al., 1996 ). Excessive irrigation creates pollution, is expensive, and promotes disease. Nutrient-laden runoff from nurseries and greenhouses can be a significant environmental concern for both ground and surface water pollution ( Majsztrik and Lea
Lloyd L. Nackley, Elias Fernandes de Sousa, Bruno J.L. Pitton, Jared Sisneroz, and Lorence R. Oki
contributor to the nutrient pollution, a limit is set on the amount of N or P that can leave the farm and move into the impaired water body. Therefore, in addition to considerations of crop need, nutrient management, particularly that for N and P, must include
Janet C. Cole, Vicki L. Stamback, and Charlie Gray
Few data are available to indicate the chemical concentration of runoff from nursery operations, and, to our knowledge, no model systems have been developed to gain such data. This paper describes such a model system, in which nursery production beds have been designed to collect and quantify runoff water and contaminant concentrations so that management practices may be identified to decrease potential pollution problems.
Martin M. Maboko and Christian P. Du Plooy
Africa, with at least 10% to 15% of water and nutrients that leach from the rooting zone with a potential risk of pollution. Further studies need to be conducted on reduced fertilizer application on different growth media, whereas investigating the
Ashley A. Thompson and Gregory M. Peck
Chesapeake Bay, where agricultural N has become an environmental pollutant. In an effort to reduce N pollution, the Environmental Protection Agency has enacted Total Maximum Daily Load limits on the amount of N that may enter the Chesapeake Bay Watershed
C. M. Geraldson
During the 1970s a mulched gradient concept was adapted by the Florida vegetable industry and the average yield of tomatoes was doubled. Currently, because of potential water restrictions and society's increasing concerns about environmental pollution, a containerized gradient concept is being evaluated. Containers, media and nutrient/water balance are major components being evaluated to maximize water use efficiency and minimize pollution and, at the same time, maintain or increase the existing competitive excellence. Three seasons of results indicate tomato yields equivalent to those produced commercially; water use has averaged 4 liters/plant/day (about 1/5 to 1/10 that used commercially; and leaching, fumigation and plastic mulches have been eliminated. The concept as a sustainable production system is considered commercially feasible.
Nitrate pollution of surfacial aquifer is fairly widespread in deep sandy soil areas of Central Florida. Since citrus is a predominant crop in this area, despite lack of conclusive evidence suggesting citrus fertilization as the source of nitrate pollution, investigations are in progress to develop Best Management Practice (BMP) recommendations for N fertilization of citrus in an effort to improve N use by the trees and to minimize potential nitrate leaching. Our ongoing studies on both young and mature trees have demonstrated that the use of improved fertilizer formulations and programmed application schedules have facilitated to decrease the rate of N application considerably without any adverse impact on tree growth and/or fruit production while minimizing nitrate leaching below the rootzone. Our approach involves developing BMP recommendations on the basis of iudicious irrigation management and generating database on N removal by the fruits, annual N contribution to the trees by mineralization of organic N, and N losses including leaching, denitrification, etc.
Nihal C. Rajapakse, Roy E. Young, Margaret J. McMahon, and Ryu Oi
The interest in using nonchemical alternatives for growth control of horticultural crops has recently increased due to public concerns for food safety and environmental pollution. Several research teams around the world are investigating alternative growth control measures, such as genetic manipulation, temperature, water and nutrient management, mechanical conditioning, and light quality manipulation. This review discusses the recent developments in light quality manipulation as a nonchemical alternative for greenhouse plant height control.
Thomas C. Holt, Brian K. Maynard, and William A. Johnson
Degraded water quality is a growing concern across the northeast and in many cases may be linked back to agricultural operations as nonpoint sources of nitrate and phosphorous pollution. Constructed wetlands have emerged as effective, low-cost methods of water treatment that have the potential to reduce agricultural nonpoint source pollution and contribute to agricultural sustainability. However, the costs of implementing treatment wetlands as a BMP are high, with little opportunity for cost recovery. We have initiated, at a wholesale plant nursery in Rhode Island, an economical solution to treating nursery runoff that incorporates into a treatment wetland the wholesale production of native and ornamental wetland plants. Our goal is to demonstrate how nursery growers may produce a high-demand crop while addressing nonpoint source pollution on their land. Over the next few years, we will evaluate the economic impact of converting nursery production space into treatment wetland production space. We also will research the feasibility of enclosing treatment wetlands in passively heated polyhouses to facilitate the year around treatment of agricultural runoff. Information gathered from both the on-farm demonstration and research sites will be extended to farmers and other agricultural businesses or professionals through outreach programming. The theory, objectives, and construction of the demonstration treatment-production wetland will be presented.
Reuben B. Beverly, Wojciech Florkowski, and John M. Ruter
3 Department of Horticulture, Coastal Plain Experiment Station, Tifton, GA 31793. This project was supported in part by funding from the Pollution Prevention Assistance Division of the Georgia Department of