Progress Report on Microirrigation in California, 2003, from Ken Shackel, J. W. Hopmans, David J. Hills, Tom Trout, Jim Ayars and Dave Bryla
Ken Shackel, U.C. Davis, Annual Report of Cooperative Regional Project, W-128
January 1, 2003 to December 31, 2003.
Publications:
Abdel-Fattah, H.M., KA Shackel, DC Slaughter. 2003a. Methodology for determining almond shaker displacement and frequency. Applied Engineering in Agriculture 19:141-144.
Abdel-Fattah, H.M., KA Shackel, DC Slaughter. 2003b. Substantial vertical tree displacements occur during almond shaker harvesting. Applied Engineering in Agriculture 19:145-150.
Presentations:
Annual meeting of the California Almond
Board, December, 2002
Annual meeting of the California Dried
Plum Advisory board, December, 2002
Graduate students:
Tiesen Cao, PhD, plant biology, UCD
Cayle Little, MS, horticulture, UCD
Progress of Work and Principal Accomplishments.
Objective 1: To evaluate and refine microirrigation management strategies to promote natural resource protection and optimal crop production.
CA: In dried plums (prunes), grower demonstration plots demonstrated substantial water savings (>50%) by allowing mild to moderate deficits in SWP (to -15 bar by harvest) with only positive effects on economic yield. In almonds, a third year of grower plots demonstrating the use of RDI to reduce hull rot and improve nut harvestability was completed and showed no negative effects on yield or nut size. In almonds, a study was completed and published demonstrating that barking injury may be due to a previously unrecognized vertical motion in shaker harvesting. Since barking injury has been widely regarded as related to irrigation management, this finding will convince almond growers that RDI management can be practiced without fear of increasing shaker injury.
Objective 2: To improve, modify, and evaluate microirrigation system design and components for natural resource protection and optimal production
Objective 3: To assess and develop decision criteria for adoption of microirrigation technologies
Objective 4: To promote appropriate microirrigation technologies through formal and informal educational activities.
CA: Presentations were made demonstrating the benefits of RDI at the annual statewide dried plum and almond industry group meetings. An industry sponsored survey of dried plum growers showed that 6% of the growers state wide are using the pressure chamber to schedule irrigation.
Usefulness of findings.
Objective 1:
CA: Plant-based RDI has allowed substantial reductions (40 - 50+%) in irrigation water applied to prune trees, while maintaining or improving economic yields. Water savings in almonds have depended on soil type and depth, with the most substantial savings (over 35%) on the deepest soils.
Objective 2:
Objective 3:
Work Planned
Objective 1:
CA: Prune and almond RDI demonstration plots will be continued in 2004, and a yield and fruit quality summary for the 3-4 year prune sites will be compiled to evaluate any medium-term effects.
Objective 4:
CA: Presentations will be made informing
growers of the benefits of site-specific management of deficit irrigation
at the annual meetings of a number of industry groups, including the California
almond board, the California dried-plum (formerly prune) board, and the
walnut and cling peach boards.
Jan W. Hopmans, University of California
Davis
Microirrigation technologies for protection
of natural resources and optimum production
Period Covered: 2002-2003
Highlights by project objective:
Proper water and soil management is essential for both sustainable agriculture and integrated food production. In general, irrigation scheduling is based on the water balance method, however, using localized irrigation, it is difficult to evaluate most of water balance terms. An additional complication arises from the non uniformity of to compensate for root suberization and relative root inactivity in the non-wetted soil. Therefore, efficient water management in micro-irrigated rooting systems depends on knowledge of the spatial and temporal distribution of root water uptake, as well as on the ability to predict variations of soil water status in the root zone after irrigation. Whereas much is known about root morphology, including the spatial distribution of roots under localized water application, information to date on the spatial and temporal distribution of root water and nutrient uptake is limited, especially for partially wetted soils.
Objective 1.
To provide experimental data for the development,
verification and calibration of multi-dimensional root water uptake model,
thereby improving microirrigation scheduling and management, a field study
was initiated in a micro-sprinkler irrigated almond orchard. Micro-irrigation
research was carried out at the Nickel’s Estate Experimental orchard, 90
km north of Davis, California, in the Sacramento River Valley. The orchard
was planted in 1990 with four different varieties of almond trees with
six years old almond trees (Prunus amygdalus) varieties using a tree spacing
of 6.6 x 4.8 m. The trees in the experimental orchard were irrigated by
surface drip, subsurface drip, and microsprinklers. Previous years’ experiments
indicated that there was an advantage, as measured by tree yield and growth,
to wetting a larger soil volume under the coarse-textured, low water holding
capacity soils of the Marine Ave. orchard. This gave an advantage
to the microsprinkler-irrigated trees in the orchard. The soil hydraulic
and root water uptake parameters, characterizing the spatial geometry of
the rooting system in the three-dimensional spatial domain were optimized,
minimizing the residuals between measured and simulated water content data
for the sprinkler-irrigated almond tree during a 16-day period, following
irrigation. With the optimized root water uptake parameters, simulated
and measured water contents during the 16-day period were in excellent
agreement for each of the investigated root water uptake models. Most significantly,
the spatial variation in flux density decreased when simplifying multi-dimensional
root water uptake to fewer dimensions, thereby justifying the proposed
multi-dimensional approach.
Despite that water application was non
uniform, soil moisture uniformity prior to irrigation was large, and was
caused by differential root water uptake in the surface soil. Throughout
the experiments, the roots of the almond tree were capable to redirect
their areas of maximum root activity towards the zones of the most favorable
water regime, thereby resulting in fairly uniform water content distributions.
Typically, zones of maximum root water uptake developed from the tree trunk
towards the outer regions of the root zone, shifting to wetter parts of
the root zone domain. Consequently, soil water depletion patterns formed
a radial pattern around the tree trunk. It was concluded that factors controlling
root water uptake in irrigated tree crops are (1) spatial distribution
of active roots, (2) root zone water distribution, and (3) distance
from the tree trunk.
Simulated spatial variations in drainage
rate and root water uptake using the multi-dimensional root water uptake
models decreased when simplifying multi-dimensional soil water flow
and root water uptake to decreasing spatial dimensions. This may
have large implications for chemical transport in root zones, as drainage
rates and corresponding chemical transport rates will vary according to
root water uptake distribution. It was shown that spatial variability
of drainage rates were large, with values increasing as corresponding root
water uptake values decrease. The increasing accurate spatial description
of root water uptake and soil water flow with increasing spatial dimension
is essential to improve model predictions of water fluxes and contaminant
transport through the root zone. Moreover, total chemical load to the groundwater
will depend on local concentration and fluxes, and their spatial variability.
Objective 2.
In their recent review of root water and nutrient uptake modeling, Hopmans and Bristow (2001) concluded that progress in the basic understanding of transport processes in the soil-plant-atmosphere continuum (SPAC) has been slow, specifically regarding interfacial fluxes at the root-soil interface. They speculated that the so-called knowledge gap of plant responses to water and nutrient limitations is caused by the historical neglect of studies of below ground processes. Consequently, water and nutrient uptake in plant growth and soil hydrological models are mostly described in an empirical way, often lacking a sound biophysical basis. This is unfortunate, as the exchange of water and nutrients is the unifying linkage between the plant root and surrounding soil environment. The simplified sink approach is adequate for non stressed plant growth conditions, and may work adequately for uniform soil conditions. However, it is clear that a different approach is needed if water and/or nutrient resources become limited. Increasingly, recommended micro-irrigation practices tactically allocate water and fertilizers, thereby maximizing their application efficiency and minimizing fertilizer losses through leaching towards the groundwater, so as to keep environmental effects of crop production within acceptable levels. The review suggested that the effectiveness of such practices requires a thorough understanding of soil properties and processes and associated plant-soil interactions in plant-stressed soil environmental conditions. This includes knowledge of the crops responses to the availability of spatially distributed soil water and plant-available nutrients, using a multi-dimensional modeling approach.
Impacts:
1. The root modeling research has led to
various publications that point out the need of a much improved understanding
of the functioning of plant roots in stressed soil conditions, especially
in micro-irrigation systems;
2. Invitations to present the root modeling
research, nationally and internationally, to find approaches that
quantify the role of micro-irrigation in efficient water management, minimizing
crop water stress and plant nutrient leaching.
Publications:
Bassoi, L.H., J.W. Hopmans, L.A. de C. Jorge, C.M. De Alencar, and J.A.M.E. Silva. 2003. Grapevine root distribution in drip and microsprinkler irrigation using monolith and the soil profile method. Scientia Agricola. Vol. 60(2): 377-387.
Hopmans, J.W., and K.L. Bristow. 2001. Current capabilities and future needs of root water and nutrient uptake modeling. Advances in Agronomy. Volume 77: 104-175, 2002.
Vrugt, J.A., M.T. van Wijk, J.W. Hopmans, and J. Simunke. 2001. One, two, and three- dimensional root water uptake functions for transient modeling. Water Resour. Res. 37:2457-2470.
Teruel, D.A., D. Dourado-Neto, J.W. Hopmans, and K. Reichardt. 2001. Structural changes in soybean root system as a response to soil phosphorus availability. Scientia Agricola. Vol. 58:5-60 (In Portuguese).
Vrugt, J.A., J.W. Hopmans and J. Simunek. 2001. Calibration of a two-dimensional root water uptake. Soil Sci. Soc. Amer. J. 65:1027-1037.
David J. Hills, U.C. Davis
Objective 2: To improve, modify, and evaluate microirrigation system design and components for natural resource protection and optimal crop production.
1. GPS auto-guidance system for subsurface drip-tape installation and maintenance. A GPS auto-guidance system was developed for placing and maintaining subsurface drip-tape in row crops. The objectives of this project were to determine the effect of spacing between cultivator disks and tractor forward speed on plant damage and the effect of deep tillage operations on drip tape damage. Two sets of split-plot field experiments were conducted (one using processing tomato transplants and the other using direct seeded tomatoes) on the UC Davis campus. The results indicated that no significant plant damage occurred at 11.2 km/h forward speed and 5 cm cultivator disk spacing from the plant line. Additionally there was no significant damage to drip tape when fertilizer shanks were operated 5 cm from the drip tape at 5.6 km/h travel speed.
2. Impact Statement: Subsurface drip irrigation has the potential for improving water use efficiency, reducing weed growth, and improving overall energy efficiency. The GPS guidance system allowed for automatic steering of the tractor and implements close to the buried drip-tape and plants without causing damage to either while operating at relatively high operational ground speeds.
3. Publications:
Abidine, A. Z., B. C. Heidman, S. K. Upadhyaya,
and D. J. Hills. 2002. Application of RTK GPS based auto-guidance
system in agricultural production. American Society of Agricultural
Engineers Paper Number 02-1152. 11 pages including 2 tables and 5
figures. July.
Aziz Z. Abidine, Brian C. Heidman, Shrini K. Upadhyaya, and David J. Hills. In Press. Application of RTK GPS based auto-guidance system in agricultural production, California Agriculture.
4. Graduate Student: Brian C. Heidman
1. Microirrigation lateral design for site-specific agriculture. Current design procedures for microirrigation systems are based on uniformity of water application. However, it is generally known that plant water requirements are non uniform within an agricultural unit, and, therefore, uniform application of water may not be efficient. A simple design procedure was developed for laterals with unequal emitter discharge rates to match variable plant water requirements, and unequal emitter spacings to match the need for unequal plant spacings. In phase one, a step-by-step (SBS) model was built to simulate the effects of study variables on lateral hydraulics. In phase two, field experiments were conducted to verify the SBS model. The percentage difference between theoretical and experimental results was satisfactory and ranged between ±6.0%. In the third phase, the segment-based analysis (SBA) technique was developed to simplify the procedure of calculating head loss in non uniform laterals. The SBA technique transformed the lateral into a virtual lateral divided into a number of equal-length segments and replaced existing emitters by a virtual emitter positioned at the center of each segment. Accuracy levels of ±5.0% were attained by using five segments. A graphical lateral design tool was developed for readily designing site specific laterals.
2. Impact Statement: Current design procedures for microirrigation systems are based on uniformity of water application. This project is developing site-specific guidelines for optimizing natural resources and minimizing environmental concerns by treating each plant differently with respect to irrigation input.
3. Publication:
Talozi, S. A., and D. J. Hills.
2002. Hydraulic design considerations for microirrigation laterals
in landscape. American Society of Agricultural Engineers Paper
Number 02-2249. 23 pages including 1 table and 11 figures.
July.
4. Graduate Student: Samer A. Talozi
Tom Trout, Jim Ayars and Dave Bryla, USDA-ARS, Fresno, Ca, W-128 Report 2003
Accomplishments:
Showed in a 3 year field trial that young peach trees used subsurface drip, surface drip and furrow irrigation water more efficiently than water applied with microsprays. Young trees irrigated with microsprays required 72% more irrigation water to maintain the same stem water potential as with subsurface drip irrigation, and 100% more water to achieve the same growth. The reason for this difference is primarily the high soil evaporation with microsprays on young trees.
Installed and tested a weighing lysimeter to determine crop coefficients for vegetable crops including broccoli, lettuce, peppers, and onion. Installed a field facility to compare surface drip, SDI, and furrow irrigation management and water use for vegetable crops.
Determined that about 50% of the microirrigation systems in the California Central Valley used higher pump pressures than should be required for these systems. Twenty five percent of the systems had pump pressures in excess of 40 psi. Sources of the excess pressure loss included undersized filters and piping, excessive pressure regulation, and excessive pressure at the emitter.
Developed equipment and management practices to safely and effectively apply soil fumigants through drip irrigation systems. Showed that efficacy of drip-applied fumigants equaled or exceeded those applied through traditional shank application. Drip fumigation has been commercialized and over 10% of California strawberries were drip fumigated in 2002.
Developed and patented a device to measure pressure in thin-walled drip tape without puncturing the tape. The “squeezer” measures to force require to compress the tape a certain amount, and converts the force to a pressure.
Publications:
Trout, T.J. and J. Gartung. Energy Use for Microirrigation. In. Energy, climate, environment and water - issues and opportunities for irrigation and drainage. Proc. of joint US CID and ASCE Env. and Water Resources Inst., San Luis Obispo, CA July 10-13, 2002. pp. 465-474.
Ajwa, H.A., T. Trout, J. Mueller, S. Wilhelm, S.D. Nelson, R. Soppe, and D. Shatley. Application of alternative fumigants through drip irrigation systems. Phytopathology 92(12):1349-1355. 2002.
Kincaid, D.C. and T.J. Trout. Squeezer: a device for indirect pressure measurement in thin-wall drip irrigation tubing. Appl. Engr. in Agri. 18(6):685-690. 2002
Kincaid, D.C. and T.J. Trout. Fluid pressure measurement by mechanical compression of thin-walled tubing. U.S. Patent #6,622,565. 2003. (Patent).
Bryla, D.R., T.J. Trout, J.E. Ayars, and R.S. Johnson. Irrigation management practices for maximizing growth and improving crop water use efficiency in young peach trees. Hort Science (In Print)
Trout, T.J., and H.A. Ajwa. Application of soil fumigants through micro-irrigation systems. Paper #032021 presented at the 2003 Ann. Meet. of the ASAE, Las Vegas, NV.
Popular Press Articles:
Plump peaches that require less water to grow are the goal of research. The Wall Street Journal and the L.A. Times, Nov. 2, 2000.
Scientist's hard work bears fruit. The Fresno Bee, Nov. 98, 2000.
Putting down roots. Western Fruit Grower, Apr., 2001
How much water and fertilizer do young trees need? The Good Fruit Grower, July, 2001
Eye in the dirt. California Farmer, Feb. 2002 (cover article and photo)
Camera exposes tree root behavior for peach producers. Capital Press, Apr, 4, 2002.
Got Uniformity? Device puts the squeeze on drip irrigation pressure differences. The Grower, Sept/Oct, 2003.
New Pressure Tester Helps Fine-Tune Irrigation Systems. Agricultural Research. July 2003.
Effectiveness of drip fumigation examined in strawberry fields. Ag Alert, Oct., 2003.
Abstracts (Oral/Poster presentations):
Bryla, D.R., Trout, T.J., Ayars, J.E., Johnson, R.S. 2000. Irrigation management practices for improving water and nutrient use efficiency and crop productivity in young peach trees. National Irrigation Symposium. Proceedings of the 4th Decennial Symposium (Addendum), Phoenix, Arizona, Nov. 14-16.
Bryla, D.R., Trout, T.J., Johnson, R.S., Ayars, J.E. 2001. Improving growth in young peach trees by subsurface drip irrigation. HortScience 36:462-463.
Bryla, D.R., Sefton, R.K., Soppe, R., Gartung, J.L., Trout, T.J., Ayars, J.E. 2002. Irrigation strategies for improving productivity and water use efficiency of vegetable crops in central California. 2002 Annual Meetings of the ASA-CSSA-SSSA, Indianapolis, Indiana, Nov. 10-14.
Bryla, D.R. 2003. Water requirements and yield of peach trees irrigated by microjet sprinklers and subsurface drip. 4th International Symposium on Irrigation of Horticultural Crops, University of California, Davis, California, Sept. 1-5.