营养胁迫下不同植物根系的反应和根际效应

研究了在营养胁迫下、小麦、番茄、玉米（不同品种）根系的适应性及其根际效应。结果表明，在缺锰胁迫下植物根系分泌更多的可溶性有机物，导致根际Ｅｈ下降，高价锰氧化物还原，根际氧化锰结合态锰活化并转化为有效态，提供植物吸收。     

有机酸对活化土壤中镉和小麦吸收镉的影响

向土壤中加入外源有机酸,研究有机酸对活化土壤中镉的作用和小麦吸收镉的影响。结果表明：有机酸对土壤中镉有一定的活化能力,对镉活化能力强弱顺序为ＥＤＴＡ〉缺铁小麦根分泌物〉柠檬酸〉苹果酸〉水。但ＥＤＴＡ却降低了小麦地上部镉的含量,缺铁小麦根分泌物明显增加了小麦地上部镉含量。与对照相比,柠檬酸和苹果酸对小麦地上部的镉含量有一定的促进作用,也增加了小麦地上部镉含量。     

锰改性猪粪炭对水稻吸收累积土壤中汞镉的影响

为了探明KMnO4改性猪粪炭对水稻吸收累积复合污染土壤中汞镉的阻控效果，通过盆栽试验研究添加不同量的锰改性猪粪炭（MZC）对水稻中汞镉累积分布特征、根际土壤有效态汞镉含量和土壤理化性质的影响，并探讨了MZC阻控水稻籽粒吸收累积汞镉的可能机制。结果表明：与空白对照相比，添加0.5%MZC使水稻籽粒的总汞、甲基汞和总镉含量分别降低了50.4%、58.4%和79.3%，同时降低了31.1%和39.9%根际土壤有效态汞和镉的含量，但增加了70.3%根际土壤总Mn含量；且添加0.5%的原始猪粪炭对水稻籽粒中总汞、甲基汞和镉含量的降幅显著小于锰改性猪粪炭的，表明经过KMnO4改性可以显著增强猪粪炭对土壤汞镉的钝化能力。水稻籽粒、茎叶中的汞镉含量和根际土壤有效态汞镉含量都随着MZC添加量的增加呈明显的降低趋势。统计分析显示水稻籽粒和茎叶中的汞镉含量与根际土壤中有效态汞、镉呈显著正相关性，而土壤中有效态汞镉含量与土壤的pH、CEC呈负相关。添加MZC使土壤pH、CEC升高，降低了根际土壤中汞、镉的生物有效性，从而减少了水稻地上部分对汞镉的吸收累积。因此，锰改性猪粪炭是一种具有应用潜力的能保障汞镉复合污染农田水稻安全生产的土壤修复剂。     

施用有机物料对土壤镉形态的影响

采用室内培养试验,研究作物新鲜秸秆和腐熟猪粪对模拟镉（Cd）污染的土壤中Cd形态转化的动态影响。结果表明,各处理土壤交换态Cd含量随培养时间均逐渐降低。碳酸盐结合态和铁锰氧化物结合态Cd含量先增加后降低, 而有机质结合态和残渣态Cd含量则逐渐增加。添加秸秆可增加土壤交换态Cd含量,但随时间延长,增幅逐渐降低, 猪粪则可降低土壤交换态Cd含量。添加有机物后土壤交换态Cd含量的变化主要是由有机质结合态或残渣态Cd含量的变化而引起。秸秆和猪粪对土壤Cd形态的转化与土壤胡敏酸（HA）和富里酸（FA）的变化有关。秸秆对能活化土壤Cd的FA增加幅度大于对能钝化土壤Cd的HA增加幅度,降低HA/FA比,但降幅随时间逐渐减少; 猪粪在整个培养阶段对HA增加幅度均大于FA的增加幅度,增加HA/FA比。秸秆和猪粪均可降低潮土pH而提高红壤pH,但只有猪粪可通过提高红壤pH降低Cd向交换态转化。添加秸秆和猪粪后,Cd由低活性态向交换态转化与HA/FA呈显著负相关。     

有机物料对土壤中外源铜形态及土壤化学性质的影响

在室内培养条件下,运用连续提取法研究了稻草,紫云英,猪粪对红壤,潮土中外源铜的形态及土壤化学性质的影响。结果表明,经过１个月培养后,两种土壤中外源铜主要以有机结合态铜为主,交换态铜的消长主要取决于有机结合态铜。在潮土中添加稻草和紫云英经在红壤中添加稻草和紫云英更有效地降低交换态铜的含量。     

不同作物根际环境对土壤重金属形态的影响

采用根垫法研究了玉米、大豆和小麦根际环境对污灌土壤中铜、镉、铅、锌形态的影响。研究结果表明：根际土壤中交换态铜含量呈现增加趋势，碳酸盐态和铁锰氧化物态金属则表现为减少趋势，有机态几无变化。形态变化的幅度与植物种类有关，其中大豆根际土壤中金属形态的变化比小麦和玉米显著。     

玉米根际土壤中不同重金属的形态变化

采用根垫法研究了不同生长时期的玉米根际土壤中铜、镉、铅、锌和铬的形态变化。结果表明 ,玉米生长 1 0 0d内不同重金属的形态变化有显著差别。交换态铜 ,碳酸盐态铜和锌 ,铁锰态铜、铅和铬 ,有机态铜、铅和铬都有明显变化。在 1 0 0d生长期间 ,不同重金属在根际土壤中的相对变化有较大幅度的波动。植物吸收主要影响根际土壤交换态铜和碳酸盐态铜和锌的变化 ,对镉和铅形态变化影响不大。     

铜污染土壤修复的有机调控研究Ⅰ.可溶性有机物和EDTA对污染红壤铜的释放作用

通过吸附-解吸试验和室内培养试验研究了EDTA和猪粪可溶性有机物(DOM)对红壤铜吸附-解吸特性的影响及对污染红壤铜的释放作用.结果表明,外加EDTA可明显降低红壤对铜的吸附率和解吸率;吸附率和解吸率与加入的EDTA含碳量的对数呈极显著的负相关.猪粪DOM在加入量小于21.9 mgL-1C时红壤铜吸附率、解吸率显著降低,符合直线方程;大于21.9 mgL-1C时则使红壤铜吸附率、解吸率逐渐增大,可以对数方程拟合,相关性达到极显著水平.EDTA对污染红壤铜的释放作用随着EDTA:Cu摩尔比的增大而迅速增大,随着铜处理时间的延长而降低;在同一培养时间,外加铜浓度50 mgkg-1时,EDTA对土壤铜的释放量占土壤铜总量的比例即提取效率高于100mgkg-1外源铜处理时的提取效率,但随着EDTA:Cu摩尔比的增大,两者的提取效率差异越来越小.     

NPK养分对Pb在土壤-玉米系统中转化行为的影响

采用根袋技术,研究了NPK养分对土壤-玉米系统中Pb转化行为的影响。试验设5个处理:NPK、NP、NK、PK和CK(不施肥)。结果表明,P对土壤中Pb有显著的固定作用,与不施P处理相比,根际与非根际土壤中交换态Pb降低了4%～9%,根际土壤残渣态Pb增加了5%～8%,非根际土壤增加了5%～12%。加入N后,土壤pH显著下降,P固Pb作用显著增强,交换态Pb降幅增加了1%～4%,残渣态增幅提高了3%～6%。根际土壤残渣态Pb含量较非根际显著降低,根际过程对土壤中残渣态Pb的形成有显著的抑制作用。这可能与根际土壤较高的可溶性有机物含量、微生物活性以及酸性环境等有关。CK处理玉米地上部Pb含量最高,施P大大降低了玉米地上部Pb含量,其约为CK处理的1/2。与NK相比,CK地上部Pb含量也显著增加。因此,Pb在低肥力污染土壤中,生物有效性更大。     

模拟氮沉降对油松幼苗土壤可溶性氮含量及有机物官能团特征的影响

为研究氮沉降对黄土丘陵区林地土壤可溶性氮及可溶性有机物官能团特征的影响,设置6个不同施氮水平0,2.8,5.6,11.2,22.4,44.8gN/(m~2·a)的盆栽油松,连续培养五年,对油松根际、非根际可溶性氮及其组分进行了研究。结果表明:氮添加会显著增加土壤可溶性总氮、可溶性无机氮和可溶性有机氮含量、可溶性有机氮占可溶性氮的比重随氮沉降的增加而成倍增加,可溶性氮及其组分均未表现出明显的根际效应。与此同时,通过不同紫外特征的研究,发现较低和较高水平氮沉降均能增加根际土水溶性有机物中芳香族化合物的积累,非根际土则无明显差异,说明氮沉降与植物的共同作用改变了土壤水溶性有机物结构。     

Organic phosphorus in upland soil

The nature and behaviour of soil organic phosphorus has been studied in many places of the world, especially in Iowa, U.S.A., and Quebec, Canada.     

Organic matter and parathion degradation in flooded soil

The effect of rice straw on parathion degradation in a flooded alluvial soil was investigated. In soils inoculated with an enrichment culture which exhibited an exceptionally high ability to hydrolyze parathion, rice straw amendments inhibited parathion hydrolysis to p-nitrophenol and diethyl thiophosphoric acid. On the other hand, in uninoculated soils, rice straw enhanced the degradation of parathion via nitro reduction. During the enhanced breakdown of parathion in uninoculated soils amended with rice straw, aminoparathion and an unidentified metabolite evidently possessing a PS bond were detected. Thus, the influence of organic matter on the persistence of parathion in flooded soil is governed by the metabolic pathway involved in the degradation.     

Organic matter mineralization in different soil aggregate fractions

The mineralization rate of the organic matter (OM) in the aggregate fractions of a gray forest soil separated by repeated sieving through sieves with different mesh sizes was assessed. The samples of the soil aggregate fractions were incubated for 141 days under constant temperature and moisture, and the C-CO₂ emission rate was measured. The mineralizable OM pool in the aggregates of <0.25, 1–0.25, and 3–1 mm in size from the soil under a forest contained easily (C₁, k ₁ > 0.1 days⁻¹), moderately (C₂, k ₂ > 0.01 days⁻¹), and difficultly (C₃, k ₃ > 0.001 days⁻¹) mineralized compounds; the C₁ and C₂ components were present in the coarser aggregates. In the arable soil, the C₁, C₂, and C₃ OM components were separated in the aggregates of <0.25 and 1–0.25 mm; the C₁ and C₃ were separated in the aggregates of 3–1 and 5–3 mm; and the C₁ and C₂ were separated in the coarsest (10–5 mm) aggregates. The highest content of potentially mineralized OM (C₀) occurred in the aggregates of 1–0.25 and 3–1 mm, but the size of the mineralizable OM pool was more dependent on the portion of the aggregate fraction in the soil than on the absolute C₀ content in the fraction. It was shown that the decrease in the share of coarse structural aggregates is accompanied by a depletion of potentially mineralized OM in the arable soil, and the formation of coarse aggregates is an important condition of the soil carbon sequestration.     

设施土壤有机碳组成特征及光学性质研究

对沈阳市东陵设施栽培土壤有机碳组成特征及其光学性质进行研究,以棚外的露地土壤为对照,结果表明:随着有机碳的增加,设施土壤非腐殖物质碳、腐殖质碳数量均明显增加,分别是露地土壤的1.61～2.45倍、1.08～2.27倍。设施土壤非腐殖质物质碳占总有机碳的比例较露地土壤大,其水浮物质碳所占百分比是露地土壤的1.19～1.65倍,而水溶性有机碳,设施土壤和露地土壤所占百分比均在2%左右。设施土壤胡敏酸和胡敏素所占总有机碳比例表现出随着有机碳含量的增加而升高的趋势,但胡敏酸碳增加的比例小于胡敏素碳。设施土壤可提取腐殖物质、胡敏酸的光密度曲线斜率、E4/E6值、ΔlogK值都小于露地土壤,表明设施土壤可提取腐殖物质、胡敏酸的分子复杂程度、芳香缩合度低于露地土壤。     

Organic and inorganic phosphate interactions with soil hydroxy-interlayered minerals

Background  

Even though extensive work has been done on P interactions with free Al- and Fe-hydroxide minerals, limited or no information exists on sorption/desorption processes of organic and inorganic phosphate forms with soil hydroxy-interlayered minerals.     

蚯蚓对红壤有机质分解的影响

The earthworms Pheretima carnosa, Drawida gisti and Eisenia foetida were studied to compare their contributions to the decomposition of various organic materials surface-applied on red soil in a 165-day greenhouse experiment. The native species Pheretima carnosa and Drawida gisti were equally effective in accelerating the decomposition of maize residue, according to fresh body weight, while commercial species Eisenia foetida had no significant influence on dry mass loss of maize residue. Liming with CaCO3 or CaO showed little effect on maize residue breakdown involved by Pheretima carnosa, but it inhibited this process involved by Drawida gisti. The capability of Pheretima carnosa to the decomposition of five kinds of organic materials was thoroughly examined. The dry mass losses in worm treatments were in the order of soybean residue ＞ maize residue ＞ pig manure ＞ semi-decayed maize ＞ ryegrass. However, the relative contributions of the earthworm to dry mass loss were in the order of pig manure (89.8%) ＞ semi-decayed maize residue (49.1%) ＞ maize residue (29.4%) ＞ soybean residue (20.9%) ＞ ryegrass residue (16.5%). Pheretima carnosa consumed 20～120 mg dry weight of organic material per gram fresh weight of biomass per day.     

Organic matter effects on phase partition of 1,3-dichloropropene in soil

The fumigant 1,3-dichloropropene (1,3-D), in combination with chloropicrin, is considered a major replacement to methyl bromide (MeBr). This study was conducted to better understand phase partitioning of 1,3-D and the role of organic matter in its adsorption to soil. Partition of 1,3-D between air and water (K(H)), and between soil and water (K(f)), was determined by quantifying the concentration in both phases upon equilibrium. At 20 degrees C, the K(H) values of (Z)- and (E)-1,3-D were 0.052 and 0.033, respectively. In four California and Florida soils, the K(f) values of 1,3-D isomers ranged from 0.39 to 8.55, and the K(oc) values ranged from 18 to 60. The relatively high K(H) and low K(f) imply that 1,3-D is highly mobile in most soils after subsurface application. Adsorption of 1,3-D in native soils and soils amended with manure compost increased with increasing soil organic matter content. This suggests that organic wastes may be applied to soil to increase 1,3-D adsorption, thus reducing its potential for offsite movement.     

Organic carbon stocks and soil erodibility in Canary Islands Andosols

Soil organic carbon (SOC) plays a key role in the structural stability of soils and in their resistance against erosion. However, and as far as andic soils are concerned, these mechanisms and processes, as well as the influence of the different types of SOC on aggregate stability, are not fully understood. The targets of this paper are: (i) to determine the content and forms of SOC in Andosols under evergreen forest vegetation [laurel (Laurus) and heather (Erica) forest] and (ii) to find out the role of soil organic matter (SOM) in the aggregate stability and in the resistance of Andosols to water erosion. Soil samples have been collected in 80 sites in a 40 km² area under udic soil moisture regime. In them, fulvic and humic acids, Walkley–Black SOC, pyrophosphate-extractable SOC, Fe and Al, potassium sulphate extractable SOC, dissolved SOC, acid oxalate-extractable Fe, Al and Si, USLE K-factor and aggregate stability have been determined. The Andosols over volcanic ash are Aluandic Andosols (non-allophanic Andosols), whereas over basaltic lava flows are Silandic Andosols (allophanic Andosols). The surface (0–30 cm) samples analyzed contain 9.5–30 kg C m^− 2 being significantly higher in allophanic Andosols (p < 0.5). Organic carbon adsorbed onto the mineral fraction (extractable pyrophosphate, C_p) accounts for 35–55% of the total SOC. All samples show a high stability to slaking and raindrop impact, being the first one highly correlated (r = 0.6) with pyrophosphate extractable C (C_p), Fe (Fe_p), and Al (Al_p) in allophanic Andosols, unlike non-allophanic ones. The stability to raindrop impact correlates with pyrophosphate extractable C (C_p) and Fe (Fe_p) in both types of soils (r = 0.3–0.6, p < 0.05). These findings suggest that the high stability to both slaking and water-drop impact is due to the occurrence of allophane–Fe–OC complexes, rather than to the total OC, and the active Fe and Al forms, generated by the weathering of volcanic materials, constitute an essential constituent responsible for C sequestration and resistance to degradation in these soils.     

Organic matter of the soil of the mountain tundra in North Fennoscandia

The accumulation of organic matter and the major nutrients associated with it (nitrogen and phosphorus) in soils of the mountain tundra is determined by the intensity of the processes of conservation of plant debris. A low nitrogen content (C : N = 12–26) is indicative of the accumulation of weakly humified organic matter. Organic phosphorus compounds mostly accumulate in organogenic horizons with organic matter humified to a greater degree.     

Organic carbon accumulation in a 2000-year chronosequence of paddy soil evolution

Considerable amounts of soil organic matter (SOM) are stabilized in paddy soils, and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. Nonetheless, the mechanisms for stabilization of organic carbon (OC) in paddy soils are largely unknown. Based on a chronosequence derived from marine sediments, the objectives of this study are to investigate the accumulation of OC and the concurrent loss of inorganic carbon (IC) and to identify the role of the soil fractions for the stabilization of OC with increasing duration of paddy soil management. A chronosequence of six age groups of paddy soil formation was chosen in the Zhejiang Province (PR China), ranging from 50 to 2000 years (yrs) of paddy management. Soil samples obtained from horizontal sampling of three soil profiles within each age group were analyzed for bulk density (BD), OC as well as IC concentrations, OC stocks of bulk soil and the OC contributions to the bulk soil of the particle size fractions. Paddy soils are characterized by relatively low bulk densities in the puddled topsoil horizons (1.0 and 1.2 g cm^− 3) and high values in the plow pan (1.6 g cm^− 3). Our results demonstrate a substantial loss of carbonates during soil formation, as the upper 20 cm were free of carbonates in 100-year-old paddy soils, but carbonate removal from the entire soil profile required almost 700 yrs of rice cultivation. We observed an increase of topsoil OC stocks from 2.5 to 4.4 kg m^− 2 during 50 to 2000 yrs of paddy management. The OC accumulation in the bulk soil was dominated by the silt- and clay-sized fractions. The silt fraction showed a high accretion of OC and seems to be an important long-term OC sink during soil evolution. Fine clay in the puddled topsoil horizon was already saturated and the highest storage capacity for OC was calculated for coarse clay. With longer paddy management, the fractions < 20 μm showed an increasing actual OC saturation level, but did not reach the calculated potential storage capacity.