Monday November 16, 2009
Ali Fares called the meeting to order at 8:20 am with a welcome and a hearty thanks to Elvin for his organization of the meeting. LeRoy Daugherty congratulated the group for the project renewal, and thanked Freddie for his leadership in writing the project summary. Dr. Daugherty shared copies of the project summaries for W2128 and W1128, and the 2008 report of activities and accomplishments for W1128.
Brad Rein gave the federal agency update. CSREES is now officially National Institute of Food and Agriculture. A main focus will be on growing the agency: big science, big issues, funding that attracts high-level scientists. Dr. Rein outlined four sub-institutes (food production and sustainability; bioenergy, climate, and environment; food safety and nutrition; youth and community development) and noted that each have the same three functions (research, extension, education). Dr. Daugherty encouraged subgroups to put in AFRI proposals where fitting to leverage funding from Multistate projects.
Ken Shackel presented on some California research intended to answer the question, how much of the water balance do you need to quantify in order to be able to effectively and efficiently schedule irrigation? He noted that conventional wisdom says ET is all you need - and probably that's the most important, but it isn't ALL of it. Their project is attempting to integrate a lot of levels of information to try to get at how the plant is responding to irrigation & to environmental factors. They are also working on measuring plant water status and comparing to RS-derived ET estimates.
Dr. Shackel also shared results of orchard mortality studies motivated by the California drought. For growers facing extreme water restrictions, how little water one can use in an orchard and still have the trees survive? Preliminary results suggest that trees learn to regulate their water use if they are managed properly.
Dana Porter shared technology transfer efforts in Texas. A main focus is on the Ogallala Aquifer Program (research & extension education). They have produced web-based tools for ET estimation as well as irrigation training programs & trainings for technical service providers. Dr. Porter noted that the response has been very positive. A big challenge has been trying to clarify and standardize terminology (eg a lot of confusion between subirrigation and subsurface irriagation). She explained that SDI has become very popular in the 9 counties surrounding Lubbock. The group discussed whether we should contribute to the Wikipedia drip irrigation page.
Research from New Mexico showed that variability in stem water potential increases dramatically with increasing mean values. Just before dawn the sample (3 trees x 3 measurements) observations are almost identical, but is as much as 5 units by noon. The group had a brief discussion of terminology and measurement. For true stem water potential measurements, a leaf must be bagged/non-transpiring (10 mins or longer) and interior, lower canopy leaves are ideal.
New Mexico also studied nitrate leaching and irrigation efficiencies in onions and pecans, in chloride tracer research that asked, how far does applied fertilizer go? Results were applied to historical fertilizer application data to approximate total nitrate leaching. But when groundwater nitrate is monitored, concentrations are very low, so somewhere nitrate is being converted - probably to nitrous oxide, suggesting soil doesn't have to be saturated for denitrification to occur. Microbial activity is theoretically quite small because these soils have so little carbon, so, more study is necessary to figure out where energy is coming from and how denitrification is happening.
The group discussed the merits and downsides of pressure bomb technology. Dr. Fares suggested that the pressure bomb is, like neutron probe, cumbersome and impractical for growers. Dr. Shackel disagreed, noting that impacts of having the data are so substantial that a grower "can't afford not to" monitor this way. With effective dataset building and analysis some growers can reduce observation "energy" required. Other growers hire people to do this monitoring. Dr. Fares noted that somehow the demands on the grower of this type of monitoring needs to be reduced. Many can't or don't want to put in the effort necessary to be able to monitor and use this information. Dr. Porter suggested that this is why models are so popular - they don't require any observations. Dr. Shackel emphasized that it's important to have a check for models, and that something that is needed is a good model that tells you when to start irrigating.
New Mexico presented irrigation scheduling data and growth assessment in poplars, and the group discussed poplar irrigation issues, and the uses and benefits of poplars. Further presentation was on xeriscaping and vegetables: developing crop coefficients (or maybe, "irrigation coefficients") for mixed canopy and non-standard ET conditions.
The group discussed that the concept of crop coefficient is not valid for RDI, because a crop coefficient is ultimately based on fully watered conditions. But there are stress coefficients that might make the method adjustable? Perhaps this question can be more fully addressed during happy hour.
Finally, New Mexico noted the need for accurate estimates of ET and IR during plant establishment, and evaluation of drip emitters under very low pressure for gravity systems.
Oregon presented on calibrating Watermark sensors on sandy soils, and comparing to other soil water devices (including temperature compensation). Dr. Shock also discussed that slight amounts of water stress tends to have greater symptoms of virus and insect damage.
Oregon has been investigating irrigation for wildflower seed production. They are trying SDI for this purpose, just to give a little water, applied deep, and not stimulating to weeds because these plants are not very competitive. Dr. Shock reported that so far this strategy seems to work well.
Finally, Oregon is involved in a project on phytopharmaceuticals - irrigating plants that produce precursors to cancer-inhibiting enzymes.
Kansas and Texas reported on collaborative work in joint technology transfer projects. They secured funding from here and there and had field days and other activities this past summerSo fra the response has been very favorable and demand for expertise is high.
They are having a session at the upcoming IA meeting, "SDI in the great plains" with 8 different papers plus some posters from the project. The project has done some "branding" - logo, shirts, etc. They have tracked the technology transfer efforts made (publication, poster presentation, etc.) and are on track to meet or exceed goals.
The group discussed difficulties in monitoring and managing non-uniformity in water application in SDI; The group particularly noted the challenges of rodent damage - nobody has a great answer. Several helpful practices include baiting field edges, trapping, keeping the area wet if possible. Definitely don't install in fall and then not use it until spring because they'll have all winter to munch on it in fluffy trenched soil.
California noted collaborative work with their SCRI project. The group noted that large projects need project managers (usually not scientist or academic). The group discussed integration of data layers to develop grower-friendly maps to guide irrigation decisions, and to model or predict yield based on remotely sensed data.
Tuesday November 17, 2009
Amy Kaleita reported on efforts to produce high-resolution soil moisture map from sparse point measurements in Iowa.
Craig Stanley shared TMDL pressures from Florida, where growers are encouraged to adhere to BMPs by some regulatory presumptions of innocence if they are in compliance. Accordingly, Florida has had BMP workshops for growers. State priority areas include improved water use and water re-use, real-time monitoring of soil moisture and nutrient status.
Dr. Stanley also shared projects on fertilization and irrigation of vegetables and horticultural plants, as well as septic system effluent management for nitrogen reduction. Installation of individual active nitrogen removal systems very expensive, so researchers are looking into passive systems, which reduce number of pumps etc. and thus keep costs low. Effluent can be distributed through drip systems over an engineered turf system.
Larry Parsons reported on projects on automatic citrus irrigation, in which soil sensors are hooked to wireless radio and cell phone systems to transmit data. Irrigation systems are tapped into data and a trigger point initiates an irrigation event. This allows self-regulative responsiveness to rain, so the system is flexible and nicely accommodates frequency irregularities.
Dr. Parsons also shared projects on using pulse irrigation for sandy soils, blueberry production, sandy soils amended with pine bark (to lower the pH), and different soil-sensor based irrigation strategies.
The group proceeded to the business meeting portion with a discussion of filing the project report covering the past year. The group also confirm last year's officer election decision that Manoj Shukla will be the next Secretary for 2010-11. It was decided that next year's meeting will be held in Des Moines, IA, Nov 17-19, 2010 (to end midday on Friday).
State reports continued with Elvin Román-Paoli discussing the response of avocados to microirrigation treatments in Puerto Rico. He also shared results of studies on fertilization and microirrigation treatments on pineapples, for which high levels of fertilization are common. Growers do not generally think irrigation will pay off, but the study results show differently.
Ali Fares shared results of modeled carbon cycling, CO2 emissions in tropical soils/weather conditions. They also assessed the effect of tillage type and extent on CO2 emissions.
Tom Zimmerman shared a project on genetically engineered rice production in semi-arid Virgin Islands because nobody else is growing rice on the island it can be genetically isolated. The company initially wanted to do flood irrigation but that would require too much water. Researchers compared drip irrigation and small plots of flood irrigation and found no significant difference between drip and flood. The group then discussed water needs of rice. Dr. Shock noted rice is very sensitive to water stress at flowering. Often irrigation water is just used as weed control or to limit tillers.
Freddie Lamm presented on the SDI system at the Colby (KS) research site, which is still going strong after 20 years. Some research suggests SDI was higher-yielding (because of higher number of kernels per ear) under normal to wetter conditions, and LEPA sprinkler was better under extreme drought.
Discussion: is the real response of yield to seasonal irrigation linear with a plateau, and just averages to look like a diminishing returns curve? Perhaps the distinction is important because it means that the average curve is perhaps representative of the long term, but not representative of the way the relationship actually functions within a given year. But perhaps the distinction is not significant because the using real data and fitting models, there is often no significant difference in the fits of a linear and curvilinear function, and of course any data will have scatter/variability that doesn't fit right along any function. Also, the likelihood that a field will be uniform is small - so probably this accounts for some curvilinearity in reality also. And of course, linear or curvilinear relationship does not mean cause and effect - no matter how you slice it, ET doesn't cause yield. Manoj: linear relationship is just a convenience, because it violates reality at both ends, it often means that at zero water you have negative yield, and that at infinite water you have infinite yield. Eventually the discussion reached the point of diminishing returns.
Objective 1. To identify and assess the significance of barriers to adoption of microirrigation.
Kansas and Texas initiated a two year long SDI technology transfer effort. Field days summarizing many years of SDI research were held in Colby, Kansas and Halfway, Texas. These events allowed interaction between University staff, USDA staff and producers which helped to identify successes and continuing challenges.
Objective 2. To reduce the technical barriers associate with microirrigation system design, performance, and maintenance.
For the fourth year corn yield was not negatively affected by various emitter spacings of 0.3, 0.6, 0.9 or 0.4 m on a deep well-drained soil in a semi-arid, summer pattern rainfall climate in Kansas. There is some soil water redistribution occurring along the subsurface dripline that helps to mitigate application differences caused by the different emitter spacings.
A summary of pressure and dripline flow rates over a twenty year period for SDI research plots at KSU indicates performance for 22 of 23 different plots are within +/- 5% of their original value. Long life SDI systems allow high microirrigation costs to be amortized over many years.
A subsurface drip irrigation (SDI) system, installed at the AgCARES research farm in Dawson County, Texas, includes approximately 20-acres divided into 22 zones. Each zone is individually metered allowing for multiple irrigation treatments (irrigation rates and times). Of the zones, 18 zones have alternate furrow (80-inch) tape lateral spacing, and 4 zones have every row (40-inch) tape lateral spacing. The inclusion of both tape spacing designs allows for side-by-side comparison of irrigation systems designs. The relatively large size of the zones (8 rows by approximately 823 ft. for the every row tape spacing; 16 rows by approximately 823 ft. for the alternate furrow tape spacing) allows for multiple research treatments within each zone, and hence for investigation of interactions between multiple agronomic X irrigation factors.
In 2005 -2008, multiple cotton varieties, plant populations, and irrigation rates were addressed in studies conducted at the location. This work complements related studies conducted at research locations (Halfway, TX and Bushland, TX) with finer textured soils (Amarillo fine sandy loam at AgCARES vs. Pullman clay loam at the other sites). Soil sampling was initiated in early 2006 to monitor salinity accumulation patterns in every row vs. alternate furrow placed subsurface drip irrigation laterals. Soil moisture monitoring and crop growth stage monitoring data from 2006 - 2008 will be used to improve understanding of water movement and root extraction patterns, as well as help to improve crop models used in ET-based irrigation scheduling. This study was concluded with the 2008 crop season; data analysis and results interpretation are ongoing.
In TX, a study is underway to evaluate emission rates through several types of drip emitters at relatively low pressures. This study will provide information with respect to using elevation head to pressurize drip distribution systems, including tank-stored harvested rainwater, for landscaping applications. Rainwater harvesting is gaining popularity as a means to meet part of the landscape irrigation demand.
A similar evaluation was conducted at Farmington, NM to compare the emitter outputs of a rigid PE dripline and a drip tape at two different pressures (10 psi and gravity-fed 2.5 psi). Mean emitter outputs of both products were at or near advertised (0.36 gph for the drip tape and 0.50 gph for the rigid PE) at 10 psi but decreased by more than 80% (to 0.05 and 0.09 gph, respectively) at 2.5 psi. Output uniformity decreased with lower pressure in the drip tape but was unaffected by pressure in the rigid PE. Research will continue in 2010 to evaluate the emitter-output vs. pressure variability of several point- source emitters.
Objective 3. To reduce existing water and nutrient management barriers associated with microirrigation.
In NY, research continued on documenting water use in a cool humid climate and extending the information to apple and fruit growers. Water use by wine grapes was measured with sap flow gauges that were calibrated for short periods with canopy gas exchange chambers (Intrigliolo et al.,2008). The mid-season Kc values varied daily from 0.25 to 0.8, but averaged 0.4 to 0.5. Unlike apple, it appears that an ETo x Kc approach is useful in NY weather conditions. A second approach for regulation of irrigation is plant water stress sensing. In collaboration with a microfluidics chemical engineer, a microtensiometer sensor is being engineered in a nanofabrication facility at Cornell University. The sensor is designed to be embedded in the wood of a perennial plant and monitor the stem water potential continuously.
In Idaho, research and extension work evaluating the performance of Decagon soil water sensors and data loggers was expanded this year. Spring and fall soil sampling to obtain gravimetric soil water content at 6-inch increments to soil depth or 4 feet maximum depth allowed a water balance to be computed. Neutron access tubes were also installed on several fields to obtain an additional soil water content measurement.
This was also the first of two years of USDA-NRCS CIG funding to evaluate farmer acceptance and performance of an on-line irrigation scheduling procedure developed at Oregon State University under Idaho climate, soil and crop conditions. Neutron probe access tubes were installed on all fields with readings taken to 5 feet or to an impeding soil layer if encountered first. Watermark sensors with Hansen data loggers were also installed on many of the fields.
In Kansas, corn was grown with subsurface drip irrigation to determine the effect of pre-anthesis water stress. Summarizing nine years of data from two different studies, corn grain yield was only affected by pre-anthesis water stress in only three years. Grain yields were highly correlated with the number of corn kernels per unit land area which suggests that this is the factor that must be optimized during the pre- and near anthesis growth period. The results indicate that corn has great ability to tolerate pre-anthesis water stress provided the water deficits can be quickly relieved through irrigation near anthesis.
In CA, an experiment was conducted to establish drought-year drip irrigation recommendations for tree survival in almonds. This project was funded by the CA almond industry in response to a severe state-wide water shortage in the 2009 season. Three irrigation regimes (0", 5"and 10") were compared to full irrigation (40"), and additional sub-plot canopy treatments designed to reduce canopy water demand (50% canopy removal, whitewash spray) were imposed. Yield and nut size effects were measured and will be reported at industry-wide meetings in December, 2009, and tree survival and carryover yield effects will be measured in the 2010 season.
The Texas High Plains Evapotranspiration Network, administered jointly through the Texas A&M AgriLife Research and Extension Centers at Amarillo and Lubbock, has added new weather stations at Pecos (in West Texas) and Lockney (in the Texas Panhandle) and is making plans to incorporate additional stations/networks in West Texas in the near future. Field research continues with project support from the USDA-ARS Ogallala Aquifer Initiative and with project funding from the Texas Water Development Board to address technical and data issues in ET networks statewide. In addition to hardware and ET network operations and management, new online ET-based irrigation scheduling tools and information resources are under development. Extension programs (producer meetings, county agent training, publications, etc.) are promoting adoption and proficiency in application of irrigation scheduling and other best management practices.
SDI research at the AgCARES and Helms research farms in Dawson and Hale counties, respectively, continues to be scheduled and/or interpreted with respect to ETc using data acquired through onsite weather stations. These data are available online through the Texas High Plains ET Network website, http://txhighplainset.tamu.edu.
An irrigation training program was developed to provide educational opportunities and informational resources to support efficient irrigation technologies and practices. A curriculum guide and resource compilation in print and electronic formats were used in six training events in Texas in 2008 and 2009. Over 350 participants attended irrigation conferences in Lubbock, Mercedes, Chillicothe, Sinton, Hondo and Amarillo. Target audiences included progressive agricultural producers, technical service providers, agencies, agricultural consultants, irrigation professionals and extension educators. According to participant surveys, 84% of attendees indicated they gained knowledge in one or more core subject matter areas, 57% indicated intention to adopt best management practices, and 75% expected to derive economic benefit from applying the knowledge and/or adopting identified practices. Continuing Education Units were offered for Texas Department of Agriculture Licensed Pesticide Applicators, Texas Certified Crop Adviser Program licensed Certified Crop Advisers, and Irrigation Association licensed Certified Irrigation Designers and Certified Agricultural Irrigation Specialists. Subject matter included soil moisture management; evapotranspiration-based irrigation scheduling; low pressure center pivot irrigation (LEPA, LESA, MESA) and subsurface drip irrigation technologies, management, maintenance and trouble-shooting; crop-specific irrigation management for key crops, tailored by region (cotton, grain and forage crops in the Texas High Plains, South Plains and Rolling Plains); USDA-NRCS EQIP cost share program requirements; and water-related regulatory and legislative issues.
Declining water resources and water-limiting agricultural production conditions in the Ogallala Aquifer Region continue to place pressure on irrigators to manage irrigation efficiently. When properly designed, installed, maintained and managed, subsurface drip irrigation (SDI) can be a highly efficient irrigation method. Obstacles to adoption of SDI include need for information on SDI system design, maintenance and management.
A collaboration between faculty of Kansas State University, Texas AgriLife Research, Texas AgriLife Extension Service and USDA-ARS at Bushland, Texas is developed educational materials and events through a technology transfer effort designed to remove informational barriers to adoption of SDI; increase awareness of advances in SDI; promote appropriate application and management of SDI; and promote SDI research programs. Educational events include field days and workshops. This year-long technology transfer effort is funded in part by the USDA-ARS Ogallala Aquifer Initiative Program, with supplemental funding from irrigation industry. Freddie Lamm (Kansas State University) and Dana Porter (Texas AgriLife Extension Service) are co-PIs on this project, but it is truly a team effort involving KSU faculty Mahbub Alam and Dan Rogers; Texas AgriLife Research Engineer James Bordovsky; Texas AgriLife Extension Serivce Irrigation Program Specialist Nich Kenny; USDA-ARS Engineer Paul Colaizzi; and other research and extension faculty from Kansas and Texas.
Field Days were held at Colby, Kansas on August 4, 2009 and Halfway, Texas on August 25, 2009. Both events were well attended, and included field tours on research farms, as well as industry and educational exhibits. A proceedings packet containing research poster printouts and a CD with research reports, fact sheets and other information was developed and distributed to all participants in these events. Presentations included research-based recommendations for crop-specific SDI management; maintenance issues; advantages and disadvantages of SDI; system design, layout, uniformity and germination issues; and other topics. Audiences included agricultural producers, irrigation professionals, USDA-NRCS personnel, agricultural and engineering consultants, and others.
The Halfway event had approximately 118 participants, and feedback was very positive. According to an evaluation survey, 63% of respondents indicated an increase in level of understanding of at least one topic; all other respondents indicated a high level of understanding both before and after the event. Forty percent of respondents indicated an increase in knowledge about SDI system components, layout and planning and SDI system maintenance and trouble-shooting; 46% indicated an increase in knowledge about irrigation best management practices to optimize benefits of the technology and improve water use efficiency; 49% indicated an increase in knowledge of advantages and disadvantages of SDI and of applicability of practices and/or technologies to their farm operations. Eighty-nine percent of respondents indicated that they received information that would be helpful in their irrigation decisions. Fifty percent indicated intentions to make changes in their irrigation practices as a result of information they received at the event.
A professional development workshop on agricultural irrigation was conducted for Texas AgriLife Extension Agents (Agriculture and Integrated Pest Management) on August 13, 2009 in Lubbock, Texas. The irrigation training curriculum and reference notebook developed for the statewide workshop series was provided to the participating agents. Along with this "train the trainer" irrigation education package, evaluation instruments and additional subject matter resources were provided to support local irrigation and water conservation programming.
Additional professional development opportunities and credit for county agents were provided for those participating and assisting with the statewide Irrigation Training Program series and the Subsurface Drip Irrigation Field Days in Kansas and Texas.
In NM, research was done to estimate the depth of water and nitrate-N (NO3-N) fronts below the rooting zone, water and NO3-N balance and irrigation and plant uptake efficiencies for two onion fields under furrow and drip irrigation systems located in the Mesilla Valley of Southern New Mexico. Soil samples were collected during the last week of each month throughout the growing season from the fields at three locations and six depths and were analyzed for NO3-N and chloride concentration. The total amounts of N fertilizer applied to furrow and drip irrigated fields were 383 and 292 kg ha-1, and total water applied was 95 cm and 81 cm, respectively. The amount of NO3-N in the drainage water estimated by chloride tracer technique was 165.9 mg L-1 for furrow and 66.8 mg L-1 for drip irrigated fields for 60-200 cm depth. The NO3-N loadings below the rooting zone were 240 kg ha-1 for furrow and 79 kg ha-1 for drip irrigated fields. The ratio of NO3-N and Cl were similar for depths below the rooting zone of both the fields. The irrigation efficiencies for the furrow and drip irrigated fields were 81% and 83%, N use efficiencies were 23.4% and 31%, and water application efficiencies were 72% and 77%, respectively. Because of the water stress conditions in irrigation systems irrigation efficiencies were similar. However, shifting from furrow irrigation to drip irrigation can lower NO3-N leaching; improve N use efficiency with lower water inputs.
In NM, phytoremediation work is being expanded at the former site of a petroleum refinery. This project is in the planning stages. This may provide a starting point for potential projects associated with the petroleum industry in this region.
Studies have been conducted at Farmington, NM to evaluate the effects of different drip-irrigation volumes on the quality of landscape plants and on yields of chile peppers, sweet corn, and tomatoes when grown in small plots. The goal is to identify climate-based, canopy adjusted, irrigation factors (i.e. crop-coefficients) for scheduling irrigations on these plants when drip irrigated. Research to date has shown a great deal of variability in the recommended factors between different species of landscape plants and has formulated recommended irrigation factors of 0.80, 0.85, and 0.70 for chile peppers, sweet corn, and tomatoes, respectively when correlated with reference ET and measured canopy area.
In NY, since the standard ETo x Kc from arid climates does not work for apple water use in NY conditions, our apple-specific Penman-Monteith equation is being incorporated into the Northeast Climate Center daily calculations of ET specific to crops and climate regions of NY, and made available to growers on the Northeast Weather Association grower web site. A grower training extension program is being developed in cooperation with regional extension specialists.
In CA, grower meetings were held to inform growers about drought-year drip irrigation strategies (100 growers, Nickles annual field day, Arbuckle, CA), deficit irrigation strategies (300 growers, Kern Co. irrigation workshop, Bakersfield, CA), and to train growers in plant-based irrigation management (30 growers, Belridge, CA), as well as articles written for dissemination to growers through industry websites (http://www.almondboard.com/Growers/orchardmanagement/Pages/Drought.aspx).
Gravity-fed drip irrigation has been installed and used for windbreak/conservation plantings on non-crop areas of the NMSU Agricultural Science Center at Farmington. Also, NMSU Agricultural Science Center staff have advised and assisted with planning and installation of drip irrigation at the Bloomfield Senior Center Community Garden. The vegetable grown in the garden are used by the community, and the drip irrigation system is a visible demonstration of drip irrigation at a small scale for food production. NMSU Agricultural Science Center staff demonstrated low-tech gravity-fed drip irrigation during Earth Day activities at Aztec Ruins National Monument.