Environmentally Sound Irrigation and Fertility Systems for Sweet Cherry Crops in the Pacific Northwest

Final Report for FW05-302

Project Type: Professional + Producer
Funds awarded in 2005: $19,585.00
Projected End Date: 12/31/2008
Region: Western
State: Oregon
Principal Investigator:
Clark Seavert
Mid-Columbia Agricultural Research Center
Expand All

Project Information

Abstract:

The objective of this project was to evaluate the impacts of drip irrigation, split N fertigation, and ground covers on water consumption, N use, and fruit productivity of sweet cherry. A field experiment was conducted using ‘Lapins’ sweet cherry at The Dalles, OR in 2005 and 2006. Two irrigation systems (single-line drip irrigation and micro sprinkler irrigation) and four ground management systems [straw mulch, white polypropylene cover, black polypropylene cover, and control (no mulch or polypropylene cover, but herbicides were used to control weeds)] were evaluated in a split-plot design with four replicates. Another field trial was implemented on ‘Regina’ cherry trees at Hood River, OR in 2006 and 2007. Five N fertigation and irrigation systems [1. control (micro sprinkler + broadcast application of dry N fertilizer on the soil surface), 2. micro sprinkler irrigation + fertigation of N fertilizer injected at the same time and interval as irrigation, 3. drip irrigation every day + fertigation of N fertilizer every day, 4. drip irrigation every two days + fertigation of N fertilizer every two days, and 5. drip irrigation every four days + fertigation of N fertilizer every four days] were evaluated in a randomized complete block design with four replicates.

Our two-year results at The Dalles showed the biggest benefit with drip irrigation was water saving. During the entire season from May to September each year, drip irrigation consumed only 21 to 26% of irrigation water relative to micro sprinkler irrigation. Black polypropylene, white polypropylene, and straw mulch covers reduced irrigation water use slightly compared with no cover. Fruit yield was statistically similar under drip irrigation and micro sprinkler. There was a trend of yield increase with straw mulch and polypropylene covers relative to no cover. Fruit quality including firmness, color, and size did not differ regardless of irrigation or ground cover system. Drip irrigation increased marketable fruit by about 4-5% (absolute value) via reducing fruit surface pitting compared with micro sprinkler. Overall, drip irrigation seems to be a good system for orchards in regions that are short of water.

At Hood River in both years, micro sprinkler irrigation plus N fertigation system resulted in significantly higher leaf N concentrations than micro sprinkler plus dry N fertilizer system after harvest. However, no increase in leaf nutrient concentrations was observed with the three drip irrigation plus N fertigation systems compared with micro sprinkler plus dry N fertilizer system. The three drip irrigation plus fertigation treatments saved over 60% of irrigation water per season relative to the two micro sprinkler treatments. Fruit yield and quality were statistically similar among the five irrigation and N management systems. Overall, drip irrigation plus N fertigation systems produce competitive sweet cherries with much less irrigation water and provide more flexibility for N fertilizer applications.

The impacts of this project on sweet cherry productivity and profitability and the environment were significant, and will be greater. About 300 targeted sweet cherry growers along with thousands of other fruit growers were educated through this project. More and more growers in the Pacific Northwest have begun to use drip irrigation, ground covers, and N fertigation on their orchards, and this trend will be magnified during the next 5 to 10 years.

Introduction

Oregon’s Mid-Columbia region boasts the highest concentration of cherry orchards in the United States. Production of sweet cherry is highly dependent on the inputs of water and nitrogen (N) fertilizer to achieve optimum yields in the Pacific Northwest. Currently, impact and micro sprinklers are the primary form of irrigation. Nitrogen fertilizer is broadcast applied on soil surface as a dry material once or twice per year. Both water and N use efficiencies are low under these management practices. Overall, the current water and N management practices have resulted in high production costs and low grower profitability, and contaminated streams and rivers due to increased N leaching losses from the soil. Furthermore, there is increasing concern about the adverse impacts of current water and N management practices on fruit quality and the storability of sweet cherry. Therefore, research is needed to develop more efficient irrigation and N management systems.

So far, little research has been done to address the effects of drip irrigation and fertigation on growth, yield, quality, and storability of orchard trees. On the other hand, enhanced yields, higher water and N use efficiencies, and improved control of weeds are reported with both drip irrigation and fertigation on some non orchard crops. For example, drip irrigation increased sweet pepper yield by 50% compared with micro sprinkler (Goyal et al., 1987). Water consumption was reduced by as much as 50% with drip irrigation relative to micro sprinkler in potato production (Waddell et al., 1999). Nitrogen use efficiency was enhanced by above 20% relative to broadcasting of dry N fertilizer to the soil surface on citrus trees (Sauls, 2004). In addition, water management is highly related to fruit quality and storability. For instance, excessive application of water or prolonged water uptake by the fruit can cause sweet cherry surface pitting (Patten et al., 2004). However, drip-irrigation and fertigation have not been tested either separately or as an integrated production system on sweet cherry in the Northwest. No guidelines are available about water and N management for drip irrigated or (and) fertigated sweet cherry.

Ground management is another key practice in sweet cherry production. Growers overwhelmly use herbicides to control weeds at present. However, herbicides are quite expensive and may hurt soil ecosystems and cause water contamination. Although no publications about polypropylene and straw mulch ground covers on sweet cherry are available, some research about mulch cover has been done on apple, and the results are encouraging. Mervin and Stiles (1994) reported that trunk cross-sectional area and fruit yield of apple were significantly enhanced due to mulch cover compared with no ground cover but with herbicide applications. Soil water availability, soil organic matter, water infiltration, saturated hydraulic conductivity, and soil temperatures were improved by mulch cover (Merwin et al., 1994). In addition, nitrate-N and benomyl fungicide leaching and runoff were reduced due to mulch cover relative to no cover but with herbicide applications (Mervin et al., 1996). All these results suggest orchard productivity, soil fertility, and soil quality are improved due to straw mulch ground cover. However, no research has been done to compare all these different ground cover management options simultaneously under different irrigation systems.

Project Objectives:

The objectives of this project were to: 1) examine the impacts of drip irrigation and N fertigation systems on sweet cherry water and N use compared with micro-sprinkler irrigation and broadcast application of dry N fertilizer systems; 2) evaluate the effects of drip irrigation and fertigation systems on fruit yield, quality, and storability of sweet cherry; and 3) compare the effects of different ground cover systems (straw mulch, white polypropylene, black polypropylene, and no cover but with herbicide applications) on fruit yield, quality, storability, and water use of sweet cherry.

Cooperators

Click linked name(s) to expand
  • Jinhe Bai
  • John and Julie Benton
  • Mel and Linda Omeg
  • Xinhua Yin
  • Jac le Roux

Research

Materials and methods:

A field experiment was conducted on the Omeg Orchards at The Dalles, OR in 2005 and 2006 to examine the impacts of drip irrigation systems and ground covers on water use and sweet cherry productivity. A 2-ha orchard block planted at a 5.4 m (between-row) × 4.8 m (in-row) spacing in 1999 with ‘Lapins’ sweet cherry on Mazzard rootstock was used in this study. Two irrigation systems (single-line drip irrigation and micro sprinkler irrigation) and four ground management systems [mulch with wheat straw (15 cm thick), white polypropylene cover (3-m wide), black polypropylene cover (3-m wide), and control (no mulch or polypropylene cover, but herbicides were used to control weeds)] were evaluated in a split-plot design with four replicates. The two irrigation systems and four ground management systems were assigned to the main and sub plots, respectively. The drip irrigation system has a capacity of 0.5 gallon of water per hour per emitter, while the micro sprinkler has a capacity of 15 gallons per hour per emitter. That means each tree receives 4 gallons of water per hour under drip irrigation, and 15 gallons per hour under micro sprinkler. Each plot included seven trees in a row, only the middle five trees were used for field measurements and yield harvest.

Another field trial was conducted on ‘Regina’ cherry trees that were planted in 2001 on Benton Orchards at Hood River, OR in 2006 and 2007. Five N fertigation and irrigation systems [1. control (micro sprinkler + broadcast application of dry N fertilizer on soil surface), 2. micro sprinkler irrigation + fertigation of N fertilizer injected at the same time and interval as irrigation, 3. drip irrigation every day + fertigation of N fertilizer every day, 4. drip irrigation every two days + fertigation of N fertilizer every two days, and 5. drip irrigation every four days + fertigation of N fertilizer every four days] were evaluated in a randomized complete block design with four replicates.

The following measurements were taken on an individual plot basis each year from both experiments. Soil moisture measurements were taken weekly at the depth of 30 cm from May to September using a neutron probe (model CPN 503). Weekly irrigation scheduling for each plot was based on actual soil moisture in relation to tree water needs, and each plot was irrigated separately. Fruit yield was determined for each plot each year. Fruit firmness, size, color, and sugar content were measured. Visual evaluation of fruit surface pitting was conducted after the fruit had been stored in a cold storage room at 33oC for four weeks. Four categories of excellent, slightly pitted, pitted, and bruised fruits were used in this evaluation. The sum of excellent fruit plus slightly pitted fruit was referred as the marketable fruit. Soil available nutrients at the depth of 30 cm, leaf nutrient concentrations, and tree vigor were measured about one month after harvest.

Research results and discussion:

At The Dalles, differences in soil available N, P, K, Ca, Mg, S, B, Zn, Mn, Cu, soil pH, and soil organic matter were mostly negligible between drip irrigation and micro sprinkler or among no cover, straw mulch, black polypropylene cover, and white polypropylene cover in August, about one month after fruit harvest in 2005. That means the effects of irrigation system and ground cover treatments on soil fertility were not significant during the first year of experimentation. However, drip irrigation had slightly lower concentrations of N, P, K, Ca, B, and Mn in leaf than micro sprinkler in August of the first year (Table 1). In 2006, drip irrigation had significantly higher N and Mn, but lower K concentrations in leaf than micro sprinkler. Our results suggest that the uptake of these nutrients by roots may be slightly reduced in the first year, but almost not affected in the second year due to the switch from micro sprinkler to drip irrigation. The four ground cover treatments had similar leaf nutrient concentrations except N and Cu in both years. The differences of nutrient concentrations in fruit were rarely significant between the two irrigation systems or among the four ground cover treatments.

The biggest benefit with drip irrigation was water saving. During the entire season from May to September, drip irrigation consumed only 21 to 26% of irrigation water relative to micro sprinkler at The Dalles in both years (Table 2). Compared with no cover, black polypropylene reduced water use by 8%, and straw mulch and white polypropylene had a 1 to 3% reduction in water use in 2005. In 2006, however, straw mulch reduced seasonal water consumption by less than 1%, and black polypropylene and white polypropylene had a 3 to 5% increase in water use compared with no cover. That means single-line drip irrigation system could save over 70% of irrigation water compared with the current irrigation system – micro sprinkler. Therefore, drip irrigation seems to be a good system for orchards in regions that are short of water.

In both years, fruit yield was statistically similar under drip irrigation and micro sprinkler (Table 2). There was a trend of yield increase with straw mulch and polypropylene covers, particularly with white polypropylene, relative to no cover, although these yield increments were statistically insignificant. Fruit quality including color, firmness, and size did not differ regardless of irrigation or ground cover system in the two years, but sugar content was greater with drip irrigation than micro sprinkler in 2006 (Table 2). It was interesting that drip irrigation increased marketable fruit (excellent fruit + slightly pitted fruit) by about 4-5% (absolute value) via reducing fruit surface pitting compared with micro sprinkler in both years. The reduction in fruit pitting was another big benefit with drip irrigation (Table 3). No benefits were found with straw mulch or polypropylene covers in reducing fruit pitting relative to no cover.

Since the weather was pretty normal in the 2005 season in terms of rainfall and temperatures, sweet cherry trees did not show any drought symptoms regardless of irrigation and ground cover treatments. In 2006, however, because July and August were much drier and hotter than normal, some trees under drip irrigation showed symptoms of drought. But the yields and fruit quality of drip irrigated trees seemed to be not significantly affected by the unusual weather conditions in 2006.

At the Hood River location in both years, micro sprinkler irrigation plus N fertigation system resulted in significantly higher concentrations of N, Mn, and Cu in leaf than micro sprinkler plus dry N fertilizer system after harvest; which suggests that the uptake of these nutrients by roots may be improved due to the switch from dry N fertilizer application on soil surface to split N fertigation under micro sprinkler in the first year. However, almost no increase in leaf nutrient concentration was observed with the three drip irrigation plus N fertigation systems compared with the current water and N management system – micro sprinkler irrigation and the application of dry N fertilizer on soil surface. The biggest benefit with drip irrigation and N fertigation systems was water saving. During the entire season from May to September, the three drip irrigation plus fertigation systems saved over 60% of irrigation water relative to the two micro sprinkler systems each year. Fruit yield and quality including fruit sugar content, firmness, and size were statistically similar among the five irrigation and N management systems. Furthermore, no difference in fruit surface pitting was observed among the five irrigation and N management systems. Overall, drip irrigation plus N fertigation systems produce competitive cherries with much less irrigation water and provide more flexibility in N fertilizer applications.

The impacts of this project on sweet cherry productivity and profitability and the environment were significant, and will be greater. For instance, about 300 targeted sweet cherry growers along with thousands of other fruit growers were educated through a variety of outreach activities during the project implementation period. The following benefits about drip irrigation, ground covers, and N fertigation were delivered to growers: Drip irrigation saves 60 to 79% of irrigation water compared with micro sprinkler irrigation. Fruit yield and quality under drip irrigation are comparable to those under micro sprinkler. Drip irrigation significantly increases the percentage of marketable fruit by reducing fruit surface pitting compared with micro sprinkler. There is a trend of yield increase with straw mulch and polypropylene covers. Split nitrogen fertigation systems produce competitive sweet cherries but provide more flexibility for split N fertilizer applications during the season, and thus can avoid N over-applications. Furthermore, the improved water and N use efficiencies with drip irrigation and fertigation will restore streamflow in streams and rivers in the region and accordingly improve the conditions for fish, and for tourism and recreation as well.

References
Goyal, M.R.; Gonzalez, E.A.; Rivera. L.E.; Chao-de-Baez-C. 1987. Sweet pepper response to drip, micro sprinkler and furrow irrigation. American Society of Agricultural Engineers. 87:2523-2533.
Merwin, I.A.; Ray, J.A.; Steenhuis, T.S.; Boll, J. 1996. Ground cover management systems influence fungicide and nitrate-N concentrations in leachate and runoff from a New York apple orchard. J. Am. Soc. Hort. Sci. 21:249-257.
Merwin, I.A.; Stiles, W.C. 1994. Orchard ground cover management impacts on apple tree growth and yield, and nutrient availability and uptake. J. Am. Soc. Hort. Sci. 119:209-215.
Merwin, I.A.; Stiles, W.C.; van-Es, H.M. 1994. Orchard ground cover management impacts on soil physical properties. J. Am. Soc. Hort. Sci. 119:216-222.
Patten, K.D.; Patterson, M.E.; Kupferman, E. 2004. Reducing surface pitting in sweet cherries. http://postharvest.tfrec.wsu.edu/pgDisplay.php?article=N1I2C.
Sauls, J.W. 2004. Texas citrus and subtropical fruits: Nutrition and fertilization. http;//aggie-horticulture.tamu.edu/citrus/nutrition/L2288.htm.
Waddell, J.T.; Gupta, S.C.; Moncrief, J.F.; Rosen, C.J.; Steele, D.D. 1999. Irrigation and nitrogen management effects on potato yield, tuber quality, and nitrogen uptake. Agron. J. 91:991-997.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

The following outreach activities were conducted to disseminate research findings to producers, agricultural professionals, local citizens, and other interested groups via on-farm field tours, field days, conferences, and publications.

Yin, X. 2005. Alternate irrigation and ground management practices for sweet cherry. Oregon Sweet Cherry Preharvest Field Tour. Oral. The Dalles, OR, Jun. 1. Over 100 growers and industry consultants from both Oregon and Washington states showed up.
Yin, X. 2005. Alternate irrigation and ground management practices for sweet cherry. Northwest Sweet Cherry Review. Oral. The Dalles, OR, Nov. 150 growers and industry consultants from Oregon, Washington, and California states attended the meeting.
Yin, X. 2005. Progress in nutrient and water management research for pears and sweet cherries. KIHR radio show. Oral. Hood River, OR, Dec. 1.
Yin, X. 2005. Effects of straw mulch and drip irrigation on nutrient and water use and productivity of sweet cherries. Annual Meetings of Washington State Horticultural Association. Poster. Wenatchee, WA, Dec. 5-7. Over 1000 growers and industry consultants from Oregon, Washington, and California states etc. attended the meeting.
Yin, X. 2006. Soil and nutrient management for sweet cherry. 2006 Oregon Sweet Cherry Growers’ Meeting. Oral. The Dalles, OR, Jan. 18. 120 growers and industry consultants from Oregon and Washington attended the meeting.
Yin, X. 2006. Split fertigation system for orchard crops. Hood River Nutrient and Water Management Tour. Oral. Hood River, OR, Jun. 27. 30 growers and industry consultants attended the meeting.
Yin, X. 2006. Sustainable nutrient and water management alternatives for sweet cherry. 2006 Oregon Sweet Cherry Growers’ Meeting. Oral. Richland, WA, Nov. 16. 140 growers and industry consultants from Oregon and Washington attended the meeting.
Yin, X. 2006. Progress in nitrogen management research for pears and sweet cherries. KIHR radio show. Oral. Hood River, OR, Dec. 7.
Melissa Hansen. 2006. Cherry ground covers. Good Fruit Grower. No.8:19.

In addition, Xinhua Yin presented the results of this project at the following national and international academic conferences.
Yin, X., J. Turner, C. Seavert, R. Guiliani, R. Núñez-Elisea, and H. Cahn. 2006. Ground cover and irrigation effects on soil fertility, mineral nutrition, and productivity of sweet cherry. 18th World Congress of Soil Science. Poster. Philadelphia, PA. Jul. 9-15.
Yin, X., C. Seavert, and J. Bai. 2006. Effects of ground cover and drip irrigation on mineral nutrition and productivity of sweet cherry. Annual Meetings of American Society for Horticultural Science. Poster. New Orleans, LA. Jul. 27-30.

Project Outcomes

Project outcomes:

The implementation of this project has had direct effects that some growers have adopted the practices of drip irrigation and straw mulch and polypropylene covers. The following growers in Wasco and Hood River counties are examples that have implemented drip irrigation on their orchards as a result of the information from this project. Tim Dahle [Dahle Orchards, (541) 993 9600] established 100 acres of new cherry orchard using drip irrigation only. Mike Omeg [Omeg Orchards, (541) 288 7253] put supplementary drip irrigation in 70 acres of orchard where water is in short supply and it is hard to keep the soil wet due to harsh weather conditions. John McClaskey [McClaskey Orchards, (541) 296 4240] is putting in drip irrigation to supplement micro irrigation in 1000 acres. There are many more growers in other areas in Oregon and Washington who have begun or are considering using drip irrigation on their orchards due to the impacts of this project.

The reason for applying drip irrigation is almost always water saving, but there are also a number of other reasons as summarized below: (1) water savings due to electricity cost; (2) water saving where the water supply is limited; (3) the ability to get sufficient water to the root zone in hot windy areas where a micro irrigation system becomes very inefficient; (4) the possibility to fertigate and improve nutrient uptake; and (5) the possibility of better fruit quality.

Recommendations:

Potential Contributions

Producers with limited water rights for their orchards are very interested in the results of our project. They believe this project will help them to use water and N more efficiently and increase cherry storability. Tree fruit producers with enough water rights are also interested in the results of this project because they believe drip irrigation and fertigation can help them to reduce the costs on irrigation and N fertilization.

Due to the impacts of this project, growers in Oregon the Pacific Northwest have begun to use drip irrigation, ground covers, and N fertigation on their orchards, and this trend will be continued and magnified during the next 5 to 10 years.

Future Recommendations

In our project, we tested the single-line drip irrigation system, and found this system saves at least over 60% of irrigation water compared with our current irrigation system – micro sprinkler irrigation. But under the single-line drip irrigation system, the between tree row grasses will dry out in July and August because no water is applied to the between row areas during the entire season. This may increase the orchard temperature and force fruit to mature earlier. Therefore, a combination of drip and sprinkler irrigation seems to be a good option to save water but still keep the between-row grass green throughout the season. We can use drip irrigation and micro sprinkler systems alternatively on the same field by running micro sprinklers during the day time and drip irrigation during the night time, or by running drip irrigation in the months of May, June, and September and micro sprinkler irrigation in the hottest months of July and August.

Another recommendation is to test double line drip irrigation system (one line on each side of the tree row). In this way, we double the tree root zone volume to receive irrigation water. The double line drip irrigation system will have stronger ability to help trees to endure severely drought conditions compared with the single line drip irrigation system.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.