Abstract Lack of environmentally safe handling of garbage is a growing problem in urban sub‐Saharan Africa (SSA). Composting the garbage for soil‐fertility management presents an opportunity for reducing the risks of environmental pollution. This study aimed at evaluating the agronomic effectiveness and nutrient‐utilization efficiency of urban market crop‐waste compost on a Eutric Ferralsol. The study was conducted in central Uganda with treatments including compost applied at 0, 5, and 10 t ha –1 (d.w. basis); inorganic N fertilizer at rates of 0, 40, and 80 kg ha –1 and inorganic P fertilizer at 0, 9, and 18 kg ha –1 . Maize ( Zea mays L.), variety Longe 4 was used as the test crop. The nutrient quality of the compost was medium with total N of 0.9% and total P of 0.45%. Compost significantly increased plant height, LAI, stover weight, and grain yield; however, there were no significant differences between the 5 and 10 t ha –1 rates. Nitrogen also had a significant effect on LAI and stover yield, though there was no significant difference between the 40 and 80 kg ha –1 rates. Likewise, P increased plant height with no significant difference between the 9 and 18 kg ha –1 rates. Mineral N at 40 kg ha –1 led to the highest increase in N uptake by plants (76%) above the control. Nitrogen‐ and P‐utilization efficiencies for the 5 t ha –1 compost rate were more than twice that of the 10 t ha –1 rate. The highest P‐utilization efficiency (69%) was obtained where 9 kg ha –1 P was applied with 40 kg ha –1 N, while the highest N‐utilization efficiency (48%) was obtained with the 5 t ha –1 compost applied together with N at 40 kg ha –1 . From the above studies, it is clear that effectiveness of the 5 t ha –1 compost rate is the most promising.
Phytoremediation of hydrocarbon-contaminated soils is a challenging process. In an effort to enhance phytoremediation, soil was artificially contaminated with known concentration of light crude oil containing Total petroleum hydrocarbon (TPH) at a concentration of 75 gkg −1 soil. The contaminated soil was subjected to phytoremediation trial using four plant species ( Oryza longistaminata, Sorghum arundinaceum, Tithonia diversifolia , and Hyparrhenia rufa ) plus no plant used as control for natural attenuation. These phytoremediators were amended with concentrations (0, 5 and 10 gkg −1 soil) of organic manure (cow dung). Results at 120 days after planting, showed that application of manure at concentrations of 5 and 10 gkg −1 soil combined with an efficient phytoremediator can significantly enhance reduction of TPH compared to natural attenuation or use of either manure or a phytoremediator alone (p<0.05). The study also showed that a treatment combination of manure 5 gkg −1 soil, with a phytoremediator gives a similar mean percentage reduction of TPH as manure 10 gkg −1 soil (p>0.05). Therefore, the study concludes that use of phytoremediators and manure 5 gkg −1 soil could promote the restoration of TPH contaminated-soils in the Sudd region of South Sudan.
Chicken litter application on land as an organic fertilizer is the cheapest and most environmentally safe method of disposing of the volume generated from the rapidly expanding poultry industry worldwide. However, little is known about the safety of chicken litter for land application and general release into the environment. Bridging this knowledge gap is crucial for maximizing the benefits of chicken litter as an organic fertilizer and mitigating negative impacts on human and environmental health. The key safety concerns of chicken litter are its contamination with pathogens, including bacteria, fungi, helminthes, parasitic protozoa, and viruses; antibiotics and antibiotic-resistant genes; growth hormones such as egg and meat boosters; heavy metals; and pesticides. Despite the paucity of literature about chicken litter safety for land application, the existing information was scattered and disjointed in various sources, thus making them not easily accessible and difficult to interpret. We consolidated scattered pieces of information about known contaminants found in chicken litter that are of potential risk to human, animal, and environmental health and how they are spread. This review tested the hypothesis that in its current form, chicken litter does not meet the minimum standards for application as organic fertilizer. The review entails a meta-analysis of technical reports, conference proceedings, peer-reviewed journal articles, and internet texts. Our findings indicate that direct land application of chicken litter could be harming animal, human, and environmental health. For example, counts of pathogenic strains of Eschericiacoli (105-1010 CFU g-1) and Coliform bacteria (106-108 CFU g-1) exceeded the maximum permissible limits (MPLs) for land application. In Australia, 100% of broiler litter tested was contaminated with Actinobacillus and re-used broiler litter was more contaminated with Salmonella than non-re-used broiler litter. Similarly, in the US, all (100%) broiler litter was contaminated with Eschericiacoli containing genes resistant to over seven antibiotics, particularly amoxicillin, ceftiofur, tetracycline, and sulfonamide. Chicken litter is also contaminated with a vast array of antibiotics and heavy metals. There are no standards set specifically for chicken litter for most of its known contaminants. Even where standards exist for related products such as compost, there is wide variation across countries and bodies mandated to set standards for safe disposal of organic wastes. More rigorous studies are needed to ascertain the level of contamination in chicken litter from both broilers and layers, especially in developing countries where there is hardly any data; set standards for all the contaminants; and standardize these standards across all agencies, for safe disposal of chicken litter on land.
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