Types of Research
This brief explores how two datasets – The Tanzania National Panel Survey (TZNPS) and the TNS-Research International Farmer Focus (FF) – predict the determinants of inorganic fertilizer use among smallholder farmers in Tanzania by using regression analysis. The (TZNPS) was implemented by the Tanzania National Bureau of Statistics, with support from the World Bank Living Standards Measurement Study – Integrated Surveys on Agriculture (LSMS-ISA) team and includes extensive information on crop productivity and input use. The FF survey was funded by the Bill and Melinda Gates Foundation and implemented by TNS Research International and focuses on the on the behaviors and attitudes of smallholder farmers in Tanzania. The two datasets produce relatively comparable results for the primary predictors of inorganic fertilizer use: agricultural extension and whether or not a household grows cash crops. However, other factors influencing input use produce results that vary in magnitude and direction of the effect across the two datasets. Distinct survey instrument designs make it difficult to test the robustness of the models on input use other than inorganic fertilizer. This brief uses data inorganic fertilizer use, rather than adoption per se. The TZNPS did not ask households how recently they began using a certain product and although the FF survey asked respondents how many new inputs were tried in the past four planting seasons, they did not ask specifically about inorganic fertilizer.
This report investigates the potential environmental and socio-economic benefits and costs of glyphosate resistant cassava. Glyphosate resistant crops (also referred to as glyphosate tolerant) have been rapidly adopted by a number of crop producers because they simplify and/or reduce the cost of weed management. Glyphosate resistant crops also provide external environmental benefits by promoting reduced tillage agriculture, decreasing erosion and increasing soil health. However, glyphosate resistant crops also have some environmental costs, potentially leading to increased use of herbicides and environmental contamination. Because transgenic glyphosate resistant cassava is not currently in use, literature on its potential environmental and socioeconomic costs and benefits is limited. Therefore, this report draws on the literature for glyphosate resistant crops that are in current use, including maize, soybeans, sugar beets and canola (rapeseed). We find that socioeconomic and environmental impacts of glyphosate resistant crops differ by crop-type, agroecological conditions, production systems and local regulatory structure. Therefore, some benefits and costs associated with other glyphosate resistant crops may not be applicable to glyphosate resistant cassava.
This brief reviews the literature and empirical evidence on waste extraction and treatment in the developing world. The brief assesses the quantity and quality of research supporting key components of program theory related to the extraction of sludge from on-site sanitation facilities and pre-disposal transport. In general, we find few empirical studies that directly evaluate the assertions of the program theory. Most of the evidence in the literature that addresses the target components of program theory is based upon case studies or general observational and experiential assertions by sanitation experts. Where appropriate, we have identified evidence in the literature according to whether case studies or informal observations formed the basis of the conclusion.
The purpose of this literature review is to provide qualitative and quantitative examples of technologies, constraints and incentives for efficient waste treatment and reuse in Sub-Saharan Africa and Southeast Asia. We present relevant case studies and expert observations and experiences on the nutrient content in urine and feces, contaminants frequently found in untreated sludge and wastewater, waste treatment technologies that may be relevant for low-income countries, risks associated with waste reuse, benefits to resource recovery in agriculture. We further discuss reasons for waste treatment failures, including urbanization, observations on challenges with market-driven reuse in less developed countries, and examples of net-positive energy facilities in Europe and the United States. Much of the evidence presented in the literature relates to wastewater treatment processes or the sludge produced from wastewater treatment as opposed to untreated fecal sludge. However, examples of risks, failures, and opportunities for raw sludge treatment and reuse are discussed when available. In some cases, empirical evidence or case studies were not available for developing countries and alternatives are presented. Overall we found the empirical evidence on waste treatment and reuse in developing countries is quite thin.