Impact of Tillage and Integrated Soil Fertility Management Practices on Carbon Balance in Maize-Based System in Northern Ghana

Abstract

An increasing world population necessitate the need to increase food production to meet the demand of a changing world. Intensified agriculture and accelerated climate crisis with increasing weather extremes threaten the resource base needed to improve crop production. Maize is an important staple food in Ghana. However, yield obtained by farmers in the guinea savannah zone of Ghana is generally low due to low soil fertility status resulting from continuous cropping coupled with low use of external inputs. Integrated Soil Fertility Management (ISFM) strategies have proven to sustainably increase maize yield. However, majority of the farmers practicing ISFM till their land conventionally, potentially resulting in substantial CO2 emissions that contribute to global climate change. Determining carbon dynamics and net ecosystem carbon balances (NECB) on ISFM practices in combination with different tillage practices might play a key role in finding new ways to mitigate the global climate crises. This has even become necessary as there is dearth of information on net carbon emissions regarding crop production systems in sub-Saharan Africa in general and Ghana in particular. One important reason for this is the fact that commercially available system to measure CO2 are highly capital-intensive. To overcome this financial limitation, recent trends within the field of low-cost microcontrollers and of NDIR CO2 sensors where used to develop an affordable, manual closed chamber based CO2 and ET flux measurement device. It uses K30FR (NDIR-CO2 sensor) and DHT22 (RH sensor) and was tested at both, laboratory and field level. Being successfully validated, the device was further used within a field trial environment in Ghana to investigate the impact of different tillage practices and ISFM technologies under maize cultivation on seasonal CO2 and ET emissions, NECB and water use efficiency (WUE) as well as grain yield. A split plot design was used with the main plot treatments being conventional tillage and reduced tillage and the subplot treatments being a factorial combination of organic and inorganic fertilizers at three levels each. Results presented here not only show that the developed low cost system was able to reliably measure CO2 and ET fluxes from which NECB and WUE could be estimated, respectively, but also that the conventional tillage system emitted right after tillage operation 65% more CO2 into the atmosphere than the reduced tillage. Furthermore, combined application of organic fertilizer (fertisoil/farmyard manure) at 5 t ha-1 and 90-60-60 kg NPK ha-1 enhanced maize grain yield, reduced net CO2 emission, sequestered more carbon and utilized applied nutrients and available water more efficiently. To safeguard the environment and enhanced soil health combined application of organic and inorganic fertilizers on reduced tillage system should hence be practiced in the study area.