demand will also lead to the greatest loss of N in leachates compared with the other systems, 2) the organic N input with the lowest C:N ratio will release plant available N at a rate most closely synchronized with crop N demand, thereby leading to the
nursery leachate and runoff. Consequently, when optimal fertilizer application rates are used, crops will perform at their best and environmental impacts will be minimized ( Cabrera, 2003 ). Controlled-release fertilizers have become the principal method
Abstract
The leachate from seed of tomato (Lycopersicon esculentum Mill., PI 341984), an accession whose seeds germinate well at low temperatures, promoted the germination of seeds of the same and other tomato cultivars. The leachate from ‘Red Rock’ seed, a cultivar whose seeds germinate poorly at low temperatures, inhibited the germination of seeds of the same and other tomato cultivars. The promotive and inhibitory effects of these leachates on seed germination is apparently highly specific and restricted to tomato seeds. The activity was highest in fresh seeds and the responses were best exhibited at low germination temperatures.
Two experiments were conducted to evaluate the effects of cyclic irrigation on leachate NO3-N concentration, container leachate volume, total effluent volume, and growth of Ilex crenata Thunb. `Compacta'. In Expt. 1, container leachate volume was reduced 34% when 13 mm of water was applied in three cycles compared to continuous irrigation of 13 mm per unit time. Forty-nine percent less container leachate volume was collected from a continuous application of 8 mm than from that of 13 mm water. In Expt. 2, container leachate volume was reduced 71% when 6 mm was applied in a single application over 30 minutes compared to 13 mm applied continuously for 1 hour. Total effluent was reduced by 14% and 10% in Expts. 1 and 2, respectively, when 13-mm irrigation was applied in three cycles compared to one continuous irrigation. Container leachate NO3-N concentrations from cyclic irrigation were generally less than leachate NO3-N concentrations from continuous irrigation treatments. The percentage of applied N leached as NO3-N ranged from 46% when 13-mm irrigation was applied in three cycles to 63% when 13-mm irrigation was applied in a single cycle. Leachate NO3-N concentration was reduced as irrigation volume was reduced from 13 to 6 mm in Expt. 2. Percentage of applied N leached as NO3-N was 63%, 56%, and 47% when 13-mm irrigation was applied in one, two, and three cycles, respectively, compared to 19%, 16%, and 15% when 6-mm irrigation was applied in one, two, and three cycles, respectively. `Compacta' holly shoot and root growth were minimally affected by cyclic irrigation or irrigation volume.
for drainage within the holder pot and thus collection of leachate. Each pot was filled with sandy loam soil. The soil particle size distribution was determined (sand 63.60% ± 0.86%, silt 27.50% ± 0.96%, and clay 8.90% ± 0.10%) using the hydrometer
seven rain events produced leachate from modules, averaging 3.6 L and 3.2 L of precipitation per module between 25 Aug. and 28 Oct. 2011 and 13 Mar. and 7 Aug. 2012, respectively. Each of the 10 fertilizer treatments was replicated three times and
Abstract
Seed leachates of ‘Kentucky 31’ and ‘Rebel’ tall fescue (Festuca arundinacea Schreb.), ‘Citation’ and ‘Manhattan’ perennial ryegrass (Lolium perenne L.), annual ryegrass (Lolium multiflorum Lam.), annual bluegrass (Poa annua L.), and ‘Mystic’ and ‘Victa’ Kentucky bluegrass (Poa pratensis L.) were evaluated for inhibition of lettuce (Lactuca sativa L. ‘Grand Rapids’) germination and seedling growth (a widely used bioassay for allelopathic effects). Different degrees of inhibition of lettuce seedling growth were found in the turfgrass cultivars ‘Rebel’ > ‘Ky31’, ‘Victa’ > ‘Mystic’, ‘Citation’ = ‘Manhattan’, and in annual bluegrass and annual ryegrass. Grass seed leachates were separated into organic and inorganic fractions using XAD-2 polystyrene resin. Organic fractions were inhibitory to lettuce seedling growth. Inorganic fractions were also inhibitory to lettuce seedling growth at high concentrations but were stimulatory at low concentrations. Germination of lettuce was not affected by leachates or their fractions.
Overhead pulse irrigation was evaluated as an alternative irrigation practice to reduce container leachate and irrigation runoff. Six irrigation treatments evaluated included 1.25 cm volume applied at 1, 2, and 3 pulses and 0.63 cm volume applied at 1, 2, and 3 pulses with a 1 hr delay between pulses. Irrigation runoff and container leachate were about 50% less in the 0.63 cm treatments compared to the 1.25 cm treatments. There was a 10-14% reduction in irrigation runoff and 29-32% reduction in container leachate when comparisons were made between the 1 pulse and 3 pulse treatments regardless of the irrigation volume applied. Shoot and root growth of Compacta holly were similar among all treatments.
One component of container production influencing the water quality concerns in the nursery industry is the amount of container effluent leaching from the container substrate. Potential exists for reduced water use, less leachate volume, and improved irrigation efficiency by altering the container design. This research compares the container leachate volume from a standard, 11.31 (# 3) container with seven 1.9-cm-diameter drainage holes to containers with one, three, or five holes with diameters of 1.9, 0.9, and 0.5 cm. Leachate volume was 41% less (312 to 182 mL) when the diameter of the drainage hole was reduced from 1.9 to 0.5 cm. Nitrate-N was 85% less (3093 to 452 mg) when the container drainage holes were reduced to 0.5 cm. Plant growth and quality of Lagerstroemia fauriei X L. indica `Hopi', crapemyrtle, was similar in all container modifications.
Nitrate nitrogen has been recommended as the best form of nitrogen for the production of poinsettia while ammonium and urea have been reported to be deleterious to poinsettia growth. Recent studies have indicated that lower nitrogen and leaching levels will produce quality poinsettias. Poinsettias were grown with 21–7–7 Acid Special (9.15% NH4, 11.85% urea), 20–10–20 Peat-lite Special (7.77% NH4, 12.23% NO3), 15-220 plus Ca and Mg (1.5% NH4, 12.7% NO3, 0.8% urea), and 15–5–15 Excel CalMag (1.2% NH4, 11.75% NO3, 2.05% urea) applied at 200 mg·L-1. Plants were fertigated by drip irrigation with zero leachate. There were no significant differences between fertilizer treatments for plant height, width, bloom diameter, and dry weight. Electrical conductivity and pH did vary significantly between treatments; however, this did not effect plant growth. Thus, by using lower nitrogen levels and zero leachate, quality poinsettias can be grown with commercial fertilizers high in ammonium/urea or high in nitrate nitrogen, or ammonium and nitrate in combination.