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Effects of land management on COâ flux and soil C stock in two Tanzanian croplands with contrasting soil texture
- Sugihara, Soh, Funakawa, Shinya, Kilasara, Method, Kosaki, Takashi
- Soil biology & biochemistry 2012 v.46 pp. 1-9
- agricultural land, carbon, carbon dioxide, carbon sinks, clay soils, climate, climate change, fertilizers, land management, plant residues, sandy soils, seasonal variation, soil depth, soil fertility, soil texture, Tanzania
- Evaluation of carbon dynamics is of great concern worldwide in terms of climate change and soil fertility. However, the annual COâ flux and the effect of land management on the carbon budget are poorly understood in Sub-Saharan Africa, owing to the relative dearth of data for in situ COâ fluxes. Here, we evaluated seasonal variations in COâ efflux rate with hourly climate data in two dry tropical croplands in Tanzania at two sites with contrasting soil textures, viz. clayey or sandy, over four consecutive crop-cultivation periods of 40 months. We then: (1) estimated the annual COâ flux, and (2) evaluated the effect of land management (control plot, plant residue treatment plot, fertilizer treatment plot, and plant residue and fertilizer treatment plot) on the COâ flux and soil carbon stock at both sites. Estimated annual COâ fluxes were 1.0â2.2 and 0.9â1.9Â MgÂ CÂ haâ»Â¹Â yrâ»Â¹ for the clayey and sandy sites, respectively. At the end of the experiment, crop cultivation had decreased the surface soil carbon stocks by 2.4 and 3.0Â MgÂ CÂ haâ»Â¹ (soil depth 0â15Â cm) at the clayey and sandy sites, respectively. On the other hand, plant residue application (7.5Â MgÂ CÂ haâ»Â¹Â yrâ»Â¹) significantly increased the surface soil carbon stocks, i.e., 3.5â3.8 and 1.7â2.1Â MgÂ CÂ haâ»Â¹ (soil depth 0â15Â cm) at the clayey and sandy sites, respectively, while it also increased the annual COâ fluxes substantially, i.e., 2.5â4.0 and 2.4â3.4Â MgÂ CÂ haâ»Â¹Â yrâ»Â¹ for the clayey andÂ sandy soils, respectively. Our results indicate that these dry tropical croplands at least may actÂ asÂ aÂ carbon sink, though the efficiency of carbon accumulation was substantially lower in sandy soil (6.8â8.4%) compared to clayey soil (14.0â15.2%), possibly owing to higher carbon loss by leaching andÂ macro-faunal activity.