The 2011 meeting was organized at Las Cruces, NM. Manoj Shukla, Chair, called the meeting to order at 8:20 am with a welcome and introduced the administrative officer, Dr. Steve Loring. Attendees introduced themselves. Steve Loring, adviser for the group, introduced himself and spoke on the importance of microirrigation in NM. He also shared his thoughts on different issues, including the future Federal Budget, the new AFRI grants, support from the Secretary of Ag, and the Specialty Crops program, the economic problems/budget cuts in most states, among others. Sammis and Lamm requested information about the Farm Bill.
Shukla opened the discussion on future meetings strategy. Among others, virtual meeting options were discussed but most of the participants did not welcome the idea. The tradition on having the meeting at the upcoming Vice-Chair place was discussed. The Secretary, Axel Garcia y Garcia from the University of Wyoming and upcoming vice-chair, talked about the pros and cons of holding the 2012 meeting in Wyoming, including the possibility of an earlier meeting due to weather conditions in the region and connections from Salt Lake City, UT, Denver, CO, and even flying to Billings, MT, and then driving to Powell, WY. Due to the cost and distance, a central place, such as Las Vegas/Reno, NV, and Orlando, FL, were proposed as alternative places to Wyoming for the 2012 meeting. As for Lamm, at centralized place we'll lose connection with university people; Schwankl added that the opportunity of technical trips will also be lost. If no other solution, Lamm suggested having a central place for a couple of years while the situation improves; then, return to normal.
Sammis brought to discussion an important issue: how to get other participants listed to attend the meetings. Lamm suggested that having our meeting along with the Irrigation Association (IA) meeting in Orlando, FL (4-5 November, 2012) and having a specific session at the meeting may get other people's interest to participate. Craig, from UFL, was asked whether he would be willing to organize the meeting and he acknowledged. Participants were asked for papers to be presented in the session; around half of the participants were willing to prepare a paper for the session. Porter said that accommodation might be an issue if our meeting is in or around Orlando, FL, but Craig suggested other options. Most participants agreed on holding our 2012 meeting in Orlando, FL. More discussion might be needed later.
Objective 1: Compare irrigation scheduling technologies and develop grower-appropriate scheduling products.
California In UC Davis, a novel approach for the automated, in-site measurement of plant stress (stem water potential, SWP) was evaluated in cherry, almond and grape under field conditions. Results show great promise for this technology, but that additional development will be needed in insulation technology and a reliable temperature compensation methodology. Idaho Data collection was initiated in 2011 using Watermark soil water sensors placed at 30 and 60 cm depths connected using wireless technology to an Irrometer receiver / data logger to schedule irrigation of strip-till and conventional till sugarbeet plots on a silt loam soil. Soil water content at 30-cm increments to 150 cm was also measured using a neutron probe. Irrigation schedules based on Watermarks, AgriMet ET estimation and neutron probe will be compared. Irrigation schedules using either neutron probe or AgriMet on silage corn will also be compared. Iowa In Iowa, a methodology for using topography and soils data to determine optimal placement of soil moisture sensors was developed, enabling a representative average soil moisture content to be obtained for an entire field based on just a handful of samples. Kansas In Kansas, research continued on evaluating the effect of early season water stresses on corn production. A presentation of this research was given at the annual international meeting of the American Society of Agricultural and Biological Engineers (ASABE). In Kansas, analysis was completed on a three year study of subsurface drip irrigated alfalfa. Results indicate that a 1.5 dripline spacing is acceptable for alfalfa production and that an irrigation level designed to replace 85% of crop evapotranspiration is recommended. A paper was presented at the Irrigation Association annual technical conference. New Mexico A field calibration of TDR sensors was carried out by pooling all the data collected from four depths (0-20, 20-40, 40-60 and 60-80 cm) at three locations under sandy loam and silt loam soil. Soil samples were also collected from each sensor depth two, four, six, ten and 13 days after irrigation for three irrigations and were converted to volumetric water content by multiplying with the soil bulk density. The optimization using the pooled TDR and measured water content did not provide a unique polynomial equation for all depths. However, when optimization was carried out for each location and depth separately, new coefficients provided a good agreement between TDR and measured water content with coefficient of determination always > 0.85. These results were published in Irrigation Science Journal and are available on-line. Several species in the oomycetous genus Phytophthora cause severe damage to specialty crops. Although Phytophthora species attack different plant species, the abiotic and biotic factors that determine plant infection and disease development are similar for all species of Phytophthora. An increased understanding of how Phytophthora species and their interaction with specialty crops are influenced by abiotic and biotic factors -would improve crop management and prevent or limit yield loss. Thrall et al (1997) has presented a simple life cycle model which describes the relationship between host and pathogen population density throughout the growing season, and over winter, for both natural and agricultural systems. This model was combined with a soil water budgets and irrigation scheduling models, Andales et al. (2006) and Ben Asher et al. (1986) Sammis et al., (1990) to predict the disease incidence of Phytophthora capsici under different irrigation scenarios. The combined host-pathogen irrigation model was tested against an experiment conducted in 1995 on Brazito sandy loam soil (mixed, thermic typic torripsamments) located at the Fabian Garcia Agricultural Research Center, Las Cruces, New Mexico using the linear probability of infection function. The experimental design was a randomized complete block design with three irrigation levels (daily trickle irrigation, 3-day trickle irrigation and alternate row furrow irrigation ) and two Phytophthora levels (non-infected (control) and infected). The experiment began in 1995 and was repeated in 1996. Every row was furrow irrigated during transplant establishment and switched to alternate row furrow irrigation thereafter. The model was also tested against an experiment conducted on drip irrigated bell peppers (variety Deystone Resistant Giant) artifically infested with Phytopthora capsici conducted by Ristaino 1991 and Ristaino and Hord 1992 in Clayton, N.C. in 1988 and 1989. Plots were drip irrigated 3 times and 15 timed during the 1988 growing season and 6 irrigations during the 1989 growing season after being infected with three levels of inoculum and a control. The disease incidence predicted by the model followed the measured data except early in the growing season where disease incidence development occurred sooner than predicted by the model for both the chile and bell pepper experiments. New York An apple-specific Penman-Monteith equation for the NY climate was developed to provide local daily estimates of water use for irrigation scheduling, and has been programmed into the daily calculations of the Climate Center at Cornell based on weather inputs from stations in apple-growing regions of NY. Research irrigation trials in commercial orchards were begun in 2011 validating this revised method. To allow continuous monitoring of plant water stress as basis for irrigation, we have developed a microfluidic microtensiometer using nanofabrication MEMS technology that has the same principle as large soil tensiometers but is only 2x5 mm. It is designed to embed in the trunk of perennial plants to directly measure stem water potential and also as a sensor in a soil tensiometer. Initial testing has been accurate down to -35 bars. Oregon Corn lily (Veratrum californicum) is being grown with automated drip irrigation at soil water tension (SWT) irrigation criteria of 5, 10, 20, 30, 40 kPa (4 replicates each) at both 2,150 and 4,900 feet elevation in OR and ID, respectively. Preliminary results show that irrigation at 10 kPa provides reasonable growth with much lower water inputs that irrigation at 5 kPa. Irrigation criteria is being examined for seed production of 20 native perennial plant species that the US Forest Service and BLM have determined would be highly desirable for rangeland restoration. Each species is being grown in a semi-arid environment at Ontario, OR using subsurface drip irrigation in replicated plots with three irrigation treatments (0, 100, and 200 mm/yr total irrigation) repeated over years. Species requirements for optimal seed yield differ from 0 to 200 mm. Results vary with year (variable rainfall) and disease load. None of the species appear to need irrigation more than 200 mm to optimize seed yield. Soil moisture sensors for irrigation scheduling instruments are being calibrated in a hanging, weighing lysimeter in a controlled temperature growth chamber and in the field in a heavy clay soil and in fine sand. Sensor performance is being measured through wetting and drying cycles at different temperatures. Instruments being compared include tensiometers, granular matrix sensors (GMS), hybrid sensors, thermocouple psychrometer readings, and capacitance probes. The above mentioned results are being communicated to growers by means of field days, workshops, grower meetings, written, and on line reports. Puerto Rico Puerto Rico has developed a procedure to estimate evapotranspiration using the remote sensing approach. Work in 2011 was initiated to expand those evapotranspiration estimates to Haiti and the Dominican Republic. The Puerto Rico algorithm estimates the daily water balance, which is useful for water resource management. Two publications resulted from support from this project and two other manuscripts are currently being developed. Texas A statewide assessment of Evapotranspiration (ET) networks was completed. This assessment addressed infrastructure, sensor quality, standardization, funding, data QA/QC, data delivery, and other issues. Technical and operations/management recommendations were developed and presented to ET Network managers and the Texas Water Development Board. A Water Management website (watermgmt.tamu.edu) was developed as a foundation for technology transfer of irrigation research and extension programs in the Texas High Plains. Information on the website includes an online user profile tool (irrigation scheduling platform using automated and manual input data to maintain crop water use and soil water storage balance); irrigation scheduling spreadsheet; educational videos and other informational resources. Wyoming An approach for the integration of biophysical factors, including stomatal conductance, soil moisture, and canopy temperature, is being studied. Preliminary results from a corn study conducted in a SDI field showed a functional relationship between the crop water stress index (CWSI), soil moisture, and stomatal conductance.
Objective 2: Develop design, management and maintenance recommendations
Arizona In Arizona, research is underway to develop of apps for design and management of SDI. This requires integrating both the soil and water relation and the hydraulic design aspects to a level that will be compatible with different smart phone operating systems. It also involves conversion of what is developed for microcomputer application into smart phone applications. The idea behind this development is to make it easier for farmers, extension specialists, and design engineers of SDI systems communicate in real time using the latest technological advances especially in regards to management of the SDI system. California UC Davis - Hopmans - New leaching guidelines were developed to minimize negative consequences of irrigating with saline waters. Irrigating with lower leaching fractions provides a more efficient use of limited water supplies. Guidelines are going to be published in California Agriculture magazine, so that farmers and irrigation managers will adopt the new guidelines. Additional activities include continuation of sensitivity analyses using computer simulation studies to evaluate variations in drip spacing, drip- line depth and irrigation frequency on leaching, soil salinity and crop yield. Much of this, material has extensively been used as supporting material to educate farm advisors on irrigation water management workshops. Kansas In Kansas, an analysis was conducted in cooperation with Texas AgriLife faculty of a number of older subsurface drip irrigation (SDI) systems in Texas. Results have indicated there is very little correlation in system uniformity and system life with the oldest system (20 years) having the greatest uniformity. Uniformity problems on nearly two-thirds of the systems appeared to have been exacerbated by incorrect operating pressure (both too low and too high) with the six best performing systems operating between 65 and 100% of the manufacturer's specified nominal operating pressure. A journal paper has been prepared and accepted on this research. Presentations were made at the regional Central Plains Irrigation Conference concerning long term research results with SDI systems in Kansas and about economic comparisons of SDI with center pivot sprinkler irrigation. At this meeting attended by water agency staff, crop consultants and producers, Kansas also displayed a number of standalone SDI informational posters and distributed free CD-Rom disks containing additional SDI information. Joint technology transfer efforts concerning SDI involving Kansas State University, Texas AgriLife and USDA-ARS were continued in 2011. These efforts included presentations at local, regional and national meetings. Oregon Drip, sprinkler, and furrow irrigation systems were being compared during 2007-2011 for onion yield, grade, storability, and thrips and iris yellow spot virus (IYSV) expression. Onion yield under drip irrigation was superior to sprinkler irrigation three of four growing seasons. Various drip irrigation SWT criteria from 10 to 30 kPa were compared during 2007-2011 for onion yield, grade, storability, and thrips and iris yellow spot virus (IYSV) expression. Onion yield and grade decreased with drier irrigation criteria. When IYSV was more severe, onion performance was more negatively affected by drier irrigation criteria. Results are being communicated to growers by means of field days, workshops, grower meetings, written, and on line reports. Puerto Rico Taro (Colocasia esculenta) is an important crop in Puerto Rico. Due to a devastating fungal disease in regions of traditional production (in wetland areas), taro has practically disappeared. In those areas. A study to determine the response of taro to SDI and plant tolerance to fungus when grown in dry conditions (like southern PR) was initiated. With the SDI technology and changes in traditional management systems, the crop can be produced commercially. Preliminary results showed that the quality and size of taro grown under a SDI system were very good. Several farmers showed interested on using the technology in their farms. Texas Lubbock, Texas - Irrigation system design, management and maintenance recommendations were presented to target audiences (including agricultural producers, crop consultants, irrigation professionals and others) at meetings (conferences, workshops); through news releases and regional newsletters; and through individual contacts. In Bushland, Texas, crop germination, yield, and water use efficiency was evaluated for two different subsurface drip irrigation (SDI) permanent bed designs (standard beds at 0.76-m centers and wide bed-twin row beds at 1.52-m centers), three drip lateral installation depths (0.15, 0.22, and 0.30-m), and four irrigation treatments (dryland, 33%, 67%, and 100% of full crop water requirements determined by neutron probe). Winter wheat was evaluated during the 2009-10 and 2010-11 growing seasons. Each season contrasted sharply in climatic conditions, with the 2009-10 season characterized by El Ni�o conditions with above average precipitation and below average temperatures, and the 2010-11 season characterized by La Ni�a conditions with record drought (~100 mm in-season precipitation) and record high temperatures. In the 2009-10 season, no significant differences in crop germination, grain yield, or water use efficiency were observed for the two bed designs or three drip lateral installation depths. In the 2010-11 season, crop germination, grain yield, and water use efficiency were significantly different across irrigation treatments, and these were less for each irrigation treatment compared with the 2009-10 season. Within an irrigation treatment, crop germination, grain yield, and water use efficiency were highly variable, but were not correlated to bed design or lateral installation depth. Therefore, crop germination, yield, and water use efficiency of winter wheat were not responsive to bed design or lateral installation depth in either year. In a concurrent experiment, crop germination, yield, and water use efficiency was compared for spray, LEPA, and subsurface drip irrigation at different irrigation treatments (dryland, 25%, 50%, 75%, and 100% of full crop water requirements determined by neutron probe). Grain corn was evaluated during the 2009 and 2010 seasons. In 2009, there were no significant differences in grain yield and water use efficiency for MESA, LESA, and SDI for the 100% irrigation rate; however, grain yield and water use efficiency was significantly greater for SDI compared with MESA and LESA at the 50 and 75% irrigation rates. Overall grain yields were lower than expected in 2009 due to soil water shortages and very high atmospheric demand around anthesis. In 2010, which was a more typical year, there were no significant differences in grain yield and water use efficiency for MESA, LESA, and SDI for all irrigation rates. In both years, grain yield and water use efficiency with LEPA was smaller compared with the other methods, which may have been related to furrow dike erosion resulting in runoff away from the yield sample area of the plots.
Objective 3: Develop best management practices for application of agrochemicals
Arizona In Arizona, research is under way to use computational fluid dynamics to understand distribution of chemicals and organisms applied or introduced through SDI systems. This is mainly to address security of the food production system from disease causing organisms introduced either intentionally or by accidentally. California New leaching guidelines were developed to minimize negative consequences of irrigating with saline waters. Irrigating with lower leaching fractions provides a more efficient use of limited water supplies. Guidelines are going to be published in California Agriculture magazine, so that farmers and irrigation managers will adopt the new guidelines. Additional activities include continuation of sensitivity analyses using computer simulation studies to evaluate variations in drip spacing, drip- line depth and irrigation frequency on leaching, soil salinity and crop yield. Much of this, material has extensively been used as supporting material to educate farm advisors on irrigation water management workshops. Kansas In Kansas, research continued evaluating the effect of nitrogen fertigation through subsurface drip irrigation on corn with three timings of N application and two irrigation levels. The goal of this research is to evaluate if carefully timed nitrogen application will maximize the yield component of kernels/ear. New Mexico In New Mexico, Pecan roots were planted in pots during 2008-2010 and were drip irrigated with solutions of EC of 1.5, 3, 5.5, and 7.5 dS/m. The project aims to evaluate the effects of different salinity levels on physiological properties of Pecan roots including bud break, canopy development, nitrogen and chloride uptake and salt tolerance. A lab test on scorched leaves did not detect the presence of bacteria (Xylella fastidiosa) responsible for Pecan Bacterial leaf spot, therefore, it was confirmed that the leaf scorching was only due to salt stress imposed on plants. No leaves were observed in the second year plants irrigated with water of salinity >5 dS m-1. The plants became stunted with decreasing stem diameter and nitrogen and chloride uptake increased with increasing salinity of irrigation water. Puerto Rico In Puerto Rico, an study to evaluate fertilization strategies for Tahit� lime (Citrus latifolia) and pineapple (Ananas comosus) was conducted. The use of drip irrigation systems became important not only for the application of irrigation but also for the proper management of fertilization in wetter conditions than normal by reducing the chance for nutrients losses. Texas Research-based recommendations have been developed for fertility management of subsurface drip irrigated cotton in the Texas Southern High Plains. Additional information will be incorporated as it becomes available to further develop and expand recommendations for additional crops and conditions.
Objective 4: Evaluate use of non-potable water through microirrigation
No activity is reported for this period