Positive ions that are available in soils absorb on grain surfaces. The total sum of cations that can be absorbed bij a soil/sediment at a certain PH is defined by the cation-exchange capacity (CEC, in meq g-1: mol equivalents per gram). The uptake of cations is an important parameter in agriculture and the larger the CEC, the more cations can be absorbed to the soil. The CEC depends highly on the pH of soil and sediments, where the CEC decreases with decreasing PH (increasing acidity). The exchange of ions on sediments occurs commonly fast on geological time scales, but the kinetics of adsorption in natural environments is still poorly understood. The strength of the bonding between the cations and the sediments varies from weak Van der Waals bondings (physical adsorption) to strong chemical bonds. The CEC is widely used for agricultural assessment because it is a measure of general soil fertility as well as an indicator of structural stability because CED is capabel of enhancing development of shrinkage cracks. The list below shows the CEC for different types of minerals. The data indicate that the CEC can vary over 2 orders of magnitude for various types of , minerals and can vary one order of magnitude within one soil type. Cation exchange capacity for different types of sediment (Eisma, 1992; Locher and de Bakker, 1990):

Cation exchange capacity.

Assessing farmer use of climate change adaptation practices and impacts on food security and poverty in Pakistan

In sub-Saharan Africa (SSA), “maize is life,” due to its importance to food security and economic wellbeing. Around 40 % of Africa’s maize-growing area faces occasional drought stress, resulting in yield losses of 10–25 %. Around 25 % of the maize crop suffers frequent drought, with losses of up to half the harvest. To reduce vulnerability and improve food security, the Drought Tolerant Maize for Africa (DTMA) project has made releases of 160 drought tolerant (DT) maize varieties between 2007 and 2013. These have been tested in experimental and farmers’ fields, and disseminated to farmers in 13 African countries through national agricultural research systems and private seed companies. Yields of the new varieties are superior to those of currently available commercial maize varieties under both stress and optimum growing conditions. Although the benefits of DT maize for African farmers have been repeatedly predicted, realization of those benefits depends on farmer uptake, which has received limited empirical study. We use new plot-level data from surveys of 3,700 farm households in six countries (Ethiopia, Tanzania, Uganda, Malawi, Zambia, and Zimbabwe) to measure DT maize adoption rates and their determinants. The data reveal considerable inter-country variation in farmer uptake of DT maize, from 9 % of maize plots in Zimbabwe to 61 % in Malawi. The major barriers to adoption include unavailability of improved seed, inadequate information, lack of resources, high seed price, and perceived attributes of different varieties. Based on the results, we recommend that seed companies and agro-dealers ensure adequate supply of DT maize seed in local markets and sell seed in affordable micro-packs (1 or 2 kg). Furthermore, the DTMA project and partners should ramp up promotional efforts to ensure widespread awareness and understanding of the benefits of the new DT maize varieties.

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Drought tolerant maize for farmer adaptation to drought in sub-Saharan Africa: Determinants of adoption in eastern and southern Africa

Practical Environmental Analysis.

Global trends in pesticides: A looming threat and viable alternatives.

Climate change is projected to have serious environmental, economic, and social impacts on Ghana, particularly on rural farmers whose livelihoods depend largely on rainfall. The extent of these impacts depends largely on awareness and the level of adaptation in response to climate change. This study examines the perception of farmers in Sekyedumase district of Ashanti region of Ghana on climate change and analyzes farmers’ adaptation responses to climate change. A hundred and eighty farming households were interviewed in February and October 2009. Results showed that about 92% of the respondents perceived increases in temperature, while 87% perceived decrease in precipitation over the years. The major adaptation strategies identified included crop diversification, planting of short season varieties, change in crops species, and a shift in planting date, among others. Results of logit regression analysis indicated that the access to extension services, credit, soil fertility, and land tenure are the four most important factors that influence farmers’ perception and adaptation. The main barriers included lack of information on adaptation strategies, poverty, and lack of information about weather. Even though the communities are highly aware of climate issues, only 44.4% of farmers have adjusted their farming practices to reduce the impacts of increasing temperature and 40.6% to decreasing precipitation, giving lack of funds as the main barrier to implementing adaptation measure. Implications for policymaking will be to make credit facilities more flexible, to invest in training more extension officers and more education on climate change and adaptation strategies.

https://tropentag.de/2010/abstracts/full/203.pdf

Farmers’ perception and adaptation to climate change: a case study of Sekyedumase district in Ghana

The hazards of pesticide exposure have been a growing concern globally. The increase of susceptibility of farmers to pesticide intoxication is due to lack of knowledge regarding safe and proper pesticide handling. The aim of this study was to evaluate cocoa farmers’ pesticide exposure by assessing the ways in which they store pesticides, operational habits exhibited during and after pesticide application and the use of personal protective equipment (PPE) during pesticide application in the Brong Ahafo Region of Ghana. Two hundred and forty (240) cocoa farmers were randomly selected and interviewed using a structured questionnaire. Majority of the farmers were aware of the negative effects of pesticides on their health and the environment if not well handled. Despite the awareness, most farmers did not handle pesticides with care and do not adhere to the use of PPE, hence, increasing their risks to danger of exposure to pesticides. Storage of pesticides in bedrooms was reported by 22.5 % of farmers; an indication of a high risk of pesticides exposure through direct inhalation. Cocoa farmers’ in the study area exhibited operational habits such as eating, drinking water and alcohol, smoking cigarette and tobacco pipes, chewing gum and sticks, talking, using the mouth to remove blockages from sprayer nozzles, stirring pesticides with bare hands, among others during pesticides application. The survey revealed that only 35 % of farmers put on full PPE while 45 % put on partial PPE [which is any or combination of the following; cap/hat, respirator, goggle, rubber glove, overall and wellington boot (rubber boot)] during pesticides application. On the other hand, 20 % of farmers in the study area applied pesticides without wearing PPE. These practices expose farmers to adverse health risks. Factors that influenced farmers’ decision to use PPE included farming experience, age of farmer, access to extension service, availability of a chemical shop, farm size and educational level. The results indicate high risks of exposure of cocoa farmers in the study area to toxicity and health hazards of pesticides due to mishandling and habits exhibited during pesticide application. There is a need to improve habits of safe use and handling of pesticides among farmers through education and training. There is also a need for education on the use of PPE during pesticides application to avoid exposure and health hazards.

/pdf/pesticides-exposure-and-the-use-of-personal-protective-28q4varu0q.pdf

Pesticides exposure and the use of personal protective equipment by cocoa farmers in Ghana

The call for reclamation of land around Korle Lagoon in Accra, Ghana, where burning of e-waste and cultivation of vegetables takes place, makes risk assessment of heavy metal contaminations importa...

Heavy metals concentration and distribution in soils and vegetation at Korle Lagoon area in Accra, Ghana

Residues of organochlorine pesticides were determined in soils and drinking water sources in cocoa growing areas in Ghana. Soil samples analysed showed the presence of four organochlorine pesticide residues namely lindane (0.005–0.05 mg/kg), beta-HCH (<0.01–0.05 mg/kg), dieldrin (0.005–0.02 mg/kg), and p,p′-DDT (0.005–0.04 mg/kg), with dieldrin occurring most frequently. Similarly, organochlorine pesticide residues detected in the water samples were lindane (0.01–0.03 µg/l), alpha-endosulfan (0.01–0.03 µg/l), endosulfan-sulphate (0.01–0.04 µg/l), dieldrin (0.01–0.03 µg/l) and p,p′-DDT (0.01–0.04 µg/l), with heptachlor occurring most frequently. The concentrations of the detected organochlorine residues in the soil samples were below their respective US maximum residues limits (MRLs) for agricultural soils, except for lindane recorded at Kwakuanya (S4) and beta-HCH recorded at Krakrom (S3) and Kwakuanya (S4). Similarly, the organochlorine pesticide residues recorded in the water samples were below and within their respective WHO MRLs for drinking water except for alpha-endosulfan at Diabaa (S2) and Kwakuanya (S4) at distance 0–15 m and Kwakuanya (S4) at distance 16–30 m, endosulfan-sulfate at Nkrankwanta (S1) and Diabaa (S2) at distance 0–15 m and heptachlor at Krakrom (S3) at distance 16–30 m which were above their WHO MRLs. The presence of the banned organochlorine pesticide residues in soil and water samples from the study area indicates that these chemicals are still being used, illegally, on some cocoa farms. Routine monitoring of pesticide residues in the study area is necessary for the prevention, control and reduction of environmental pollution to minimize health risks.

/pdf/assessment-of-organochlorine-pesticide-residues-in-soils-and-502drwizmz.pdf

Assessment of organochlorine pesticide residues in soils and drinking water sources from cocoa farms in Ghana

Pests and diseases are recognised as major factors responsible for the decline in cocoa yield in Ghana. This has resulted in an increased use of pesticides to increase productivity. The regular application and indiscriminate use of chemicals have been associated with unintended environmental and human health consequence. The objective of this study was to determine levels of 13 organophosphorus pesticide residues in soils and drinking water sources in and around cocoa farms in Brong Ahafo region of Ghana. Organophosphorus pesticide residues were determined by the use of a high resolution Varian CP-3800 Gas Chromatograph equipped with pulse flame photometric detector (PFPD) in 32 soils and 64 drinking water samples from 16 cocoa farms in the Dormaa West District of Ghana. Four organophosphorus residues were detected in the soil and water samples at varying concentrations. The organophosphorus residues detected in soil samples were chlorpyrifos (0.01–0.04 mg/kg), profenofos (0.02–0.04 mg/kg) and pirimiphos-methyl (0.01–0.04 mg/kg) while the organophosphorus residues recorded in the water samples were chlorpyrifos (0.01–0.05 µg/L), diazinon (0.01–0.04 µg/L) and pirimiphos-methyl (0.01–0.03 µg/L). The concentrations of organophosphorus pesticide residues in the soil samples analysed from the various sites were generally below and within US MRLs for agricultural soils. However, mean concentrations of chlorpyrifos and pirimiphos-methyl recorded at Nkrankwanta (S1) were found to be above their respective US MRLs for agricultural soils. The trends of organophosphorus pesticide residues in the water samples analysed from the various distances to cocoa farms decreased with increase in distance to cocoa farm (ranking; 0–15 > 16–30 > above 30 m). All organophosphorus pesticide residues recorded in the water samples from the various sites within the various distances were below and within their respective WHO MRLs for drinking water except chlorpyrifos at Diabaa (S2) and Kwakuanya (S4) at distance 16–30 m and diazinon at Kwakuanya (S4) at a distance 0–15 m which exceeded their WHO MRLs. There were no significant (p > 0.05) sites differences in mean values of pesticide residues detected in soils and water samples. The presence of organophosphorus in the samples analysed was an indication of the use of the pesticides by cocoa farmers in the study area to control pest and diseases. The pesticide residues in the soil poses danger to soil organisms as well as contaminate surrounding water bodies through runoff and leaching. In addition, there is the likelihood of translocation of these residues from the soil into the cocoa beans and other crops (like vegetables that are commonly intercropped with cocoa) through the root system, thereby posing health risks to consumers. Chlorpyrifos and diazinon concentrations in drinking water exceeded their respective WHO MRLs at some sampled sites and may pose health hazard to farmers’ household and the communities.

/pdf/organophosphorus-pesticide-residues-in-soils-and-drinking-rfilc39got.pdf

Benedicta Y. Fosu-Mensah

Papers

Farmers’ perception and adaptation to climate change: a case study of Sekyedumase district in Ghana

Pesticides exposure and the use of personal protective equipment by cocoa farmers in Ghana

Heavy metals concentration and distribution in soils and vegetation at Korle Lagoon area in Accra, Ghana

Assessment of organochlorine pesticide residues in soils and drinking water sources from cocoa farms in Ghana

Organophosphorus pesticide residues in soils and drinking water sources from cocoa producing areas in Ghana