Lack of clarity regarding the relationship between hydroperiod and decomposition dynamics has long been a barrier to the development of a clear understanding of floodplain biogeochemistry. Relationships between hydroperiod and decomposition processes were investigated using a controlled, field approach on the Ogeechee River floodplain in south Georgia. The study intent was to develop cause‐effect relationships between specific flooding regimes and decomposition parameters. Microcosms designed to manipulate flooding regimes were installed and used in combination with litterbags containing abscised foliage. Treatments were designed to mimic realistic hydroperiod‐nutrient inflow scenarios and included: a nonflooded control, flooded for 6 mo, flooded for 3 mo, flooded intermittently for 4 mo, flooded for 3 mo with elevated P inflow, and flooded for 3 mo with elevated N inflow. Mass, C, N, and P dynamics were studied for a 106‐wk period. Flooding stimulated mass, C, N, and P loss. The data suggest that single, brief flooding regimes may stimulate mass and C loss to the greatest extent. The proportion of N and P remaining after 106 wk was only marginally different among flooding regimes. However, temporal patterns of immobilization‐mineralization were strongly influenced by the nature of the flooding regime.

Two commonly used management practices for weed control in container plant production are hand pulling and herbicide applications. There are problems associated with these methods including crop phytotoxicity and environmental concerns associated with off-target movement of herbicides. Other nonchemical weed control methods could reduce herbicide-based environmental concerns, mitigate herbicide-resistance development, and improve the overall level of weed control in container nursery production. Readily available tree-mulch species, eastern red cedar (Juniperus virginiana), ground whole loblolly pine (Pinus taeda), chinese privet (Ligustrum sinense), and sweetgum (Liquidambar styraciflua) were harvested, chipped, and evaluated at multiple depths with and without the herbicide dimethenamid-p. Pine bark mini-nuggets were also evaluated. Mulches were applied at depths of 1, 2, and 4 inches and evaluated over three 30-day periods for their effectiveness in suppressing spotted spurge (Chamaesyce maculata), long-stalked phyllanthus (Phyllanthus tenellus), and eclipta (Eclipta prostrata). After 30 days, herbicide/mulch combinations, as well as mulch treatments alone, had reduced weed fresh weight 82% to 100% with 1 inch of mulch. By 168 days after treatment, dimethenamid-p had lost all efficacy, and mulch depth was the only factor that still had significant effects, reducing spotted spurge fresh weight by 90%, 99.5%, and 100% with depths of 1, 2, and 4 inches, respectively. The economics of mulch weed control will depend on variables such as available time, nursery layout, location, and availability of resources, equipment, among others. Regardless of variable economic parameters, data from this study reveals that any of these potential mulch species applied at a depth of at least 2 inches will provide long-term weed control in nursery container production.

Agriculture is one of the largest contributors of greenhouse gas (GHG) emissions. To date, much work on reducing GHG emissions has centered on row crops, pastures, forestry, and animal production systems, while little emphasis has been placed on specialty crop industries such as horticulture. In this horticulture container study, Japanese boxwood (Buxus microphylla Siebold & Zucc.) was used to evaluate the interaction of irrigation (overhead vs drip) and fertilizer placement (dibble vs incorporated) on GHG emissions (CO2, N2O, and CH4). Plants were grown in 11.4 L (#3) containers with a 6:1 pine bark:sand substrate with standard amendments. All containers received 6.35 mm (0.25 in) water three times daily. Gas samples were collected in situ using the static closed chamber method according to standard protocols and analyzed using gas chromatography. Total cumulative CO2 loss was not affected by differences in irrigation or fertilizer placement. Total cumulative N2O efflux was least for drip-irrigated plants, regardless of fertilizer placement. For overhead-irrigated plants, N2O efflux was greatest for those with incorporated fertilizer. Efflux of CH4 was generally low throughout the study. Findings suggest that utilizing drip irrigation could decrease N2O emissions, regardless of fertilizer placement. However, when limited to overhead irrigation, dibbled fertilizer placement could decrease N2O emissions. Index words: carbon dioxide, methane, nitrous oxide, trace gas Species used in this study: Japanese boxwood (Buxus microphylla Siebold & Zucc.)

Peat and perlite have served as industry standards in greenhouse substrates for over 50 years. The continued availability of peat, paralleled with its inert characteristics, as well as its ability to stay generally pathogen-free have all contributed to its success in the horticulture industry. Expanded perlite has long been used as an amendment in container mediums to provide air space to container substrates without adding to bulk density or affecting substrate pH and EC. However, due to increased restrictions on the harvesting of peat, as well as fluctuations in fuel prices necessary for shipping, the future availability of peat is a largely unknown factor in greenhouse production. Additionally, growers consider perlite to be a general nuisance due to the lung and eye irritation problems. Because of these problems, researchers have focused on identifying and evaluating possible alternatives to standard substrates. These studies evaluated three possible substrate alternatives for use in greenhouse production, including fresh sweetgum (SG), hickory (H), and eastern redcedar (RC), in addition to WholeTree (WT) substrate. Three greenhouse annual crops (petunia, impatiens, and vinca) were planted in varying ratios of these species mixed with peat. Plants grown with SG and H as amendments did not perform as well as a traditional peat:perlite mix with respect to flower number, growth indices, and plant dry weight. However, plants grown in RC tended to be equivalent to those grown in a traditional mix. Data showed that greenhouse producers could amend their standard greenhouse substrate with up to 50% eastern redcedar with little to no differences in plant growth.

Flumioxazin is commonly used in nursery production for PRE weed control. Container nursery producers are of the opinion that the granular formulation is less effective than the sprayable formulation. Under the hypothesis that the granular formulation may require more water for activation, an experiment was conducted to evaluate the interaction of flumioxazin formulation, rate, and activation moisture for PRE control of spotted spurge in a pine-bark substrate. Experiment consisted of a factorial arrangement of four experimental variables; flumioxazin formulation (granular and spray), and flumioxazin rate (0.28 and 0.42 kg ai ha−1), substrate moisture level at the time of application (dry, medium, and wet), and after-application irrigation level (a single irrigation at 0.6, 1.3, 2.5, and 5.1 cm). Treated pots were seeded with spotted spurge 2 d after the herbicide application, which was 1 d after the first irrigation. Control as indicated by spotted spurge counts and fresh weight was influenced only by flumioxazin rate and formulation. The sprayable formulation provided excellent control regardless of rate. Granular formulation was generally less effective, and additional activation moisture did not improve efficacy. Further studies were conducted with the granular formulation to determine the maximum separation distance between the spotted spurge seed and herbicide prills at which control is possible. Individual prills and spotted spurge seeds were placed on media surface at progressively increasing separation distances. Nonlinear regression of seedling survival data revealed that ≥99% control required a prill–seed separation of ≤5.2 mm. This prill–seed separation requirement is only marginally obtained with the current registered rate, i.e., 0.42 kg ai ha−1 or 168 kg product ha−1. The relationship between control and prill–seed separation distance cannot be manipulated by additional activation moisture. Inadequate contact between the spotted spurge seeds and the flumoioxazin-containing prills is likely the sole cause of inadequate control.