念青唐古拉山东南坡高寒草原生态系统表层土壤活性有机碳的影响因素研究

高寒草原是青藏高原广泛分布的植被类型。本文以念青唐古拉山东南坡高寒草原生态系统为对象,采用野外调查与室内分析相结合的方法,对影响高寒草原生态系统表层(0~20cm)土壤活性有机碳分布的因素进行了研究。结果表明:念青唐古拉山东南坡高寒草原生态系统表层(0~20cm)土壤活性有机碳平均含量为2.61±0.31g·kg?1;影响表层土壤活性有机碳分布的地形因子是海拔和坡度,植被因子是0~10cm、10~20cm土层地下生物量,物理因子是0~10cm、10~20cm土壤含水量和0~20cm土壤容重,化学因子是土壤全钾含量。其中0~10cm、10~20cm土壤含水量和0~20cm土壤容重影响达显著水平。在海拔4421~4598m范围内,随着海拔升高,表层土壤活性有机碳含量表现出增加→减少→增加→减少的分布特征。     

不同节水稻作模式对土壤理化特性和土壤酶活性影响研究

针对南方丘陵区季节性干旱现状与目前稻田单一化的连作耕作制度对农田环境造成的不利影响因素,通过4a田间定位试验研究了节水稻作模式下土壤理化性状和土壤酶活性变化规律影响.结果表明,与该区常规稻作模式相比.在试验设计范围内,节水稻作模式下稻田的土壤理化性状明显改善,随着耕种年限增加,土壤容重下降,而孔隙度增加.土壤通透性增强,有效阻止土壤次生潜育化和土壤酸化.提高了土壤pH值;就土壤酶活性而言,节水稻作模式处理酶活性常规稻作模式相比.除转化酶外,其它酶活性均有不同程度的增加,尤其对磷酸酶与脲酶影响最大.     

模拟池塘底泥无机磷形态与上覆水体可溶性活性磷含量的关系及其控制

取两个池塘底泥和上覆水进行室内模拟水体小环境试验,设对照组及5个处理组,进行4个月培养,采用连续分组法测定底泥中无机磷形态及其含量,分析底泥潜在无机磷变化及其与上覆水体可溶性活性磷（DRP）含量的关系。结果表明,池塘底泥中无机磷各形态含量依次为钙10结合磷（Ca10-P）〉闭蓄态磷（O-P）〉铝结合磷（Al-P）〉铁结合磷（Fe-P）〉钙8结合磷（Ca8-P）〉钙2结合磷（Ca2-P）;4个月后两池塘底泥中的Ca2-P和Fe-P增加,Ca10-P、O-P、Al-P减少;上覆水体中DRP含量与O-P、Ca2-P、Ca8-P和Ca10-P之间呈显著正相关;底泥中无机磷各形态对上覆水体中DRP含量的直接影响大小依次为O-P〉Ca8-P〉Ca2-P〉Ca10-P〉Fe-P〉Al-P;5个处理组上覆水体中DRP含量都低于对照组;沸石与芽孢杆菌组合处理的上覆水体中DRP含量最低,表明采用沸石与芽孢杆菌组合进行底泥处理是控制上覆水中DRP含量的有效方法。     

长期免耕对东北地区玉米田土壤有机碳组分的影响

Increasing evidence has shown that conservation tillage is an effective agricultural practice to increase carbon (C) sequestration in soils. In order to understand the mechanisms underlying the responses of soil organic carbon (SOC) to tillage regimes, physical fractionation techniques were employed to evaluate the effect of long-term no-tillage (NT) on soil aggregation and SOC fractions. Results showed that NT increased the concentration of total SOC by 18.1% compared with conventional tillage (CT) under a long-term maize (Zea mays L.) cropping system in Northeast China. The proportion of soil large macroaggregates ( 2000 μm) was higher in NT than that in CT, while small macroaggregates (250-2000 μm) showed an opposite trend. Therefore, the total proportion of macroaggregates ( 2000 and 250-2000 μm) was not affected by tillage management. However, C concentrations of macroaggregates on a whole soil basis were higher under NT relative to CT, indicating that both the amount of aggregation and aggregate turnover affected C stabilization. Carbon concentrations of intra-aggregate particulate organic matter associated with microaggregates (iPOM m) and microaggregates occluded within macroaggregates (iPOM mM) in NT were 1.6 and 1.8 times greater than those in CT, respectively. Carbon proportions of iPOM m and iPOM mM in the total SOC increased from 5.4% and 6.3% in CT to 7.2% and 9.7% in NT, respectively. Furthermore, the difference in the microaggregate protected C (i.e., iPOM m and iPOM mM) between NT and CT could explain 45.4% of the difference in the whole SOC. The above results indicate that NT stimulates C accumulation within microaggregates which then are further acted upon in the soil to form macroaggregates. The shift of SOC within microaggregates is beneficial for long-term C sequestration in soil. We also corroborate that the microaggregate protected C is useful as a pool for assessing the impact of tillage management on SOC storage.     

韩江流域典型区不同森林类型土壤理化性质初步研究

采用野外调查、取样和室内实验分析相结合的方法,以梅江区为研究区域,系统研究了不同森林类型土壤理化性质特征和差异。结果表明:在4种林地中,表层土壤砂粒含量以马尾松林地为最高,天然常绿阔叶林地最低;黏粒含量大小依次为马尾松林＜人工桉树林＜次生灌丛＜天然常绿阔叶林地。不同森林类型对土壤养分状况具有很大的影响,阔叶林林地能很好地促进有机质、N、P和K含量的增加,改善土壤养分状况,但在人工桉树林、次生灌丛和马尾松林地等3种林分中,土壤养分呈现出逐渐下降趋势,特别是土壤表层养分下降趋势尤为明显。最后针对现状,提出了相应建议以维护韩江流域典型区林地利用的可持续发展。     

农牧交错区退耕还林地土壤恢复特征的研究——以内蒙古卓资县为例

以卓资县退耕还林地为研究对象,探讨不同退耕还林地土壤理化性质的变化规律及改良作用。初步研究结果表明:退耕还林以后土壤黏粒总体含量均高于耕地,其中表土层增加不显著,亚表层、下层增加较多;在不同的退耕还林地中,表层土壤容重明显高于亚表层和下层的土壤容重;不同退耕还林模式下土壤有机质含量均随土层深度增加而递减,表现出明显的表聚性;不同林地类型之间的全量N、P、K的含量变化差异显著,而不同土层深度的全量P、K的差异不显著;不同退耕林地的速效N、P、K的含量变化幅度较大。总体来看当地实施退耕还林后,对土壤的改良效果明显,有效的改善了当地生态环境。     

荔枝果园治理措施对侵蚀退化赤红壤理化性质的影响

通过对稻草覆盖和客土措施(Ⅰ和Ⅱ)建立荔枝果园14年后严重侵蚀赤红壤理化性质进行研究。结果表明:①建立荔枝园后,采取措施的果园土壤的物理性质有明显改善,表层土壤容重和结构体破坏率呈措施Ⅰ<措施Ⅱ<对照的变化趋势。措施Ⅰ和措施Ⅱ表层土壤最大持水量分别是对照的1.75倍和1.65倍,措施Ⅰ和Ⅱ>0.25 mm水稳性团聚体含量分别比对照增加51.88%和42.52%。②措施Ⅰ和措施Ⅱ表层土壤有机质、全N、全P、全K和土壤速效性养分含量明显提高,其中土壤速效K含量增加幅度最大。③利用灰色关联法对土壤肥力进行综合评价,果园不同治理措施土壤物理、化学性质排列顺序为:措施I(1.000)>措施II(0.782)>对照I(0.333),措施I(0.923)>措施II(0.801)>对照I(0.333),表明果园覆草措施是改良侵蚀退化赤红壤的有效途径之一。     

Effect of selenite additions on microbial activity and dynamics in three soils incubated under aerobic conditions

Three soils were incubated for 4-day periods with selenite (0-5 mg Se kg⁻¹) and the effect of straw amendment was also studied for one of these soils. The same soil was also incubated for up to 6 weeks, with and without straw and selenite (0-2 mg Se kg⁻¹). Changes in microbial activity (oxygen respiration) and dynamics (total, fungal biomass; bacterial density number) were assessed. Selenium fractionation and volatilization were also quantified. Selenium addition had no marked effect on respiratory activity, total and fungal biomass whatever the incubation period, but inhibited the growth of heterotrophic bacteria in the longer term. When straw was added, the same trend was observed with more variability. The volatilization losses of Se differed between soils but did not vary significantly over the 6-week period and were not affected by straw addition. Freshly added Se was more easily extracted than native soil Se and its extractability decreased with time, whereas no change in the fractionation of native Se was observed. This study shows that moderate additions of Se may influence microbial dynamics in aerated soil but could not establish a causal link with changes in Se fractionation.     

深松耕作和秸秆还田对农田土壤物理特性的影响

[目的]为了增加中国干旱半干旱地区农田土壤蓄水保墒能力。[方法]采用野外试验和室内分析相结合的方法研究了深松和深松结合秸秆还田耕作技术对晋中北部地区两种主要类型土壤物理特性的影响。[结果]深松可以打破土壤犁底层,显著降低黏土和壤土10—30cm土层范围内的土壤容重;调节土壤孔隙度,增加了黏土10—30cm土层范围内的土壤总孔隙度、毛管孔隙度和非毛管孔隙度,同时增加壤土10—30cm土层土壤总孔隙度、毛管孔隙度和20—30cm土层土壤非毛管孔隙度;改善黏土和壤土20—30cm土层土壤固、液、气3相状况;深松结合连年秸秆还田进一步优化了壤土耕层环境,同时显著降低了玉米拔节期土壤地表结皮的厚度和紧实度。[结论]深松结合连年秸秆还田和深松耕作技术可以缓解土壤板结状况,增加降雨入渗。     

采煤塌陷对土壤理化性质影响的研究进展

煤矿开采导致地表塌陷,并改变原有土壤理化性质。为了更好地开展矿区土地复垦,进行土壤重构,必须要对塌陷区土壤理化性质进行分析研究。本文综述了塌陷对土壤理化性质的影响以及土壤理化性质空间变异的国内外研究现状,总结当前研究存在的问题,并提出以后塌陷区土壤理化性质研究方向,为塌陷区土壤理化特性变化机理揭示提供指导。