中国农业科学 ›› 2014, Vol. 47 ›› Issue (20): 4007-4015.doi: 10.3864/j.issn.0578-1752.2014.20.009

• 土壤肥料·节水灌溉·农业生态环境 • 上一篇    下一篇

施肥对洞庭湖平原水稻土团聚体特征及其有机碳分布的影响

李文军1,杨基峰2,彭保发1,崔京珍3   

  1. 1湖南文理学院资源环境与旅游学院,湖南常德 415000
    2湖南文理学院化学化工学院,湖南常德 415000
    3湖南文理学院生命科学学院,湖南常德 415000
  • 收稿日期:2014-05-13 修回日期:2014-07-13 出版日期:2014-10-16 发布日期:2014-10-16
  • 通讯作者: 李文军,E-mail:liwenjun1982@126.com
  • 作者简介:李文军,E-mail:liwenjun1982@126.com
  • 基金资助:
    国家自然科学基金(41201297)、土壤与农业可持续发展国家重点实验室开放基金(0812201239)、湖南省重点建设学科(产业经济学、应用化学)

Effects of Fertilization on Aggregate Characteristics and Organic Carbon Distribution in a Paddy Soil in Dongting Lake Plain of China

LI Wen-jun1, YANG Ji-feng2, PENG Bao-fa1, CUI Jing-zhen3   

  1. 1College of Resources and Environment and Tourism, Hunan University of Arts and Science, Changde 415000, Hunan
    2College of Chemistry and Chemical Engineering, Hunan University of Arts and Science, Changde 415000, Hunan
    3College of Life Sciences, Hunan University of Arts and Science, Changde 415000, Hunan
  • Received:2014-05-13 Revised:2014-07-13 Online:2014-10-16 Published:2014-10-16

摘要: 【目的】团聚体是土壤重要的物理属性,也是土壤有机碳的主要固存场所。研究长期不同施肥对洞庭湖平原红壤性水稻土团聚体数量、稳定性、分形特征及其有机碳含量及分布的影响,为区域双季稻田施肥管理提供理论依据。【方法】以国家稻田土壤肥力与施肥效应长期试验为平台(1986—2013),运用湿筛法获得不同粒级水稳性团聚体,分析对照(不施肥,CK)、单施氮磷钾肥(NPK)、低量有机肥与氮磷钾肥配施(LOM,有机肥氮比例为30%)和高量有机肥与氮磷钾肥配施(HOM,有机肥氮比例为60%)4种处理影响下耕作层(0—20 cm)土壤粒径>0.25 mm的水稳性团聚体数量(WR0.25)、平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)及其有机碳含量与分布的变化特征。【结果】除粒径>5 mm的土壤团聚体外,水稳性团聚体含量和团聚体对土壤有机碳的贡献率均随团聚体粒径减小呈现逐渐增加的趋势,而团聚体有机碳含量则呈现逐渐降低的变化趋势,其变化特征在不同处理间表现一致。长期不同施肥对2—5 mm和0.5—2 mm团聚体含量影响最大,与对照相比,施肥处理中上述两粒级团聚体含量分别增加35.5%—64.5%和6.2%—14.7%。施肥后团聚体的WR0.25、MWD、GMD分别增加8.6%—12.5%、7.1%—15.1%、13.7%—28.4%,而D值降低2.3%—3.5%,说明长期施肥增强团聚体稳定性,改善团聚体结构。单施氮磷钾肥和氮磷钾肥配施有机肥均可显著提高各粒级团聚体中有机碳含量(P<0.05),并始终表现出HOM强于LOM、LOM强于NPK的处理效应,与对照相比,HOM处理各级团聚体中有机碳含量较对照提高了22.1%—36.6%。水稳性大团聚体是土壤有机碳的主要载体,不同处理间>0.25 mm团聚体中有机碳的分量占土壤有机碳的比例表现出HOM(83.5%)>LOM(81.6%)>NPK(79.2%)>CK(69.9%)的顺序。施肥各处理均可显著提高>5 mm、2—5 mm、0.5—2 mm三级团聚体中有机碳对土壤有机碳的贡献率,且主要影响土壤有机碳在2—5 mm和0.5—2 mm两级团聚体中的分配率。>0.5 mm的各级团聚体含量与土壤有机碳含量呈极显著正相关(P<0.01),说明施肥后土壤新增有机碳主要向>0.5 mm的水稳性团聚体中富集。【结论】长期实行NPK平衡施肥及与有机肥配施有利于洞庭湖平原红壤性水稻土水稳性团粒结构的形成及大团聚体中有机碳的积累,与单施氮磷钾肥处理相比较,施用有机肥特别是高量有机肥与化学氮磷钾肥配施更有利于土壤良好结构体的形成和固碳能力的增强,是更优的稻田施肥模式。

关键词: 施肥, 团聚体特征, 洞庭湖平原区, 水稻土, 有机碳分布

Abstract: 【Objective】As an important soil physical attribute, soil aggregates are the major site for soil organic carbon sequestration, so the impacts of long-term fertilization on aggregates characteristics and organic carbon distribution in a reddish paddy soil were studied in Dongting Lake Plain, China, which can provide a theoretical evidence for fertilization management in double cropping rice area. 【Method】Undisturbed soil samples at 0-20 cm layer were collected from a 27 years (1986-2013) field experiment, which was established in the Hanshou county in Hunan province. The experiment included 4 treatments: CK (without fertilization), NPK (N, P, K fertilizer application), LOM (combined application of NPK and 30% organic manure fertilizers), HOM(combined application of NPK and 60% organic manure fertilizers). All soils were separated into five aggregate-size classes (>5 mm, 2-5 mm, 0.5-5 mm, 0.25-0.5 mm and <0.25 mm) by wet sieving method and the macro aggregates fractions (>0.25 mm) were chosen for results analysis. The amount, mean weight diameter, geometric mean diameter, fractal dimension of water-stable aggregates which denoted by WR0.25, MWD, GMD and D were exampled, separately. The aggregate-associated organic carbon was also measured.【Result】In addition to the size group of >5 mm, along with decreasing of particle sizes, the proportion of water-stable aggregates and the contribution rate of aggregates fractions to soil organic carbon (SOC) in the treatments increased, while the water-stable aggregate-associated organic carbon presented an opposite trend. Both the proportion of aggregates in the 2-5 mm and 0.5-2 mm size fractions were significantly increased under fertilization treatments when compared to CK treatment and the increasing rate was up to 35.5%-64.5% and 6.2%-14.7%, respectively. Fertilizer application also increased the value of WR0.25, MWD, and GMD of aggregates by 8.6%-12.5%, 7.1%-15.1%, and 13.7%-28.4%, respectively. As for the fractal dimension, its value of fertilization treatments decreased by 2.3%-3.5% than that of CK, which suggesting that long-term addition of chemical N, P, K fertilizers or organic manure was beneficial to the improvement of soil structure. Long-term fertilization significantly increased the contents of organic carbon in various sizes of aggregates and the effect was much more obvious when combined application of organic manure and chemical N, P, K fertilizers, the content of aggregate-associate organic carbon of HOM treatment reached the highest, with the amplification up to 22.1%-36.6% when compared to CK. It also showed that 69.9%-83.5% of the SOC was concentrated in the macro water-stable aggregates and the percentage among different treatments decreased in the order of HOM>LOM>NPK>CK. As for the contribution rates of aggregates to bulk SOC, there was a significant increase when the aggregates with size fractions >0.5 mm under fertilization treatments, while the allocation rates of SOC in the aggregates with size fractions of 2-5 mm and 0.5-2 mm were more sensitive to fertilization application. The results of correlation analysis revealed that there exists a significant positive correlation between the percentages of soil water-stable aggregates with the size of >0.5 mm and the content of SOC, indicating that newly enriched SOC mostly appeared in the size group of >0.5 mm. 【Conclusion】After long-term chemical N, P, K fertilizers or organic manure application, the contents of macro water-stable aggregates and organic carbon in reddish paddy soil increased obviously. Compared with single chemical N, P, K fertilizers application, chemical manure mixed with 60% organic manure application showed more obvious effects on the improvement of soil structure and the enhancement of soil carbon sequestration and was considered as the best fertilization mode for the tested paddy soil.