Theme 5-2: Drought Management and Climate Change--Poster Sessions
Description
Land degradation caused by the loss of SOC in continuously cultivated agricultural systems is a major problem in many sub-Saharan Africa countries. The integration on perennial forage grasses in cropping systems has the potential to enhance SOC sequestration. The main objective of this study is to compare soil organic carbon (SOC) under perennial forages with SOC under annual food crops, specifically maize (Zea mays). A survey was conducted in Njombe district in the Southern Highlands of Tanzania to identity farmers with planted forages that are more than five years old and with neighbouring maize plots. Survey results identified Rhodes grass (Chloris gayana) as the currently dominating forage in the district. Soils from 55 sets of paired sites, Rhodes versus adjacent maize plot, were sampled at depths of 0-20 and 20-50 cm. Total SOC and soil texture were determined for the two depths, while the aggregate fractions and their SOC content were determined only for the 0-20 cm. Average SOC content in Rhodes was higher than maize at both depths, but the differences in the paired plots was not significant. Across all sites, the SOC stocks in the 0-20 cm averaged 47.10 ±10.04 for Rhodes and 47.66±9.83 Mg C ha-1 for adjacent maize plots. The average SOC content in the large macroaggregate fractions was higher in the Rhodes plots, which indicates an increase in the physical carbon protection in soils under perennial forages. The results in this study suggest that there is a slight improvement in soil quality in soils under Rhodes grass, but further analysis on other soil organic matter indicators, e.g. particulate organic matter (POM) would be needed to understand the differences in the two land uses.
Included in
Soil Carbon Accumulation under Perennial Forage Grasses in the Southern Highlands of Tanzania
Land degradation caused by the loss of SOC in continuously cultivated agricultural systems is a major problem in many sub-Saharan Africa countries. The integration on perennial forage grasses in cropping systems has the potential to enhance SOC sequestration. The main objective of this study is to compare soil organic carbon (SOC) under perennial forages with SOC under annual food crops, specifically maize (Zea mays). A survey was conducted in Njombe district in the Southern Highlands of Tanzania to identity farmers with planted forages that are more than five years old and with neighbouring maize plots. Survey results identified Rhodes grass (Chloris gayana) as the currently dominating forage in the district. Soils from 55 sets of paired sites, Rhodes versus adjacent maize plot, were sampled at depths of 0-20 and 20-50 cm. Total SOC and soil texture were determined for the two depths, while the aggregate fractions and their SOC content were determined only for the 0-20 cm. Average SOC content in Rhodes was higher than maize at both depths, but the differences in the paired plots was not significant. Across all sites, the SOC stocks in the 0-20 cm averaged 47.10 ±10.04 for Rhodes and 47.66±9.83 Mg C ha-1 for adjacent maize plots. The average SOC content in the large macroaggregate fractions was higher in the Rhodes plots, which indicates an increase in the physical carbon protection in soils under perennial forages. The results in this study suggest that there is a slight improvement in soil quality in soils under Rhodes grass, but further analysis on other soil organic matter indicators, e.g. particulate organic matter (POM) would be needed to understand the differences in the two land uses.
