Rain gardens have become a widespread stormwater practice in the United States, and their use is poised to continue expanding as they are an aesthetically pleasing way to improve the quality of stormwater runoff. The terms rain garden and bioretention, are now often used interchangeably to denote a landscape area that treats stormwater runoff. Rain gardens are an effective, attractive, and sustainable stormwater management solution for residential areas and urban green spaces. They can restore the hydrologic function of urban landscapes and capture stormwater runoff pollutants, such as phosphorus (P), a main pollutant in urban cities and residential neighborhoods. Although design considerations such as size, substrate depth, substrate type, and stormwater holding time have been rigorously tested, little research has been conducted on the living portion of rain gardens. This paper reviews two studies-one that evaluated the effects of flooding and drought tolerance on the physiological responses of native plant species recommended for use in rain gardens, and another that evaluated P removal in monoculture and polyculture rain garden plantings. In the second study, plants and substrate were evaluated for their ability to retain P, a typical water pollutant. Although plant growth across species was sometimes lower when exposed to repeated flooding, plant visual quality was generally not compromised. Although plant selection was limited to species native to the southeastern U.S., some findings may be translated regardless of region. Plant tissue P was higher than either leachate or substrate, indicating the critical role plants play in P accumulation and removal. Additionally, polyculture plantings had the lowest leachate P, suggesting a polyculture planting may be more effective in preventing excess P from entering waterways from bioretention gardens. The findings included that, although monoculture plantings are common in bioretention gardens, polyculture plantings can improve biodiversity, ecosystem resilience, and rain garden functionality.

Tomatoes are the most abundantly produced greenhouse vegetable crop in the United States. The use of composted substrates has increased in recent years for the greenhouse production of many vegetables, bedding plants, and nursery crops. `Blitz' tomatoes were grown during the spring and fall growing seasons in six substrate blends of pine bark ( PB), a traditional production substrate in the southeastern US, and cotton gin compost (CGC), an agricultural by-product, to assess the potential use of CGC as a viable replacement for PB for the production of greenhouse tomatoes. Treatments ranged from 100% PB to 100% CGC. Plants grown in substrates containing CGC produced similar total yields during both seasons compared to plants grown in 100% PB. In both seasons marketable yields were similar across all treatments. Similarly, cull fruit was not different across treatments. Substrates containing 60% or more CGC had significantly higher electrical conductivity (salt) levels both initially and throughout both growing seasons than did 20 and 40% CGC and 100% PB substrates. Water holding capacity increased as the percent CGC increased in each substrate, indicating the need for adjusted irrigation volume for substrates containing CGC compared to the 100% PB. Results indicate that CGC has potential to be used as an amendment to PB in greenhouse tomato production.

Urbanization causes alteration of the thermal regime (surface, air, and water) of the environment. Heated stormwater runoff flows into lakes, streams, bays, and estuaries, which potentially increases the base temperature of the surface water. The amount of heat transferred, and the degree of thermal pollution is of great importance to the ecological integrity of receiving waters. This research reports on a controlled laboratory scale test to assess low impact development (LID) stormwater control measure impacts on the thermal characteristics of stormwater runoff. We hypothesize that LID stormwater control measures (SCMs) such as pervious surfaces and rain gardens/bioretention can be used to mitigate the ground level thermal loads from stormwater runoff. Laboratory methods in this study captured and infiltrated simulated stormwater runoff from four infrared heated substrate microcosms (pervious concrete, impervious concrete, permeable concrete pavers, and turf grass), and routed the stormwater through rain garden microcosms. A data logging system with thermistors located on, within, and at exits of the microcosms, recorded resulting stormwater temperature flux. Researchers compared steady state temperatures of the laboratory to previously collected field data and achieved between 30% to 60% higher steady state surface temperatures with indoor than outdoor test sites. This research helps establish baseline data to study heat removal effectiveness of pervious materials when used alone or in combination as a treatment train with other stormwater control measures such as rain gardens/bioretention.

In-season nitrogen (N) management is a common challenge in organic vegetable production. This is especially true when using polyethylene mulch combined with fertigation. Soluble organic N sources suitable for fertigation in organic vegetable production are needed. The objective of this research was to evaluate an organic fish fertilizer in a squash/collard rotation and to compare its effectiveness to inorganic sources. A 2-year crop sequence of yellow squash ( Cucurbita pepo ) and collards ( Brassica oleracea var. acephala ) was used. To eliminate the rotation order effect, the crops were switched each year: yellow squash-collard in Year 1 and collard-yellow squash in Year 2. Three N sources were used along with a zero N control: hydrolyzed fish fertilizer (HFF), inorganic N source with secondary and micronutrients (INORGWM), and inorganic N without secondary or micronutrients (INORGWO). Three N rates and a control were also included: 1) N at the recommended rate (152 kg·ha −1 for yellow squash and 110 kg·ha −1 for collards); 2) N at 80% of the recommended rate; 3) N at 60% of the recommended rate; and 4) a zero N control. Year 2012 yellow squash had a 30% higher yield when grown with inorganic N as compared with squash grown in HFF. Year 2012 collards had a 21% higher yield when grown with INORGWM as compared with collards grown in the HFF. In the second year, highest yields of collards were again produced in the INORGWM treatments followed by those grown in the HFF treatments. Second-year squash grown in the inorganic N treatments produced highest yields, and squash grown in the HFF had a 16% lower yield as compared with those grown in the two inorganic N sources. INORGWO produced lower marketable collard yields than INORGWM or HFF as a result of sulfur deficiency. Although yields were reduced in the crops grown in HFF treatments, the premium price and resultant profit associated with organic products were enough to offset the reduced yield. If growers can obtain the price premiums associated with organic produce, the use of HFF could be an economically feasible option in organic vegetable production.

Live stakes are cuttings taken from dormant woody plant species used to establish riparian vegetation. Although many species may be suitable, black willow (Salix nigra) is the species of choice in streambank stabilization projects in the southeastern United States. Studies were conducted on four species native to the southeastern United States that have potential for success as live stakes. Black willow, silky willow (Salix sericea), silky dogwood (Cornus amomum), and Virginia sweetspire (Itea virginica) were evaluated for biomass differences among species, effect of soaking stakes in tap water for 48 hours prior to installation, and differences in survival attributed to season of harvest.The,experiment was conducted at the Paterson Horticulture Greenhouse Complex, Auburn University, Alabama. Each species was established from live stakes and had 100% survival when harvested during the dormant season. Total biomass of soaked and nonsoaked live stakes of silky dogwood was greater than soaked and nonsoaked black willow live stakes at nine months. This was driven by belowground biomass. At nine months, silky dogwood belowground biomass for nonsoaked stakes was greater than belowground biomass for black willow, silky willow, and Virginia sweetspire. Belowground biomass of soaked silky dogwood stakes was similar to belowground biomass of silky willow and greater than belowground biomass of black willow. Soaking live stakes, collected in the dormant season for 48 hours resulted in only one significant total biomass difference between soaked and nonsoaked in the species silky dogwood at six months. After nine months of growth, there were no differences between soaked and nonsoaked live stake biomass. Virginia sweetspire, a shrub, consistently had less biomass, diameter, and height than the other species. However, the nine month root:shoot ratio of Virginia sweetspire was greater than both willow species and similar to silky dogwood. There was 0% survival of black willow, silky willow, and silky dogwood after six months when live stakes were harvested during the growing season irrespective of soaking treatment. Live stakes ofVirginia sweetspire harvested in the growing season had a survival rate of 80% for soaked stakes and 67% for nonsoaked stakes.The four native species evaluated in this study became established and survived as live stakes. These species are candidates for use in riparian enhancement and restoration projects, which will assist with increasing riparian plant diversity.