Dr. Zengeni obtained her BSc and MPhil (Soil Science) from the University of Zimbabwe, and PhD (Soil Science) from Nelson Mandela Metropolitan University, Port Elizabeth. She previously worked for the Ministry of Agriculture in Zimbabwe as a researcher (2004-2005), before joining Bindura University of Science Education, Zimbabwe as a lecturer from 2005 to 2012.
Her PhD was on assessing soil carbon and carbon dioxide effluxes under different vegetation environments in the Eastern Cape Province, South Africa. She currently lectures several Soil Science modules at the University of KwaZulu Natal, South Africa. Her areas of interest includes soil science, solid waste management, carbon research, indigenous knowledge systems and natural resource management. She has published various papers in peer reviewed journals.
Dr. Zengeni obtained her BSc and MPhil (Soil Science) from the University of Zimbabwe, and PhD (Soil Science) from Nelson Mandela Metropolitan University, Port Elizabeth
Crop residue decomposition in soils is of major importance for maintaining soil carbon (C) stocks and nitrogen (N) mineralization, which are vital for soil fertility improvement and climate change mitigation. The impact of biochemical quality on decomposition and N mineralization of sorghum cultivars and/or crop residue parts is not well documented. Thus in the present study, field and laboratory experiments spanning 168 and 120 days respectively, were used to assess the rate of decomposition and N mineralization in soils of residues from five sorghum cultivars and to relate the results with residue quality (i.e. lignin: N ratio) over time. Results showed that high-quality residues (i.e., from cultivars of Mamolokwane and OS-Potch) exhibited rapid decomposition (>50% DM loss) and elevated carbon dioxide emissions in shoots, attributed to a low lignin: N ratio. While low-quality residues (i.e., from cultivars AS8 and KZ5246) initially underwent net nitrogen immobilization, transitioning to mineralization at later stages. Notably, shoots consistently released more N than roots, with distinct NO3-N mineralization values ranging from 22.7 to 11.5 mg N/kg for OS-Potch and KZ5246 shoots and 20.6 to 9.3 mg N/kg for their root residues. Results suggested that low-quality sorghum residues, particularly KZ5246 and AS8 roots, release carbon and nitrogen at a slower rate, providing potential for carbon storage and limited nitrogen availability compared to high-quality residues like OS-Potch shoots.