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Winter mulch increases soil CO₂ efflux under Phyllostachys praecox stands

Jiang, Peikun, Wang, Hailong, Wu, Jiasen, Xu, Qiufang, Zhou, Guomo
Journal of soils and sediments 2009 v.9 no.6 pp. 511-514
Phyllostachys violascens, bamboo shoots, control methods, costs and returns, dissolved organic carbon, fertilizer rates, field experimentation, forest plantations, greenhouse gas emissions, harvest date, rice hulls, rice straw, risk reduction, shoots, soil respiration, soil temperature, straw mulches, China
Purpose The bamboo species Phyllostachys praecox has been planted in large areas of southern China for the production of edible bamboo shoots. In recent years, high rates of fertilizer application and heavy winter mulch have been employed to achieve an earlier harvest of the shoots and a better economic return. Little is known about the potential impact of these intensive management practices on the receiving environment. Therefore, a field experiment was conducted to quantify the effect of winter mulch on soil CO₂ efflux, which contributes to greenhouse gas emissions. Materials and methods The field study was established in 6-year-old P. praecox stands for the period between December 2006 and February 2007 in Lin'an County, Zhejiang Province, China. The treatments included a 200-mm mulch with rice straw and rice husks, and a control without mulch. Soil CO₂ efflux rates and soil temperature changes were measured monthly and comparisons were made between the treatments. Results and discussion Soil CO₂ efflux rates in the mulch treatment were 10.98 and 4.27 µmol m⁻² s⁻¹ in December 2006 and January 2007, respectively, which was eight times greater than soil CO₂ efflux rates measured in the non-mulch control treatment in the corresponding months. The significantly higher temperature and increased dissolved organic carbon in the mulch treatment were considered to have contributed to the enhanced soil CO₂ emission. Conclusions Heavy winter mulch in a P. praecox plantation can greatly enhance soil respiration rates due to increases in both soil temperature and readily mineralizable labile organic matter. The increased CO₂ emissions from soil respiration under winter mulch treatments can potentially reduce the greenhouse gas emission mitigation function of the bamboo forest plantations. It is recommended that new management practices be developed to alleviate the impacts of winter mulch on the environment.