Stocking Density Optimization for Enhanced Bioconversion of Fly Ash Enriched Vermicompost.

Although it is widely agreed that stocking density critically affects the rate of vermicomposting, there is no established stocking density for mixtures of fly ash and other waste materials. This study sought to optimize (Savigny, 1826) stocking density for effective biodegradation and nutrient release in a fly ash-cow dung-waste paper (FCP) mixture. Four stocking densities of 0, 12.5, 25, and 37.5 g worms kg were evaluated. Although the 12.5, 25, and 37.5 g worms kg treatments all resulted in a mature vermicompost, stocking densities of 25 and 37.5 g worms kg resulted in faster maturity, higher humification parameters, and a significantly lower final C/N ratio (range 11.1-10.4). The activity of ß-glucosidase and fluorescein diacetate hydrolysis enzymes showed faster stabilization at stocking densities of 25 and 37.5 g worms kg, indicating compost stability and maturity. Similarly, a stocking density of 25 g worms kg resulted in the highest release of Olsen-extractable P and (NO + NO)-N contents. The 0-, 12.5-, 25-, and 37.5-g treatments resulted in net Olsen P increases of 16.3, 38.9, 61.0, and 53.0%, respectively, after 10 wk. Although compost maturity could be attained at stocking densities of 12.5 g worms kg, for faster production of humified and nutrient-rich FCP vermicompost, a stocking density of 25 g worms kg seems most appropriate.

Optimization of fly ash incorporation into cow dung-waste paper mixtures for enhanced vermidegradation and nutrient release.

This study was conducted to establish an appropriate mixture ratio of fly ash (F) to optimized cow dung-waste paper mixtures (CP) to develop a high-quality vermicompost using earthworms (). Fly ash was mixed with cow dung-waste paper mixtures at ratios of (F:CP) 1:1, 1:2, 1:3, 2:1, and 3:1 or CP alone and composted for 14 wk. Olsen P, inorganic N (NO, NO, and NH), C:N ratio, ash content, microbial biomass C, and humification parameters were measured together with scanning electron micrograph images to determine compost maturity. Based on C:N ratio, the extent of vermidegradation of the waste mixtures followed the decreasing order (F:CP) of 1:3 > 1:2 > 1:1 > CP alone > 2:1 > 3:1. Similarly, Olsen P was significantly higher ( < 0.05) where earthworms were added. The mean percentage increase in extractable P was in the order CP alone > 1:2 > 1:3 > 1:1 > 2:1 > 3:1, with earthworm addition almost doubling P release across the 1:1, 1:2, and CP alone treatments. Fly ash incorporation enhanced conversion of organic N to the plant-available inorganic forms, with the 1:3 treatment resulting in the highest conversion. Scanning electron micrograph images confirmed the extent of vermidegradation reflected by the various humification parameters determined. Fly ash incorporation at the 1:2 ratio proved to be the most appropriate because it allows processing of more fly ash while giving a vermicompost with desirable maturity and nutritional properties.

Effects of a precomposting step on the vermicomposting of dairy manure-waste paper mixtures.

Thermophilic composting is being promoted as a means of sanitizing waste materials prior to vermicomposting. The precomposting duration is, however, critical to the success of the vermicomposting phase as it affects worm biomass. This study evaluated the effectiveness of different precomposting periods (0, 1, 2, 3 and 4 weeks) on the sanitization and vermicomposting of dairy manure-waste paper mixtures. The parameters measured were coliform bacteria and protozoa oocyst numbers, earthworm growth, as well as stabilization and nutrient content of vermicomposts. Over 95% of fecal coliforms, Escherichia coli and of E. coli 0157 were eliminated from the waste materials within 1 week of precomposting and total elimination of these and protozoan oocysts was achieved after 3 weeks of precomposting. Microbial biomass carbon and water soluble carbon of waste mixtures decreased with increase in precomposting time and impacted negatively on earthworm growth and subsequent stabilization of the dairy manure-paper waste mixtures. Vermicomposts from waste mixtures precomposted for over 2 weeks were less stabilized, less humified and had lower nutrient contents than vermicomposts from waste mixtures precomposted for 1 week or less. A precomposting period of 1 week was found to be ideal for the effective vermicomposting of dairy manure-waste paper mixtures.

Complementary nutrient effects of separately collected human faeces and urine on the yield and nutrient uptake of spinach (Spinacia oleracea).

A glasshouse experiment was conducted to evaluate the combined use of separately collected human faeces and urine as fertilizer for spinach (Spinacia oleracea) production. Seven human faeces N : urine N combinations (1 : 7 to 7 : 1) each supplying 200 kg N ha(-1) were evaluated along with sole human faeces, sole urine, inorganic fertilizer and an unamended control. Complementary application of the two resources, human faeces and urine, increased fresh and dry matter yields only in treatments having high proportions of urine. Nitrogen uptake followed the same trend but the opposite trend occurred for P uptake indicating that urine was a better source of N whereas human faeces were the better source of P. Potassium uptake was not influenced by the two resources. The minimal improvement observed in the fertilizer value of human faeces when co-applied with urine suggested that co-application of the two resources may not give an added yield advantage when compared with sole human faeces.

Assessment of nutrient quality, heavy metals and phytotoxic properties of chicken manure on selected commercial vegetable crops.

Due to rapid expansion in the poultry industry, production of poultry manure has also consequently increased, resulting in unplanned disposal of this manure to the soil in some cases, with possible negative environmental consequences. In this study, 10 separate poultry manure samples were collected from different sites located in the central Eastern Cape, South Africa and characterized for chemical and phytotoxic properties. The poultry manures had an average neutral pH (range 6.94 - 7.97) whilst the electrical conductivity was highly variable from 2.45 dS/m to 12.3 dS/m between the 10 sites. The high conductivity values recorded in some of the manures indicate that caution may need to be practiced when directly applying these manure to the soil, to avoid buildup of soluble salts. All samples showed a very high concentration of total P (1963.1 mg/kg - 2644.1 mg/kg) with the plant available fraction ranging from 21.3% - 37.7% of the total P. All the heavy metals measured (Cr, Cu, Ni, Pb and Zn) were below the maximum permissible limits set by the U.S. Environmental Protection Agency. However, some of the poultry manure showed some level of phytotoxicity based on the plant bioassay, with some samples, recording a germination index less than 50% for the different crops evaluated. However, this bioassay may not be conclusive and there is need to evaluate this phytotoxicity in real world field applications as there is paucity of information on this aspect regarding poultry manure. Such filed studies can be used to evaluate alternative strategies such as planting and harvest intervals between application of these manures and planting or harvesting. It is also suggested that further biodegradation through composting or vermicomposting may be required to improve nutrient content and reduce the presence of phytotoxic compounds in some of the poultry manures before use as soil amendments.

Qualitative and quantitative effects of ozone and/or sulfur dioxide on field-grown potato plants.

Solanum tuberosum L. cv Norchip plants were grown in open-top chambers in the summer of 1986. Plants were treated with charcoal-filtered air, nonfiltered air, or nonfiltered air supplemented with 33, 66, or 99% of the ambient ozone (O3) concentrations from 1000 to 2000 h eastern daylight time daily. In addition, plants received charcoal-filtered air plus 0, 0.15 (393 microg m(-3)), 0.34 (891 microg m(-3)), or 0.61 (1598 microg m(-3)) ppm sulfur dioxide (SO2) from 0900 to 1200 h once every 14 d for a total of four treatments. Ozone induced a linear reduction in number and weight of Grade One (> 6.35-cm diameter) potato tubers and in total weight of tubers. Ozone also induced linear reductions in the percentage of dry matter of tubers and linear decreases in glucose and fructose content of Grade One tubers. Sulfur dioxide induced a stimulation and then decline of the number, percentage of dry matter, and sucrose content of Grade One tubers. The SO2 response best fit a quadratic curve. No O3 x SO2 interactions were detected for any of the yield or quality functions measured.

Effects of pesticides on the reticuloendothelial system.

The information available concerning the effects of compounds utilized as pesticides on functions of the reticuloendothelial system is quite limited. Review of selected examples of such studies in this and other reports (3) reveals considerable diversity in terms of species of experimental animal, purity and dose of pesticide, length of exposure, and class of pesticide employed. Observations include depression, enhancement, or no significant effect on the selected reticuloendothelial system function studies. With the present available information it is difficult to formulate general conclusions or to predict whether or not any individual pesticide will consistently and significantly alter any specific function of the reticuloendothelial system. At the present time, it is not known if pesticides within a single chemical class act in a similar manner in regard to their ability to influence reticuloendothelial system function. In addition, the relationship, if any, between the toxic, mutagenic teratogenic, or carcinogenic potential of any pesticide and its ability to alter the reticuloendothelial system is also unknown. More extensive systematic studies in experimental animal models would appear to be required before protocols to effectively evaluate the potential of pesticides to influence reticuloendothelial system function in man can be developed.

Evaluation of human urine as a source of nutrients for selected vegetables and maize under tunnel house conditions in the Eastern Cape, South Africa.

The introduction of ecological sanitation (ECOSAN) toilets in South Africa has created opportunities for safer sanitation and recycling of human excreta, as fertilizers, in rural and peri-urban areas. A study was carried out to evaluate the fertilizer value of human urine (0 to 400 kg N ha(-1)) for maize and tomato, compared to urea, in a tunnel house. Dry matter yield of both maize and tomato, harvested at 9 and 10 weeks after planting, respectively, increased with increasing N rate (both as urine or urea) up to 200 kg N ha(-1). Urea reduced soil electrical conductivity (EC) whereas urine increased it. Leaf tissue Na, in both crops, also increased with urine application. A follow-up study was carried out with two crops with contrasting sensitivity to salinity and using a wider range of N application (0 to 800 kg N ha(-1)). The results indicated increased root and leaf dry-matter yield of beetroot (tolerant to salinity) with increased urine rates up to the highest rate of 800 kg N ha(-1), whereas the leaf and root dry-matter yield of carrot, which is sensitive to salinity, peaked at the low urine application rate of 50 kg N ha(-1). Soil EC increased with urine application up to 4.64 and 13.35 mS cm(-1), under beetroot and carrot, respectively. Generally the results showed that human urine compared well with urea as a source of N for crops but optimum rates depend on the sensitivity of the crops to soil salinity, which should be monitored where human urine is regularly used for fertilizing crops.

Ozone-Induced Reduction in Quantity of Ribulose-1,5-bisphosphate Carboxylase in Alfalfa Foliage.

The concentration of ribulose-1,5-bisphosphate carboxylase was measured in the foliage of ;Moapa 69,' ;Ladak,' and ;Vernal' cultivars of alfalfa (Medicago sativa L.) after plants were exposed to 0.25 or 0.30 microliters per liter ozone for 2 hours. The quantity of ribulose-1,5-bisphosphate carboxylase decreased 80%, 68%, and 36% in leaves which did not exhibit ozone symptoms and to undetectable levels, 99% and 79% in symptomatic foliage for each cultivar, respectively.

Detection of herpes simplex virus infection of female genitalia by the peroxidase-antiperoxidase method alone or in conjunction with the Papanicolaou stain.

The sensitive peroxidase-antiperoxidase (PXAPX) method individually and in conjunction with the Papanicolaou (PAP) stain was used to detect herpes simplex virus (HSV) in specimens from human female genitalia. Initial studies using a model system of HSV-1 or HSV-2-infected Vero cells established (i) acetone as the most effective fixative, (ii) optimal dilutions of preimmunization and anti-HSV serum for differentiation of infected from noninfected cells, (iii) optimal concentration of 3,3'-diaminobenzidine tetrahydrochloride and H2O2 for maximal staining of infected cells with minimal background reaction, and (iv) removal of endogenous peroxidase with absolute MeOH. These various parameters, once established, were utilized in the PXAPX or PXAPX-PAP on human specimens from the vulva or cervix. In these specimens, examined by standard light microscopy, PXAPX-positive cells were dark brown with a single nucleus or multiple nuclei. By coupling the PAP to the PXAPX, detailed nuclear observations of PXAPX-positive cells were possible and revealed nuclear changes consistent with HSV infection, including syncytium formation, chromatin condensation, and an occasional Cowdry type A inclusion. The PXAPX and PXAPX-PAP correlated (r = 0.742) over a period of 72 h with HSV isolation from these samples.