We have created this Blog and the database to provide a place where the scientific community can share and update the fast growing knowledge and data on the study of greenhouse gas CO2, CH4, and N2O fluxes in Africa.

We are grateful for the numerous researchers and technicians who provide invaluable data. It is impossible to cite all the references due to limited space allowed and we apologize for the authors whose work has not been cited.

Frimpong et al. 2011. Does incorporation of cowpea-maize residue mixes influence nitrous oxide emission and mineral nitrogen release in a tropical luvisol?

Frimpong, K., Yawson, D., Baggs, E., Agyarko, K., 2011. Does incorporation of cowpea-maize residue mixes influence nitrous oxide emission and mineral nitrogen release in a tropical luvisol? Nutrient Cycling in Agroecosystems 91, 281-292

Abstract
In the face of climate change, quantification of the emission of nitrous oxide from soils in relation to sufficient N availability for crop uptake has assumed much significance. This study used the 15N stable isotope technique, under controlled laboratory conditions, to quantify the interactive effect on and relative contributions of the component species to N2O emission and mineral N dynamics in a tropical luvisol incorporated with different rates of cowpea-maize residue mixtures. The results show that increasing the maize residue proportion in the mixture significantly decreases N2O emission compared to the sole cowpea incorporation but increases mineral N concentration compared to sole maize residue incorporation. It is concluded that mixing low C:N ratio cowpea residue with high C:N ratio maize residue has potential for N management in tropical legume-cereal intercropping systems with the view to minimizing N2O emission while making N available for crop uptake. 
 
Keywords  Nitrous oxide emission – Mineral N – Cowpea-maize residue –  15N stable isotope

Hickman et al. 2010. Impacts of Increasing Chemical Fertilizer Use On Nitrous Oxide Emissions From a Smallholder Agricultural System in Western Kenya.

Impacts of Increasing Chemical Fertilizer Use On Nitrous Oxide Emissions From a Smallholder Agricultural System in Western Kenya.

Jonathan Hickman, Tropical Agriculture Program, The Earth Institute at Columbia University, Palisades, NY, Cheryl Palm, Tropical Agriculture and Rural Environment Program, Earth Institute, Columbia University, Palisades, NY, Jianwu (Jim) Tang, The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA and Jerry Melillo, Marine Biological Laboratory, The Ecosystems Center, Woods Hole, MA

SSSA 2010 International annual meetings, Oct. 31 - Nov. 4, Long Beach, CA, USA

Abstract

Impacts of increasing chemical fertilizer use on N2O emissions from a smallholder agricultural system in western Kenya. Over the last several decades, agricultural soils in many parts of sub-Saharan Africa have become depleted of nitrogen (N) and other nutrients, creating challenges to achieving food security in many countries. At only 8 kg N/ha/yr, average fertilizer application rates in the region are an order of magnitude lower than typical rates in the United States, and well below optimal levels. Increased use of nutrient inputs is a centerpiece of most African Green Revolution strategies, making it important to quantify the impacts of this change in practices. Increased N inputs are invariably accompanied by losses of N to the atmosphere as nitrogen oxides, including the greenhouse gas nitrous oxide (N2O). Several investigations of greenhouse gas emissions from sub-Saharan agricultural systems have been conducted over the last 20 years, but they typically include only two levels of fertilizer additions, and so are unable to identify potentially important thresholds in the response of trace gas emissions to fertilization rate. Here we examine the response function of N2O emissions to 5 different levels of inorganic fertilizer additions in a maize field in Maseno, Kenya during the 2010 long rainy season. We used an RCB design incorporating 5 levels of inorganic fertilizer additions (0, 50, 75, 100, and 200 kg/ha). We measured trace gas fluxes daily for one week starting the day before fertilizer application, followed by weekly measurements until trace gas emissions subsided to control levels. In order to identify thresholds in the N2O response, we use a stepwise backwards regression to identify departures from linearity in the mean chamber flux relative to the level of N fertilizer applied. Preliminary data suggest that N2O emissions may be slow to increase with increasing fertilizer additions, though important threshold effects may emerge. The identification of emission response thresholds combined with information to be collected on crop yield responses can provide insight into how to manage fertilizer use to optimize crop production per unit greenhouse gas emitted.

Source: http://a-c-s.confex.com/crops/2010am/webprogram/Paper61989.html