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P. Jobin, J. Caron, C. Menard, and B. Dansereau

Low water retention in hanging baskets is a constraint in urban floriculture and hydrogel addition is an alternative. However, growth may be reduced with such a product depending on the substrate used. This study was conducted to determine the combined effects of substrate and type of hydrogel on the growth of Surfinia plants produced in hanging baskets. During Spring 1998, three rooted cuttings of Surfinia (Petunia × hybrida `Brilliant Pink') were transplanted into 30-cm hanging baskets. Plants were transplanted into one of the following substrates: 1) Pro-Mix BX, 2) a blend of 4/5 Pro-Mix BX and 1/5 compost, or 3) 1/3 perlite 1/3 vermiculite and 1/3 compost (v/v). These three substrates were amended with two types of hydrogels. The first type, Soil Moist, is an acrylic-acrylamide copolymer and the second type is Aqua-Mend, an acrylic polymer. Plants were grown for 8 weeks under standard irrigation and fertilization practices. Plant growth characteristics, percent dry weight, mineral nutrition, and growth index were determined. Substrate physical properties such as available water content, unsaturated hydraulic conductivity and total porosity were measured. The dry weight and growth index of plants in Pro-Mix BX amended with both types of hydrogels were greater than those plants growing in Pro-Mix BX without hydrogel. Plants growing in substrates 2 and 3 with hydrogels were smaller or similar respectively than those plants growing in substrates without hydrogel. Their effects on physical properties of substrates and plant growth will be discussed.

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Gray R. Bachman

The horticulture industry continues to show interest in using stabilized organic wastes as a component of container media. Vermicompost, also known as worm-worked waste or worm castings, is one of these materials of interest and can be produced from a number of organic wastes, including manure wastes. One issue that has not been addressed is the uniformity of vermicomposts produced from wastes of different sources. Are all vermicomposts created equal? The uniformity of vermicompost is important for growers to consider when using as a medium amendment. This research project investigated the physical properties of vermicompost 1) from different sources of wastes and 2) from a single waste source sequentially sampled over time. The first stage determined the physical properties of vermicompost from beef manure, hog manure, and peat-based media used by two earthworm growers. There were significant differences between the four vermicomposts in bulk density, air volume, percent air volume, percent volumetric moisture, total porosity, and water holding capacity. The second stage involved determining the physical characteristics of vermicompost produced from beef manure collected at the Illinois State University Research Farm from cattle receiving a consistent diet through the year. Manure was collected bimonthly. There was no difference in vermicompost bulk density among the samples. There were significant differences in air volume, percent air volume, percent volumetric moisture, total porosity, and water holding capacity. These changes in vermicompost physical characteristics must be quantified for growers to accurately predict performance as a growth medium amendment.

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Brian E. Jackson, Amy N. Wright, and Jeff L. Sibley

In the southeastern United States, inconsistent pine bark (PB) supplies and overabundance of cotton gin by-products warrant investigation about the feasibility of replacing PB with cotton gin compost (CGC) for container horticultural plant production. Most research on the use of composted organic substrates for horticultural plant production has focused on shoot growth responses, so there is a need to document the effect of these substrates on root growth. In 2004, `Blitz' tomato (Lycopersicon esculentum), `Hot Country' lantana (Lantana camara `Hot Country'), and weeping fig (Ficus benjamina) were placed in Horhizotrons to evaluate root growth in 100% PB and three PB:CGC substrates containing, by volume, 60:40 PB:CGC, 40:60 PB:CGC, and 0:100 PB:CGC. Horhizotrons were placed in a greenhouse, and root growth in all substrates was measured for each cultivar. Physical properties (total porosity, water holding capacity, air space, and bulk density) and chemical properties (electrical conductivity and pH) were determined for all substrates. Physical properties of 100% PB were within recommended guidelines and were either within or above recommended ranges for all PB:CGC substrate blends. Chemical properties of all substrates were within or above recommended guidelines. Root growth of all species in substrates containing CGC was similar to or more enhanced than root growth in 100% PB.

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Russell Tweddell, G.M. Olah, André Gosselin, and Antoine Karam

Several studies have demonstrated the importance of physical, chemical and microbiological properties of compost on Agaricus bisporus growth and yield. However, to our knowledge, no experimentation has been conducted to determine the effect of storage on the properties of spawned compost. For this study, our objective was to compare the properties of spawned compost stored under different temperature regimes. The microflora and, the chemical and physical properties of prespawned compost pressed in shrink wrapped blocks were first determined and mushroom yield evaluated. Subsequently, composts that had been stored at 4°C, 15°C, 24°C for 10 and 14 days were analysed for the same variables. Our results showed that storage temperature affected some properties of compost but these changes did not affect mushroom yield.

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April D. Edwards, Steven E. Newman, and Adolph J. Laiche

Kenaf (Hibiscus cannabinus) is an alternative fiber crop being grown in Mississippi that maybe used as a tree-less fiber substitute for making paper. A by-product in this process is the pithy light-weight fiber core. The objective of this study was to examine the chemical and physical properties of kenaf fiber core as a medium component in growing woody ornamentals and compare to pine bark. Comparisons of media in which Ilex crenata `Cherokee' and Rhodoendron eirocarpum `Wakabuisi' were grown were made. The physical and chemical properties including bulk density, total pore space, water retention, pH and soluble salt concentrations were determined. Aged kenaf had lower pH values than fresh and both aged and fresh kenaf had higher pH values than pine bark. The total pore space of kenaf was lower than the pore space of pine bark. At the termination of the study, the kenaf media had considerable shrinkage, which was considered unsuitable for a long-term crop.

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Robert Boozer, Eric Simonne, and Jim Pitts

A clear polyester plastic was evaluated to determine if its physical properties were suitable for vegetable plasticulture. Integrity of the clear plastic was greatly reduced if edges were damaged or torn, resulting in ripping during the mulch lading process. All six punching devices evaluated for planting holes performed well on the black plastic. Flame burner rated highest for the clear plastic and the lowest rating was achieved with the standard transplanter wheel punch. Clear plastic deteriorated quickly and by 78 days after laying was brittle. Where paint treatments provided adequate coverage, deterioration was greatly reduced. Weed growth under clear plastic was a problem early, but weeds soon died due to heat accumulation under the clear plastic. Despite a lower cost, limited agricultural use could be made of this material.

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Shelly D. Dueitt and Steven E. Newman

Rice hulls, a by-product of the rice milling process, were used at various rates to substitute sphagnum peat moss in greenhouse media. Previous studies demonstrated that media containing rice hulls replacing the vermiculite fraction grew plants equal to or better than traditional peat vermiculite blends. The objective of this study was to determine if rice hulls can replace sphagnum peat moss in a greenhouse medium. Physical properties, including bulk density, total pore space, and water retention were determined in media blended with fresh or aged rice hulls, sphagnum peat moss, and vermiculite. The bulk density of the media increased with increasing levels of fresh rice hulls. The pore space in media containing both fresh and aged rice hulls decreased over time during the crop production cycle and the pH increased.

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Laurie E. Drinkwater, Deborah K. Letourneau, Fekede Workneh, Marita Cantwell, Ariena H.C. van Bruggen, and Carol Shennan

Twenty commercial tomato production systems were compared in a multidisciplinary on farm study. The aim was to determine if organic (ORG) and conventional (CNV) systems differed in terms of agronomic criteria or indicators of underlying ecological characteristics. Field level measures of inputs, yields, fruit quality, arthropod abundance and management operations were made. Also, multiple samples within each field were taken to measure soil chemical and physical properties, root pathogen populations, disease incidence, and pest damage levels for multivariate analysis. Management effects on agronomic criteria (yield, fruit quality, pest damage) were small, whereas differences in soil N pools, microbial activity, pathogen populations and arthropod communities between ORG and CNV sites were sufficiently robust to be distinguished from site to site variation. Relationships between management, crop productivity and fruit quality will be discussed.

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Bielinski M. Santos and James P. Gilreath

Purple nutsedge can easily penetrate polyethylene mulch films. However, there are no reports on possible differences among mulch films. Because of this situation, field trials were conducted in Ruskin and Bradenton, Fla., during 2002 and 2003. In Spring 2002, the treatments were a) no mulch, b) black Pliant High Barrier mulch, and c) green Klerk's Virtually Impermeable Film (VIF). In Spring 2002, the films were a) black Pliant High Barrier, b) black IPM Bromostop, c) metallized Pliant, and d) green Klerk's VIF. The number of nutsedge emerged through the films was determined. No fumigants or herbicides were applied. Results indicated that the Klerk's VIF had the lowest nutsedge densities. No nutsedge control differences were found between the IPM Bromostop and the metallized Pliant films. These differences might be due to the physical properties of the films, including stretching and thickness.

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J.P. Mitchell, C. Shennan, D. Peters, and R.O. Miller

Sustainable alternatives for saline drainage water management in areas such as California's San Joaquin Valley are needed. Previous work has demonstrated the short-term potential for reuse of saline drainage water for irrigation in this area. Results from our 6-year cyclic drainage reuse study, however, indicate that soil structural problems may occur which can greatly reduce stand establishment and crop yields in periodically salinized soils. To prevent these problems, we are evaluating the effectiveness of winter cover crop incorporation and gypsum applications relative to conventional fallows, for improving/maintaining soil physical properties and crop productivity in cyclically salinized soils. Six winter cover crop/fallow treatments have been imposed upon a rotation of tomatoes, tomatoes and cotton as summer crops. By monitoring water use, relevant soil physical and chemical properties as well as crop performance during the course of this 3-year rotation study, we are assessing the potential benefits and constraints of using winter cover crops in drainage water reuse systems.