By Calvin Chong, University of Guelph, Department of Plant Agriculture - Vineland, Horticultural Research Institute of Ontario, Vineland Station, Ontario


“Water, water everywhere” has been getting a lot of attention lately. In a 1998 Landscape Trades article, I highlighted global and local concerns about water quality and scarcity.(1) Numerous newspaper and TV releases have echoed similar concerns. According to Dr. Sandra Postel, renowned expert on water use and member of the Global Water Policy Project, U.S.A., the new millennium wars will be about water — not oil.(3) Water is the basis of all life. Unlike oil, which has other alternatives, such as natural gas or solar energy, water has no substitutes.

     Despite Canada’s apparent abundance of water, we are not immune from water issues. For example, in the Okanagan Valley, B.C., farmers constantly “battle” with industry and consumers for water; up to one-third of wells in Ontario have nitrate levels in excess of the 10 mg/L desirable threshold. Note also last year’s Walkerton tainted water incidence that left half of the town’s 5,000 people sick and several dead.


Addressing the concerns
In 1999, Landscape Ontario’s membership at large — much to the credit of our industry — identified “water conservation and irrigation/fertilizer run-off” as two of four major concerns of the nursery, landscape and turf industry. Since the early 90s, the Ornamental Nursery Research Program at Vineland/University of Guelph, in co-operation with Drs. Glen Lumis and Paul Voroney at the University, has received support from Waterdown Garden Supplies, Landscape Ontario Horticultural Trades Foundation and Growers’ Group, and the Industrial Research Assistance Program (IRAP) of the National Research Council of Canada for various research projects dealing with wastewater and nutrient recycling (2, 4, 5, 6). Prior to that, we routinely used water conserving drip irrigation for all types of nursery culture, including container (pot-in-pot) and field-grown shade tree production.

     During pre-conference and conference tours at the 50th Annual Meeting of the International Plant Propagators’ Society Eastern Region in the Chicago area, we visited the famous Chicago Botanic Garden, The Morton Arboretum and several impressive nurseries.

     In view of the emerging concerns for water and hints about forthcoming legislation to deal with water and nutrient management for farms, this article describes two Chicago-area nurseries that have for years addressed these concerns, that is, conserving water and nutrients by using trickle technology and modern recycling practices.



Wilson Nurseries
Located among native stands of oak in the northern Illinois countryside about one hour’s drive north of Chicago, Wilson Nurseries is renowned for its “from propagation to maturity” total concept since its beginning in 1975. Plants are propagated in nine meticulously tidy propagation houses, each with raised beds contained and delineated by neatly laid concrete blocks, adjustable side walls and moving irrigation booms — all designed to provide optimal rooting uniformity and growth. The rooted cuttings are planted in 50 acres (20 ha) of contoured, erosion-free liner beds for a specified time. From these beds, liners are transplanted and grown to marketable size in their 600-acre (240-ha) field nursery or 50-acre (20-ha) container site. In recent years, Wilson has added perennials and hard goods to offer a complete “one-stop” for their customers.

     While Wilson Nurseries takes much pride in doing business “the old fashioned way”— with lots of commitment — they are far from being old fashioned. Fourteen years ago, they committed to using drip irrigation and recycled wastewater. This has been a major and innovative undertaking, not to mention a big plus for the environment, considering that 140 acres (56 ha) of field-grown trees and shrubs as well as all container plants are grown this way.

     The irrigation run-off from both field and container ranges drains into a huge tile-terraced pond of several million gallons. An estimated 80 per cent of the run-off is recycled. Herbicides are not used.

     Container: The typical container mix is 50 per cent bark, 25 per cent peat and 25 per cent sand. Within each row of neatly placed containers spaced 18, 24 or 30 inches (46, 61 or 76 cm) apart, depending on size, the trickle line runs over the top of the containers. The line branches from a lateral at the start of the row and is folded and anchored at the end. Half-gallon (2 L) in-line emitters are positioned one per container.

     Typically plants are supplied with between three-quarters and one gallon of water per day in three 15- to 20-min. periods. During the first year, plants are supplied nutrients primarily by pre-incorporated controlled-release fertilizer. In the second or subsequent years, plants are fed primarily by in-line liquid feed (200 ppm nitrogen) pumped from a central location, equipped with a whole range of neatly installed fertigation equipment, including various pumps, fertilizer mixers, storage tanks and acidification equipment to lower water pH.

     Field: Similar to the container plants, each field-grown tree or shrub is trickle-irrigated through a half-gallon in-line emitter. Pressure compensating emitters are used to allow more uniform delivery because of the large variances in water pressure occurring in extended irrigation lines typically used in long field rows. In the container nursery, regular, less expensive, non-pressure compensating emitters are used since rows are relatively short and have little variance in water pressure.

     Currently, field-grown trees or shrubs are trickle-irrigated only when needed. This is done by hauling and pumping water from a large water source to designated field sections. Most of the irrigation lines run on top of the ground, and are preferred to under­ground lines. There are several sites with buried lines. Before winter, all lines are “blown out” to prevent damage by freezing of water trapped in the lines.


Midwest Groundcovers
Ground covers, produced by the millions, are the traditional favourites and specialties at Midwest Groundcovers, which also boasts a full line of quality nursery stock. From a very humble start in 1969 — a few back-yard cuttings — Midwest has grown rapidly to occupy a fully developed 165-acre (66-ha) container nursery in St. Charles, a western suburb of Chicago. Recent expansion includes a more comprehensive line of perennials, ornamental grasses, native plants and a complete line of hardy roses.

     In over 2,200 polyhouses and adjunct fields, Midwest produces a “breathtaking” 19 million cuttings and one million container plants per year. New facilities, developed in 1994, include several attractive gardens. Besides serving as display for its customers, these gardens are also used as trial plots to observe the performance of new introductions (nearly 100 in the program) before committing to full-scale production. Midwest is also developing a 210-acre (84-ha) farm in southwest Michigan. The company prides itself on a working environment that fosters high morale and long-term retention of its employees.

     Wastewater recycling: At the St. Charles operation, a special 20-acre (8-ha) area referred to as Hickory was designed for growing container plants with drip irrigation. All run-off is trapped and re-circulated.

     The area has 440 96 ft. long x 13 ft. (29 m x 4 m) wide polyhouses and grows about 200,000 units, most (80 per cent) in a five-gallon size. Of the remainder, 15 per cent are in two gallon and five per cent in one gallon sizes. Initially, Hickory was a subdivision stripped of its topsoil and badly eroded. The area was extensively tiled and regraded to catch all run-off water in a series of four interconnected ponds, each located at progressively lower levels in an adjacent gully area. The first two are the larger “reservoirs.” The third is a smaller “irrigation pond,” from which the water is withdrawn and re-circulated. The fourth is a shallow [1 ft. (30 cm) deep] “settling pond.”

     A 30 ft. x 20 ft. (9m x 6m) pumping station, located next to the irrigation pond, contains a Volmatic injector system with three separate irrigation stations, each controlling a different part of the Hickory nursery. Additionally, each station is equipped with both a 40 HP and a 10 HP pump for high or low volume dispensing, respectively, depending on daily or seasonal fertigation needs.

     The containers are spaced typically 20 or 24 inches (51 or 61 cm) apart. Similar to Wilson Nurseries, the trickle line at Hickory runs over the top of the containers and is held by pins stuck into the container mix at periodic intervals within the row. The five-gallon (20-L) containers are typically trickle-irrigated through Netafim in-line emitters although, presently, the one- or two-gallon (four- or eight-litre) containers are watered overhead by sprinklers. Because the standard container mix is a heavy mixture of pine bark, spent mushroom compost, peat moss, and sand, containers are irrigated only two or three times per week. With each irrigation, plants are liquid fed usually with 200 ppm nitrogen. In spring and fall, the nitrogen concentration is slightly increased or decreased, respectively.

     To decrease the pH of the water, “mild” N-Furic acid, is injected into the water supply. Previously, “strong” sulfuric acid was used. Media samples are sent regularly to a California laboratory for complete analysis. Electrical conductivity, a quick measure of the soluble salts content or fertility level, and also pH and media porosity are routinely analysed on site. According to Gary Knosher, operations manager at Midwest Groundcovers, these tests allow the production manager to adjust the nutrient levels of the wastewater. While he had no actual data on how much fertilizer is saved, Knosher assured me that “a lot is recycled — at least half.”


Conclusion
It is instructive to know that using trickle irrigation and recycling wastewater in a big way are realities in North American nursery production. In Holland, which sets the pace for our growing industries, greenhouses and nurseries had a total recycling system in place since November 1998. Legislation for this procedure was put into practice two years ahead of schedule.

     Our research data at Vineland indicates that up to 77 per cent of nitrogen, 77 per cent of phosphorous and 57 per cent of potassium are saved when nutrients are re-circulated. All fresh and run-off water is recyclable except for that used by the plants (5). According to Dr. Ruguo Huang, Agronomist and Manager for Amco Farms Inc., a large greenhouse operation in Leamington, which practices total nutrient and wastewater recycling, his operation uses up to 75 per cent less nutrients and saves between $6000 and $8000 per acre ($15,000 and $20,000 per ha) in fertilizer costs. Dr. Postel (3) indicates that, compared to conventional flood irrigation practices, drip irrigation reduces water use typically by 30 to 70 per cent, increases crop yields by up to 90 per cent, and produces better quality plants. Drip irrigation technology “will make and continue to make a big difference in worldwide water conservation,” adds Dr. Postel.

     Apart from environmental benefits, and adherence to possible legislation, which may require Ontario farms and nurseries to conserve water and nutrients, recycling practices also have a large economic benefit.


References
1.     Chong, C. 1998. Water quality: Why it concerns us. Landscape Trades 20(5):18-20. 2.     Jarecki, M.K., C. Chong, and R.P. Voroney. 1999. Compost run-off water for irrigation of grasses and ornamental trees. Paper presented at the 34th Central Canadian Symposium on Water Pollution Research, Burlington, ON, 8-9 Feb. 1999. 3.     Postel, S. 2000. Water, population, and environment: Challenges for the 21st century. Presented at one of The Kenneth Hammond Lectures on Environment, Energy and Resources, University of Guelph, 26 Oct. 2000. 4.     Purvis, P., C. Chong and G.P. Lumis. 1999. Nutrient and water recycling in nursery containers. Landscape Trades 21(1):65-68. 5.     Purvis, P., C. Chong and G.P. Lumis. 2000. Recirculation of nutrients in container nursery production. Canadian Journal of Plant Science 80:39-45. 6.     Purvis, P., C. Chong and G.P. Lumis. 2000. Recirculating nutrients in containers. American Nurseryman 192(10):54-55.