水耕历史对稻田-田埂过渡区土壤物理性质与水-氮分布的影响
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华中师范大学城市与环境科学学院

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国家自然科学基金青年项目(41601215),国家自然科学基金面上项目(41771261),中央高校基本科研业务费(CCNU20QN030)


Effects of Paddy Rice Cultivation History on Soil Physical Properties and Water/Nitrogen Distribution in the Intermediate Zone between Paddy Field and Bund
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College of Urban and Enviromental Sciences, Central China Normal University

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The Youth Program of National Natural Science Foundation of China(No. 41601215),The General Program of National Natural Science Foundation of China(No. 41771261) , Fundamental Research Funds for the Central Universities(No. CCNU20QN030)

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    摘要:

    选取水耕年限分别为2年、19年和>100年稻田,通过野外样品采集与室内分析结合的方法,对比了稻田田内和田埂土壤物理性质与水-氮分布差异,揭示了水耕历史对稻田-田埂过渡区土壤物理性质与水-氮流失过程的影响机制。结果表明,耕作活动影响了稻田-田埂过渡区土壤容重、孔隙、土壤水分特征曲线和饱和导水率(Ks)等物理性质。随着水耕年限的增加,田内耕作层与田埂表土层、田内犁底层与田埂硬质层的容重差异增大;耕作层的中小孔隙(直径<0.03 mm)含量增加,其他土层的总孔隙和大孔隙(直径>0.3 mm和>0.03 mm)含量降低;田内土壤的Ks下降速度较田埂更快。在测定的吸力范围内(0~100 kPa),2年和19年的耕作层与表土层持水能力相近,而100年耕作层持水能力高于表土层;2年和100年的硬质层与犁底层持水能力相近,而19年硬质层持水能力更强;19年和100年田埂底土层持水能力较田内强。随着水耕年限增加,耕作层与表土层Ks差异减小,硬质层与犁底层Ks差异增加,2年、19年和100年硬质层的Ks分别是对应犁底层的1.10倍、6.90倍和6.32倍,100年田埂底土层的Ks明显高于田内。土壤物理性质的变化影响稻田-田埂过渡区的水-氮分布特征,主要表现为2年稻田的水-氮含量明显低于19年和100年稻田,且19年和100年稻田的水-氮在耕作层聚集。当水耕年限较短时,水-氮同时通过田内和田埂区域快速流失;随着水耕年限的延长,水-氮更易通过田埂发生渗漏。老稻田新修田埂的硬质层土壤会发生退化,再次成为水-氮快速流失位点。因此,对于耕作年限长的稻田,其田埂区域的水-氮渗漏更应引起重视。

    Abstract:

    【Objective】Lateral seepage around the paddy bund is an important pathway for water loss in the paddy rice field. Revealing the evolution process of soil physical properties and the characteristics of soil water and nitrogen distribution in the intermediate zone between paddy field and bund is important. This is crucial for understanding the mechanism of water and nitrogen loss in the intermediate zone. 【Method】The intermediate zone between paddy field and bund with a cultivation history of 2 y, 19 y, and >100 y was considered for this study. Soil properties, including soil bulk density, equivalent porosity, soil water retention curve, saturated hydraulic conductivity (Ks), soil water content and soil nitrogen concentration were determined through field sampling and laboratory analysis. The evolution process of soil physical properties and the mechanism of water and nitrogen loss in the intermediate zone were evaluated. 【Result】The paddy rice cultivation history affected soil physical properties. With the cultivation history extending, the difference in soil bulk density between paddy field plow layer (PL) and paddy bund surface layer (SL), and between paddy field plow pan (PP) and paddy bund hard pan (HP) increased. The microporosity (with diameter <0.03 mm) in PL and SL increased with paddy rice cultivation history, while the macroporosity (with diameter >0.3 mm and >0.03 mm) decreased in other soil layers for both in paddy field and bund. This showed a quicker decrease rate in the paddy field than for the bund. Differences in soil water holding capacity (SWHC) between paddy fields and bund were identified in the measured water suction range (0~100 kPa). Similar SWHC was observed between PL and SL in both 2 y and 19 y paddy rice fields, while a much higher SWHC was found in PL than SL in >100 y paddy rice fields. Also, a similar SWHC between PP and HP were identified in both 2 y and 100 y paddy rice fields, while a much higher SWHC was found in PP than HP in the 19 y paddy rice field. A higher SWHC was observed in the paddy bund subsoil layer (BSL) than the paddy field subsoil layer (FSL) for both 19 y and >100 y paddy rice fields. With paddy rice cultivation history extending, the differences in Ks between PL and SL decreased, while it increased between PP and HP. For example, the Ks in PP was 1.10, 6.90, and 6.32 times that in HP for 2 y, 19 y, and >100 y paddy rice fields, respectively. Also, a much higher Ks was observed in bund than the field for >100 y paddy rice field, while no significant differences were observed for the other two fields. The soil water and nitrogen distribution patterns were affected by the evolution of soil physical properties in both paddy fields and bund. Also, a higher soil water content and soil nitrogen concentration were observed in 19 y and >100 y paddy rice fields than in 2 y paddy rice fields, which was mainly accumulated in the PL for both 19 y and >100 y paddy rice fields. 【Conclusion】For the young paddy rice field, soil water and nitrogen rapidly seepage from both paddy fields and bund identically. With the paddy rice cultivation history extending, soil water and nitrogen are expected to be lost more quickly from the paddy bund than the field. For >100 y paddy rice fields, the PP in the newly built bund will degrade with time, then the paddy bund will be the key site for soil water and nitrogen lose again. Therefore, the soil water and nitrogen loss from the paddy bund should be given more attention, and the focus should be more on old paddy than young paddy rice fields.

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陈露,张海林,易军,刘秀芸,刘目兴,李胜龙,周黎.水耕历史对稻田-田埂过渡区土壤物理性质与水-氮分布的影响[J].土壤学报,,[待发表]
chenlu, zhanghailin, yijun, liuxiuyun, liumuxing, lishenglong, zhouli. Effects of Paddy Rice Cultivation History on Soil Physical Properties and Water/Nitrogen Distribution in the Intermediate Zone between Paddy Field and Bund[J]. Acta Pedologica Sinica,,[In Press]

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