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Martin P.N. Gent and Richard J. McAvoy

, 1977 ). The runoff of water, fertilizer, and pesticides resulting from these irrigation methods is a potential risk to the quality of the environment in proximity to a greenhouse operation. Subirrigation, and in particular ebb and flow, systems are more

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Manuel Chavarria, Benjamin Wherley, James Thomas, Ambika Chandra, and Paul Raymer

. Replicate studies consisting of four salinity levels of 2.5 (control), 15, 30, and 45 dS·m –1 EC were supplied via subirrigation into 1-m × 1-m × 5-cm-deep ebb and flow benches, similar to the method published by Raymer et al. (2005) . The control

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N.S. Khoury, E.J. Holcomb, J.W. White, and M. Rand

Excessive electroconductivity measurements have been observed in the surface layer of subirrigated substrates. A hydrophilic gel and rockwool were used as pot mulches in order to reduce the surface layer salt buildup by absorbing the salts and/or reducing evaporation.

Six treatments of `Crimson Fire' and `Victoria' CVI geraniums were grown in 11 cm. pots. Treatments were: Trt 1 - top irrigation, N source 20-10-20; trt 2 - subirrigation, N source 20-10-20; trt 3 - subirrigation, N source in equal portions of 20-10-20 and CRF, gel mulch; trt 4 - subirrigation, N source CRF, gel mulch; trt 5 - subirrigation, N source in equal portions of 20-10-20 and CRF, wool mulch; trt 6 - subirrigation, all N source CRF, wool mulch.

Pots were divided into 3 equal volume portions. Electroconductivity, as a measure of soluble salt (SS) level, was taken. All treatments had increasing SS levels with increasing pot height. Trt 2 had surface layer salt levels significantly higher than trt 1. `Victoria' trts 3,4,5 and 6 surface layers had significantly lower SS levels than trt 1 surface layers. `Crimson Fire' trt 4's surface layer had significantly lower SS levels than the surface layer of trt 1. Trts 4 and 6 bottom layers of both cultivars had significantly lower SS levels than all other treatments.

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Mingying Xiang, Justin Q. Moss, Dennis L. Martin, and Yanqi Wu

acclimation period, daily subirrigation was applied to all the pots by solution tanks (50 gal) that were fitted with a water pump and timer. The greenhouse nonpotable water source used in this study had a pH of 7.8, an electrical conductivity (EC) level of 0

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Patricia R. Knight, D. Joseph Eakes, Charles H. Gilliam, and Harry G. Ponder

Seed geraniums (Pelargonium × hortorum Bailey `Scarlet Elite') were grown in 10-cm pots in a 1 pine bark : 3 peat moss : 1 perlite medium from 18 March until 5 May 1993. Plants received Osmocote 14N-6.1P-12.5K and either conventional overhead (CO), drip (DI), or subirrigation (SI). Subirrigation produced greater shoot and root dry weights than CO or DI. Plants grown using DI produced fewer branches than plants grown using CO or SI. Plants receiving SI reached anthesis before plants receiving CO or DI. Method of irrigation had no influence on total root, soil, or leachate N, but SI did increase total shoot N.

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Mingying Xiang, Justin Q. Moss, Dennis L. Martin, Kemin Su, Bruce L. Dunn, and Yanqi Wu

capacity with a nutrient solution containing 2.6 g·L −1 N 13-2-13 + 6Ca + 3Mg of a plug special fertilizer solution. The grasses under prior salinity stress were flushed overhead daily with a 300 mL solution for 7 d before switching to subirrigation for 8

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Charles E. Barrett, Lincoln Zotarelli, Lucas G. Paranhos, Brian S. Taylor, Peter Dittmar, Clyde W. Fraisse, and John VanSickle

in air temperature and potential nutrient losses from heavy rainfall events. Seepage irrigation (subirrigation) with broadcast fertilizer application dominates the cabbage industry in Florida, adding to the potential for nutrient loss. Seepage has low

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Albert T.Y. Mak and D.M. Yeh

Effects of nitrogen application on growth, stomatal conductance, transpiration, and chlorophyll content were studied in Spathiphyllum Schott 'Sensation' grown in sphagnum peat (SP)- and coir dust (CD)-based media with top-irrigation or subirrigation. Maximum shoot dry weight occurred at 8 mM N in plants grown in SP-based medium under top-irrigation and subirrigation, and in CD-based medium under subirrigation. For plants in CD-based medium under top-irrigation, maximum shoot dry weight was obtained at 16 mm N. In SP- or CD-based medium, shoot dry weight was greater at 4 and 8 mm N under subirrigation than under top-irrigation. Stomatal conductance and transpiration were reduced by nitrogen deficiency (0 N), greatly enhanced by 4 mm N, and decreased gradually at higher N levels. Chlorophyll content increased with increasing N concentration up to 8 mm. The percentage of maximum total dry weight increased quadratically as leaf N content increased from 1.5% to 3.5%. Nitrogen at 16 and 32 mm increased the number of leaves with marginal necrosis. Reduced growth and more leaves with marginal necrosis occurred in SP- or CD-based media with EC > 1.25 dS·m-1 in the middle and bottom layers.

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J.W. Prevatt, G.A. Clark, and C.D. Stanley

Three vegetable irrigation systems, semi-closed subirrigation (seepage), fully enclosed subirrigation (seepage), and drip irrigation, were evaluated for use on sandy soils with naturally high water tables to determine comparative irrigation costs for tomato production. Investment, fixed (ownership), and variable (operating) costs were estimated for each irrigation system. The investment costs of the drip irrigation system were significantly greater than those for the semi-closed and fully enclosed irrigation systems. The variable costs, however, for the semi-closed system were considerably less than those for the fully enclosed and drip irrigation systems. The semi-closed irrigation system, therefore, was determined to be the least-cost tomato irrigation system under present fuel cost and nonlimiting water supply conditions.

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P. Tardif, J. Caron, I. Duchesne, and J. Gallichand

Overhead sprinkler systems in nurseries use large amount of water and fertilizers and generate runoff losses that may alter the quality of surface or subsurface water. Moreover, the cost associated with these losses is important. Water recycling may reduce that cost and the losses to the environment. Our objective was to evaluate the performance of two recycling systems (recycling and storing water in a tank and recycling solution through subirrigation on capillary mats) relative to a conventional overhead sprinkler system with no recycling. Two species (Prunus × Cistena and Spirea japonica `Little Princess') and seven substrates were used on plots subject to these irrigation practices. Treatments were compared for the water balance and the plant growth. After the first season, preliminary results showed that water and nutrient consumption were 65% less for sprinkler irrigation with recycling and with subirrigation on capillary mats. Plant yield and soil water content were statistically the same for the three treatments.