Abstract
Plant roots are primary factors to contribute to surface and deep soil carbon sequestration (SCS). Perennial grasses like vetiver produce large and deep root system and are likely to contribute significantly to soil carbon. However, we have limited knowledge on how root and shoot decomposition differ and their contribution to SCS. This study examined biomass production and relative decomposition of vetiver which was grown under glasshouse conditions. Subsequently the biomass incubated for 206 days, and the gas analysed using ANCA-GSL. The results confirmed large shoot and root production potential of 161 and 107 Mg ha−1 (fresh) and 67.7 and 52.5 Mg ha−1 (dry) biomass, respectively with 1:1.43 (fresh) and 1:1.25 (dry) production ratio. Vetiver roots decomposed more rapidly in the clay soil (p < 0.001) compared with the shoots, which could be attributed to the lower C:N ratio of roots than the shoots. The large root biomass produced does indeed contribute more to the soil carbon accumulation and the faster root decomposition is crucial in releasing the carbon in the root exudates and would also speed up its contribution to stable SOM. Hence, planting vetiver and similar tropical perennial grasses on degraded and less fertile soils could be a good strategy to rehabilitate degraded soils and for SCS.
Highlights
Soils globally are important in sequestering atmospheric carbon and can significantly affect greenhouse gas flux [1–3]
We examined vetiver’s (Chrysopogon zizanioides) above- and belowground biomass production where plants were grown under glasshouse conditions in sandy soil, in addition to the relative decomposition rates of the grass shoot and root biomass when incubated with three Australian soil textures with different initial properties
The analysis indicated that the difference between the shoot decomposition in the clay and silt soils were significantly different (p = 0.001), and that both were significantly higher than in the sand (p = 0.001)
Summary
Soils globally are important in sequestering atmospheric carbon and can significantly affect greenhouse gas flux [1–3]. Maximizing the carbon input, and minimizing the rate of organic matter decomposition after deposition in soil, are two important factors that can help to increase the amount of carbon sequestered from the atmosphere [4]. Perennial grasses, due to their deep root systems, might contribute significantly to soil carbon [7,8], via biomass inputs and slow mineralization processes due to slow OM turnover at depth [12]. Studies report that a large root biomass can support substantial soil microorganism populations and their metabolic processes, and contribute significantly to soil organic matter decomposition and carbon turnover [9]. A precise relationship between root biomass and soil organic carbon [13] is not, easy to establish because soil OM decomposition depends on several interacting factors including climate, litter quality, water and nutrient availability, soil type/texture and biotic activity [14–16]
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