In some ways, maintaining nursery crops is similar to maintaining floriculture crops. The major distinctions are in the magnitude of the operations and the degree of grower control. Watering, fertilizing, and controlling pests in the greenhouse are almost totally under the grower’s control and have little impact outside the operation. With nursery production, the leaching and runoff of surface and irrigation water, fertilizers, and pesticides have the potential to affect the environment of people far beyond the nursery’s property lines. Consequently, full consideration must be given not only to what is applied but also to where it goes after application.
Both field and container nurseries receive the natural irrigation of rainfall and supplemental irrigation controlled by the grower. Provision must be made for a reliable source of water, such as an irrigation pond, deep well, or municipal water supply. (Use of a municipal water supply can add greatly to the cost of production.) Following application, the runoff water must be absorbed on site or diverted into municipal storm sewers or nearby streams. Water that is not absorbed on site must be free of toxic waste, excessive fertilizer salts, and other nonbiodegradable materials. Excess irrigation water is often collected in a holding pond and used again to water container crops, thereby minimizing the amount of water that leaves the nursery. Where soluble salt levels are too high, the runoff water can be diluted with other water until a safe salt level is attained. A holding pond will permit some heavy particulate materials to settle out before the water is reused. In other situations, leach fields may be necessary to remove undesirable materials before the water is reused or permitted to escape into streams or public systems. Regulations differ among communities, and the prospective nursery grower should consult local water authorities while the nursery is still in the planning stages. The authorities can offer suggestions on how the local water quality standards can be met most efficiently. The assistance should be sought, not avoided, by nursery growers.
In a few regions of the United States, the local water is too alkaline for direct use on nursery crops. The soluble salts in the water would quickly harm the plants, and irrigation equipment would plug up almost as quickly. Therefore, settling ponds are often needed to permit precipitation of the salts before the water is used on the plants. In extreme situations, the water must be distilled before it is suitable for use.