Leguminous green manure can drive the stabilisation of the increased soil organic carbon on dryland
Date
2019-03-05
Authors
Yao, Z.
Xu, Q.
Chen, Y.
Liu, N.
Huang, L.
Adl, S.
Zhang, D.
Li, Y.
Zhang, S.
Cao, W.
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Quantifying field management on stabilised soil organic carbon (SOC) can be utilised to elucidate the management efficacy on mitigating climate change over the long-term. To achieve this goal, we measured the physico-chemically protected C in aggregates and their contribution to the SOC of the bulk soil to determine whether growing leguminous green manure (LGM) instead of summer fallow can drive the formation of the stable SOC. The field study was a split-plot design with 4 main treatments: growing Huai bean, soybean and mung bean as LGM while fallow as control. The sub-treatments included 4 synthetic N rates (0, 108, 135 and 162 kg ha-1) for the winter wheat. Huai bean significantly increased the mass ratio of the large macroaggregates and the mean weight diameter and geometric mean diameter in the 0-10 cm soil layer compared with the fallow. Huai bean and soybean significantly increased the content of the mineral-associ ated OC (MOC), while all the LGM treatments increased the content of the intra-microaggregate particulate OC (iPOC) by 12-24% in the 0-10 and 10-20 cm soil layers. The increased SOC content in the bulk soil for the LGM treatments compared to the fallow was mainly attributed to the increase in the protected C (iPOC+MOC), which accounted for 69-89% of the total increase, with the exception of 37% for mung bean in the 10-20 cm soil layer. The correlation analysis further suggests that only the increase in the protected C was positively linearly correlated with the SOC change. In conclusion, LGM instead of summer fallow can increase the SOC in the bulk soil mainly by increasing the protected C, which supports the concept that introducing the LGM can be an efficient alternative to mitigate climate change by sequestering the C in the soil for a prolonged period.
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Soils and Crops Workshop