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its nondestructive procedure, simple sample collection (i.e., application of deionized water to the substrate surface and collection of leachate for analysis), and direct interpretation of nondiluted measured analytes ( Cavins et al., 2004 ). PT

Open Access

Woven polypropylene groundcloth is used extensively in plant nurseries as a permeable and durable surface for container plant production. To better understand the fate of overhead sprinkler irrigation water, we designed and constructed runoff platforms (2.7 m2) to measure runoff and leachate from single irrigation events as affected by slope and underlay substrates. Groundcloth-covered platforms at slopes of 1.5% and 11% were tested with each of five underlay treatments: no underlay, coarse sand, 50% coarse sand and 50% no underlay (CS50), gravel, and native sandy soil. We applied 0.9 cm of irrigation at 1.8 cm·h-1 and determined runoff and leachate volumes. Runoff percentage [runoff × 100%/(runoff + leachate)] increased at the 11% slope for each underlay treatment. Mean (n = 10) runoff percentages (RP) for the 1.5% and 11% slopes were 0.5% and 15.7%, respectively, for no underlay, 0.1% and 1.1% for coarse sand, 0.1% and 0.7% for CS50, 0.7% and 2.5% for gravel, and 0.1% and 3.1% for native sandy soil. The low RP observed indicate that a high percentage of nutrients and agrichemicals associated with container leachate would move into the underlying substrate or soil rather than directly running off into surface waters.

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Nutrient release characteristics of four different controlled-release fertilizers (Osmocote, Nutricote, Polyon, and Multicote) were monitored during an 11-month period in a simulated outdoor nursery production facility. Although no plants were used in the experiment, fertilization rates, irrigation regimes, and cultural practices simulated those typically used to produce fast-growing, high-nutrient-requiring containerized woody ornamentals. Fertilizer prill release characteristics were monitored through analyses of leachates, which were collected weekly. Concentrations of Mg, Mn, Zn, Cu, and Mo were relatively high during the first 5 to 10 weeks of the experiment, then declined and usually stabilized during the remainder of the study. However, Mn and Zn displayed erratic increases in concentrations several times throughout the study. Calcium concentrations did not increase until the fifth week, rapidly peaked to about 300 mg·L–1, and then decreased and leveled off to ≈80 to 100 mg·L–1 during the remainder of the study. Several significant differences were observed between treatments. The Osmocote treatment had significantly greater Ca and Mg concentrations in the leachate than the other fertilizer types during the last 6 weeks of the study, whereas the Nutricote treatment often had significantly greater Fe concentrations than leachates from other treatments, especially during the last 26 to 35 weeks of the study, and significantly greater Zn concentrations than the other CRFs during the last 21 weeks of the study. Based upon U.S. Environmental Protection Agency guidelines, concentrations of Fe were often more than the allowable limit of 0.3 mg·L–1 with all fertilizer types, but especially with Nutricote. Concentrations of Mn and Cu also exceeded federal guidelines, particularly during the first several weeks of the study.

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growth index, overall appearance, leachate EC, and pH among potting mix treatments. Overall appearance rankings at all time points were combined and analyzed using a one-way ANOVA, with differences among means determined according to Tukey’s multiple

Open Access

This research determined the effects of two commercial arbuscular mycorrhizal fungi (AMF) inocula, organic slow-release fertilizer (OSRF), and inorganic controlled-release fertilizer (ICRF) on plant growth, marketability and leachate of container-grown Ipomoea carnea N. von Jacquin ssp. fistulosa (K. Von Martinus ex J. Choisy) D. Austin (bush morning glory) grown outdoors under high temperature summer conditions (maximum container media temperature averaged 44.8 °C). Uniform rooted liners were planted into 7.6-L pots containing a pasteurized substrate [pine bark and sand (3:1, by volume)]. The AMF treatment consisted of BioterraPLUS and MycorisePro and a noninoculated control (NonAMF). Fertilizer treatments included OSRF [Nitrell 5-3-4 (5N-1.3P-3.3K)] and ICRF [Osmocote 18-7-10 (18N-3.0P-8.3K)]. OSRF was tested at three rates: 8.3, 11.9, and 16.6 kg·m-3, which were respectively, 70%, 100%, and 140% of manufacturer's recommended rate, while ICRF was tested at two rates: 3.6 and 7.1 kg·m-3, which were, respectively, 50% and 100% of manufacturer's recommended rate. The P levels were equivalent between 70% and 140% OSRF and, respectively, 50% and 100% ICRF. Greatest growth [leaf, shoot, flower bud, and flower number; root, leaf, shoot, and total plant dry mass (DM); growth index; leaf area]; N, P, and K uptake; leaf chlorophyll; and plant marketability occurred with BioterraPLUS plants at 50% and 100% ICRF rate and MycorisePro at the 100% ICRF rate. Greater plant growth occurred with increasing fertility levels; however, plants at the 140% OSRF (same P level as 100% inorganic SRF) had poorest growth, in part due to high temperature. While AMF enhanced growth of plants with OSRF at all concentrations, better growth and marketability occurred with ICRF than OSRF plants inoculated with AMF. AMF plants at the 50% ICRF had comparable or better growth, higher N, P, and K and marketability than NonAMF plants at either 100% OSRF or ICRF. AMF were able to survive under high temperature and colonize plants grown from low to high fertility conditions. AMF inoculation had minimal effect on container leachate (pH and electrical conductivity). However, the larger-sized AMF plants at 100% ICRF rate had greater total leaf tissue N, P, and K, suggesting greater nutrient utilization—thus reduced potential risk for leachate runoff.

Free access

Plug-rooted liners of common ninebark [Physocarpus opulifolius (L.) Maxim.] were grown in 6-L nursery containers filled with 73% composted pine bark, 22% sphagnum peat moss, and 5% pea gravel (by volume). Plants were fertilized with Polyon (Nutryon) 17–5–12 (17N–2P–5K) 6-month controlled-release fertilizer at various rates (2.5, 4.5, 6.5, and 8.5 kg·m-3) pre-incorporated, topdressed, or dibbled (placed under the liner at potting). Plants were trickle-irrigated daily with low (0.4-L), middle (0.8-L), or high (2.0-L) volumes of water to maintain leaching fractions of <0.15, 0.25–0.35, or >0.60, respectively. Regression analysis indicated that growth of ninebark increased from 30 to 109 g/plant with increasing rates of incorporated fertilizer (mean over irrigation volumes), from 27 to 71 g/plant with topdress and from 59 to 103 g/plant with dibble. Electrical conductivity (EC, mean over five dates) of the leachate throughout the season was highest with dibble (0.85 dS·m-3), intermediate with incorporated (0.81 dS·m-3), and least with topdressed (0.76 dS·m-3). With low irrigation volumes, growth of ninebark increased from 42 to 81 g/plant with increasing rates of fertilizer (mean over methods), and from 39 to 105 g/plant with middle or high volumes (common regression curve). With low irrigation volumes, leachate EC increased from 0.74 to 0.94 dS·m-3 with increasing rates of fertilizer, and from 0.75 to 0.81 dS·m-3 with middle or high volumes.

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Irrigation of sand-based golf greens with ozonated water may affect grass growth and chemical processes in the root zone. The objective of this study was to evaluate the effects of ozonated and aerated water on bentgrass growth and root zone chemistry in sand-based greens over a 12-month period. Creeping bentgrass (Agrostis stolonifera) cores [10 cm diameter × 12 cm depth (3.9 × 4.7 inches)] were collected from a sand-based bentgrass nursery and placed in columns designed to collect leachate water. Cores were placed in a greenhouse and irrigated with 1) municipal tap water [6 to 8 mg·L-1 (ppm) dissolved oxygen (DO)], 2) aerated tap water (12 mg·L-1 DO), or 3) ozonated tap water (aerated plus 0.8 mg·L-1 ozone). Leachate was periodically collected and analyzed for pH, electrolytic conductivity (EC), and nutrients. Grass clippings were weighed and analyzed for total nitrogen (N) and phosphorus (P). Roots were periodically collected from selected cores to determine root distribution. At 40 and 90 days after initiating water treatments, bentgrass irrigated with ozonated water had a higher chlorophyll index than bentgrass irrigated with tap water. After 128 and 157 days, bentgrass clipping weights were significantly greater for the cores irrigated with ozonated water and, to a lesser extent, aerated water. At 61 and 149 days, nitrate (NO3-N) and EC levels were elevated in leachate from aerated and ozonated samples, suggesting increased mineralization of organic matter in those bentgrass cores. Ozonated water increased bentgrass crown weights, but had no effect on root mass. Ozonated water did not affect bentgrass tissue N and P concentrations. Statistically significant effects from ozonated water occurred within the first few months, but sustained benefits were negligible.

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A paucity of data exists on the water quality impacts of fertilizer nutrients used for turfgrass management. The primary macronutrients N and P have been shown to cause the eutrophication of surface water bodies, and excessive nitrate (NO- 3) concentrations in drinking water have been linked to methemoglobinemia in infants. Several studies have indicated that runoff quantities from high-quality turf areas are minimal; therefore, nutrient transport by this mechanism should not be a major concern. The leachability of N is favored by the presence of soluble forms in permeable soils receiving rainfall or irrigation in excess of field capacity. Most of the factors contributing to this condition are manageable. However, a wide range of turfgrass types, uses, and management expertise make it difficult to generalize the overall impact of turfgrass fertilization on water resources. While research has demonstrated the ability to minimize nutrient loading, characterization of nonresearch sites is critical to gain a legitimate understanding of environmental impacts. Once developed, best management practices can be effective only if understood and adopted by applicators.

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Two experiments were conducted to compare the growth of `Ultra White' petunia (Petunia ×hybrida) plants in a subirrigation system versus in a hand-watered system. In Expt. 1, petunia plants were watered with 50, 100, or 150 ppm (mg·L-1) of N of Peter's 20-10-20 (20N-4.4P-16.6K) and in Expt. 2, Nutricote 13-13-13 (13N-5.8P-10.8K) type 100, a controlled release fertilizer, was incorporated into the growing substrate, prior to transplanting, at rates of 3, 6, or 9 lb/yard3 (1.8, 3.6, or 4.5 kg·m-3). In both experiments, there was no difference in petunia shoot dry mass or final flower number between the irrigation systems at the lowest fertilization rate but differences were evident at the higher fertilization rates. In Expt. 1, shoot dry mass and flower number of subirrigated petunia plants fertilized with 100 ppm of N was greater than for hand-watered plants fertilized at the same rate. However, subirrigated petunia plants fertilized with 150 ppm of N were smaller with fewer flowers than hand-watered petunia plants fertilized with 150 ppm of N. Substrate electrical conductivity (EC) concentrations for petunia plants subirrigated with 150 ppm of N were 4.9 times greater than concentrations in pots hand-watered with 150 ppm of N. In Expt. 2, subirrigated petunia plants fertilized with 6 and 9 lb/yard3 were larger with more flowers than hand-watered plants fertilized at the same rates. Although substrate EC concentrations were greater in subirrigated substrates than in hand-watered substrates, substrate EC concentrations of all hand-watered plants were about 0.35 dS·m-1. Subirrigation benches similar to those used in these experiments, appear to be a viable method for growing `Ultra White' petunia plants. However, the use of Peter's 20-10-20 at concentrations greater than 100 ppm of N with subirrigation appeared to be detrimental to petunia growth probably because of high EC concentrations in the substrate. On the other hand, the use of subirrigation with Nutricote 13-13-13 type 100 incorporated at all of the rates tested did not appear to be detrimental to petunia growth.

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Stock plants of Pelargonium zonale `Empress' were grown for 130 days on coarse tuff medium in a greenhouse. Four N concentrations (50, 100,200, and 400 mg N/liter) and three NO3 -: NH4 +: ratios (70:30, 60:40, and 40:60) were applied. The development of mother plants, production of cuttings, and the recovery of applied N were measured. Number of cuttings was not affected by any treatments except for the low N concentration. The proportion of absorbed N was higher than that of water in the plants treated with 50 or 100 mg N/liter, while those fertilized with 200 or 400 mg N/liter absorbed more water relative to N uptake. Nitrogen recovery efficiency decreased from 70% to 10% for the 50- to 400-mg N/liter treatments, respectively. Percentage of applied N lost by leaching (30% to 70%), and N that could not be accounted for (0.5% to 20%), increased with increasing N concentration and NH4 + percentage in the solution. The minimum concentration to be used in fertilization of Pelargonium mother plants is 100 mg N/liter. Optimal N supplied ranged between 100 and 200 mg N/liter.

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