Carbon sequestration in soil beneath long-term Miscanthus plantations as determined by abundance
Introduction
Miscanthus (Miscanthus x giganteus Greef and Deu.) is a perennial rhizomatous grass native to East Asian tropic and subtropic regions and with a considerable biomass production potential even under cool temperate climatic conditions [1]. Miscanthus regularly shows an annual aboveground biomass production of 10– dry matter ha−1 under NW European growth conditions [2], [3], [4], [5] and research over the past two decades suggests Miscanthus as a potentially important bioenergy crop [1], [6]. Previous research has focused on management and economy in relation to establishment and productivity, harvest and storage, and combustion feasibility [6], whereas research on the impact of Miscanthus on SOC turnover remains scarce [5], [7].
The replacement of conventional cropping systems with annual crops, frequent soil tillage and relatively small returns of crop residues by a highly productive perennial bioenergy crop may introduce an increase in SOC. Under NW European climatic conditions, the harvest of Miscanthus is normally postponed until spring in order to achieve biomass with a reduced content of moisture and minerals, conditions that are desirable for biomass intended for combustion in energy plants. From late autumn when the crop becomes senescent due to adverse climatic conditions and until harvest in early spring, 25–50% of the dry matter (mostly leaves and non-woody tops) is shed from the plant [1]. Total pre-harvest and harvest losses may account for as much as two-thirds of autumn standing biomass. The biomass left after harvest will accumulate on the ground and eventually contribute to the SOC pool. Studies on other fast-growing perennial bioenergy crops (e.g. switchgrass; Panicum virgatum L.) established on cultivated land have demonstrated their ability to sequester carbon (C) in the soil, although reported responses show variable and occasionally rather moderate increases in SOC contents [8], [9], [10], [11], [12]. With regard to Miscanthus grown in NW European climate, data on C sequestration in soil is urgently needed to fully evaluate the environmental benefits of this bioenergy crop.
The discrimination against the isotope associated with photosynthesis results in plant biomass that is depleted in relative to atmospheric CO2 [13], the degree of depletion reflecting the type of photosynthetic pathway. Plants with the Calvin cycle pathway (C3-plants) become distinctly lower in than plants with the Hatch-Slack pathway (C4-plants). Traditional crops and native vegetation in cool temperate regions are all C3-plants, while fast-growing grasses originating from warmer climate zones (e.g. maize, sugar cane and Miscanthus) rely on the C4 photosynthetic pathway. This difference between C3 and C4 plants in abundance provides a unique tool to study C turnover on sites where long continued C3 vegetation has been replaced by C4 plants [14], [15], [16].
In this study, we report on C sequestration and turnovers in soil beneath 9 and 16 year old Miscanthus plantations established on a loamy sand with an arable history of C3 plants. Measurements of the / ratios in the soil down to depth in Miscanthus plots and in nearby reference plots with a C3 plant history allow us to estimate the fraction of SOC derived from Miscanthus as well as changes in overall SOC storage. Recently a similar approach has been adopted for switchgrass sites situated under a considerably warmer climate in the south-eastern USA [10].
Section snippets
Site
Soil was sampled in May 1999 from two adjacent experimental fields (field A and H) at Hornum, North Jutland, Denmark (56°50′N, 09°26′E) carrying Miscanthus plantations of different age. The Miscanthus was established in a 1 by grid (one plant per m2) in field A in 1983 (16-year old in 1999; termed Mis-16) and in field H in 1990 (9-year old in 1999; termed Mis-9). Two nearby fields without any history of C4 plants were sampled for reference, Ref-1 in May 1999 and Ref-2 in November 2000.
Biomass production
Aboveground production and harvestable plant biomass have been reported by Jørgensen [20]. Dry matter yields at spring harvest varied between 8 and in the period from 1986 to 1992 in the Miscanthus plantation established in 1983 (Mis-16). From 1993 to 1996, yields have been or less due to effects of severe drought in 1992 and frost in early June 1993 [20].
The amount of dry matter recovered in rhizomes/stubbles varied between cylinders (Table 1), with average yields of 10.9 and
Conclusions
Cultivation of Miscanthus for 9–16 years caused only moderate changes in the SOC storage on this coarse loamy soil. However, measurements of changes in stable C isotope ratios revealed that a large fraction of the SOC pool was accounted for by Miscanthus derived C. After 9 and 16 years, respectively, 13% and 31% of the SOC present at 0– was derived from Miscanthus. This indicates that a significant fraction of the SOC in this soil layer is involved in short- to medium-term turnovers. In the
Acknowledgements
We gratefully acknowledge the valuable support provided by our colleagues Uffe Jørgensen and Jens Bonderup Kjeldsen, Department of Agroecology, Danish Institute of Agricultural Sciences. We appreciate their commitment to the Miscanthus experiments. This work was financially supported by The Danish Energy Agency (Project: Biomass for energy: effects on the soil carbon balance in agriculture and forestry, grant no. 51161/98-0036).
References (33)
- et al.
MiscanthusEuropean experience with a novel energy crop
Biomass and Bioenergy
(2000) - et al.
Seasonal dynamics of nutrient accumulation and partitioning in the perennial C4-grasses Miscanthus x giganteus and Spartina cynosuroides
Biomass and Bioenergy
(1997) Genotypic variation in dry matter accumulation and content of N, K and Cl in Miscanthus in Denmark
Biomass and Bioenergy
(1997)- et al.
A review of carbon and nitrogen balances in switchgrass grown for energy
Biomass and Bioenergy
(1998) - et al.
Soil management impacts on soil carbon sequestration by switchgrass
Biomass and Bioenergy
(2000) - et al.
Carbon sequestration in perennial bioenergy, annual corn and uncultivated systems in southern Quebec
Agriculture, Ecosystems and Environment
(2001) - et al.
Natural abundance as a tracer for studies of soil organic matter dynamics
Soil Biology and Biochemistry
(1987) - et al.
Spatial and temporal distribution of the root system and root nutrient content of an established Miscanthus crop
European Journal of Agronomy
(1999) - et al.
Movement and turnover of soil organic matter as indicated by carbon isotope measurements
Soil Biology and Biochemistry
(1978) - et al.
Estimate of organic matter turnover rate in a savanna soil by 13C natural abundance measurements
Soil Biology and Biochemistry
(1990)
Carbon turnover and nitrogen mineralization potential of particulate light soil organic matter after rainforest clearing
Soil Biology and Biochemistry
Soil organic matter and soil quality—lessons learned from long-term experiments at Askov and Rothamsted
Cultivation of Miscanthus under West European conditionsseasonal changes in dry matter production, nutrient uptake and remobilization
Plant and Soil
Effect of the organic residues of Mischanthus x giganteus on the soil organic matter level of arable soils
Journal of Agronomy and Crop Science
Why do basic research? A lesson from commercial exploitation of Miscanthus
New Phytologist
Auswirkungen des Anbaus von Miscanthus x giganteus auf chemische und physikalische Bodeneigenschaften
Zeitschrift für Pflanzenernährung und Bodenkunde
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