolata nana), (b): Creeping Australian Saltbush (Rhagodia spinescens); (c): Rosemary (Rosmarinus officinalis ‘Roman Beauty’), (d): Gold Emu Bush (Eremphila glabra ‘Mingenew Gold’); (e): Coyote Bush (Baccharis x ‘Starn’ Thompson); (f): Saltillo Evening Primrose (Oenothera stubbei); (g) Buckwheat (Eriogonum fasciculatum ‘Warriner Lytle’); (h) Sea Heath (Frankenia thymifolia); (i) Lantana (Lantana montevidensis); (j) Jasmine (Trachelospermum jasminoides); (k) Honeysuckle (Lonicera japonica); and (l) Ice plant (Delosperma cooperi ‘John Profitt’).

Each 10 feet × 10 feet plot was equipped with four quarter-circle (pop-up heads) sprinklers, all four connected to a solenoid valve allowing independent irrigation control for each plot. To eliminate plot edge effect and avoid interference between adjacent plots, adequate borders (~ 4 feet) were considered. Two Weathermatic smart evapotranspiration-based irrigation controllers were installed and wired to all the solenoid valves. In addition, two Badger flowmeters, and two Weathermatic weather sensors were installed and attached to the smart controllers. A total of 288 Acclima true TDR-315L soil moisture sensors were installed at the center of 36 plots. The sensors were installed at 8 depths up to 5 feet deep to monitor soil water status within and below the active root zone of the plants.

Recently, we started imposing a varying degree of irrigation treatments. We introduced four irrigation treatments in early September. Four irrigation treatments were set to schedule autonomously to fulfill 100% of reference evapotranspiration for all species. The irrigation level was reduced to 80% in late September across the treatments. However, there is a difference in the frequency of irrigation applications. One treatment allows the smart controller to apply irrigation 7 days per week while the remaining treatments restrict the irrigation applications to 5, 4, and 3 days per week. We will collect digital images from plots (for visual assessment) as well as NDVI data using handheld and drone-mounted sensors. These data will be analyzed along with the soil moisture data to determine the patterns of water uptake and the response of different species to the irrigation treatments.

Colorado: Four ET-based irrigation scheduling presentations were given to a broad audience. The presentation events and audiences were:

2019 August 28, Measurements of dry bean evapotranspiration in the Arkansas Basin using a precision weighing lysimeter, Dry bean Field Day, Lucerne, CO. (13 attendees – bean processors, farmers, Extension agents)

2019 February 26-27. Irrigation scheduling using a water balance model and soil moisture sensors. 31st Annual Central Plains Irrigation Conference, Kearney, NE, (Invited; 40 producers, crop advisors, and researchers attended across 2 sessions)

2019 February 7, Variable Rate Irrigation and its Feasibility in the San Luis Valley (Modeling approach using the Water Irrigation Scheduler for Efficient Application), Southern Rocky Mountain Ag Conference, Monte Vista, CO. (Invited; rated 4.53 out of 5.0 by audience; ~ 75 attendees – farmers, crop consultants, agricultural scientists)

2019 January 31, Irrigation Timing (ET and Water Balance Modeling Approach), MillerCoors, Golden, CO. (Invited; 8 barley agronomists from Western U.S. and 3 managers)

Florida: Ferrarezi Citrus Horticulture Lab

Study 1: Plant density, fertilizer type and irrigation systems for sweet orange production at the Indian River District

Sweet oranges (Citrus sinensis) are impacted by huanglongbing (HLB), a disease associated with Candidatus Liberibacter asiaticus. The disease is threatening the citrus industry, with devastating effects on fruit production. Higher plant density can increase fruit yield per area under high HLB pressure, maximizing income and extending grove survival until a definite cure is found. This study evaluated the effect of tree planting density, fertilizer type and irrigation systems on fruit yield and quality. ‘Valencia’ orange on ‘Kuharske’ citrange (C. sinensis × Poncirus trifoliata) trees were planted in Sept/2013 (2,995 trees in 1.61 ha). We tested three treatments: standard tree spacing (3.8×7 m, 357 trees/ha) + dry granular fertilizer + microsprinkler irrigation (one emitter per tree; microsprinkler 50 green nozzle, 16.7 GPH at 20 psi) (Bowsmith, Exeter, CA), high density staggered ([2.7×1.5×0.9 m]×6.1 m, 953 trees/ha) + fertigation + microsprinkler irrigation (one emitter per two trees), and high density staggered + fertigation + drip irrigation (two lines per row; Emitterline 0.58 GPH at 10 psi, 12-inch spacing) (Jain Irrigation), in a complete randomized block design with eight replications.

Study 2: Effect of propagation methods on citrus rootstock water uptake

Huanglongbing or greening disease increased the need for new plantings and resetting in the field. To meet the high tree demand, citrus nurseries need high-quality, fast-growing rootstocks. Vegetative propagation is an alternative to the traditional seedling production due to the increased turnaround in the nursery. However, it may induce changes in the root system architecture and the development of adventitious roots instead of the taproot, altering root morphology and potentially the water uptake performance. The objective of this study was to compare the plant water uptake of citrus rootstocks propagated using different methods. We tested four citrus rootstocks {‘Swingle’ [Citrus paradisi × Poncirus trifoliata], ‘US-942’ [‘Sunki’ (Citrus reticulata) × ‘Flying Dragon’ (Poncirus trifoliata)], ‘US-897’ [‘Cleopatra’ (Citrus reticulata) × ‘Flying Dragon’ (Poncirus trifoliata)], and ‘US-802’ [‘Siamese’ (Citrus grandis) × ‘Gotha Road’ (Poncirus trifoliata)]} and three propagation methods (seed propagation, stem cuttings and tissue culture).

Study 3: High-density grapefruit production in open hydroponics system

Precise irrigation and fertigation management provide a less-limiting environment to roots while minimizing over-irrigation and leaching of nutrients. This concept can improve tree growth in the presence of HLB and help optimize water and nutrient use. Higher tree density can increase fruit yield per area under high HLB pressure. We conducted a study to evaluate the efficiency of open hydroponics on ‘Ray Ruby’ grapefruit production under different irrigation systems and tree density. We tested a combination of rootstocks (Sour orange and US897), tree spacing [standard and high density staggered (HDS)], fertilization (dry granular and fertigation), and irrigation systems (drip and microjet).

Louisiana:  This year, work continued on developing the STAMP irrigation scheduling tool for Louisiana agronomic producers.  This scheduling tool is a spreadsheet using the soil water balance or checkbook method.  The spreadsheet was prepopulated with agronomic and soil data so that minimal information was required for field use.  The calculations were updated to handle surface runoff and surface storage using the curve number method.  The model was tested for its ability to predict an appropriate irrigation schedule against a two-year field plot study.  Future work on this tool includes developing a users manual and updating the infiltration calculations to better estimate effective depths of irrigation and rainfall.

During the testing of the STAMP irrigation scheduling tool, it was observed that there are few reliable resources for estimating reference evapotranspiration (ET_O) and rainfall within the state.  These two pieces of information are critical to calculating a predictive irrigation schedule.  Thus, a study was initiated to evaluate the use of atmometers for measuring ET_O in the field.  Three atmometers were installed at the LSU AgCenter Red River Research Station in Bossier City, LA as replications.  These devices were installed within 50 m of a research-grade weather station to estimate ET_O from both data sources for comparison.  This study was replicated at the LSU AgCenter Dean Lee Research Station in Alexandria, LA.  Rainfall variability and data quality is also being evaluated.  We have collaborated with Dr. Clement Sohoulande from USDA ARS in Florence, SC to run all available precipitation data through his model to characterize our rainfall patterns and determine spatial divergence in those patterns.  All of this work is ongoing.

Minnesota:  Since the last report, efforts to promote efficient irrigation management practices throughout the state are continued through educational and training opportunities. Various field days and workshops were organized attended by farmers, county agents, and soil water conservation districts (SWCD).

An on-farm irrigation water management program was started this year where ETgage and soil moisture-based irrigation scheduling was compared with control fields without irrigation management. The project was carried in close collaboration with farmers and SWCDs. The goal of this program is to establish an ETgage network in the irrigated regions of the state where irrigators can use ETgage data for reference ET in case weather stations are not available. Right now we started with three demonstration fields but the goal is to expand the network.

Currently, in Minnesota, most of the irrigators are either using hand-feel or the checkbook method for irrigation scheduling. The checkbook method is based on the simplified estimate of water inputs, water stored in the soil profile based on its water holding capacity and water out, based on crop water use. The major drawback of this method is that the crop water use (ET) tables that are used in the checkbook method were developed around three decades ago. With the change in hybrids and management practice, ET values need to be updated. Also, if the checkbook method is not supported by weekly soil moisture measurement, it may result in over-irrigation by as much as 50%. The other goal of the irrigation management program is to promote advanced methods of irrigation scheduling. Through various educational events, farmers and agency personals were familiarized with different methods of irrigation scheduling including soil moisture sensors, Irrigation Management Assistant tool (http://ima.respec.com/), ET based irrigation scheduling and how to utilize these methods in their practices to enhance crop water use efficiency and reduce irrigation-induced environmental pollution and encourage the adoption of best irrigation management practices through workshops, training and demonstration field days.

In collaboration with the Minnesota Department of Agriculture, a new weather station was installed in Dakota County, MN which is one of the highest irrigated counties of the state. This weather station will provide daily ET values for efficient irrigation water management.

Nebraska:  The Nebraska Agricultural Water Management Network (NAWMN) functions continued in 2018 and 2019. The Network provides climate data, soil moisture data and how they can be used for irrigation management in agricultural production fields under different irrigation methods (surface, subsurface drip and center-pivot irrigation). The NAWMN [http://water.unl.edu/cropswater/nawmn (Irmak, 2006; Irmak et al. 2010; 2012)] was formed from an interdisciplinary team of partners, including UNL Extension, Natural Resources Districts (NRD), USDA-Natural Resources Conservation Service (NRCS), farmers, crop consultants, and other agricultural professionals o encounter some of the water availability vs. agricultural production issues through an unprecedented effort since 2004-2005 and. The main goal of the Network is to enable the transfer of high-quality research-based information to farmers and their advisors through an unparalleled series of demonstration projects (>850) established in farmers’ fields throughout Nebraska and implement newer tools and technologies to address and enhance crop water use efficiency, water conservation, and reduce energy consumption for irrigation and reduce nitrogen leaching to ground and surface water resources.

The fundamental objective of the NAWMN is to integrate science, research and education/outreach principles to provide citizens the best information available to help them to make better-informed decisions in their irrigation management practices.

The Network has been having significant impacts on both water and energy conservation and reduction in nitrogen leaching to ground and surface water resources due to farmers adopting/implementing technologies, information and strategies learned in NAWMN in their irrigation management practices. The network has grown to be the largest coordinated agricultural water management program in the United States. The Network presented an excellent example as to how and what a dedicated and committed team can accomplish through working in harmony and selflessly towards a common goal of protecting and sustaining prestigious natural resources.

SPECIFIC GOALS AND OBJECTIVES:

• Transfer high-quality research-based information and data on soil water status, crop water use, and crop growth stage measurements to farmers and their advisors through a series of demonstration projects established in their fields. Pictures of some examples of the field activities to provide extensive one-on-one training to citizens in the production fields are provided in the Appendix. 
• Foster adoption of newer irrigation/water management technologies to help farmers to increase water use efficiency, save water, reduce energy consumption, and protect environmental services.
• Enhance communication and enable idea and information exchange between growers, crop consultants, academics, NRDs, NRCS, DNR, irrigation districts, etc.
• Educate youth on soil and water resources and advanced/next-generation technologies. 
• Enhance the scientific literacy of current and next-generation producers and agricultural professionals in agricultural and related topics (the Network Team was actually initiating programs on scientific literacy back in 2005 when this concept was not on the radar screen at UNL).
• Develop next-generation water, soil, and crop management tools to continue technology implementation in agriculture and be recognized as one of the best in agricultural research and education in the nation/world.
• Quantify short- and long-term measurable impacts of the Network.

The NAWMN is one of the largest and most impactful research-based programs in Nebraska that accomplished substantial adoption of technology and information transfer in agriculture through strong and dedicated partnership of university faculty, private industry, state and federal agencies, producers, irrigation districts and crop consultants and changed the behavior of producers in terms of how they managed water resources. The Network is an excellent example of one of the very few large-scale programs that accomplished varitable integration of science, research and Extension/outreach/education to make a difference in the real world. Currently, over 1,500 active farmer partners/collaborators participate in the NAWMN program.

Oklahoma:  Efforts were continued at Oklahoma State University toward promoting the use of sensor-based technologies to improve irrigation scheduling:

1. As part of a multistate project (Oklahoma, Texas, and Kansas) funded by USDA-NRCS Conservation Innovation Grant, six demonstration sites were established across western Oklahoma, with a total irrigated area of about 750 acres. These sites were under variable soils, crops, and irrigation systems and were instrumented in collaboration with local producers. The performance of different types of commercially-available sensors in developing improved irrigation scheduling was investigated.

1. An irrigation scheduling technology demonstration event was organized on Sep. 11, 2019 at the Oklahoma Panhandle Research and Extension Center.

Utah:  In 2019 we worked with 12 growers in central Utah to determine yield impacts from replacing and updating pivot sprinklers/nozzles and of decreasing as section nozzle flowrates by 10 percent. As part of research we used Washington State’s Irrigation Scheduling application (Kc based) to schedule a portion of each field to schedule irrigations, another portion of each field was scheduled using soil moisture sensors, and the balance of each field was irrigated based on irrigators preference.  While the yield differences were not great, the research showed that irrigation amount could be decreased without significantly impacting yield.

Washington: In Washington we continue to develop and revise our irrigation scheduler online tool and mobile app.  We are currently revising it using the grower’s irrigation design capacity (irrigation system’s capable application rate to the field as a whole in in/day or gpm/acre, etc.) such that the grower simply has to enter system on and system off times.  This works well for center pivots and most solid-set systems where the grower simply has to make decisions as to whether they can shut the system down for a few days and when they need to leave it running.

Objective 3.  Coordinate the development of quality control (QC) procedures for weather data used for irrigation scheduling.

Colorado: Short-term weather forecasts (up to 7 days) during the 2019 growing season have been downloaded via the aWhere (http://www.awhere.com/) Weather Info API. The weather forecasts will be compared to selected Colorado Agricultural Meteorological Network (CoAgMet) station data in a historical (hindsight) analysis that will assess the accuracy and usability of the information in forecasting irrigation requirements. Two peer-reviewed papers on the use of predictive weather in irrigation scheduling were also published in the Journal of the American Water Resources Association.

Washington: I have been essentially frozen out of this work in our state and it is handled by our AgWeatherNet director and his staff.