Publication Date:
2015-04-28
Description:
The use of deep-rooting pasture species as a management practice can increase the allocation of plant carbon (C) below-ground and enhance C storage. A 2-year lysimeter trial was set-up to compare changes in C stocks of soils under either deep- or shallow-rooting pastures and investigate whether biochar addition below the top 10 cm could promote root growth at depth. For this i) soil ploughing at cultivation was simulated in a silt loam soil and in a sandy soil by inverting the 0–10 and 10–20 cm depth soil layers, and a distinctive biochar (selected for each soil to overcome soil-specific plant growth limitations) was mixed at 10 Mg ha −1 in the buried layer, where appropriate; and ii) three pasture types with contrasting root systems were grown. In the silt loam, soil inversion resulted in a general loss of C (2.0 – 8.1 Mg ha −1 ), particularly in the buried horizon, under shallow-rooting pastures only. The addition of a C-rich biochar (equivalent to 7.6 Mg C ha −1 ) to this soil resulted in a net C gain (21–40% over the non-biochar treatment, P 〈 0.10) in the buried layer under all pastures; this overcame the loss of C in this horizon under shallow-rooting pastures. In the sandy soil all pastures were able to maintain soil C stocks at 10–20 cm depth over time, with minor gains of C (1.6 – 5.1 Mg ha −1 ) for the profile. In this soil, the exposure of a skeletal and nutrient-depleted soil layer at the surface may have fostered root growth at depth. The addition of a nutrient-rich biochar (equivalent to 3.6 Mg C ha −1 ) to this soil had no apparent effect on C stocks. More research is needed to understand the mechanisms through which soil C stocks at depth are preserved. This article is protected by copyright. All rights reserved.
Print ISSN:
1757-1693
Electronic ISSN:
1757-1707
Topics:
Energy, Environment Protection, Nuclear Power Engineering
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