Landscape
And
Nursery
Dialog
Mary Ann Rose
Commercial Landscape
& Nursery Specialist
The Ohio State UniversitySeptember, 1996
Water Quality - Regulatory Issues and Management
Keywords: water quality, runoff, regulations, best management practices, irrigation, nursery, business management
A bout 130 members of Ohio's nursery industry attended the OSU/Scotts Short Course and Field Day held at The Scott's Co. on July 24. This day-long program focused on environmental issues and best-management practices for container production. The excellent attendance for this program and the feedback that I have received since then demonstrates that there is a desire in our industry to learn more about environmental issues, notably water quality issues.
I think that I can speak for most of us in the audience that we were inspired by Jerry Lee's often humorous and sometimes sobering presentation, "Growing Quality Plants While Protecting Our Environment." Jerry is in charge of regulatory issues and capital projects for Wight Nursery, which has 1100 acres in container production at their largest facility in Georgia. In his presentation, Jerry described a regulatory environment in the South where nurseries are coming under scrutiny. Southern states are moving towards monitoring water use and water discharge from ground and surface waters. In some of the states, nurseries are required to obtain water use and/or discharge permits; Wight nursery alone has twenty-five water-use permits! Moratoriums also have been placed on new well construction in some areas due to excessive pumping from aquifers.
Wight Nursery was informed one day several years ago that all discharge from the nursery had to stop. Jerry said that the very rapid implementation of a solution across the entire nursery was very expensive! Jerry's advice based on his experience: know more about your nursery than anyone else, particularly what you may be discharging. Wight nursery now accomplishes this by frequent monitoring for nitrates, pH, EC, and dissolved oxygen;
they sample from collection ponds as well as from natural bodies of water up- and downstream from their nursery. Furthermore, it's essential to have a plan in place for eliminating runoff if and when the regulatory ax falls. Jerry warned that those who might consider selling out because environmental mandates should know that potential buyers will be required by banks to have a environmental site assessment. Problems revealed by an assessment could make or break a sale.
What about Ohio? The Clean Water Act and the Coastal Zone Management Act are two examples of federal legislation that could lead to regulation in Ohio. The state of Ohio is in comparatively early stages of dealing with these bills and has yet to come up with management plans for each program. The good news, according to Larry Antosh of the Ohio EPA, is that the nursery industry has a clean record in Ohio and is not an obvious target of this legislation. That's not to say, however, that nurseries will feel no impact from this legislation five years or ten years down the road. Jerry Lee's advice to Ohio's nursery industry is to be proactive now: participate in the development of the state management plans so that inflexible 'solutions' are not foisted on us. Having some options for compliance will be essential.
What can individual nurseries do? Wight nursery eliminated fertilizer runoff by reducing fertilizer inputs and by improving the water drainage and collection systems. They looked closely at how much fertilizer they were putting on and found that they could grow quality plants at nutrient levels below published 'optimum' levels. They found that nitrate levels in their recycling ponds ranged from 15 to 30 PPM N, and adjusted soluble fertilizer injection
up or down according to the N levels in the irrigation water. Superphosphate incorporation into growing media was eliminated entirely since recent research indicates this once-common amendment leaches from container media in 4 to 6 weeks. Collection pond capacities were increased to hold all irrigation runoff from the nursery as well as storm water from a one-half inch rainfall.
To reduce the potential for pesticide contamination, Wight Nursery built a state-of the-art mix and load facility and purchased an electrostatic sprayer. The cost for both was great ($35,000-facility, $6500-sprayer) but paid off in reduced liabilities and significantly less chemical usage.
Best Management Practices (BMPs) for managing and reducing runoff from nurseries. Nurseries have multiple options for managing runoff of water and nutrients. Note that many BMPs center around irrigation practices since they have a great effect on the volume of runoff.
1. Monitor nitrate and soluble salt levels in collection ponds and natural bodies of water up- and downstream from the nursery.
2. Monitor growing medium fertility and avoid excessive fertility levels. Determine sufficient nutrient levels for your crops. Sufficiency levels may be lower than expected.
3. Engineer irrigation systems for uniformity of application.
4. Use drip irrigation for larger container sizes to reduce water usage and runoff.
5. Use cyclic irrigation to reduce water use and runoff. When water is applied to pots in a single irrigation event, a significant proportion may channel through large pores or along sides of the pot. Water that channels rapidly does not wet the medium. In cyclic, or pulse irrigation, the growing medium is wetted much more efficiently by applying water in 2 or 3 irrigation events spaced at least one hour apart. Cyclic irrigation is practical only when automated.
6. Increase the water-holding capacity of container media to reduce leaching.
7. Group plants according to water and nutrient needs, and place heavy water- and fertilizer-requiring plants farthest from collection ponds, lakes and rivers.
8. Irrigate in the early morning hours.
9. Minimize plant spacing where overhead irrigation is used, move up to larger pot sizes when the plant canopy impedes water penetration into the medium
10. Eliminate superphosphate from the growing medium.
11. Stagger fertilizer application over time to limit peaks in fertilizer discharge. Use lower rates of fertilizer for late-season potting.
12. Grade the nursery to efficiently direct runoff water to collection ponds.
13. Construct collection ponds to hold all irrigation runoff plus storm water runoff from a 1/2 inch rainfall occurring over a 48-hour period.
14. Construct grass-lined waterways to filter sediment and runoff.
15. Seed or sod newly constructed slopes and barren areas with a permanent cover. Plan grading operations around times of year that are optimal for seeding perennial grasses or legumes: March through May and late August through October. Temporary covers or mulch may be used if timing is not suitable for sowing a permanent cover.
16. Use vegetated filter strips along edges of the nursery, particularly where lakes and streams border the nursery.
17. Direct runoff through a constructed wetland to filter environmental contaminants.
The list above includes both low- and high-cost options for reducing runoff and increasing fertilizer- and water-use efficiency. While nurseries may not be able to implement all the BMPs, certainly most can benefit by implementing some of them.
