Robert C. Abaidoo

Bio: Robert C. Abaidoo is an academic researcher from Kwame Nkrumah University of Science and Technology. The author has contributed to research in topics: Fertilizer & Soil fertility. The author has an hindex of 33, co-authored 178 publications receiving 3638 citations. Previous affiliations of Robert C. Abaidoo include University of Hawaii & International Institute of Tropical Agriculture.

Pesticide and pathogen contamination of vegetables in Ghana's urban markets.

Abstract: The objective of the study was to determine and compare the current level of exposure of the Ghanaian urban population to hazardous pesticide and fecal coliform contamination through the consumption of fresh vegetables produced in intensive urban and periurban smallholder agriculture with informal wastewater irrigation. A total of 180 vegetable samples (lettuce, cabbage, and spring onion) were randomly collected under normal purchase conditions from 9 major markets and 12 specialized selling points in 3 major Ghanaian cities: Accra, Kumasi and Tamale. The samples were analyzed for pesticide residue on lettuce leaves, total and fecal coliforms, and helminth egg counts on all three vegetables. Chlopyrifos (Dursban) was detected on 78% of the lettuce, lindane (Gamalin 20) on 31%, endosulfan (Thiodan) on 36%, lambda-cyhalothrin (Karate) on 11%, and dichloro-diphenyl-trichloroethane on 33%. Most of the residues recorded exceeded the maximum residue limit for consumption. Vegetables from all 3 cities were fecally contaminated and carried fecal coliform populations with geometric mean values ranging from 4.0 x 10(3) to 9.3 x 10(8) g(-1) wet weight and exceeded recommended standards. Lettuce, cabbage, and spring onion also carried an average of 1.1, 0.4, and 2.7 helminth eggs g(-1), respectively. The eggs were identified as those of Ascaris lumbricoides, Ancylostoma duodenale, Schistosoma heamatobium, and Trichuris trichiura. Because many vegetables are consumed fresh or only slightly cooked, the study shows that intensive vegetable production, common in Ghana and its neighboring countries, threatens public health from the microbiologic and pesticide dimensions. Standard recommendations to address this situation (better legislations, law enforcement, or integrated pest management) often do not match the capabilities of farmers and authorities. The most appropriate entry point for risk decrease that also addresses postharvest contamination is washing vegetables before food preparation at the household or "chop" bar (street restaurant).

Irrigated urban vegetable production in Ghana: microbiological contamination in farms and markets and associated consumer risk groups.

Abstract: Ghana is a typical low-income sub-Saharan African country facing significant sanitation challenges. In Ghana, fresh salads are not part of the normal diet, but have become a common supplement to urban fast food served in streets, canteens and restaurants. In Accra, about 200 000 people consume from such supplements every day. The figure also describes the size of the risk group from contamination, which comprises all income classes including the poor and children. The purpose of this study was to investigate widespread water pollution in urban and peri-urban areas, where 95% of the lettuce consumed in the city is produced. Over 12 months (April 2004-June 2005), lettuce samples from the same production sites in two cities were followed and analyzed along the "farm to fork" pathway for total and faecal coliform (FC) and helminth egg numbers. Questionnaire surveys were conducted among producers, sellers and consumers to quantify lettuce flows to the final risk group. The study identified the farm as the main point of lettuce contamination. Besides the irrigation water, contamination was also attributed to manure application and already contaminated soil. Despite poor sanitary conditions in markets, post-harvest handling and marketing did not further increase the farm-gate contamination levels. To reduce the health risk associated with the consumption of contaminated lettuce; safer farming and irrigation practices are required while the remaining risk could best be addressed where lettuce is prepared for consumption.

Irrigated urban vegetable production in Ghana : Sources of pathogen contamination and health risk elimination

Abstract: Microbiological water and crop contamination was monitored on urban vegetable farms in Ghana. Faecal coliform and helminth egg contamination levels of irrigation water from drains, streams and shallow wells significantly exceeded WHO recommendations for unrestricted irrigation. High faecal coliform levels exceeding common guidelines for food quality were also recorded on lettuce irrespective of the irrigation water source, with significantly lower coliform concentrations on lettuce irrigated with piped water than with shallow well or stream water. Higher crop contamination levels were observed in the rainy season in spite of lower irrigation frequencies, compared to the dry season. The main species of helminth eggs isolated in water and on lettuce were Ascaris lumbrecoides, Hymenolepis diminuta, Fasciola hepatica and Strogyloides larvae. Results from field trials showed that apart from wastewater, already contaminated soil as well as poultry manure also contribute to crop contamination, but contributions from these sources could be only partially quantified. The need to reduce the potential health risks resulting from faecal coliform and helminth contamination of urban and peri-urban vegetables thus needs a more holistic approach than a simple focus on irrigation water quality. Copyright © 2005 John Wiley & Sons, Ltd. La contamination de l'eau microbiologique et de la recolte a fait l'objet d'un controle dans les fermes de culture de legumes au Ghana. Les niveaux de contamination des coliformes fecaux et des œufs d'helminthe irrigues par l'eau provenant des canalisations, courants, et dans les bas-fonds ont depasse de facon plus que significative les recommandations de l'OMS concernant l'irrigation illimitee. Des niveaux de coliformes fecaux eleves depassant les directives communes relatives a la qualite de la nourriture ont egalement ete enregistres pour la laitue sans tenir compte de l'irrigation des sources d'eau, avec des concentrations de coliformes excessivement basses sur la laitue irriguee a l'aide d'eau potable, que sur celle irriguee avec de l'eau de puits, ou de l'eau des ruisseaux. Des niveaux plus eleves de contamination des recoltes ont ete remarques durant la saison des pluies en depit des irrigations plus espacees, en comparison avec la saison seche. Les especes principales des œufs d'helminthe isolees dans l'eau et sur la laitue etaient des larves de Ascaris lumbrecoides, Hymenolepis diminuta, Fasciola hepatica et de Strogyloides. Les resultats des essais dans les champs ont montre que sauf les eaux residuaires, un sol deja contamine ainsi que le fumier de volaille contribuent a la contamination des cultures, bien que la contribution de ces sources pourrait etre uniquement quantifiee de maniere partielle. La necessite de reduire les risques sanitaires potentiels provenant de la contamination des coliformes fecaux et des œufs d'helminthe qui affecte les legumes poussant dans des zones periurbaines a lors besoin d'une approche plus holistique qu'une simple demarche relative a l'irrigation de la qualite de l'eau. Copyright © 2005 John Wiley & Sons, Ltd.

Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

Abstract: Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, nutrient deficiency, fertilizers, heavy metals, and pesticides is reviewed. These major stress factors suppress the growth and symbiotic characteristics of most rhizobia; however, several strains, distributed among various species of rhizobia, are tolerant to stress effects. Some strains of rhizobia form effective (N2-fixing) symbioses with their host legumes under salt, heat, and acid stresses, and can sometimes do so under the effect of heavy metals. Reclamation and improvement of the fertility of arid lands by application of organic (manure and sewage sludge) and inorganic (synthetic) fertilizers are expensive and can be a source of pollution. The Rhizobium-legume (herb or tree) symbiosis is suggested to be the ideal solution to the improvement of soil fertility and the rehabilitation of arid lands and is an important direction for future research.

Smart investments in sustainable food production: revisiting mixed crop-livestock systems.

Abstract: Farmers in mixed crop-livestock systems produce about half of the world’s food. In small holdings around the world, livestock are reared mostly on grass, browse, and nonfood biomass from maize, millet, rice, and sorghum crops and in their turn supply manure and traction for future crops. Animals act as insurance against hard times and supply farmers with a source of regular income from sales of milk, eggs, and other products. Thus, faced with population growth and climate change, small-holder farmers should be the first target for policies to intensify production by carefully managed inputs of fertilizer, water, and feed to minimize waste and environmental impact, supported by improved access to markets, new varieties, and technologies.