As the farm labor force in California continues to shrink and costs continue to climb, growers have been compelled to mechanize much of their farming tasks. Harvesting is one of the most labor-intensive tasks for California raisin growers, and fortunately, mechanical harvesting is an option for them. The technology has been around for quite some time now; however, some growers have been hesitant to convert to mechanized harvesting for one reason or another. For many, it’s a question of finance. Many of the old Thompson raisin vineyards are not set up to be mechanically harvested, but times are changing.
Total acreage harvested by mechanical means in 2018 was 45,429, nearly 30 percent of the State’s total raisin-type grape acreage, according to the Pacific Region Office of USDA’s National Agricultural Statistics Service. The Overhead Trellis Management System was used on 13,346 bearing acres in 2018, accounting for 8.8 percent of the total raisin-type grape acreage. Fresno and Madera County growers have 49 and 42 percent of the Overhead Trellis acreage in the State, respectively. Kern County growers have 6 percent of the Overhead Trellis acreage. Other mechanical harvest systems include Continuous Tray at 20 percent of the raisin acreage, South Side with 0.4 percent and Open Gable with about 1.2 percent of the raisin-type grape acreage.
Although Fresno County has the most acreage with mechanical harvesting, at 32,991, that acreage only represents 31 percent of the Fresno County raisin-type grape acreage. Kern and Madera County growers harvest 11 and 43 percent of their raisin-type grape acreage by mechanical means, respectively.
By variety, Thompson Seedless grape acreage with mechanical harvesting is 32,191 or 25 percent of the total raisin-type grape acreage. Fifty percent of the Fiesta grape acreage is harvested mechanically and 68 percent of the Selma Pete acreage is harvested mechanically.
Most California raisins are produced by sun drying after placing bunches on paper trays on terraces between vine rows. The Overhead Trellis System has led to increased production of dried-on-the-vine raisins, increased machine harvesting, and decreased hand labor use.
Procedures
The Pacific Region Office of USDA’s National Agricultural Statistics Service, in cooperation with the California Department of Food and Agriculture, conducts an annual grape acreage survey. The 2018 Grape Acreage Report, published in April, summarized the latest survey results. At the request of the raisin industry, an additional question was added to the grape acreage survey form the past ten years to gather information on raisin-type acreage that is harvested mechanically. In addition to the mechanical harvest data, producers were asked to update acreage by variety and year planted. Growers were initially contacted by mail and follow up was done by telephone. This report summarizes data for mechanical harvest methods of raisin-type grapes. The totals included are only for those that voluntarily reported to this survey.
Acknowledgments
We sincerely thank the many vineyard operators, owners, and management for firms providing the information. Funding for the raisin-type grape acreage report was provided by the Raisin Administrative Committee.
Mechanical Harvest Methods
Overhead Trellis– Grapes are dried directly on the vine, forming a canopy over the rows. It allows the mechanical grape harvester to get underneath and gather the dried fruit.
South Side Trellis– In an east-west row orientation vineyard, an angled cross-arm is added to each trellis stake to support two wires on which fruiting canes are tied. The southern exposure of the fruit facilitates drying. The raisins may be harvested mechanically with a south side harvester.
Continuous Tray– Grapes are mechanically harvested and laid out on a continuous (rather than individual) thin sheet of paper where they dry in the sun for two to three weeks.
Open Gable – Trellis wires are connected between rows of v-shaped supports. The unique V-shape lets in additional sunlight and traps the heat. This greatly improves ripening and drying. Raisins are harvested mechanically with a harvester that has been modified to place the raisins in bins instead of gondolas.
A team of researchers at Washington State University is putting satellites and drones to work in the hunt for better wheat varieties to help feed a growing world more sustainably.
WSU scientists launched a new project this spring, developing techniques that let satellites and flying drones identify and study wheat varieties from overhead. The research is funded by a $500,000 grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture.
Their effort could speed up research into better, more productive wheat varieties and could give growers powerful new tools to improve farming.
Machines can Sense Crop Traits Faster
Grown on more acres than any other crop, wheat is a staple that feeds more than a third of the world’s population. To help meet growing global demand, and keep ahead of devastating pests, pathogens, and a changing environment, wheat breeders develop improved varieties.
An important part of that process is phenotyping: measuring the way plant genes are expressed physically, in order to select the best plants to breed for improved yield, grain quality, and resistance to stress and disease.
In the past, this work was done by hand. But with modern cameras and sensors, satellites could take phenotyping to a new level, helping scientists and growers quickly and accurately study how wheat varieties are performing in the field.
“Satellite imagery could help wheat breeders find genes that maximize yield and fight stress and disease, and help farmers learn which varieties grow best in their areas,” said lead scientist Zhiwu Zhang, the Washington Grain Commission Distinguished Professor for Statistical Genomics at WSU’s Department of Crop and Soil Sciences. “No one has been able to do this yet, but the rewards are highly worth the effort.”
While scientists can already learn a lot about crops from the wavelengths of light they emit—water stress, for example, shows up in the infrared region of the electromagnetic spectrum—part of the project’s challenge is to learn whether wheat varieties and their physical characteristics can be differentiated by their spectral data.
“Sensors are getting better every day,” said team member Sindhuja Sankaran, an associate professor and sensor technology researcher at WSU’s Department of Biological Systems Engineering. “As resolution increases and camera costs drop, we have more powerful tools to sense how crops are performing.”
To help satellite sensors understand what they are looking at, WSU researchers will use unmanned aerial vehicles, better known as drones, to gather visual and infrared imagery from wheat plots. Flying over WSU experimental farms across eastern Washington starting this summer, drone cameras will collect data to be matched to satellite imagery. Success in this matching process will give scientists the ability to identify and study wheat varieties from orbit.
Sensors Could Save Time in the Field
Arron Carter and Mike Pumphrey, winter and spring wheat breeders with WSU’s Department of Crop and Soil Sciences, are excited about the potential of overhead sensing to speed up the painstaking process of selection.
“In our breeding programs, time means everything,” Carter said.
Every year, he and Pumphrey plant several thousand experimental varieties of wheat. Each variety represents an investment of time and field capacity.
“If I can use a sensor on a drone or satellite to select only the best, and remove the rest a year early, I’ve increased my capacity and saved time that’s better spent on varieties that show more promise for Northwest farmers,” Carter said.
Beyond breeding, the team’s research could ultimately help growers around the world use satellite imagery to predict yields, monitor performance, and protect their crops from drought.
“Right now, we’re looking at Pacific Northwest wheat, but this could have implications across the globe,” Carter said. “Our imagination is the limit to what this technology could do.”
Other team members working on the project include postdoctoral researcher Yang Hu and graduate students James Chen, Chongyuan Zhang and Worasit Sangjan. Zhang also thanks CAHNRS’ Office of Research and Agricultural Research Center for assistance with the grant application.
By: Seth Truscott, College of Agricultural, Human & Natural Resource Sciences
A 26-episode weekly video series has debuted on YouTube to help train the next generation of vegetable crop workers and increase their use of effective stewardship practices in vegetable production.
Projections for near-future retirements of people working in California’s agricultural production, marketing and post-harvest handling sectors indicate severe re-staffing needs in the coming years. Technological advances have reduced manual labor in agriculture, but increased the need for skilled labor to maintain the sustainability of the vegetable industry.
The video series is offered on theUC Agriculture and Natural Resources (UC ANR) YouTubepage on a playlist titled “Expanding the Capacity and Training of a New Generation of California Vegetable Producers.” UC ANR is the outreach arm of the University of California which, among other services, provides agricultural research, teaching and advising in all California counties.
As powdery mildew begins to develop resistance to our traditional fungicides, it is more important than ever that growers apply just the right products at the right times, and a new mildew spore trapping technology is now available to help growers better diagnose what’s out in the field. Watch this brief interview with Dan Rodrigues from Vina Quest and the Cal Poly Viticulture & Enology Department as he explains.
Ceres Imaging, an aerial imagery and analytics company that improves decision making by providing farmers a comprehensive view of their farm, next month will present the first two webcasts of the Advances in Imagery audio series. The company is providing this free program in collaboration with Malcolm Media, publisher of American Vineyard Magazine, Pacific Nut Producer Magazine and more.
Advances in Imagery is a continuing education audio web series that brings together agricultural experts and top producers to discuss how imagery and other ag data tools are advancing the farming industry. Episode attendees qualify for continuing education credits.
“With so many new technologies out there, it’s sometimes difficult for growers to cut through the noise and see what is actually valuable at the farm level. Our hope is that Advances in Imagery will help growers learn from one another what does, and what doesn’t make sense given today’s technology,” said Matthew Malcolm, Managing Editor of California Ag Network and its parent company Malcolm Media.
Ash Madgavkar, founder and CEO at Ceres Imaging, added, “Ceres Imaging has always been a research-driven company. We’re excited to be working with the California Ag Network to offer relevant and easily accessible continuing education credit opportunities for growers.”
Episode One, called Advances in Fertility Management for Wine Grapes, will take place 4-5 p.m. PDT on June 4. Lowell Zelinski, president of the Independent Grape Growers of the Paso Robles Area, is the featured speaker. This episode will kick off with a discussion between Zelinski and Jerome Pier, Agronomist at Nutrien Ag Solutions. The second half of the episode will focus on how imagery analytics can empower farmers to lower their input costs and increase their yields.
Episode Two, Advances in Fertility Management for Tree Nuts, is scheduled for 2-3 p.m. PDT on June 6. David Doll of The Almond Doctor and former UC Cooperative Extension Farm Advisor will begin this series by talking to a local nut grower. This will be followed by a discussion on the cost and yield benefits of imagery analytics.
About Ceres Imaging
Ceres Imaging is a California-based precision agriculture company that helps growers and farm advisors make proactive in-season decisions using aerial imagery and data analytics. Backed by university-validated science, Ceres Imaging uses proprietary sensors, analytics, machine learning models and plant science to help growers gain a more comprehensive picture of their farm. Ceres Imaging takes the guesswork out of in-season decision making and supports its customers with expert agronomists and local customer support. For more information, visit CeresImaging.net.
About Malcolm Media Since 1992, Malcolm Media Ag Publishing has been producing the finest, most informative agricultural publications in the West. Our editorial team is journalistically talented with backgrounds and extensive experience in agriculture. Our publications American Vineyard, California Fresh Fruit, California Dairy, Pacific Nut Producer and Vegetables West are read by more growers, producers, and pest control advisors (PCAs) than any other industry publications. They are best read in the field, and California Ag Network is the industry’s online news hub for agricultural information in the State. Visit MalcolmMedia.com to learn more.
The International Milk Genomics Consortium (IMGC) announced the hiring of Jennifer Smilowitz, Ph.D. as its Director of Scientific and Strategic Development. The IMGC has established an inspiring vision to join mechanistic milk science with the innovators who bring science to practice. Its monthly publication, SPLASH!® reviews findings from current scientific articles on milk and lactation and has more than 1,700 subscribers along with thousands of social readers. Its annual Symposium joins together more than 85 international scientists, experts and innovators from varied disciplines, as well as industry, to share emerging scientific trends and findings in the study of lactation and milk.
“Jennifer Smilowitz is uniquely qualified to guide the next exciting phase of the IMGC,” said Bruce German, Ph.D., founding member of the IMGC and director of Foods for Health Institute, Department of Food Science and Technology, University of California, Davis. “She has an impressive history of mechanistic research science combined with clinical research studies. Few people in the milk world have as much success in building new knowledge and bringing that science to commercial reality.”
Smilowitz attended the inaugural IMGC Symposium in Napa, CA in 2004 and has since participated as either an attendee or invited speaker. As a result, Smilowitz has engaged in active collaborations with other attendees that have generated over 20 publications and demonstrated clinical safety and efficacy for several new products either in or on their way to the marketplace.
“The tools of modern science are accelerating our understanding of mammalian genomics and lactation,” said Smilowitz. “Understanding the functions and impact of milk on, and innovating novel, effective approaches in science for, human health require cross-disciplinary and multi-collaborative approaches.”
Smilowitz plans to use her first-hand experiences with the IMGC and her extensive background in milk and lactation research to further improve the profile of the IMGC and the successful networking environment that has been established.
“It is time for the IMGC to broaden and accelerate the collaborations between the scientific community and the innovators who can make that science happen,” she said. “In the next two years, we will develop new initiatives that will propel collaborations between the scientific community and industry.”
Smilowitz is a faculty affiliate in the Department of Food Science and Technology and Associate Director of the Human Studies Research Program for the Foods for Health Institute at UC Davis. She holds a doctoral degree in Nutritional Biology with an emphasis in Endocrinology from UC Davis and is a fellow of the UC Davis School of Management.
To learn more about how you can interact with the IMGC or its annual Symposium, please contact Jennifer Smilowitz, Ph.D. at jsmilowitz@milkgenomics.org
About the International Milk Genomics Consortium (IMGC):
WASHINGTON, April 30, 2019 — Agriculture Secretary Sonny Perdue announced today the availability of a new web-based tool – developed in partnership with the University of Wisconsin – to help dairy producers evaluate various scenarios using different coverage levels through the new Dairy Margin Coverage (DMC) program.
The 2018 Farm Bill authorized DMC, a voluntary risk management program that offers financial protection to dairy producers when the difference between the all milk price and the average feed cost (the margin) falls below a certain dollar amount selected by the producer. It replaces the program previously known as the Margin Protection Program for Dairy. Sign up for this USDA Farm Service Agency (FSA) program opens on June 17.
“With sign-up for the DMC program just weeks away, we encourage producers to use this new support tool to help make decisions on participation in the program,” Secretary Perdue said. “Dairy producers have faced tough challenges over the years, but the DMC program should help producers better weather the ups and downs in the industry.”
The University of Wisconsin launched the decision support tool in cooperation with FSA and funded through a cooperative agreement with the USDA Office of the Chief Economist. The tool was designed to help producers determine the level of coverage under a variety of conditions that will provide them with the strongest financial safety net. It allows farmers to simplify their coverage level selection by combining operation data and other key variables to calculate coverage needs based on price projections.
The decision tool assists producers with calculating total premiums costs and administrative fees associated with participation in DMC. It also forecasts payments that will be made during the coverage year.
“The new Dairy Margin Coverage program offers very appealing options for all dairy farmers to reduce their net income risk due to volatility in milk or feed prices,” said Dr. Mark Stephenson, Director of Dairy Policy Analysis, University of Wisconsin, Madison. “Higher coverage levels, monthly payments, and more flexible production coverage options are especially helpful for the sizable majority of farms who can cover much of their milk production with the new five million pound maximum for Tier 1 premiums. This program deserves the careful consideration of all dairy farmers.”
For more information, access the tool at fsa.usda.gov/dmc-tool. For DMC sign up, eligibility and related program information, visit fsa.usda.gov or contact your local USDA Service Center. To locate your local FSA office, visit farmers.gov/service-locator.
Emission devices or emitters are vital component of drip/microirrigation systems as they control the dripping (emission) of water and fertilizer solution to the plant.Drip emitters basically slow down the flow rate to a “trickle” by dissipating the energy of the flow through frictional resistance.This makes it possible to deliver water and fertilizer solution to the plant in a frequent localized manner and at, essentially, constant rate; and that is the principal advantage of this method of irrigation.
Efficiency of a drip irrigation system refers to the ratio of the water delivered to the plant to satisfy its water requirements to the total applied water.High efficiency of a drip system is usually desired. Emission uniformity (EU) is a prerequisite for the high efficiency of the system as will be explained later.
Though drip systems are designed around EU, emission uniformity of the system is also influenced by the emitter selection.Therefore, the emitter should be selected prior to the initiation of the system design.Changing the emitter choice after completion of the design could degrade the system.Proper selection of emitter enables using smaller diameter laterals, longer laterals or less sub-main lines which means less costly system while maintaining the desired system uniformity and efficiency.
To help you select the appropriate emitter, a discussion of emitters flow characteristics are presented followed by a description of some of the commonly used types of emitters.A guideline for emitter selection is then provided.
Emitter Flow Characteristics
Drip emitters regulate water flow by dissipating the flow energy through frictional resistance.Laminar flow emitters regulate water flow by dissipating energy via friction against the walls of long and narrow path.Microtubes and spiral path emitters are examples of laminar flow emission devices.
On the other hand, turbulent flow emitters regulate water flow by dissipating energy by friction against the walls of the water passage and also between the particles themselves during their turbulent movements.Orifices, nozzle emitters, tortuous path emitters and jets or sprayers are typically turbulent emitters.The drip tapes that utilize orifices are also turbulent flow devices.
Laminar Flow Emitters
In a laminar flow the fluid particles move along parallel paths in layers or laminas.The magnitude of the velocities of adjacent laminas is not the same and liquid viscosity (i.e., resistance to poring) is dominant in controlling liquid movement and suppresses any conditions that may cause turbulence.
Hydraulic investigations showed that in a laminar flow, the flow rate “Q” of the emitter is directly proportional to the operating pressure and a change in operating pressure will produce an equal percentage of change in flow rate, i.e., if (H1/H2) = 1.1, then (Q1/Q2) = 1.1, and a change of 10 percent in operating pressure would result in a change of 10 percent in flow rate.
Therefore, the flow rate through laminar flow emitters is pressure sensitive (i.e., less pressure compensating, see turbulent flow emitters below).It is also temperature sensitive since it is influenced by the changes in viscosity of water which changes with temperature, i.e., the higher the water temperature the lower the water viscosity and the larger the discharge rate Q.Laminar flow emitters are also more susceptible to clogging because of their low flow velocity and their relatively long and narrow flow path.However, laminar flow emitters are inexpensive and with proper system maintenance will have satisfactory performance.These emitters are more suitable for short run laterals, where head loss is not very large and flow rate would not suffer large change between emitters.
Turbulent Flow Emitters
In turbulent flow the particles of the fluid moves in a haphazard fashion in all directions.While the viscosity is dominant with laminar flow, both inertia (that property of matter because of which a force must be exerted on a body in order to accelerate it) and viscosity affect the turbulent flow pattern.
Therefore, for turbulent emitters hydraulic investigations showed that the flow rate Q will vary with the square root of the operating pressure H, i.e., Q1/Q2 = [H1/H2]1/2 , and a change in operating pressure H of 10 percent would produce a corresponding change in flow rate Q of only 5 percent, i.e., if[H1/H2] = 1.10, then Q1/Q2 = [H1/H2]x = [H1/H2]1/2 =1.05.Thus, turbulent flow devices are less sensitive to pressure variations (more pressure compensating) than laminar devices, i.e., the same pressure change will produce much smaller change in discharge rate with turbulent flow emitters than with laminar flow ones.
The practical application of this conclusion is that if all other factors being equal, the length of laterals for turbulent drip tape for a given design uniformity could be longer than those of laminar drip tape while maintaining the same desired value of EU.Where the length of the lateral line is fixed (e.g., by field dimensions) the use of turbulent drip tape, for instance, will result in higher uniformity than laminar one due to less flow rate variation with turbulent flow.Hydraulic investigations also showed that the flow rate, Q, with turbulent flow emitters is independent of viscosity and therefore it is much less affected by water temperature than laminar flow emitters.Moreover, the flow path of the turbulent emitters is wider than that of the laminar flow ones which make them less susceptible to clogging than the laminar flow emitters.
Discharge Exponent, x
The exponent “x” mentioned above is usually referred to as the “discharge exponent”.The value of this exponent is usually close to unity (≈ 0.7 – 0.8) for laminar flow emitters and about 0.5 – 0.6 for turbulent flow emitters.
Coefficient of Variation, Cv
Manufacturing variability is a common industrial phenomenon where no two items are made exactly the same particularly for items of very narrow internal passages such as drip emitters.A minute change in the dimension of these passages could make a significant difference in the emitter discharge rate especially the pressure compensating ones.The coefficient of manufacturing variability for the emitter (Cv) is used as a measure of expected variations in discharge of new emitters from the average discharge, qa, of a particular sample of the given emitters when operated at a constant pressure head.Usually, emitter manufacturers provide the values of Cv for their products.
The discharge rate of representative sample of emitters operating at a given pressure essentially follows a bell-shaped normal distribution curve. Where qais the average emitter discharge, approximately 68 percent of the discharge rates fall within (qa ± Cv) , 95 percent of the discharge rates fall within (qa ± 2 Cv), and 99.7 percent of the discharge rates fall within (qa ± 3 Cv).
This means that for Cv values of 10% (0.10)samples of emitters with qaof 1gph, 68 percent of emitter discharge rate would fall within the discharge range of (qa ± Cv) or0.9 to 1.1 gph, 95% percent of emitter discharge rate would fall within the range of (qa ± 2 Cv) or 0.8 to 1.2, and 99.7 percent of emitter discharge rate would fall in the range of (qa ± 3 Cv) or 0.7 and 1.3 gph respectively.
Also for Cv values of 5% (0.05) samples of same emitters. 68 percent of discharge rate would fall within the discharge range of (qa ± Cv) or 0.95 to 1.05 gph, 95% of discharge rate would fall within the range of (qa ± 2 Cv) or 0.9 to 1.1, and 99.7 percent of discharge rate would fall in the range of (qa ± 3 Cv) or 0.75 and 1.25 gph respectively.
Therefore, the smaller the Cv value of a given sample of emitters the less different, or the more uniform, is the sample and the better the emission uniformity (EU) of water in the field.Table 1 provides the ranges and the common evaluations (classification) of Cv values.
Table 1. Coefficient of manufacturer variability, Cv
A higher Cv values, is used for line-source tubing because it is difficult to keep Cv and price both low.However, because line-source outlets are usually closely spaced the effect of higher Cv value on discharge uniformity is minimized.
Emission Uniformity, EU
Emission uniformity (EU) is a critical characteristic around which drip irrigation system is designed.EU indicates how uniform the system applies water in the field.High EU is a prerequisite for high efficiency.Irrigation efficiency could be expressed as how much of the applied water is added to the plant root zone.
It is not possible to acquire high efficiency with low uniformity, EU, because with low uniformity higher percentage of the field area will receive either less water or more water than the average application needed to satisfy the crop water requirements.To remedy this deficiency more water will need to be applied to the field to satisfy the requirements of the under-irrigated parts of the field.This will result in over-irrigating the rest of the field and that means more water is lost away from the root zone resulting in lower irrigation efficiency.
With high EU, only small percentage of the field will be under-irrigated and the volume of water needed to provide for the under-irrigated parts of the field will be much smaller, the losses will be smaller as well, therefore, the efficiency will be higher.However, it is possible to have a low efficiency with high EU.This is not contradictory to what was previously stated that high EU is a prerequisite for high efficiency. For example, if high EU is achieved in a field but excessive amount of water is applied to that field by applying irrigation water for much longer period of time than scheduled for delivering the estimated water requirements of the crop (i,e., over-irrigation) then, large amount of water will be lost away from the root zone and the irrigation efficiency will be low despite the achieved high EU.
Fig. 1. Typical layout of a microirrigated system
B:Types of Emitters
Emitters are usually grouped according to their flow patterns (e.g., laminar and turbulent flow), wetting patterns (e.g., point-source, line-source, multi-exit emitters), and special functions (e.g., pressure compensating and flushing emitters).Some emitters may combine more than one attribute, e.g., pressure compensating line-source emitter (drip tape).
Flow Pattern
* Laminar & Turbulent Flow Emitters
Turbulent flow emitters have the advantage of being less sensitive to pressure variation (i.e., more pressure compensating), less sensitive to water temperature variations, less susceptible to clogging and allow for longer lateral runs or less pressure variation for the same length of lateral run than laminar flow emitters.Laminar flow emitters are less expensive and more suitable for short-run laterals.On-line, in-line and drip tape come in either laminar or turbulent flow type.Both laminar and turbulent flow emitters may come in standard or pressure compensating type.
Wetting Pattern
*Point-Source and Line-source emitter
Drip irrigation with water discharged from emission points that are rather widely spaced, usually 3 ft or more, is commonly referred to as point-source application.When water is discharged from more closely spaced outlets it is called line-source application.Examples of point-source is on-line and in-line emitters (see Fig’s. 2 & 3).The most common discharge rate of point-source emitters is 1 gph.Other available sizes are 0.5, 1.5, 2.0 gph.Point-source emitters come in standard and pressure compensating models.
On-line emitters are commonly used for irrigating orchards and vineyards.The PE (polyethylene) laterals are usually laid on the ground surface (see Fig. 2).This type of emitters offers the user the advantage of installing an emission device exactly where wanted and the emitters are serviceable.Their disadvantage is that the end user must manually insert each emitter.
In-line emitters or drip lines are similar to on-line emitters but in this configuration they are pre-inserted into the PE tubing at specified intervals during the tubing extrusion process (see Fig. 3).The emitters may be cylindrical or flat “boat shaped”, and are attached to the inner tube wall via a controlled heating/adhesion process.Labor savings for the end user may be substantial since emitters are factory pre-installed.The drawback is that emission devices may exist where not needed, and they are not serviceable. Drip-line may be installed below the surface such that the soil surface may be kept dry.Both on-line and in-line emitters come in regular and pressure compensating types.
Examples of line source are single chamber and double chamber drip of relatively thin tubing, commonly known as “drip tapes” (see Fig. 4).Single chamber tubing has orifices punched or more complex emitters fabricated or inserted at intervals of 2 ft or less along the tubing.Double chamber tubing is a hose that has both a main and auxiliary bore separated by a single wall.Widely spaced inner orifices are punched in the separator wall between the main and the auxiliary bore; for each inner orifice, three to six exit orifices are punched at intervals of 0.5 to 2 ft in the outer wall of the auxiliary bore.
Drip tape may be classified according to their flow pattern as either turbulent or laminar.Turbulent drip tape controls flow rate by means of orifices or tortuous flow paths, while laminar tape utilizes small tubes or capillaries to control flow rate.These two types of drip tape exhibit different flow rate response to pressure variation (as explained earlier) and they are not mutually exchangeable for the purpose of system design.
Water is distributed evenly along the length of the drip tape through emission devices that may be spaced anywhere from 4” to 24” apart.Tube wall thicknesses vary from .004” to .015” (4 mil to 15 mil), emitter flow rates from 0.07 to 0.34 gph, and tube diameters from 5/8” to 1-3/8”.Drip tape is used extensively for irrigating vegetable and field row crops e.g., strawberries and tomatoes.It may be installed above or below the ground, and may be retrieved for multi-season reuse or disposed of at the end of each season.Drip tape is relatively inexpensive and is ready to install without any additional emission device installation labor.
*Sprayer, Jets or microsprinklers(see Fig. 7 & 8)
These are small applicators designed to spray water to cover an area of 10 to 100 ft2.Jets are mounted on risers or stakes (see Fig. 8) and spray water through the air as separate streams that create various foot printpatterns of water in the soil.A variety of patterns are available including full circle, half circle, hi/low trajectory, butterfly, etc.The versatility of patterns provides a great deal of flexibility for the end user to accurately apply water only where wanted, such as enveloping each tree in an orchard without wetting the trunk.Wetted diameter ranges from 10 to 35 ft and discharge rate from 5 to 30 gph.Flow through jets is turbulent with discharge exponent x = 0.5.Jets are commonly used on orchard crops like almond and citrus and on light textured soils.
Special Function
*Pressure-Compensating Emitters
This type of emitters provides varying degree of flow regulation with discharge exponent “x” value ranging from 0.0 to 0.4.For complete flow regulation x = 0.0.Pressure compensating devices may be either laminar or turbulent.In either case, these devices utilize the inlet pressure to modify the flow path size, shape or length.In this way, pressure-compensating devices are able to deliver the correct flow rate over a fairly wide range of inlet pressures, and within that range their flow rates are relatively constant.Pressure-compensating emitters are useful for use in undulating fields.
Pressure compensating emitters suffer from the drawback that the elastomeric material used in their construction has a tendency to change their properties as they age. The following graphs (Fig’s. 9 & 10) show the difference in performance between pressure-compensating and non pressure-compensating emitters.
*Flushing Emitters
This type of emitters is designed to have a flushing flow of water to clear the discharge opening every time the system is turned on.Continuous flushing emitters permit continuous passage of large solid particles whileoperating.Some on-line emitters and drip tape are manufactured with flushing capabilities.
*Multi-Exit Emitters(see Fig. 6)
Some on-line emitters supply water to two or more points through small diameter auxiliary tubing; they are used in orchards where large trees may require several emission points for each tree.They are usually more expensive than single exit emitters.
E.A Guideline for Emitter Selection
The pressure variation within the system and the flow characteristics of the selected emission devices influence the uniformity of water distribution (EU) of a drip/microirrigation system.While the control of pressure variation by proper system design is certainly required, the selection of the emitter device itself is also vital for achieving the desired high EU and high system efficiency (e.g., x & Cv).Moreover, emitter selection is critical for specifying the water treatment and the filtration equipment for the drip system.Filtration requirement for a given emitter is specified by the emitter manufacturer.User preference might also be a factor and personal and local experience may influence the choice of emitter.
However, two very important items to be considered in emitter selection are the percentage area wetted, which is related to delivering the required amount of water to the plant at the design pressure, and the reliability of the emitter against clogging and malfunctioning.
It is recommended to provide a sufficient number of emission points to wet between one-third and one-half of the horizontal cross sectional area of the potential root-zone.Field observations have shown that the density of emission points required to obtain such percentage of wetting can be based on an assumed discharge of 1 gph emitters.For perennial crops, the number of emitters can be increased with the age of the plant and stage of growth.However, the initial pipe network must be designed to meet the needs of the mature plants.It is usually recommended that the filtration process should remove all particles larger than one-tenth the diameter of the emitter passage way.Also, regular flushing of laterals can significantly reduce emitter clogging (see Fig. 11).
Conclusion
Generally, the selection of an emitter depends on the soil to be wetted, plants to be grown and their water requirements, quality of irrigation water and emitter discharge. The cost ofemitter should be also be considered as the average total cost of emitters may amount to about 20-25 percent of the total cost of the system.The following points together with above provided explanations may provide a guideline for emitter selection.
First determine the general type of emitter that best fits the needs of the crop to be irrigated and the area to be wetted, i.e., continuous wetting pattern for vegetable crops where a drip tape could be suitable, on-line emitters for irrigating orchard crops,jets where relatively coarse textured soil prevails or where light water applications with large foot print could be more suitable for the crop requirements.The use of pressure compensating emitters may be advantageous for undulating terrain.
Second, according to the required discharge, spacing, and other field conditions, choose the specific emitter needed, i.e., which drip tape, jet pattern, or on-line emitter could be more fitting for supplying the water requirements of the crop, e.g.,for drip tape, is it going to be for one season, 4 mil, or for several seasons, 25 mil.Third, determine the required discharge (q) and operating pressure head (H) for the average emitter that fits the system design and prevailing conditions (e.g., water quality, soil properties, weather conditions).
It is also important to examine the emitter characteristics described above i.e., x, Cv, filtration requirements.Emitters with discharge exponent (x) closer to 0.5 is more pressure compensating, less sensitive to temperature changes and less susceptible to clogging than the ones with the value of x closer to one. The smaller the Cv value for the emitter the more uniform is water application in the field.Emitters with Cv between 0.03 to 0.05 are expected to provide higher EU and consequently higher system efficiency than the ones with Cv between 0.07- 0.09.
Filtration requirement as stated by the emitter manufacturer should also be considered, the smaller the required mesh number (number of opening per inch) the less susceptible the emitter to clogging.Emitters that require mesh number 160 is less susceptible to clogging than the ones that requires 260 mesh number for filtration.However, the filtration requirements as stated by the emitter manufacturer should be fulfilled.Also, enquire with emitter manufacturers regarding the tolerance of emitter components to chemicals such as acid and chlorine usually used for system cleaning and disinfection.Finally, local and personal experience should be taken into consideration.
For more information, visit www.agridrip.com or contact F.A.Hassan, an irrigation & Soils Consultant at Agro Industrial Management at “fahassan@aol.com“
Researchers and growers are tackling the formidable tree nut pest Navel Orangeworm from all fronts. One method underway is in utilizing the same sterile insect technology and facility that eradicated pink bollworm from the cotton industry years ago. There have been some challenges in adapting the system for Navel Orangeworm, as shared by Bob Klein from the Pistachio Research Board; however there is great potential for this program to aid growers in managing this pest. Watch this brief interview with Bob and read more about it in Pacific Nut Producer Magazine.
Western Growers has officially launched an interactive directory that acts as a marketplace for agricultural technology (agtech) startups. Found at https://www.agtechpages.com, the Western Growers AgTech Innovation Directory allows users to identify, research and connect with start-up companies who are developing technologies and innovations to solve the biggest issues facing the agriculture industry. These startups are specializing in everything from automation and traceability to data management and aerial imagery.
“As the agtech industry grows and the number of startups continue to increase, farm operators do not necessarily have the time to vet each startup to determine if a partnership is viable,” said Hank Giclas, Western Growers’ senior vice president, strategic planning, science & technology. “The vision of Western Growers AgTech Innovation Directory is to streamline that process, saving farmers time and money by allowing them to easily search for the startup and technology that meets their most immediate needs.”
The directory enables users to learn details about each startup including team size, years in business and product/service descriptions. It also provides access to metrics such as acres deployed, community ratings, funding raised and business reviews.
The advanced search function of the directory allows users to quickly find desired startups. Filter categories include the following:
Location
Issues Addressed (food safety, labor availability, water supply/quality, compliance costs, data management, planning & optimization, etc.)
Solutions Offered (automation/mechanization, pest management, imagery & mapping, traceability, water treatment, irrigation hardware/software, predictive analytics, etc.)
Crops/Commodities
In addition to serving farmers, the directory will provide agtech start-up companies with the abilit
y to connect directly with growers and potential clients, as well as provide venture capitalists with the opportunity to explore a startup’s progress prior to investing. The directory is open to the public; however, only Western Growers and Western Growers Center for Innovation & Technology (Center) members will be able to post comments and reviews.
The launch of the Western Growers AgTech Innovation Directory is part of the Center’s efforts to accelerate the development and adoption of agricultural technologies. Today, the Center houses 50 startups that are inventing solutions to allow farmers to continue feeding the nation and world.
About Western Growers
Founded in 1926, Western Growers represents local and regional family farmers growing fresh produce in Arizona, California, Colorado and New Mexico. Our members and their workers provide half the nation’s fresh fruits, vegetables and tree nuts, including half of America’s fresh organic produce. For generations we have provided variety and healthy choices to consumers. Connect with and learn more about Western Growers on our Twitter and Facebook.
Western Growers has officially launched an interactive directory that acts as a marketplace for agricultural technology (agtech) startups. Found at