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Carol A. Miles

Improving sweet corn fertilizer-N efficiency promotes a more vigorous and healthy crop, rewards the grower with greater profits, and protects our water resources from nitrate-N pollution. Two areas of research that have the potential to improve the efficiency of fertilizer-N applications are the Minolta SPAD 502 chlorophyll meter and the presidedress soil N test. The SP meter is a rapid and nondestructive technique for assessing sweet corn leaf levels, and SP readings have been correlated to leaf N concentration. A presidedress soil N test measures the amount of soil N that will be available to the plant during the remainder of the growing season. SP meter readings combined with presidedress soil N analyses may be used to determine crop N needs and fertilizer-N sidedress application rates. Basing fertilizer-N sidedress application rates on actual crop N needs will reduce excess fertilizer-N applications and the resulting leaching of nitrates.

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James L. Green, James A. Robbins, and Bruce A. Briggs

A closed, insulated, pallet production system (CIPPS) has been designed to meet current challenges: 1) Elimination of production related pollution. 2) Reduction and conservation of resources. 3) Improvement of working conditions. 4) Alternatives to pesticides. 5) Prevention of temperature extremes and rapid temperature fluctuations in the plant environment. Biological feasibility of CIPPS was established in research on pathogen epidemiology, water and fertilize efficiency, plant growth and development in CIPPS. Water and fertilizer ion movement-removal in the closed system was plant-driven in response to growth and transpiration; water and fertilizer use in CIPS was 10% of that applied to open containers. Growth of 28 plant species ranging from herbaceous annuals to woody perennials was greater in CIPPS than in control, individual containers. Phytophthora cinnamomi did not spread from inoculated to noninoculated plants within CIPPS. Inoculation with nonpathogenic bacteria increased plant growth (gfw) in CIPPS but not in open plant containers.

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W.H. Tietjen, J. Grande, P.J. Nitzsche, T. Manning, and E. Dager

Remote areas of the United States and developing nations depend on either electric grid extension or diesel power for operating crop irrigation systems. However, electric grid extension is expensive and often impractical. Diesel pumps are expensive, polluting, and require maintenance to operate. Utilizing the energy of the sun, captured by photovoltaic panels, to power irrigation systems offers a cost-effective, pollution-free, and maintenance-free alternative. Solar-powered pumping systems are capable of delivering water from rivers or wells in volumes up to 2000 gal/min. Combining solar power with drip irrigation takes advantage of the natural coincidence of peak energy from the sun and the crop's peak need for water. In 1999, cabbage was grown comparing solar and conventionally powered drip irrigation systems at the Rutgers Univ. Snyder Research and Extension Farm, Pittstown, N.J. The solar system was operated by a 1.5-horsepower motor powered by 18 solar modules.

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R. Scott Johnson, Harry Andris, and Shanti Handley

Foliar urea sprays offer an alternative to soil applied fertilizers which could greatly reduce the potential for nitrate pollution of groundwater, The approach in the past has been to apply relatively small doses of urea in order to minimize leaf phytotoxicity. Our approach is to apply relatively large doses in the fall when leaf phytotoxicity is not a serious concern. Results on peach trees in the field indicated rapid uptake of foliar applied solutions of 4.3 to 8.8% urea (w/w) (2.0 to 4.0% N). About 80-90% of the urea was absorbed by the leaf within 24 hours. Leaf N levels suggest the majority of this urea was translocated from the leaf into the tree within 1 week despite damage to the leaf. There were no negative effects on flowering, fruit set and production in the following year as long as a very low biuret formulation of urea was used.

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Gary W. Knox, Fred Burkey, and Christine Kelly-Begazo

The Florida Yards & Neighborhoods Program (FYN) provides special educational and outreach activities directed at the community to help Floridians reduce pollution and enhance their environment by improving landscape management. The Commercial Landscape Industry Professionals program (CLIP) was developed to provide training in FYN principles to Florida's landscape professionals. CLIP was pilot-tested from 1997 to 1999 in the six-county Indian River Lagoon area of coastal east-central Florida. Teaching resources, audiovisuals, teaching outlines, and reference materials were developed to create an FYN/CLIP curriculum, which was delivered to landscape maintenance personnel through a series of training programs. In addition, the pilot program developed marketing approaches, incentives, and recognition programs for landscape professionals to encourage their participation in CLIP training programs. Evaluations of training programs and results of pre- and post-test questionnaires demonstrate the effectiveness of the FYN/CLIP program.

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Monica Ozores-Hampton and Deron R. A. Peach

Land application and landfilling are the most common destination for biosolids in the United States. When properly treated and managed in accordance with the existing state and federal regulations and standards, biosolids are safe for the environment and human health. Application of biosolids in vegetable production as an organic amendment to soils can increase plant growth and produce comparable crop yields with less inorganic nutrients than a standard program of commercial synthetic fertilizers. No application rate of treated biosolids alone will produce crop yields equivalent to commercial fertilizers. Biosolids may be used in conjunction with fertilizer thus lessening the application rate required. The major obstacles to public acceptance are issues concerning water pollution, risk of human disease, and odors. Additionally, heavy metals are an issue of bias with public perception. To ensure safe use of biosolids to a vegetable production systems the agronomic rate (nutrient requirement of the vegetable crop grown) should be calculated before application for the specific crop.

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P.R. Johnstone and T.K. Hartz*

Heavy P fertilization in the Salinas Valley of California has increased soil P concentration to levels of environmental concern. To determine the correlation of various soil test procedures with P pollution potential from agricultural land in this region, soil was collected from 30 fields, most in long-term vegetable rotations. Soils were analyzed for bicarbonate-extractable P (Pbc), calcium chloride-extractable P (Pcc), bio-available P (Pba, by an anion-resin membrane technique), and %P saturation (Psat, by an enrichment technique). The soils were then exposed to a simulated irrigation event, and soluble P concentration in runoff determined. In a separate experiment the effect of cover cropping on sediment and soluble P concentration in runoff was investigated; containers of six soils were planted with oats (Horteum vulgare L.), and then compared to containers of fallow soil. Pcc, Pba and Psat were all highly correlated (r = 0.86, 0.89 and 0.90, respectively) with Pbc, which ranged from 15-177 mg·kg-1. Soluble P concentration in runoff was highly correlated with all measures of P status (r = 0.98, 0.93, 0.85 and 0.83 for Pcc, Pba, Psat and Pbc, respectively). These results suggest that while Pbc, the standard agronomic measure of soil P status, is a useful indicator of P pollution potential, Pcc (a simple laboratory procedure that could be adapted as an on-farm `quick test' technique) may be superior for that purpose. Across soils, cover cropping reduced soluble P concentration in run-off by 41%, and sediment in the runoff by 85%.

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D.R. Earhart, V.A. Haby, M.L. Baker, and A.T. Leonard

Primary environmental concerns regarding application of poultry litter (PL) for crop production are nitrate leaching into ground water and increased levels of P in the soil that can erode into surface water. This study was initiated to investigate use of warm- and cool-season annual forage crops to remove excess nutrients supplied by PL in rotational-cropping systems on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults). PL was applied at one (1×) or two (2×) times the recommended rate in the spring, fall, or spring and fall. Rates were based on N requirement of the crop and percent N in the litter. Comparisons were made to fertilizer blends (FB) and control treatments with no PL or FB. After 3 years of treatments, NO3-N increased at the 122-cm depth by 30 and 50 mg·kg–1 from the 1× and 2× rate, respectively. The greatest accumulation was from FB (72 mg·kg–1). With PL applied in spring only, spring vegetables followed by a fall cover showed a significant reduction in NO3-N leaching and accumulation. Regardless of cropping system, rate, or time of application, P concentration increased by 40 mg·kg–1 in the surface 15 cm of soil when compared to FB. If applied in an environmentally sound manner, PL will be less of a threat to pollution of ground water than similar rates of FB. Applying PL rates sufficient to meet crop needs for N results in P accumulation that can lead to nonpoint source pollution of surface waters.

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Michael D. Frost, Janet C. Cole, and John M. Dole

Improving the quality of water released from containerized production nurseries and greenhouse operations is an increasing concern in many areas of the United States. The potential pollution threat to our ground and potable water reservoirs via the horticultural industry needs to receive attention from growers and researchers alike. `Orbit Red' geraniums were grown in 3:1 peat:perlite medium with microtube irrigation to study the effect of fertilizer source on geranium growth, micronutrient leaching, and nutrient distribution. Manufacturer's recommended rates of controlled-release (CRF) and water-soluble fertilizers (WSF) were used to fulfill the micronutrient requirement of the plants. Minimal differences in all growth parameters measured between WSF and CRF were determined. A greater percentage of Fe was leached from the WSF than CRF. In contrast, CRF had a greater percentage of Mn leached from the system than WRF during the experiment. Also, regardless of treatment, the upper and middle regions of the growing medium had a higher nutrient concentration than the lower region of medium.

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Yuan-ling P. Lin, E. Jay Holocomb, and Jonathan P. Lynch

Soilless growing media are used extensively in the greenhouse, especially for the potted plant production. Unlike soil having a phosphorus (P)-fixing ability, soilless media allows greater P leaching from the media. Leaching of excess P results in inefficient fertilizer utilization and effluent pollution. In hydroponic and sand-culture systems, alumina adsorbed with P (P-alumina) has been developed as a P source to maintain buffered P concentrations in nutrient solutions. This P-alumina has not been used with soilless media; however, it may have a potential of serving as a P source for plant growth and a P buffer to alleviate P leaching in soilless media. Marigolds were grown in soilless media (peat moss: vermiculite: sand=2:2:1, v/v/v) with P-alumina at various concentrations being substituted for sand. These marigolds were fertilized with a nutrient solution containing no additional P, while the control was fertilized with complete nutrient solution. In four cultivars of marigolds, me P-alumina treatments produced comparable or superior growth and floral production compared to plants provided with complete nutrient solutions or conventional fertilizer. 70% of applied P was leached in conventional treatments compared to only 2% in the P-alumina treatments.