退化红壤肥力障碍特征及重建措施

本主要通过11年的长期定位试验,研究了退化红壤养分库（NPK）的重建措施及产量效果以及纠正酸害（铝害）的途径。本为第一部分。研究表明,我国南方红壤及砖红壤养分水平较低,这是长期土壤退化的结果,根据对1021个标本的数据分析,磷素退化最严重,其次是氮,再次是钾。研究发现,纠正红壤酸度过低可以通过施用碱性磷肥（钙镁磷肥）来达到,这既补充了磷又纠正了酸害,一举两得。     

退化红壤肥力障碍特征及重建措施Ⅰ.退化状况评价及酸害纠正措施

本文主要通过11年的长期定位试验,研究了退化红壤养分库(NPK)的重建措施及产量效果以及纠正酸害(铝害)的途径.本文为第一部分.研究表明,我国南方红壤及砖红壤养分水平较低,这是长期土壤退化的结果,根据对1021个标本的数据分析,磷素退化最严重,其次是氮,再次是钾.研究发现,纠正红壤酸度过低可以通过施用碱性磷肥(钙镁磷肥)来达到,这既补充了磷又纠正了酸害,一举两得.     

长期施肥对红壤性水稻土磷素积累与形态分异的影响

通过红壤性水稻土１９ａ肥料长期定位试验,结果表明,不施磷处理的土壤磷素处于耗竭状态,耕层土壤会磷含量持续下降,但耕层以下土层的全磷尚未耗损;连年施磷的土壤耕层全磷含量提高,提高的幅度呈现明显量级关系。在本试验条件下,土壤中各组分无机磷含量以Ｆｅ－Ｐ和Ｏ－Ｐ为主体,各占土壤无机磷总量的４４．６３％和３１．２７％;其次是Ａｌ－Ｐ和Ｃａ１０－Ｐ,分别占１１．８７％和８．０１％,Ｃａ２－Ｐ占３．５２％;Ｃａ８－Ｐ只有当土壤无机磷达到一定丰度和供磷强度时才存在,对水稻磷素营养的贡献无实际意义。各组分无机磷对水稻的有效性以Ｃａ－Ｐ〉Ａｌ－Ｐ〉Ｆｅ－Ｐ〉Ｏ－Ｐ〉Ｃａ１０－Ｐ;而对水稻磷素营养的贡献则以Ｆｅ－Ｐ〉Ｏ－Ｐ〉Ａｌ－Ｐ〉Ｃａ２－Ｐ〉Ｃａ１０－Ｐ;长期耗磷或施磷、土壤各组分无机磷减少或增加量的排列顺序与土壤中各组分无机     

退化红壤肥力障碍特征及重建措施Ⅱ.磷、氮、钾库重建措施

本文为本系列的第二部分。研究表明，在退化红壤磷库重建中，施用磷肥，可迅速重建磷库，显著降低土壤的磷素最大吸附量，可以增加红壤保水能力，表明施用磷肥有着多重作用。有机肥在退化红壤养分库重建中有着重要作用，它可更快地重建土壤磷库、钾库。对提高土壤全氮水平也比单用化肥为快。结果充分说明，在恢复重建退化红壤养分库时，本文的有关措施是有效的，而且磷、钾库的重建可以比较迅速地达到。     

山西省菜园土壤磷素积累特征及流失风险分析

为了解山西省不同区域菜园土壤磷素积累以及流失情况, 本文分析了菜园土壤磷饱和度(DPS)、Mehlich3-P、Olsen-P与水溶性磷(Pw)的积累特征.结果表明: 山西各地菜园土壤4种磷素(土壤全磷、水溶性磷、Olsen-P和 Mehlich3-P)积累明显, 已经远远超过作物需求量; 土壤表层水溶性磷含量随着土壤磷饱和度(DPS)、Olsen-P、Mehlich3-P含量的增加而增加; 且Mehlich3-P与Olsen-P、水溶性磷与Olsen-P、水溶性磷与Mehlich3-P之间具有极显著相关性, 相关系数分别为0.976 6、0.923 2、0.962 0 (P<0.01); 当磷饱和度大于46.64%、Olsen-P大于81.88 mg·kg-1、Mehlich3-P大于164.59 mg·kg-1时, 水溶性磷含量上升幅度迅速增大, 由此将土壤磷饱和度为46.64%、Olsen-P 为81.88 mg·kg-1、Mehlich3-P为164.59 mg·kg-1和水溶性磷为8.05 mg·kg-1初步确定为山西省菜园土壤磷素流失的临界值.该结果将为探讨山西农田土壤磷素的养分管理和环境风险评估提供重要的理论依据.     

长期施肥下红壤磷素积累的环境风险分析

以长期(始于1988年)施肥的旱地红壤为材料,研究了土壤磷积累与磷吸附的关系,通过分析土壤磷素吸附特征参数及面向环境的土壤磷素表征值的变化,讨论了长期施肥下旱地红壤磷素积累的环境风险。结果表明:长期施磷可显著增加红壤磷素的累积量,降低土壤对外源磷的固持能力,提高土壤的有效磷及易解吸磷的量。供试的7个试验处理,除NK处理及花生秸秆本田还田处理外,土壤有效磷均高于20mg kg-1,已达到丰磷状态,但只有配施厩肥处理的土壤磷素存在环境风险。因此,应在兼顾土壤磷素的农业效应和环境安全的前提下,建立新的施肥制度,使磷素资源的利用更加合理化。     

土壤积累态磷研究Ⅲ.几种典型土壤中积累态磷的形态特征及其有效性

采用Ｈｅｄｌｅｙ土壤磷的分级方法研究了我国几种典型土壤和长期定位试验肥料残留磷（积累态磷）的形态，并根据生物耗竭试验后不同级磷的减少讨论了各级磷的有效性。结果表明，即使在固磷能力很强的红壤上，积累态磷也大部分存在于可被作物利用的磷的形态中。这就是为什么磷肥的积累利用率高的基本原因。     

长期施肥红壤性水稻土磷素演变特征及对磷盈亏的响应

研究双季稻种植制度下长期不同施肥红壤性水稻土磷素含量及磷素有效性演变特征及其对土壤磷盈亏(磷平衡)的响应,为南方双季稻区红壤性水稻土科学施磷提供依据。以35年长期肥料定位试验为平台,研究不同施肥处理土壤全磷、有效磷及磷活化系数(PAC)的演变规律,计算不同处理土壤-作物系统每年磷素盈亏量及累积磷素盈亏量,探讨土壤全磷、有效磷及PAC与累积磷盈亏量的响应关系。结果表明,不施磷肥的CK和NK处理土壤全磷、有效磷和PAC随试验年限呈持平或下降趋势;不施磷肥仅施猪粪的NK+PM处理土壤全磷呈缓慢上升趋势,有效磷和PAC呈下降趋势;施化学磷肥或化学磷肥配施稻草的NP、NPK、NP+RS和NPK+RS处理土壤全磷在试验前10年上升速率较快,之后25年上升速率变缓或随时间变化不显著,土壤有效磷在试验前5年急剧升高,之后随时间变化速率减缓或基本持平。CK、NK和NK+PM处理35年土壤PAC平均值较试验初始值分别下降33.2%、29.7%和16.6%,NP、NPK、NP+RS和NPK+RS土壤PAC较初始值分别提高66.2%、60.6%、65.6%和52.9%。不施磷肥导致红壤性水稻土磷素亏缺,不施化学磷肥仅施猪粪土壤磷素基本持平,施用化肥磷及化肥磷配施稻草土壤磷素盈余。土壤全磷、有效磷及PAC与土壤磷累积盈亏量均呈极显著正相关关系,土壤每盈余磷100 kg hm-2,全磷含量提高0.03 g kg-1,有效磷提高1.20 mg kg-1,土壤PAC上升0.09%。外源磷投入是影响土壤磷素及磷有效性的重要因素,在本试验条件下,长期不施磷或磷投入不足导致土壤磷亏缺,进而导致土壤磷及磷有效性降低,而化肥磷及有机无机磷配施促进了土壤磷盈余及土壤磷素肥力的提高。     

长期不同施肥对红壤性水稻土磷素及水稻磷营养的影响

【目的】合理的土壤磷素管理对作物生产和环境保护具有重要意义。南方双季稻田土壤磷素特征及磷素吸收信息相对缺乏,本文利用江西省稻田土壤质量演变定位监测试验为平台,系统分析长期不同施肥措施下土壤全磷、磷活化系数及水稻磷素吸收量的变化特征和全磷与磷盈亏的响应关系等,为指导磷肥合理施用提供重要科学依据。【方法】从1984年开始在江西省南昌市进行长期定位试验,设置8个处理,分别为不施肥对照(CK),PK、NP、NK、NPK、70%化肥氮+30%有机肥氮(70F+30M)、50%化肥氮+50%有机肥氮(50F+50M)、30%化肥氮+70%有机肥氮(30F+70M)。早稻施用纯N、P2O5和K2O量分别为150、60和150 kg/hm^2,晚稻分别为180、60和150 kg/hm^2。早、晚稻施用的氮、磷、钾化肥均分别为尿素、过磷酸钙和氯化钾,有机肥分别为紫云英(N、P2O5、K2O含量分别为0.30%、0.08%、0.23%)和腐熟猪粪(N、P2O5、K2O含量分别为0.45%、0.19%、0.60%)。除30F+70M处理,其余处理均为等氮磷钾设计。于1984-2012年每年早、晚稻收获期采集秸秆和稻谷计产,并于晚稻收获后,测定土壤全磷和有效磷含量。分析土壤全磷、磷活化系数(PAC)及早、晚稻磷素吸收量随种植年限的变化规律,研究土壤全磷含量与磷累积盈亏的响应关系。【结果】经29年连续试验,NK处理土壤全磷含量以每年4.6 mg/kg的速度下降,而含磷化肥处理土壤全磷含量升高速率为3.3~19.4 mg/(kg·a)。有机无机配施处理(70F+30M、50F+50M和30F+70M)升高速率平均为16.1 mg/(kg·a),是施NPK肥处理的4.89倍。施磷土壤全磷含量平均增至1.07 g/kg (2010-2012平均值),较初始值提高了1.18倍。不施磷肥处理土壤磷活化系数(PCA)由试验初始的4.24%下降至2.5%左右,施磷肥处理则均显著升高,其中有机无机配施处理平均升高至8.51%,平均年升高速率是施NPK处理的2.89倍。早、晚稻磷素吸收量,施磷肥(PK、NP和NPK)和化肥配施有机肥处理(70F+30M、50F+50M和30F+70M)均显著高于CK,提高幅度分别为29.9%~124%和28.6%~103%,均衡施肥(NPK、70F+30M、50F+50M和30F+70M)磷素吸收量显著高于不均衡施肥(PK和NP)处理,前者平均分别较后两者提高了38.7%和32.9%。早、晚稻产量与磷素吸收量呈极显著线性正相关关系,每吸收磷(P) 1 kg,早稻和晚稻产量分别可提高115和106 kg/hm^2。不施肥(CK)条件下,土壤全磷变化与累积磷盈亏间无显著相关关系,施NK肥处理土壤中每亏缺磷100 kg/hm^2,土壤全磷含量降低6.0 mg/kg,施化学磷肥的3个处理,土壤中每盈余磷100 kg/hm^2,平均提高9.3 mg/kg,而3个有机–无机配施处理,土壤中每盈余磷100 kg/hm^2,平均增加63.3 mg/kg,是无机磷肥的6.78倍。【结论】无论是单施化学磷肥,还是有机无机配施均有效提高土壤全磷含量及磷活化系数,且在等磷量投入条件下,有机无机配施较单施化肥的效果更优。建议减少中国南部红壤性稻田土壤的总磷输入量和提高有机肥施用比例,以改善粮食生产和保护环境。     

退化喀斯特植被恢复过程中的土壤抗蚀性变化

运用时空互代法,以喀斯特山区不同植被恢复阶段为研究对象,坡耕地与人工林为对照,通过室内分析,采用主成分分析方法,探讨了其土壤抗蚀性。结果表明：土壤中有机质、>0.25 mm水稳性团聚体含量、<0.05 mm粉黏粒含量、<0.001 mm黏粒含量和结构性颗粒指数可以作为评价土壤抗蚀性的最佳指标。各样地土壤抗蚀性综合指数大小排序为灌草丛>乔灌过渡林>灌木林>乔木疏林>人工林>草坡>坡耕地。喀斯特山区,坡耕地土壤抗蚀性能最差;植被恢复过程中,土壤的抗蚀性能先逐渐变好,后逐渐变差,转折点在灌草阶段。以灌草搭配的植被恢复模式可能比较适合喀斯特地区。     

我国中亚热带丘陵地区红壤的肥力恢复

There are about 1.27 million ha of upland red soils derived from Quaternary red clay facing the degradation in the low-hilly region of the middle subtropical China. From the aspects of chemistry, physics and microbiology, the processes of soil fertility restoration in the surface layer (0~20 cm) under three types of land use patterns (i.e. citrus orchard, tea garden and upland) in two provinces were studied in this work. Results showed that the reclamation of eroded waste land improved most of soil properties. Soil organic matter, total N and P, available P and K, and exchangeable Ca and Mg increased, but soil total K and exchangeable Al decreased. Soil pH decreased by 0.5 unit in the pure tea plantation for 20 years. Soil reclamation increased the percentage of soil microaggregates (<0.25 mm), especially those with a diameter of 0.02~0.002 mm. Soil total porosity increased in the cultivated lands with the increase of soil aeration and capillary porosity. The number of soil microorganisms increased with reclamation caused mainly by the huge increase of the total amount of bacteria. With the cultivation, the activity of soil urease and acid phosphatase increased, but that of invertase dropped.     

退化石灰岩红壤区四种人工林旱季土壤水分的空间变异

采用地统计学的方法,研究了江西修水退化石灰岩红壤区四种人工林在高温干旱季节土壤水分空间变异规律及其分布格局。结果表明:(1)不同类型人工林的土壤水分表现出不同的空间变异性。枫香纯林土壤水分的结构方差比为0·551,梾木×香椿混交林为0·730均介于0·25～0·75之间,表现出中等程度的空间相关性;青桐×桤木混交林的为0·841,香椿纯林的为0·934,均大于0·75,表现出强烈的空间相关性。(2)梾木×香椿、青桐×桤木混交林土壤水分在水平方向和垂直方向上空间变异程度比枫香纯林、香椿纯林低混交林土壤水分的分布更均匀。(3)0～10cm层土壤含水量的变异程度较10～20cm土层和20～40cm土层大,即随土层深度增加土壤水分分布趋于均匀。     

退化喀斯特植被恢复与土壤微生物特征的关系

The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade.In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanism of degraded karst regions,we measured microbial biomass C and basal respiration in soils during vegetation restoration in Zhenfeng County of southwestern Guizhou Province,China.The community level physiological profiles(CLPP) of the soil microbial community to were estimated determine if vegetation changes were accompanied by changes in functioning of soil microbial communities.The results showed that soil microbial biomass C and microbial quotient(microbial biomass C/organic C) tended to increase with vegetation restoration,being in the order arboreal community stage > shrubby community stage > herbaceous community stage > bare land stage.Similar trend was found in the change of basal respiration(BR).The metabolic quotient(the ratio of basal respiration to microbial biomass,qCO 2) decreased with vegetation restoration,and remained at a constantly low level in the arboreal community stage.Analyses of the CLPP data indicated that vegetation restoration tended to result in higher average well color development,substrate richness,and functional diversity.Average utilization of specific substrate guilds was highest in the arboreal community stage.Principle component analysis of the CLPP data further indicated that the arboreal community stage was distinctly different from the other three stages.In conclusion,vegetation restoration improved soil microbial biomass C,respiration,and utilization of carbon sources,and decreased qCO 2,thus creating better soil conditions,which in turn could promote the restoration of vegetation on degraded karst regions.     

退化喀斯特植被恢复对土壤微生物数量及群落功能多样性的影响

采集不同恢复阶段的土壤样品,采用微生物培养法研究了退化喀斯特植被恢复对土壤微生物数量、群落功能多样性的影响。研究结果表明随着退化喀斯特植被的恢复,土壤微生物数量增加,表现为乔木群落阶段灌木群落阶段草本群落阶段裸地阶段。土壤微生物群落代谢功能分析表明:植被恢复往往导致较高的平均颜色变化率、物种丰富度和功能多样性。乔木群落阶段的平均诱导底物利用率最高,明显地与其他3个恢复阶段不同。总之,植被恢复使得土壤微生物数量增加,碳源平均利用率增强。因此,创造了更好的土壤条件更有利于退化喀斯特植被的恢复。     

中国红壤丘陵区基于突变模型的生态恢复措施下土壤恢复评价

Current methods that utilize simple data or models to evaluate soil restoration under ecological restoration are not sufficiently rigorous.Soil restoration under ecological restoration measures was evaluated in the red soil hilly region of China by applying the catastrophe model.Among 89 soil sites selected,26 (29.21％) were in the middle lobe,10 (11.24％) in the upper lobe,and 53 (70.79％) in the lower lobe of the process surface in the Cusp catastrophe model.The catastrophic direction of the 26 unstable soil sites was to the upper lobe of the process surface according to vegetation cover change and fieldwork.There was a significant negative correlation of the variation in bifurcation set (△ value) with vegetation cover increase,and a higher vegetation cover increase was related to higher unstable probability.The four ecological restoration measures were listed in the order:low-quality forest improvement (LQFI) ＞ arbor-bush-herb mixed plantation (ABHMP) ＞ orchard improvement (OI) ＞ closing measures (CM) according to the proportions of unstable soil sites,which were all higher than no restoration measure,while they were in the order:LQFI ＜ ABHMP ＜ OI ＜ CM according to their △ values,which were all lower than those of no restoration measure.Farmers' assessment of soil restoration under the four ecological restoration measures was in accordance with the proportions of unstable soil sites and inversely proportional to the △ value.Therefore,farmers' assessment can prove the evaluation of soil restoration under ecological restoration measures based on catastrophe model.     

Mechanisms behind soil N dynamics following cover restoration in degraded land in subtropical China

Purpose

Nitrogen (N) is an important nutrient for re-vegetation during ecosystem restoration, but the effects of cover restoration on soil N transformations are not fully understood. This study was conducted to investigate N transformations in soils with different cover restoration ages in Eastern China.

Materials and methods

Soil samples were collected from four degraded and subsequently restored lands with restoration ages of 7, 17, 23, and 35 years along with an adjacent control of degraded land. A ¹⁵N tracing technique was used to quantify gross N transformation rates.

Results and discussion

Compared with degraded land, soil organic carbon (SOC) and total N (TN) increased by 1.60–3.97 and 2.49–5.36 times in restoration land. Cover restoration increased ammonium and nitrate immobilization, and dissimilatory nitrate reduction to ammonium (DNRA) by 0.56–0.96, 0.34–2.10, and 0.79–3.45 times, respectively, indicating that restoration was beneficial for N retention. There were positive correlations between SOC content and ammonium and nitrate immobilization and DNRA, indicating that the increase in soil N retention capacity may be ascribed to increasing SOC concentrations. The stimulating effect of SOC on ammonium immobilization was greater than its effect on organic N mineralization, so while SOC and TN increased, inorganic N supply did not increase. Autotrophic and heterotrophic nitrification increased with increasing SOC and TN concentrations. Notably, heterotrophic nitrification was an important source of NO₃^??N production, accounting for 47–67% of NO₃^??N production among all restoration ages.

Conclusions

The capacity of N retention was improved by cover restoration, leading to an increase in soil organic carbon and total N over time, but inorganic N supply capacity did not change with cover restoration age.

     

不同恢复年限侵蚀红壤生态化学计量特征

为了解侵蚀红壤碳、氮、磷分配格局及化学计量特征,本文在长汀县侵蚀红壤区选取不同恢复年限(2、13、30、33年)、立地条件相近、样地情况基本一致的马尾松林作为研究对象,以未治理侵蚀地(CKl)和次生林(CK2)为对照,对其土壤总有机碳、全氮和全磷质量分数及其化学计量比的特征进行测定和分析.结果表明:1)随恢复年限的增加,土壤总有机碳和全氮质量分数呈线性增加,土壤全磷质量分数无显著变化,恢复2 ～33 a的马尾松林土壤总有机碳、全氮和全磷质量分数仍显著低于CK2土壤,表明土壤肥力的恢复是一个漫长的过程.2)土壤C∶N、C∶P、N∶P随恢复年限的增加呈上升趋势,恢复2～33 a的马尾松林土壤C∶N逐渐趋向CK2.3)土壤C∶N和C∶P与土壤总有机碳质量分数呈正显著相关,土壤N∶P与全氮质量分数呈显著正相关,土壤N∶P与全磷质量分数相关性不显著,表明侵蚀退化红壤恢复过程中,土壤化学计量比主要受土壤碳和氮质量分数的控制,暗示着侵蚀红壤现阶段的植被恢复对N素的响应比对P素的响应更敏感.