黄小娟, 郝庆菊, 吴艳. 紫色水稻土轻组有机质的季节动态研究[J]. 中国生态农业学报(中英文), 2012, 20(12): 1579-1585. DOI: 10.3724/SP.J.1011.2012.01579
引用本文: 黄小娟, 郝庆菊, 吴艳. 紫色水稻土轻组有机质的季节动态研究[J]. 中国生态农业学报(中英文), 2012, 20(12): 1579-1585. DOI: 10.3724/SP.J.1011.2012.01579
HUANG Xiao-Juan, HAO Qing-Ju, WU Yan. Seasonal dynamics of soil light fraction organic matter in purple paddy soils[J]. Chinese Journal of Eco-Agriculture, 2012, 20(12): 1579-1585. DOI: 10.3724/SP.J.1011.2012.01579
Citation: HUANG Xiao-Juan, HAO Qing-Ju, WU Yan. Seasonal dynamics of soil light fraction organic matter in purple paddy soils[J]. Chinese Journal of Eco-Agriculture, 2012, 20(12): 1579-1585. DOI: 10.3724/SP.J.1011.2012.01579

紫色水稻土轻组有机质的季节动态研究

Seasonal dynamics of soil light fraction organic matter in purple paddy soils

  • 摘要: 以位于重庆市北碚区西南大学试验农场(30°26′N, 106°26′E)的紫色水稻土为研究对象, 利用重液(NaI, 密度1.8 g·cm-3)对土壤中轻组组分进行提取, 对土壤中轻组有机质在整个油菜生长季的季节变化情况进行分析与讨论。结果表明: 表层(0~30 cm)土壤轻组物质(LF)的含量为2.95%~5.51%, 平均值为4.38%; 土壤轻组有机碳含量(LFOC)和轻组氮含量(LFN)的变化范围分别为1.44~3.72 g·kg-1和0.08~0.17 g·kg-1, 其平均值分别为2.79 g·kg-1和0.14 g·kg-1。LFOC具有明显的季节变化(P<0.05), 其含量在油菜生长中期最高, 其次是生长后期, 而在生长初期最低; LFN的季节变化趋势与LFOC一致, 但季节差异性不显著(P>0.05)。轻组有机碳分配比例(LFOC/SOC)的变化范围为9.21%~24.47%, 具有明显的季节变化(P<0.05), 其变化趋势与LFOC的季节变化一致; 而轻组氮的分配比例(LFN/TN)变化范围为4.55%~12.58%, 无明显的季节变化。轻组C/N比值季节变化范围为18.52~25.04, 平均值为20.66, 全土C/N比值的变化范围为9.04~14.36, 平均值为11.66, 说明轻组有机质的生物可利用性较土壤总有机质高。相关分析表明, 轻组有机碳、氮含量分别与根系生物量、根系碳含量、根系氮含量呈极显著(P<0.01)或显著(P<0.05)正相关; 回归分析表明, 土壤轻组有机碳、氮含量变化的40%~60%可由根系生物量、根系碳氮含量决定, 说明根系是调控紫色水稻土轻组有机碳、氮季节变化的主要生态因子。

     

    Abstract: Soil light fraction is a critical soil quality improvement factor as it regulates soil fertility and minimizes negative environmental impacts. An experiment was established at Southwest University Farm (30°26′N, 106°26′E) in Chongqing. The farm belongs to the Key Field Station for Purple Soil Eco-Environment Monitoring of the Ministry of Agriculture, China. The 0~30 cm soil of the farm under rice/rape rotation system was sampled. The experiment aimed to quantify short-term dynamics of light fraction organic carbon (LFOC) and nitrogen (LFN) during rape growing season. Light fraction was extracted by NaI at a density of 1.8 g·cm-3. The results showed that soil light fraction content in the 0~30 cm soil was 2.95%~5.51% during rape growing season, with an average value of 4.38%. The ranges of LFOC and LFN were 1.44~3.72 g·kg-1 and 0.08~0.17 g·kg-1, with average values of 2.79 g·kg-1 and 0.14 g·kg-1, respectively. Dry weight of LFOC showed distinct seasonal variations, with maxima occurring in mid-growing season, followed by late-growing season. Minimal dry weight of LFOC appeared at the start of the growing season. However, no significant seasonal variations (P > 0.05) were noted in LFN contents in the same period. The observed seasonal variation trend for LFN was similar to that of LFOC. The ratio of LFOC to SOC determined by content (LFOC/SOC) was 9.21%~24.47%, with marked seasonal variations (P< 0.05). This variation trend was similar to that of LFOC. There was no marked seasonal variation in the ratio of LFN to TN (LFN/TN), with a range of 4.55%~12.58% and average of 9.63%. This was higher than those for other areas, suggesting that organic nitrogen in purple paddy soils of Southwest China more easily mineralized with stronger N supply than in other areas. Average C/N ratio of light fraction organic matter was 20.66, with a range of 18.52~25.04. This was higher than that of the total soil (11.66), indicating that bio-availability of light fraction organic matter was higher than soil organic matter. Correlation analysis showed that both LFOC and LFN were positively correlated with root biomass, root carbon and nitrogen (P< 0.01 or P < 0.05). This indicated that root was the main regulator of seasonal dynamics of LFOC and LFN content. Also regression analysis showed that root biomass, root carbon and nitrogen content accounted for 40%~60% of soil LFOC and LFN content. Therefore plant root was concluded to be the key control factor of seasonal variations of LFOC and LFN in the study area.

     

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