Title：Miscanthus sacchriflorus exhibits sustainable yields and ameliorates soil properties but potassium stock without any inputs over a 12‐year period in China

Journal：GCB Bioenergy

Abstract

The perennial C₄ Miscanthus spp. is used in China for bio-fuel production and its ecological functions. However, questions arise as to its economic and environmental sustainability in abandoned farmland where the costs should be very low. Little is known about its yield performance and effects on soil properties when it was harvested annually without any inputs in China. To address these questions, an experiment was implemented for 12 years on annually harvested Miscanthus sacchariflorus planted in 2006 and managed without fertilization, irrigation or any other inputs. We determined biomass yields each year, biomass allocation and soil properties before and after its cultivation. Biomass yields of M. sacchariflorus reached peak value (29.67 t/ha) three years after cultivation and maintained at a stable level (averaged 22.22 t/ha) during 2012-2017. Its root shoot ratio increased due to more biomass allocated into below-ground with time. Long term cultivation of M. sacchariflorus increased organic carbon contents, pH (for the absence of fertilization), microbial carbon, nitrogen and phosphorus contents, and soil carbon nitrogen ratios (0-100 cm). Soil bulk density was decreased significantly (P < 0.05) independent of soil depths. Annual harvest didn’t reduce total nitrogen and phosphorus, available nitrogen and potassium but total potassium contents of soil (0-100 cm). Cultivation of M. sacchariflorus increased available phosphorus contents in 40-100 cm soil and reduced that value in 20-40 cm soil. Biological nitrogen fixation provided ~218.74 kg/ha/yr (1 m soil) nitrogen for the system  nitrogen export by biomass harvest and stabilizing nitrogen levels of soil. In conclusion, M. sacchriflorus exhibited sustainable biomass yields and ameliorated soil properties but the decrease of total potassium stocks after 12 years’ cultivation without any inputs. These conclusions could provide important information timely for government and encourage farmers to promote large scale utilization of M. sacchriflorus on the abandoned farmland in China.

本研究在国内外首次报道了在一种特定的管理模式下（一次性种植能源植物荻后不进行施肥、灌溉等任何管理，并且每年收获地上部生物质）能源植物荻的产量表现及其对土壤理化性质的影响，发现该种植物在此种模式下表现出了产量的可持续性，并且能够改善土壤理化性质，但是值得注意的是应该适时补充钾元素。该研究首次在田间尺度上、5年的时间跨度范围内计算出非共生固氮菌对该种植系统的供氮量，可达218.74kg/ha/yr （1m深土层），明确了非共生固氮菌的供氮作用。该研究能够为政府和农民在能源植物荻的种植和推广应用中提供颇具价值的信息，而且为将来高效固氮菌株的筛选提供了有力证据，为芒属类植物研究群体提供了很好的研究参考。

心得体会：该论文自去年年初开始准备撰写，先后经历拒稿重投，补充实验，大修的过程，先后得到该领域6名审稿专家审阅，并获得很多建树性意见，最终在今年5月份接收。该期刊虽影响因子不是很高，但该项研究成果能够予以发表，并在世界范围内进行传播，还是颇感欣慰。再次也衷心希望从事此方面研究或感兴趣的研究同仁多多交流。最后还要感谢为此份研究工作及论文的发表给予支持、帮助的所有人员。