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Xiuling Tian and Youbin Zheng

-suppressing growing substrates and the addition of beneficial microorganisms. Compost teas (water extracts from the fermentation of compost materials) have been reported to act as natural pesticides and may contain various biopesticidal microbes and organic chelators

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Yifan Hu and Allen V. Barker

Uses of immature composts are difficult due to wide C:N ratio, high NH4 content, and phytotoxins, such as phenols and low molecular weight organic acids. This research focused on toxicity from high NH4 content. A compost of biosolids and wood chips was used. The compost was treated with (NH4)2SO4 to 2000 mg N·kg-1 (dry weight) to simulate an immature compost. The same compost without any external NH4 was used as a mature compost. Different proportions (regimes) of compost and soil provided 1/3, 1/6, and 1/12 compost (by volume). Each regime received potassium treatment at 0 or 0.6 g K·kg-1 as KC1. A nitrate treatment, at the same N rate as NH4 in immature compost, was factored into both mature and immature composts. For the mature compost, adding K generally decreased tomato (Lycopersicon esculentum Mill.) growth (measured by shoot mass) regardless of regimes. Adding Ca(NO3)2 to mature compost greatly increased plant growth for the regimes of 1/6 and 1/12. When the regime was 1/3, this increase diminished. For the immature compost, adding nitrate restricted plant growth due to excessive amount of N, including already high amounts of NH4. This response was especially true for the 1/3 regime. Adding K to immature compost greatly increased plant growth for the regimes of 1/3 and 1/6; K suppressed plant growth at the regime of 1/12. The results indicated that using K properly can effectively reduce immature compost toxicity due to high amount of ammonium. E-mail barker@pssci.umass.edu

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Kimberlv A. Klock and George Fitzpatrick

Three compost products [biosolids (SYT), refuse derived fuel residues (RYT), and municipal solid waste (MSW)] were compared to a commercial bedding plant medium of 60% Sphagnum peat: 25% shredded bark: 15% aerolite to support Impatiens wallerana `Accent Red' growth. The treatments consisted of 100% compost as a stand alone medium plus blends in which compost was combined with control medium components at 60% compost or 30% compost. Shoot dry mass of plants grown in 100% SYT and RYT was greater than shoot dry mass of Impatiens plants grown in 100% MSW. Plants grown in SYT showed an increase in shoot dry mass from 1.29 to 1.64 g as the percentage of compost in the mix increased from 0% to 100%, while plants grown in MSW showed a linear decrease in. shoot dry mass from 1.29 to 0.18 g. Shoot dry mass of plants grown in RYT did not differ significantly from 0% to 100% compost in the media.

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S.M. Scheiber, Richard C. Beeson Jr, and Sudeep Vyapari

practices. Incorporation of organic matter or compost in annual landscape beds is widely recommended to improve water and nutrient-holding capacities, particularly in sandy soils ( Warren and Fonteno, 1993 ). However, organic matter is highly variable

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Danielle D. Treadwell, Nancy G. Creamer, Greg D. Hoyt, and Jonathan R. Schultheis

compost and cover crops are integral components in organic management systems. Compost is applied to promote soil biological activity ( Raviv, 2005 ), suppress disease ( Stone et al., 2003 ), increase soil organic C ( Jackson et al., 2004 ) and supply

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Allen V. Barker

Activators are suggested as adjuvants to accelerate rates of composting of plant residues. Three activators, two microbial preparations and one enzyme-based material, were assessed. The feedstock for composting was a 1:1 volumetric ratio of vegetative food wastes and autumn leaves from broadleaf trees. Composting was conducted in 0.35-m3, covered, plastic bins. In one experiment, the bins were filled to capacity twice, once at treatment initiation and at 1 week later. Treatments included no activator, an addition of each microbial preparation individually, addition of the enzyme-based activator individually, and additions of one of the microbial preparations and the enzyme-based activator in combination. The individual applications were at full-strength according to recommendations on the labels, and the combinations were at full-strength or at half-strength according to the recommendations. Piles in the bins were turned weekly, and activators were added weekly or only once according to the manufacturers' recommendations. Composting proceeded for 60 days. In a second experiment, the same protocols were followed with the modification that feedstock was added to each bin weekly for 60 days, followed by a 30-day curing period. Temperatures of the compost were recorded weekly. Piles were moistened weekly after turning. None of the activators accelerated the rate of composting relative to the rate with no activators. Rate of composting was evaluated by comparison of the weekly temperatures of the piles, the volume of compost produced, and the texture of the compost. Tomato (Lycopersicon esculentum Mill.) plants grew equally well in composts from each of the treatments. The conclusion was that compost activators did not modify the process or quality of compost produced from food and tree-leaf residues.

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H.M. Mathers, S.B. Lowe, C. Scagel, D.K. Struve, and L.T. Case

in the nursery industry today are pine bark, hardwood bark, sand, soil, industrial clays and aggregates, composted yard, garbage and animal wastes such as biosolids/sludge, rice hulls, peanut hulls, mushroom compost, peatmoss, coir (a by-product of

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Ronnie W. Schnell, Donald M. Vietor, Richard H. White, Tony L. Provin, and Clyde L. Munster

soluble nutrients and organic C to soil ( Johnson et al., 2006a ), a high C- to-N ratio of composted municipal biosolids (CMB) reportedly limited turfgrass growth rate and development of dark green color ( Linde and Hepner, 2005 ). If the balance of N

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Kimberly K. Moore

The ornamental horticulture industry uses a variety of materials as ingredients in growing substrates for many ornamental plants. There are many attributes that make growing substrates effective, including good aeration and drainage, availability at an acceptable price, and chemical attributes conducive for plant growth. In recent years there has been a trend in which more traditional organic components, such as Canadian sphagnum peat, have been partially replaced by an increasing array of waste-product compost. Plant response to increasing quantities of compost in the potting mix, and to different types of compost are variable. This paper reviews some important issues in the utilization of urban waste compost products.

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R.C. Funt and A.K. Hummell

Compost increases nutrient availability, cation exchange capacity, and micronutrients in the soil. In urban areas, yard waste consisting of grass clippings, leaves, and woody materials can be composted. The purpose of this study was to compare the effects of soil-composted municipal sludge and soil-composted yard waste mixtures on strawberry plants grown in the greenhouse. Earliglow strawberry plants were planted in pots containing a soil mix of 0%, 10%, 20%, or 40% by volume of composted municipal sludge or composted yard waste. Plants were grown in the greenhouse with supplemental lighting. Soil-compost mixes having greater the 90 mhos of soluble salts were detrimental to the plants; plant survival was reduced by 80% in the 40% composted sludge–soil mix within 2 weeks after transplanting. Plants survived and grew in all other treatments. Composted yard waste at 20% to 40% by volume increased leaf K and B, but decreased P, Ca, and Mg.