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B. L. Sawhney

Abstract

Analyses of a number of leaf composts showed that the composts generally contain excessive salts. Greenhouse and laboratory observations suggest that when leaf compost is used in large proportions in a soil mix for container-grown plants, salts may damage young seedlings transplanted in the mix. Excess salts can be removed by leaching with liberal quantities of water before transplanting. Leaf compost is well-buffered at about pH 7, which is considered optimal for most plants. However, since leaf compost tends to resist acidification, it may cause the pH of mixes containing large amounts of compost to remain higher than that considered suitable for such plants as azalea, rhododendron and laurel.

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Guangtian Cao, Tingting Song, Yingyue Shen, Qunli Jin, Weilin Feng, Lijun Fan, and Weiming Cai

the compost, and the dry matter holds potential valuable nutrients of A. bisporus ( Straatsma et al., 1994 ). Thus, changes in the Agaricus sp. of fungi are crucial to mushroom production. In this study, we investigated the changes in microflora of

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Theodore J.K. Radovich, Archana Pant, Ian Gurr, Ngyuen V. Hue, Jari Sugano, Brent Sipes, Norman Arancon, Clyde Tamaru, Bradley K. Fox, Kent D. Kobayashi, and Robert Paull

imported fertilizers increased from $300 to $1000 per ton between 2006 and 2008, which increased the demand for local organic fertilizers to keep local producers competitive. Compost, meat meal, and seaweeds are good sources of nutrients, although

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Carl J. Rosen, Thomas R. Halbach, and Bert T. Swanson

Composting of municipal solid waste (MSW) has received renewed attention as a result of increasing waste disposal costs and the environmental concerns associated with using landfills. Sixteen MSW composting facilities are currently operating in the United States, with many more in the advanced stages of planning. A targeted end use of the compost is for horticultural crop production. At the present time, quality standards for MSW composts are lacking and need to be established. Elevated heavy metal concentrations in MSW compost have been reported; however, through proper sorting and recycling prior to composting, contamination by heavy metals can be reduced. Guidelines for safe metal concentrations and fecal pathogens in compost, based on sewage sludge research, are presented. The compost has been shown to be useful in horticultural crop production by improving soil physical properties, such as lowering bulk density and increasing water-holding capacity. The compost can supply essential nutrients to a limited extent; however, supplemental fertilizer, particularly N, is usually required. The compost has been used successfully as a sphagnum peat substitute for container media and as a seedbed for turf production. High soluble salts and B, often leading to phytotoxicity, are problems associated with the use of MSW compost. The primary limiting factor for the general use of MSW compost in horticultural crop production at present is the lack of consistent, high-quality compost.

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Jongtae Lee

agricultural chemicals. Thus, nutrient management for sustainable crop production depends on compost from animal manures or organic fertilizers. Compost can serve as an alternative to mineral fertilizers for improving soil structure ( Dauda et al., 2008 ) and

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Roberto G. Lopez and Diane M. Camberato

costs of petroleum resins used in manufacturing plastic containers and environmental impacts of plastic disposal, coupled with advanced technologies in biodegradable and compostable products and changing public perception, indicate an opportunity for

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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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Patricia Millner, Sara Reynolds, Xiangwu Nou, and Donald Krizek

of inadvertently introduced foodborne illness pathogens, phytopathogens, or pests. COMPOST Although production in protected structures occurs with soilless media such as coir, peat, perlite, pine bark, rockwool, or vermiculite and inorganic nutrient

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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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Nikolaos Ntoulas, Panayiotis A. Nektarios, and Efthimia Nydrioti

) have been customarily used on green roofs. Organic substances such as peat and composts have also been used but at smaller participation percentages to prevent substrate subsidizing as a result of decomposition ( Williams et al., 2010 ). As substrate