Robert C. Abaidoo

Effectiveness of common and improved sanitary washing methods in selected cities of West Africa for the reduction of coliform bacteria and helminth eggs on vegetables

Objective  To analyse and improve the effectiveness of common indigenous washing methods for the reduction of faecal coliform (FC) populations on the surface of wastewater‐irrigated vegetables and to determine simple factors affecting their efficacy.

Reducing microbial contamination on wastewater-irrigated lettuce by cessation of irrigation before harvesting

Objective  To assess the effectiveness of cessation of irrigation before harvesting in reducing microbial contamination of lettuce irrigated with wastewater in urban vegetable farming in Ghana.

Reducing health risks from wastewater use in urban and peri-urban Sub-Saharan Africa: applying the 2006 WHO guidelines

Where rapid urbanization is outpacing urban capacities to provide sound sanitation and wastewater treatment, most water sources in city vicinity are heavily polluted. This is of great concern as many of the leafy vegetables eaten raw in the cities are produced in these areas. Following the new WHO guidelines, different non-treatment options at farm, market, and kitchen level were field tested for health risk reduction with special consideration to efficiency and adoption potential. As most households are used to vegetable washing (although ineffectively), an important entry point for risk reduction is the increased emphasis of the new guidelines on food preparation measures. A combination of safer irrigation practices (water fetching, on-farm treatment, and application), the allocation of farmland with better water sources, and improved vegetable washing in kitchens appear to be able to reduce the potential risk of infections significantly, although it might not be possible to reach the ideal threshold without some kind of wastewater treatment. The on-farm trials carried out in Ghana also explored the limitation of other risk reduction measures, such as drip irrigation, crop restrictions and cessation of irrigation under local circumstances considering possible incentives for behaviour change.

Effect of low-cost irrigation methods on microbial contamination of lettuce irrigated with untreated wastewater

Objective  To assess the effectiveness of simple irrigation methods such as drip irrigation kits, furrow irrigation and use of watering cans in reducing contamination of lettuce irrigated with polluted water in urban farming in Ghana.

Soil and Crop Contamination Through Wastewater Irrigation and Options for Risk Reduction in Developing Countries

Wastewater irrigation is becoming a global phenomenon, as a result of global water scarcity and increased pollution of water sources. While this practice offers many opportunities, human health risks from contaminated soils and crops irrigated with wastewater pose the greatest challenges to this practice. In this chapter, contaminants in wastewater of most relevance to soil and crop, such as pathogens, heavy metals, and other organic contaminants as well as the related human health and environmental risks are discussed. There is a general consensus that untreated wastewater contaminates soils and crops and poses health risks, however the threats vary widely. While wastewater treatment is the best choice to address this problem, a number of low-cost technological options and health protection measures exist to address the contamination challenges, especially in developing countries. These include irrigation methods, farm-based measures for improving water quality, choice of crop, water application techniques, soil phytoremediation, zoning, and postharvest measures. For comprehensive risk reduction, a combination of these measures is recommended, especially where comprehensive wastewater treatment is not feasible.

Perception on untreated wastewater irrigation for vegetable production in Ghana

Using household-level survey data, this study investigates farmers’ perceptions on untreated wastewater use for irrigation of vegetable farms in urban and peri-urban Kumasi of Ghana. Empirical results from an ordered probit model show that there is some relationship between personal characteristics of farmers such as age, education and gender, and perceptions of farmers on health-related risks of untreated wastewater use for irrigation. Policy efforts should be geared toward updating the knowledge, skills and attitudes of producers through frequent training and workshops so that wastewater irrigation farmers in Ghana would better appreciate health-related risks of waster irrigation and how to adopt risk mitigating strategies. Further research for a more in-depth analysis on those relationships in the short-term with immediate emphasis on improving adoption of safer irrigation technologies among wastewater irrigation farmers is recommended.

Response of Corn Genotypes to Weed Interference and Nitrogen in Nigeria

Abstract The effects of nitrogen (N) rate and weed interference on the grain yield of four corn genotypes were investigated in 2002 and 2003 at Ikenne (7°38′N, 3°42′E), Shika (11°11′N, 7°38′E), and Samaru (10°24′N, 7°42′E) in Nigeria. Nitrogen (N) at 0, 30, 60, and 90 kg N ha−1 were the main plot treatments. Weed-free (weeded weekly), low (intrarow weeds only), and high (zero weeding) weed pressure were the subplot treatments. Four corn genotypes (ACR8328 BN C7, Low-N-Pool C2, Oba Super II, TZB-SR) were the sub-subplot treatments. Weed density was higher at Shika and Samaru than at Ikenne, and the order of average weed biomass 8 to 10 weeks after planting was Samaru (271 g m−2) > Ikenne (236 g m−2) > Shika (161 g m−2). Corn genotype and N rate had no effect on weed biomass except at Samaru where fertilized treatments had higher weed biomass than the unfertilized treatments. Corn leaf area (LA) increased with increasing N rate at all locations regardless of weed pressure and genotype, except at Shika where ACR8328 BN C7, Oba Super II, and TZB-SR did not show any clear N response; LA was highest in the weed-free and lowest in the unfertilized treatments for all genotypes and locations, and weed pressure treatments. Low-N-Pool C2 had the highest LA, which was 1.3 times larger than in Oba Super II, which had the lowest LA. Nitrogen rate, weed pressure, and genotypes significantly affected corn leaf chlorophyll content. Chlorophyll content was higher in the fertilized treatments than the unfertilized treatments, and higher in the weed-free treatments than the low or high weed pressure treatments. ACR8328 BN C7 and Oba Super II had significantly more chlorophyll than the other genotypes. Low-N-Pool C2 showed a linear grain yield response with the increase in N rates. ACR8328 BN C7 did not respond to N application. Compared with the results in the weed-free treatment, high weed pressure reduced grain yield in all genotypes by more than 65% at Samaru, 50% at Shika, and 35% at Ikenne.

Maize-grain legume intercropping for enhanced resource use efficiency and crop productivity in the Guinea savanna of northern Ghana

Highlights • Productivity of different intercropping patterns was tested in Guinea savanna of northern Ghana.• Land Equivalent Ratios in intercropping systems are greater under low soil fertility conditions.• Competitive balance between intercrops in poor fields leads to greater Land Equivalent Ratios.• Within-row maize-legume intercropping is more productive than distinct row systems.• Radiation use efficiency is higher in intercrops than in sole crops.

Growth and yield responses of cowpea to inoculation and phosphorus fertilization in different environments

Cowpea (Vigna unguiculata) is a major source of dietary protein and essential component of the cropping systems in semi-arid regions of Sub-Saharan Africa. However, yields are very low due to lack of improved cultivars, poor management practices, and limited inputs use. The objectives of this study were to assess the effects of rhizobia inoculant and P on nodulation, N accumulation and yield of two cowpea cultivars in Mozambique. Field study was conducted in three contrasting environments during the 2013/2014 and 2014/2015 seasons using randomized complete block design with four replications and four treatments. Treatments consisted of seed inoculation, application of 40 kg P2O5 ha-1, inoculation + P, and a non-inoculated control. The most probable number (MPN) technique was used to estimate the indigenous bradyrhizobia populations at the experimental sites. The rhizobia numbers at the sites varied from 5.27 × 102 to 1.07 × 103 cells g-1 soil. Inoculation increased nodule number by 34–76% and doubled nodule dry weight (78 to 160 mg plant-1). P application improved nodulation and interacted positively with the inoculant. Inoculation, P, and inoculant + P increased shoot dry weight, and shoot and grain N content across locations but increases in number of pods plant-1, seeds pod-1, and 100-seed weight were not consistent among treatments across locations. Shoot N content was consistently high for the inoculated plants and also for the inoculated + P fertilized plants, whereas the non-inoculated control plants had the lowest tissue N content. P uptake in shoot ranged from 1.72 to 3.77 g kg-1 and was higher for plants that received P fertilizer alone. Inoculation and P either alone or in combination consistently increased cowpea grain yield across locations with yields ranging from 1097 kg ha-1 for the non-inoculated control to 1674 kg ha-1 for the inoculant + P treatment. Grain protein concentration followed a similar trend as grain yield and ranged from 223 to 252 g kg-1 but a negative correlation between grain yield and protein concentration was observed. Inoculation increased net returns by

Probabilistic quantitative microbial risk assessment model of norovirus from wastewater irrigated vegetables in Ghana using genome copies and fecal indicator ratio conversion for estimating exposure dose

104–163 ha-1 over that for the control. The results demonstrate the potential of improving cowpea grain yield, quality and profitability using inoculant, although the cost-benefit for using P at the current fertilizer price is not attractive except when applied together with inoculant at low P site.