Aziz Shiralipour

Effects of compost and phosphate amendments on arsenic mobility in soils and arsenic uptake by the hyperaccumulator, Pteris vittata L.

Chinese brake fern (Pteris vittata L.), an arsenic (As) hyperaccumulator, has shown the potential to remediate As-contaminated soils. This study investigated the effects of soil amendments on the leachability of As from soils and As uptake by Chinese brake fern. The ferns were grown for 12 weeks in a chromated-copper-arsenate (CCA) contaminated soil or in As spiked contaminated (ASC) soil. Soils were treated with phosphate rock, municipal solid waste, or biosolid compost. Phosphate amendments significantly enhanced plant As uptake from the two tested soils with frond As concentrations increasing up to 265% relative to the control. After 12 weeks, plants grown in phosphate-amended soil removed >8% of soil As. Replacement of As by P from the soil binding sites was responsible for the enhanced mobility of As and subsequent increased plant uptake. Compost additions facilitated As uptake from the CCA soil, but decreased As uptake from the ASC soil. Elevated As uptake in the compost-treated CCA soil was related to the increase of soil water-soluble As and As(V) transformation into As(III). Reduced As uptake in the ASC soil may be attributed to As adsorption to the compost. Chinese brake fern took up As mainly from the iron-bound fraction in the CCA soil and from the water-soluble/exchangeable As in the ASC soil. Without ferns for As adsorption, compost and phosphate amendments increased As leaching from the CCA soil, but had decreased leaching with ferns when compared to the control. For the ASC soil, treatments reduced As leaching regardless of fern presence. This study suggest that growing Chinese brake fern in conjunction with phosphate amendments increases the effectiveness of remediating As-contaminated soils, by increasing As uptake and decreasing As leaching.

Uses and benefits of MSW compost: A review and an assessment☆

Abstract Soil incorporation of composted municipal solid waste (MSW) usually results in a positive effect on the growth and yield of a wide variety of crops and the restoration of ecologic and economic functions of land. Agricultural uses of MSW have shown promise for a variety of field crops (e.g., maize, sorghum, forage grasses) and vegetables for human consumption (e.g., lettuce, cabbage, beans, potatoes, cucumbers). Responses by plant systems have ranged from none to over a twofold increase in yield. Specific responses are crop and site dependent. In most cases, yields were highest when composts were applied with fertilizer management programs. In some cases, elevated trace metal uptake was noted with lead and boron of greatest concern. Where long-term monitoring has been possible, benefits persist and actually accrue when sound soil/crop management practices are followed. Levels of toxic elements in plants for human consumption are either not well known or thresholds were not reached, as little mention was made in the literature. Container-grown ornamental crops are not for human consumption and this concern does not apply. However, they are high value commodities, and therefore, safe, satisfactory growth is important. Because composts can replace peats and barks which are becoming expensive, this application shows great promise. Silvicultural or forestry applications also represent a nonconsumptive, potentially large use of compost. These uses range from low volume/high value nursery and Christmas tree applications to high volume/low value uses in forest regeneration. Land reclamation whether for minespoil, landfill cover or soil stabilization as in the establishment and rehabilitation of road shoulders represents another potential beneficial use. However, tonnages recycled in this way will be less than in agriculture and silviculture. Compost utilization will occur in response to a number of factors including their benefits to soil-plant systems, especially those having economic value. As important, however, is the realization by policymakers that composting and compost use in agro or natural ecosystems are an integral part of the entire waste management system. Thus, a systems perspective that includes full cost accounting of waste collection, handling, and processing must incorporate marketing, distributing, and recycling in a life cycle analysis that reflects external costs and societal benefits for composting-based solid waste systems to be competitive.

Physical and chemical properties of soils as affected by municipal solid waste compost application

Abstract The organic matter content of composted MSW is high and its addition to soil often improves soil physical and chemical properties and enhances biological activities. Most agricultural benefits from MSW compost application to soil are derived from improved physical properties related to increased organic matter content rather than its value as a fertilizer. Composts provide a stabilized form of organic matter that improves the physical properties of soils by increasing nutrient and water holding capacity, total pore space, aggregate stability, erosion resistance, temperature insulation and decreasing apparent soil density. Application of MSW compost improves the chemical properties by increasing pH (in acid soils), electrical conductivity, cation exchange capacity, and soil nutrient content.

Conversion of biomass into methane gas

Land, marine and agricultural residues were subjected to a bioassay for an ultimate methane yield. Bioassays were performed in 250 ml serum bottles, incubated at 35°C. Methane yields were calculated from the percent methane in the gases formed and the total volume of gas produced. Methane yields from woody plants were lower in general than from other plant resource groups. High methane yields were obtained from several aquatic plants, some crop residues, and some root and tuber plants. Because of potentially high biomass productivity and high methane yields, water hyacinth (Eichhornia crassipes (Mart.) Solms) and Napiergrass (Pennisetum purpureum L.) were selected for intensive study. Methane yield varied among different groups, various species within each group and different parts of the same plant species. Treatment of plants with various nutrients, especially N, during the growth period and the age of the plants at harvesting time affected the methane production.

Phytotoxic effects of a short-chain fatty acid on seed germination and root length of Cucumis sativus cv. 'Poinset'.

Many studies indicate short-chain volatile fatty acids, especially acetic acid, are produced during the composting process of organic material. If a compost has not gone through a curing process and matured, its application can result in delay, inhibition or suppression of seed germination and plant growth. The mechanism of these phytotoxic effects has not been well investigated. Some studies have attributed phytotoxic effects to high ionic strength or pH imbalance.Our investigation indicated the inhibitory effect of acetic acid on seed germination and root elongation gave results suggesting a metabolic phenomenon. Further research on specific action of this acid is recommended.

Effects of Surface Application of MSW Compost On Cotton Production – Soil Properties, Plant Responses, And Nematode Management

Equipment was modified and/or developed for broadcast and banded applications of municipal solid waste (MSW) compost at selected rates to agricultural land for cotton production. Replicated tests were conducted for four years to determine the effects of compost on soil properties, crop yield, and nematode populations. Soil type in the test field was Faceville loamy sand. Broadcast application of compost significantly reduced soil compaction in the top 30 cm of soil in cotton rows and row-middles compared to no compost application. Banded application did not affect compaction in the row middles. Columbia lance nematode densities decreased in all compost-treated plots during all four years of study. Several plots treated with compost had nematode densities comparable to those found in the plots treated with Temik 15G nematicide. Compost application significantly increased the soil organic matter content and soil nitrogen content at six and 14 weeks after planting. However, the compost did not affect the leaf nitrogen content of the cotton plant during the same sampling periods. In 1996, 1997, and 1998, all rates of added compost significantly increased seed cotton yield. Yield increase was proportional to application rate. There were very few carry-over compost effects from each previous years treatments on either soil organic matter, soil nitrogen, or seed cotton yield.

Greenhouse Broccoli and Lettuce Growth Using Cocomposted Biosolids

The benefits of compost applications on various soil types were demonstrated in greenhouse studies. A compost prepared from yard waste feedstock cocomposted with biosolids at a 1:1 ratio was used to grow broccoli (Brassica oleracea botrytis, var. ‘Brigadeer’) and leaf lettuce (Lactuca sativa, var. ‘Lallorosa’) at 0, 15, 30, and 60 dry tons per acre (t/a). Surface soil from three dominant regional soil types (Arnold loamy sand, Goleta loam and Todos-Lodos clay loam) was used in plastic pots in the greenhouse studies.All rates of compost applications increased the height and dry weight of broccoli shoots and dry weight of lettuce shoots in the various soil textures tested. In loam and clay loam soil, optimal rates of compost applications were 30 to 60 t/a for broccoli and 15 to 30 t/a for lettuce. In loamy sand soil, optimal rates for broccoli and lettuce were 30 and 15 t/a, respectively. Broccoli showed less phytotoxicity symptoms to higher compost loads than did lettuce, probably because of more tolerance...

Using Compost Products in Vegetable Production

Six compost products and nitrogen (N) from ammonium nitrate fertilizer were utilized in field experiments to grow lettuce (Lactuca sativa var. ‘Lollarosa’) and broccoli (Brassica oleracea botrytis, var. ‘Brigadeer’) crops to evaluate the effect of various compost products and N application on crop yields. The basic design of the site for each compost type was a replicated split-split plot with compost type on the main plot, three rates of compost application (0, 37, 74 Mg ha−1) on the split plots and three supplemental N rates (0, 75, 150 kg ha−1) applied to split-split plots. Application rates of 37 Mg ha−1 and 74 Mg ha−1 for all compost types resulted in significant yield increases for lettuce and broccoli. Lettuce yields were significantly different for the different compost types and for combinations of compost rate by nitrogen rate. Broccoli yields were affected by the combination of compost type, compost rate, and N rate applied. In both cases, higher yields were obtained for higher compost rates, with the effect of supplemental N rate less important at these high compost rates.

Chemical prevention of growth reduction caused by supraoptimal temperatures in Arabidopsis thaliana

Abstract In attempts to prevent the detrimental effects of supraoptimal temperatures, biotin, sucrose, malic acid, and the growth retardant phosfon-S were individually added to the agar suspension on which Arabidopsis thaliana plants were grown aseptically under both optimal and supraoptimal temperature regimes. Biotin induced increases over the untreated plants of 54 per cent in fresh weight and 66 per cent in dry weight at supraoptimal temperatures, while the corresponding biotin-induced increases over the untreated plants in fresh and dry weights at optimal temperatures were 38 and 15 per cent, respectively. Addition of 1 per cent sucrose induced 58 per cent increases in fresh and 70 per cent in dry weights of plants grown under supraoptimal temperatures, while under optimal temperature conditions, sucrose actually reduced the fresh weight 12 per cent and had only a slight (2 per cent) promotive effect on dry weights. Phosfon-S increased the fresh and dry weight 30 per cent and 16 per cent respectively, under supraoptimal temperatures and 27 and 9 per cent under the optimal temperatures. Malic acid caused a reduction in both fresh and dry weights under both temperature regimes. However, malic acid treatment was found to increase the number of seed pods, seeds, and the number of secondary roots. The size of seed pods and seeds was greatly increased by malic acid treatment under both temperature conditions.