Mr Toru Hamamoto1, Prof Nhamo Nhamo2, Dr. David Chikoye3, Prof Yoshitaka Uchida1
1Hokkaido University, Sapporo, Japan, 2Zimbabwe Open University, , Zimbabwe, 3IITA, , Zambia
This study aimed to investigate effects of organic amendment on soil biological (soil fauna and microbes) community and soil carbon (C) dynamics under different soil types in Zambia (sub-Saharan Africa). Soil organisms are strongly correlated to decomposition and soil C stock when applied C sources into soils such as organic amendments in agriculture. Although the use of organic amendments is common agricultural practice, it remains unknown the effectiveness of materials of different quality and soil types on the biological activity in southern African soils.
Thus, we conducted field experiments at two locations in Zambia (Lusaka and Kabwe). Lusaka and Kabwe had sandy loam soils and loamy sand soils. Lusaka had higher soil C concentration than Kabwe. A split-plot design was used with crop type (cassava, maize, soybean and control (bare)) as the main plot and soil amendment (chemical fertilizer, cattle manure, poultry manure, maize residue, and control) as the subplot factors. Soil fauna was collected by pitfall traps every 2 weeks during crop growing season (from Dec 2017 to Apr 2018). CO2 emissions and soil moisture were measured at the same timing. Bacterial community (16S rRNA gene) was also analyzed from extracted DNA from those sampled soils (Ion PGM). The total number of soil fauna in each site was totally different; we found around 1000/200 individuals at Lusaka/Kabwe. On the other hand, CO2 emissions and microbial diversity at Kabwe significantly increased due to organic amendments.
In conclusion, organic amendments might have indirectly (soil fauna) influenced soil carbon dynamics in IITA, while directly influenced in Kabwe due to lack of carbon sources. More data is required to explain the phenomenal differences between C dynamic and soil types in Zambia.
Toru HAMAMOTO is a Ph.D. student (3rd year)at Hokkaido University, Japan. His research is focusing on soil C dynamics and that interaction with soil biology in Sub-Sharan Africa. He did field experiment in Zambia to investigate how organic amendments contribute to soil C sequestration for agricultural productivity.
If you are interested, please email hamamotoru[at]gmail.com or go to our lab website (http://www.uchidalab.com/)