| Phyllostachys praecox is one of the best bamboo species used for edible bamboo shoot production. Due to its advantages of high production, rapid growth, early shoot period, and delicious taste, Phyllostachys praecox has been widely planted in the south of China. In the past several years, a method centered on heavy fertilization and use of organic mulch in the winter has gained popularity as a core technique for producing bamboo shoots early and with increased productivity. Consequently, the above intensive management would make great influence on the soil organic carbon content and forms. An experiment was conducted in typical phyllostachys praecox stands located in Lin'an, Zhejiang Province to investigate the chemical behaviour of various mulching materials including bamboo leaves and rice straw, and the impact of mulching on soil carbon (C) dynamics using solid state 13C-nuclear magnetic resonance (NMR) and to study the dynamic change of soil respiration and the relationship between soil respiration and environmental factors during 2009. The results obtained were summarized as follows:1)A field study was conducted to investigate the decomposition of various mulching materials including bamboo leaves and rice straw during 2009. The results showed that the bamboo leaves and rice straws were decomposited by 79.30% and 67.54%, respectively. The carbon content of bamboo leaves and rice straws decreased by 14.80% and 15.32%, nitrogen content increased by 15.77% and 173.26%, C / N decreased by 26.36% and 67.50% respectively. Alkyl C content increased but O-alkyl C content decreased by 11.21% and 13.29%, respectively in the decomposing mulching materials. Additionally, the aromatic C content decreased; A/O-A ratio was significantly increased, while the aromaticity was significantly reduced.2)A field study was conducted to investigate the impact of the mulching on soil carbon (C) dynamics during 2009. The results showed that with the treatment of mulching soil organic carbon content increased by 22.15% and the soil respiration rate increased by 5.47μmol·m-2·s-1. Alkyl C content increased but O-alkyl C content decreased in the decomposing mulching materials, whereas aromatic C content increased initially but decreased at later stage, indicating degradation of lignin. The residual materials had a significantly higher A/O-A ratio, but lower aromaticity than those in the original materials. Soil beneath the mulches rapidly built up organic C which was dominated by O-alkyl C with reduced aromaticity, indicating increased C lability. Mulching treatment enhanced soil respiration rate. An early removal of the mulching materials in spring significantly reduced soil respiration. It is recommended that mulching materials should be removed as early as practical to reduce CO2 emission associated with mulch treatment, which may help maintain soil organic matter stability for long term C sequestration.3)A experiment was conducted in typical phyllostachys praecox stands located in Lin'an, Zhejiang Province to study the dynamic change of soil respiration and the relationship between soil respiration and environmental factors. The results showed that the soil total respiration rate, heterotrophic respiration rate, and autotrophic respiration rate of phyllostachys praecox were 5.42, 2.24 and 2.89μmol·m-2·s-1 respectively. The annual dynamic pattern was represented with a double-peak curve and changed greatly.The amount of CO2 released from phyllostachys praecox was 73.40 t·hm-2·a-1, including 45.67% heterotrophic respiration and 54.32% autotrophic respiration. RS, RH and RA had strong exponential correlations with soil temperature, especially the temperature at 5 cm depth. The Q10 value at 5 cm depth was 1.70, 1.68 and 1.48 respectively. The relativity of soil temperature in 5 cm depth, atmospheric temperature at 8:00, WSOC, TOC and soil respiration is remarkable, while the relativity of soil water content, relative humidity at 8:00 , WSON and soil respiration is not remarkable. |
PDF Full Text Request