Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distrib...Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distribution,SOC (Soil organic matter) contents and the natural abundance of 13 C in these aggregates were studied.Significant difference in size of the aggregates and organic carbon storage in the studied soils were found after 5 years of the crop rotation on the soil.SOC was mainly found in 0.02～0.25mm fraction of aggregates in the soils.The aggregates in layers deeper than 35cm became coarse and richer in SOC under corn peanut sweet potato rotation.Young carbon derived from corn tended to be accumulated in the coarse fractions as revealed by heavier stable carbon composition in those aggregates from deep layer under the rotation system containing corn crop.Compared to the soil under think pine forest,All soils under crop rotation system showed rapid increase of SOC at rates ranging from 0.14C g·kg -1 ·a -1 to 0 22C g·kg -1 ·a -1 ,with the highest under corn peanut sweet potato system.Thus,the significance was indicated for increasing SOC storage by crop rotation in paludalfs and for reinforcing terrestrial carbon retention of atmospheric CO 2.展开更多
白浆土是我国东北地区主要低产土壤之一,土体中白浆层通气透水能力极差,生物酶活性很低,导致土壤表旱表涝严重,旱田作物根系有效土层一般只有20 cm左右。自20世纪80年代开始,包括深松在内的机械改土逐渐演变为白浆土的主要改良方式。为...白浆土是我国东北地区主要低产土壤之一,土体中白浆层通气透水能力极差,生物酶活性很低,导致土壤表旱表涝严重,旱田作物根系有效土层一般只有20 cm左右。自20世纪80年代开始,包括深松在内的机械改土逐渐演变为白浆土的主要改良方式。为了探讨不同机械改土方式的改土效果,研究采用3种机械改土方式,依次为普通深松犁、秸秆心土混合犁、心土间隔混拌犁,并以普通深松犁为对照,在典型白浆土上开展改土试验。机械作业后,分别测定土壤物理性质及土壤酶活性。结果表明：秸秆心土混合犁、心土间隔混拌犁处理后,白浆层的硬度降低至7～9 kg cm-2,远低于对照白浆层硬度10～14 kg cm-2;固相分别为47.74%、50.13%,均低于对照53.16%;容重与对照相比分别降低了14.01%、10.19%。与对照相比,秸秆心土混合犁、心土间隔混拌犁降低了白浆层过氧化氢酶活性,秸秆心土混合犁处理降低了白浆层脲酶和蔗糖酶活性、增加了淀积层脲酶和蔗糖酶活性;两个处理与对照相比大豆分别增产21.34%、4.94%。秸秆心土混合犁、心土间隔混拌犁改善了土壤不良的理化性质,同时对土壤酶活性有很大的影响。研究为机械改良白浆土的评价方法探索了新途径。展开更多
文摘Paludalfs under different crop rotation systems in North Huai region,China were sampled and soil aggregates were separated by ultra sonic dispersion followed by sedimentation and centrifuging.The particle size distribution,SOC (Soil organic matter) contents and the natural abundance of 13 C in these aggregates were studied.Significant difference in size of the aggregates and organic carbon storage in the studied soils were found after 5 years of the crop rotation on the soil.SOC was mainly found in 0.02～0.25mm fraction of aggregates in the soils.The aggregates in layers deeper than 35cm became coarse and richer in SOC under corn peanut sweet potato rotation.Young carbon derived from corn tended to be accumulated in the coarse fractions as revealed by heavier stable carbon composition in those aggregates from deep layer under the rotation system containing corn crop.Compared to the soil under think pine forest,All soils under crop rotation system showed rapid increase of SOC at rates ranging from 0.14C g·kg -1 ·a -1 to 0 22C g·kg -1 ·a -1 ,with the highest under corn peanut sweet potato system.Thus,the significance was indicated for increasing SOC storage by crop rotation in paludalfs and for reinforcing terrestrial carbon retention of atmospheric CO 2.
文摘白浆土是我国东北地区主要低产土壤之一,土体中白浆层通气透水能力极差,生物酶活性很低,导致土壤表旱表涝严重,旱田作物根系有效土层一般只有20 cm左右。自20世纪80年代开始,包括深松在内的机械改土逐渐演变为白浆土的主要改良方式。为了探讨不同机械改土方式的改土效果,研究采用3种机械改土方式,依次为普通深松犁、秸秆心土混合犁、心土间隔混拌犁,并以普通深松犁为对照,在典型白浆土上开展改土试验。机械作业后,分别测定土壤物理性质及土壤酶活性。结果表明：秸秆心土混合犁、心土间隔混拌犁处理后,白浆层的硬度降低至7～9 kg cm-2,远低于对照白浆层硬度10～14 kg cm-2;固相分别为47.74%、50.13%,均低于对照53.16%;容重与对照相比分别降低了14.01%、10.19%。与对照相比,秸秆心土混合犁、心土间隔混拌犁降低了白浆层过氧化氢酶活性,秸秆心土混合犁处理降低了白浆层脲酶和蔗糖酶活性、增加了淀积层脲酶和蔗糖酶活性;两个处理与对照相比大豆分别增产21.34%、4.94%。秸秆心土混合犁、心土间隔混拌犁改善了土壤不良的理化性质,同时对土壤酶活性有很大的影响。研究为机械改良白浆土的评价方法探索了新途径。
