铵、钾同时存在时, 土壤对铵的优先吸附

The water stability of aggregates in various size classes separated from 18 samples of red soils under different managements, and the mechanisms responsible for the formation of water-stable soil aggregates were studied. The results showed that the water stability of soil aggregates declined with increasing size, especially for the low organic matter soils. Organic matter plays a key role in the formation of water-stable soil aggregates. The larger the soil aggregate size, the greater the impact of organic matter on the water stability of soil aggregates. Removal of organic matter markedly disintegrated the large water-stable aggregates (> 2.0 mm) and increased the small ones (< 0.25-0.5mm) to some extent, whereas removal of free iron(aluminium) oxides considerably destroyed aggregates of all sizes, especially the < 0.25-0.5 mm classes. The contents of organic matter in water-stable aggregates increased with aggregate sizes. It is concluded from this study that small water-stable aggregates (< 0.25-0.5 mm) were chiefly cemented by Fe and Al oxides whilst the large ones (> 2.0 mm) were mainly glued up by organic matter. Both free oxides and organic matter contribute to the formation and water stability of aggregates in red soils.     

鄂南第四纪粘土红壤团聚体的稳定性及其稳定机制初探

用湿筛法和LeBissonnais法研究了鄂南第四纪红粘土母质发育的两种侵蚀程度的红壤团聚体的稳定性,并且分析了影响供试土壤团聚体稳定性的土壤性质。结果表明,轻度侵蚀的耕作土壤团聚体的稳定性较低,在水的作用下易崩解成较小粒径的水稳性团聚体;强度侵蚀的土壤表层团聚体的稳定性较高,崩解后产生较多的水稳性大团聚体。引起土壤团聚体破坏的主要作用机制是土壤团聚体中的闭蓄空气爆破引起的消散作用;研究区第四纪红壤团聚体的主要胶结物质是土壤中的粘粒、游离氧化铁铝和无定形铁。由于供试土壤中有机质含量很低,在本研究中,有机质含量与土壤团聚体稳定性之间没有显著正相关关系。     

黄土高原植被自然恢复中土壤团聚体特征

Field investigations and laboratory analysis were conducted to study the characteristics of soil water-stable aggregates during vegetation rehabilitation in typical grassland soils of the hilly-gullied loess area. The relationship between water- stable aggregates and other soil properties was analyzed using canonical correlation analysis and principal component analysis. The results show that during the natural revegetation, the aggregates 〉 5 mm dominated and constituted between 50% and 80% of the total soil water-stable aggregates in most of the soil layers. The 2-5 mm aggregate class was the second main component. The mean value of water-stable aggregates 〉 5 mm within the 0-2 m soil profile under different plant communities decreased in the following order： Stipa grandis 〉 Stipa bungeana Trin. 〉 Artemisia sacrorum Ledeb. 〉 Thymus mongolicus Ronn. 〉 Hierochloe odorata （L.） Beauv. Clay, organic matter, and total N were the key factors that influenced the water stability of the aggregates. Total N and organic matter were the main factors that affected the water stability of the aggregates 〉 5 mm and 0.5-1 mm in size. The contents of Fe2O3, Al2O3, and physical clay （〈 0.01 mm） were the main factors which affected the water stability of the 1-2 and 0.25-0.5 mm aggregates.     

Aggregation in soils with small amounts of swelling clays. I. Aggregate stability

The respective role of organic materials and poorly-ordered Al and Fe hydrous oxides on soil aggregate stability was studied in silty soils with little swelling clay, using both multivariate analysis and physico-chemical approaches. Soil disaggregation is a function of the hydrophobic character of organic matter (OM), which depends on the nature of the organic materials, cationic environment and the aggregating effect of Al and Fe hydrous oxides.
Two kinds of aggregates >50 μm can be distinguished in organic soils, one being about six times more stable than the other. In soils poor in organic matter, weak aggregates dominate; the binding agents are Ca or Al OM rich in polysaccharides and peptides.     

稻田植茶后土壤团聚体水稳性变化特征及影响因素分析

采用野外调查与室内分析相结合的方法,研究名山地区稻田植茶后土壤团聚体水稳性变化特征及其影响因素。结果表明:稻田及植茶后的土壤水稳性团聚体含量在各粒径及土层间表现不同,稻田、茶园5年和10年土壤水稳性团聚体含量总体上随着粒径的减小呈先降低后上升的趋势,茶园15年水稳性团聚体含量则随着粒径的减小逐渐增加。从不同土层来看,在0—20,20—40cm土层中,随着稻田植茶年限的增加,土壤团聚体含量以2mm粒径团聚体为主转变为以0.25mm粒径团聚体为主,而在40—60cm土层中,总体上0.25mm粒径团聚体占据着主要地位;在0—20cm和20—40cm土层,稻田植茶后土壤团聚体水稳性逐年下降,由大到小依次为水稻田茶园5年茶园10年茶园15年,而在40—60cm土层,土壤团聚体水稳性由大到小依次为茶园5年茶园10年水稻田茶园15年,不同土层中团聚体的水稳性与0.25mm粒径团聚体含量呈正相关关系。稻田及稻田植茶后的土壤团聚体水稳性受土壤的理化性质影响,其中受0.25mm粒径团聚体含量、土壤容重、总孔隙度的影响较显著。就所测养分而言,稻田土壤团聚体的水稳性影响因素为有机质和游离氧化铁,茶园5年的影响因素为有机质和阳离子交换量(CEC),茶园10年的影响因素为有机质、CEC和有效磷含量,而茶园15年的影响因素主要是CEC含量。     

Aggregation and organic matter in subarctic Andosols under different grassland management

Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.     

The capacity of soil particles for spontaneous formation of macroaggregates after a wetting-drying cycle

The capacity of soil particles for spontaneous formation of aggregates >0.25 mm was studied in a laboratory experiment. The particles from soil aggregates (3-1 mm) (initially aggregated particles, APs) and initially free particles (FPs) of <0.25 mm in size were isolated from the soddy-podzolic and chernozemic soils under fallow and from the arable soddy-podzolic soil. The aggregates of 3-1 mm were ground and passed through a 0.25-mm sieve. Then, the aggregates and free particles were poured with water and dried, and the content of the formed aggregates and their water stability were determined; in the samples from the arable soddy-podzolic soil, the organic carbon content was also determined in the newly formed aggregates. The FPs from the untilled soils formed almost no aggregates. At the same time, the APs from these soils manifested the ability for the spontaneous formation of aggregates, including water-stable aggregates. In the arable soddy-podzolic soil, on the contrary, both FPs and APs demonstrated the capacity for spontaneous self-organization into aggregates. The water stability of the self-organized aggregates from the arable soil was similar regardless of their source (APs or FPs). It was supposed that the ability of the FPs from the arable soil to form macroaggregates reflects the mechanical degradation of the aggregates in the soil: tillage results in the degradation of the aggregates, and the particles capable of spontaneously aggregation temporarily fall in the fraction of <0.25 mm. The water-stable aggregates produced from the APs or FPs of the arable soil contained more organic carbon (1.89%) in comparison with the water-stable aggregates separated from the initial 3- to 1-mm aggregates of this soil (1.31%).     

护坡人工混凝土壤不同粒级团聚体分布特征及其抗蚀性研究

为了定量评价人工混凝土壤生态护坡基材的抗蚀性,室内测定了其团聚体分布特征和各抗蚀性指标,并与立地条件相似的自然土壤进行了对照分析。结果表明:与自然土壤相比,人工混凝土壤中 > 0.25 mm机械稳定性团聚体含量、> 0.25 mm水稳性团聚体含量R_0.25、平均重量直径MWD、几何平均直径GWD与有机质含量均显著提升,可蚀性因子K、结构破坏率PAD、分形维数D与分散率均显著降低;同时,抗蚀性主成分值提高了2.53倍。这均证实人工混凝土壤团聚状况和团聚度有所改善,抗蚀性较自然土壤有较大的提升。相关性分析表明 > 0.25 mm水稳性大团聚体含量R_0.25和有机质含量与其他抗蚀性指标之间均存在极显著的相关性。综合分析可知,由于添加了水泥和天然有机物料,人工混凝土壤的水稳性大团聚体含量和有机质含量明显提升,因此导致其稳定性与抗蚀性显著优于原材料之一的自然土壤。     

中国亚热带红壤团聚体稳定性与土壤化学性质的关系

The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and Al oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of the severely eroded soils were more stable than those of the slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates, especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0-0.2 mm, while for the severely eroded soils it was 5.0-2.0 mm and 1.0-0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm. In addition, aggregate stability was positively and often significantly correlated with Fe_d, Al_d, Fe_o and clay content, but significantly and negatively correlated to SOC.     

Influence of soil properties on the aggregation of some Mediterranean soils and the use of aggregate size and stability as land degradation indicators

Soil aggregation in relation to other soil properties was studied along a climatological transect in the Southeast of Spain. Three sites were selected along this transect ranging from semiarid to subhumid climatological conditions. The aggregate size distribution, the macro and microaggregate stability of the superficial soil horizon and their relations with other soil properties were analysed. Large aggregates (>10, 10–5, 5–2 mm) were present in highest proportions in the most arid of the studied areas. These large aggregates were associated with high values of water-stable microaggregates; however, they did not improve soil structure and are related to high bulk densities and low water retention. Aggregates 1–0.105 mm were positively correlated to medium, fine, very fine sand and silt fractions and to organic matter. Aggregates <0.105 mm were positively correlated to organic matter and clay content. Small aggregate sizes (1–0.105 and <0.105 mm) had a positive influence on soil water retention and they seem a good indicator of soil degradation.Water stability of microaggregates showed a positive correlation with clay content while the stability of the macroaggregates depended on the organic matter content when the organic matter content was greater than 5 or 6%. Below that threshold the carbonate content was strongly correlated with aggregate stability. A general conceptual scheme of associations between aggregate size distribution, water-stable microaggregation and textural characteristics for the area was developed.The land use history affecting soil overlaps the pattern of climatological situations and has to be taken into account. Aggregate size distribution and stability can be used as indicator of soil degradation, but not as a unique parameter.     

外源铜和镍在土壤中的化学形态及其老化研究

采用连续提取法测定了外源铜和镍进入田间土壤后的化学形态分布,比较研究了这2种重金属在3种不同类型土壤(红壤,水稻土和潮土)中随老化时间的形态转化和分布.结果表明,外源铜以残留态(40%～60%)和EDTA可提取态(40%)为主;随老化时间,EDTA可提取态、易还原锰结合态及铁铝氧化态向残留态转化;外源镍在酸性红壤中以可交换态(40%)和残留态(30%～50%)为主,在中性水稻土中以EDTA可提取态(30%)和残留态(30%～50%)为主,在碱性潮土中以铁铝氧化态(20%)和残留态(40%)为主.随老化时间,水溶态、可交换态、EDTA可提取态等向残留态转化.土壤pH较低时水溶态和可交换态含量较高,但是同时随老化时间的降低量也明显;pH较高时有利于易还原锰结合态和有机质结合态的转化.     

利用方式对红壤水稳定性团聚体形成的影响

本文研究了五种利用方式对红壤水性团聚体形成的影响。结果表明，＞稳定性团聚体含量：林地＞旱地＞荒地＞茶园＞果园。水稳定性团聚体数量以及团聚的水稳定性均与有机质的含量呈正相关。红壤开垦后，有机抽分解加快或补充减少是导致团聚体稳定性下降和水稳定稳定团聚体减少的主要原因。同理，恢复和改良红壤结构性及结构稳定性的关键是增加有机质的投入。     

耕作方式对黄绵土水稳定性团聚体形成的影响

研究了不同耕作方式对黄绵土水稳性团聚体形成的影响。结果表明,>0.25mm土壤水稳定性团聚体含量:免耕+秸秆覆盖(NTS)>免耕(NT)>传统耕作+秸秆还田(TS)>传统耕作(T),团聚体稳定率:免耕+秸秆覆盖(NTS)>免耕(NT)>传统耕作+秸秆还田(TS)>传统耕作(T)。水稳定性团聚体数量以及团聚体的水稳定性均与耕作方式有关。免耕+秸秆覆盖(NTS)、免耕(NT)和传统耕作+秸秆还田(TS)有利于土壤水稳定性团聚体的形成。分析结果同时说明,采用适当耕作方式的同时增加土壤有机质更有利于土壤团聚体的形成和稳定性的增加。     

Aggregate Stability and Its Relationship with Some ChemicalProperties of Red Soils in Subtropical China

The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and A1 oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of the severely eroded soils were more stable than those of the slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates,especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0-0.2 mm, while for the severely eroded soils it was 5.0-2.0 mm and 1.0-0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm.In addition, aggregate stability was positively and often significantly correlated with Fed, Ald, Feo and clay content, but significantly and negatively correlated to SOC.     

Regionalization for rice yield estimation by remote sensing in Zhengjiang province

The role of organic matter in the formaiton and stability of soil aggregates in mulberry plantation in the Hang-Jia-Hu Plain,northern Zhejiang Province,was evaluated in this study,A positive correlation was found between water-stable aggregate contents and organic matter contents in the ulberry plantation soils,which supported the hypothesis that organic matter was the main eenting agent in formation of aggregates.A close correlation was also foud between statility ofaggregate ad organic matter contents.Regression analysis showed that total nitrogen content was also an idicator of water-stable aggregate content and stability.The aggregate size distribution indicated that the water-stable aggregats 1-0.25mm in diaeter with the decreast of aggregate sizes,and the aggregates 1-0.25mm in diameter had the maximum organic matter content.     

黑土开垦后水稳性团聚体与土壤养分的关系

Water-stable aggregates, which are an index for the evaluation of the structural properties of the soil, are affected by many factors. Zhaoguang Farm, Longzhen Farm, and Jiusan Farm were chosen as the representative study sites in the region of black soils, a typical soil resource in Northeast China. The variation in the content of 〉 0.25 mm water-stable aggregates and its relationship with the nutrients in black soil were investigated after different years of reclamation. The results showed that the 〉 0.25 mm water-stable aggregates were more in the surface than in the subsurface soil and they changed in the following order： Longzhen Farm 〉 Zhaoguang Farm 〉 Jiusan Farm. The water-stable aggregates decreased sharply at the initial stage of reclamation and then became stable gradually with time. They were significantly correlated with the contents of organic C, total N, total P, and CEC in black soil, with the correlation coefficients r being 0.76, 0.68, 0.61, and 0.81 （P 〈 0.01）, respectively; however, their relationships with available P, available K, and total K were unclear. These showed that organic matter was the cementation of soil water-stable aggregates. Increasing decompositions and decreasing inputs of organic matter after reclamation were responsible for the amount of reduction of the water-stable aggregates. Thus, to maintain good soil aggregate structure, attention should be paid to improvement of soil nutrient status, especially the supply of organic C and N.     

吉林省西部氟病区苏打盐碱土氟的赋存形态及分布特征

为了研究吉林省西部氟病流行区农田土壤的氟形态及其分布特征,采用连续浸提法,对该区域内45个表层土壤和6个剖面土壤的氟含量进行了测定,并与土壤理化性质进行相关分析。结果表明,表层土壤全氟含量变化范围为200~450 mg/kg,平均值为266.17 mg/kg,低于全国土壤氟背景值和对照黑土,但是其生物有效性强,水溶态氟和交换态氟平均含量分别为13.73、8.49 mg/kg,均高于对照黑土。土壤剖面中,残余态氟和全氟含量呈40~60 cm0~20 cm20~40 cm;铁锰结合态氟分布较均匀;其他形态氟则随着土层加深呈降低趋势。交换态氟与其他形态氟间呈显著或极显著的正相关关系,为各形态氟相互转换的过渡形式。pH与水溶态氟、有机束缚态氟、铁锰结合态氟呈极显著或显著正相关,与交换态氟呈极显著负相关;碳酸钙、CEC分别与水溶态氟和交换态氟呈极显著正相关;另外,有效磷与交换态氟呈显著正相关;有机质与水溶态氟、铁锰结合态氟和有机束缚态氟呈显著或极显著正相关;游离氧化铁和游离氧化铝分别与交换态氟和铁锰结合态氟呈显著或极显著正相关。降低苏打盐碱土pH是降低氟生物有效性的首选方法。通过对以上土壤参数进行分析,为今后降低该区域土壤中氟的生物有效性提供技术支持。     

南方茶园土壤酸化特征及交换性酸在水稳性团聚体中的分布

通过采集浙江省杭州西湖龙井茶园土壤,研究茶园土壤剖面的酸度特征、养分变化以及交换性酸在水稳性团聚体中的分布特征,以了解南方茶园土壤的酸化过程。结果表明:茶园表层土壤(0-20cm)酸化严重,最低的pHH2O值达到4.0,并且有明显的深层化趋势;表土的有机质和速效磷含量较高,速效磷含量最高可达138.2mg/kg;表土团聚体分级表明茶园土壤有良好的团聚体结构,具有良好的水稳性;除了交换性H+在0.5～0.25mm和0.25～0.106mm水稳性团聚体之间没有明显差别外,交换性酸总量、交换性H+和交换性Al 3+含量均随着水稳性团聚体粒径的减小而降低;水稳性大团聚体中交换性Al 3+相对交换性H+占有明显的优势,而在0.106～0.05mm水稳性微团聚体中交换性H+占有明显的优势。交换性酸总量、交换性H+和交换性铝主要分布于>2mm和2～0.5mm水稳性团聚体中,同时在不同粒级团聚体中的分布随粒径的减小而降低。     

不同土地利用方式对岩溶山地土壤团粒结构的影响

研究了 5种利用方式对岩溶山地土壤水稳定性团聚体的影响。结果表明 :>0 .2 5 mm水稳定性团聚体为草坡 >林地 >弃耕地 >果园 >耕地 ;林地、草坡的土壤表层和亚表层水稳定性团聚体以 >2 mm为主 ,而果园、弃耕地、耕地土壤 >2 mm的水稳定性团聚体较小。水稳定性团聚体以及团聚的水稳性均与有机质的含量呈正相关 ,林地、草坡开垦后 ,土壤有机质分解加快或补充减少是土壤团聚体水稳定性下降及数量减少的主要原因。坡耕地退耕后 ,土壤团聚体可得到恢复。     

长期日光温室试验条件下不同施肥处理对土壤团聚体稳定性和铁铝氧化物含量的影响

Soil in greenhouses is likely to suffer a gradual decline in aggregate stability. Determination of the effects of different fertiliser practices on soil aggregate stability is important for taking advantage of solar greenhouses. Soil aggregate stability and iron(Fe) and aluminium(Al) oxide contents were investigated in a 26-year long-term fertilisation experiment in greenhouse in Shenyang, China,under eight fertiliser treatments: manure(M), fertiliser N(FN), fertiliser N with manure(MN), fertiliser P(FP), fertiliser P with manure(MP), fertiliser NP(FNP), fertiliser NP with manure(MNP), and control without any fertiliser(CK). A wet sieving method was used to determine aggregate size distribution and water-stable aggregates(WSA), mean weight diameter and geometric mean diameter as the indices of soil aggregate stability. Different fertiliser treatments had a statistically significant influence on aggregate stability and Fe and Al oxide contents. Long-term application of inorganic fertilisers had no obvious effects on the mass proportion of aggregates. By contrast, manure application significantly increased the mass proportion of macroaggregates at the expense of microaggregates. All treatments, with the exception of FNP, significantly increased the stability of macroaggregates but decreased that of microaggregates when compared with CK. Aggregation under MP and MN was better than that under M and MNP; however,no significant differences were found among inorganic fertiliser treatments(i.e., FN, FP, and FNP). A positive relation was found between pyrophosphate-extractable Fe and WSA(r = 0.269), but no significant relations were observed between other Fe and Al oxides and aggregate stability.