Storage effects on the community level physiological profiles of Mediterranean forest soils

Community level physiological profiles (CLPPs) have been implemented in many European soil monitoring programmes as a rapid tool for the assessment of the functional properties of soil microbial communities. However, this technique has not been harmonized among different laboratories. In this experiment, the changes of the CLPPs after storage of three Mediterranean forest soils were characterised for two sampling depths. The methods to store the samples were cooling, freezing and room temperature storage. Data presented in this study provide evidence that substantial changes can occur to the soil microbial community functions, regardless of the kind of storage. Changes in functional diversity and substrate evenness depended on the profile and sampling depth. The rate of consumption of the groups of substrates, however, shifted towards an enhanced utilisation of carboxylic acids, phenols and/or amines after 1 month storage at 4 °C, regardless of the profile or sampling depth. This was attributed to the physical disruption of soil aggregates and exposure of relatively recalcitrant occluded organic matter. These effects levelled out during 1-year storage. The great sensitivity of CLPPs to storage treatment suggests to take care for immediate analysis after sampling. In case fresh samples are not available, freezing is recommended as a convenient alternative; in that case, however, the kinetic approach is required for data analysis.     

外源木炭对苄嘧磺隆在土壤中吸附-解吸的影响

采用振荡平衡法研究了除草剂苄嘧磺隆在3个不同粒径木炭和2种不同类型土壤中的吸附-解吸特征,重点考察了外源木炭对苄嘧磺隆在土壤中吸附-解吸过程的影响。结果表明,苄嘧磺隆在土壤和木炭中的吸附-解吸符合Freundlich方程。木炭对苄嘧磺隆有很强的吸附能力,木炭粒径越小,吸附能力越强。添加木炭能显著提高土壤对苄嘧磺隆的吸附量,木炭添加量越多,苄嘧磺隆吸附量越大,相对的解吸量越少。苄嘧磺隆在土壤和木炭中的解吸过程呈明显的滞后效应,且滞后效应随着苄嘧磺隆初始浓度增大和土壤中木炭添加量增大而逐渐加强。该项研究表明,以木炭作为人工添加吸附剂可有效的减少苄嘧磺隆从土壤中的流失。     

The effect of soil texture and organic amendment on the hydrological behaviour of coarse-textured soils

To gain more insight into the hydrological behaviour of coarse-textured soils, the physical properties of artificially created soil mixtures with different texture were determined. The mixtures were prepared according to the specifications of the United States Golf Association (USGA) for constructing putting greens. In addition, the effect of 10 vol.% organic matter addition was studied. The soil moisture retention and hydraulic conductivity relationships of the different mixtures were determined and their hydrological behaviour was studied using the numerical model SoWaM. Both texture and organic matter addition substantially affected the hydraulic properties. Hydraulic conductivity significantly increased with increasing coarseness while moisture retention decreased. On the other hand, organic matter addition reduced saturated hydraulic conductivity by a factor of 10 to 100 and distinctly increased moisture retention capacity. The amounts of total available water were increased by the addition of organic matter between 144% (slightly coarse texture) and 434% (very coarse texture). Results indicate that the mixtures can contain only 2–16% plant available water and therefore need frequent irrigation to maintain plant growth. Addition of organic matter seems a good solution to reduce the irrigation water requirements but it increases the risk of ponding or runoff because of large reductions in the saturated hydraulic conductivity sometimes to below the rate of 3.6 m/day recommended by the USGA.     

The impact of different forest types on phytolith-occluded carbon accumulation in subtropical forest soils

Purpose

Occlusion of carbon in phytoliths is an important biogeochemical carbon sequestration mechanism and plays a significant role in the global biogeochemical carbon cycle and atmospheric carbon dioxide (CO₂) concentration regulation at a millennial scale. However, few studies have focused on the storage of phytolith and phytolith-occluded carbon (PhytOC) in subtropical forest soils.

Materials and methods

Soil profiles with 100-cm depth were sampled from subtropical bamboo forest, fir forest, and chestnut forest in China to investigate the variation of phytoliths and PhytOC storage in the soil profiles based on amass-balance assessment.

Results and discussion

The storage of phytoliths in the top 100 cm of the bamboo forest soil (198.13?±?25.08 t ha^?1) was much higher than that in the fir forest (146.76?±?4.53 t ha^?1) and chestnut forest (170.87?±?9.59 t ha^?1). Similarly, the storage of PhytOC in the bamboo forest soil (3.91?±?0.64 t ha^?1) was much higher than that in the fir forest soil (1.18?±?0.22 t ha^?1) and chestnut forest soil (2.67?±?0.23 t ha^?1). The PhytOC percentage in the soil organic carbon pool increased with soil depth and was the highest (4.29 %) in the bamboo forest soil. Our study demonstrated that PhytOC in soil was significantly influenced by forest type and the bamboo forest ecosystem contributed more significantly to phytolith carbon sequestration than other forest ecosystems.

Conclusions

Different forest types have a significant influence on the soil PhytOC storage. Optimization of bamboo afforestation/reforestation in future forest management plans may significantly enhance the biogeochemical carbon sink in the following centuries.

     

Effects of water amendment on basal and substrate-induced respiration rates of mineral soils

Summary We studied the effects of amending soils with different volumes of water or glucose solution on respiration rates measured as CO₂ evolution. Basal respiration was not significantly affected by the volume of water amendment, but substrate-induced respiration in static soil solutions was significantly reduced by increasing water contents. Inhibition of substrate-induced respiration was removed by continuously agitating the incubation vessels. Estimates of substrate-induced respiration rates for six soils differed markedly, depending on whether the vessels were stationary or agitated during the incubation. Agitation allowed increased discrimination between substrate-induced respiration rates for the soils, while static incubation only differentiated the soil with the highest substrate-induced respiration rate from the other soils.     

The stone and boulder content of Swedish forest soils

Stone and boulder content has a strong influence on many soil processes and is a crucial factor to take into account when estimating element pools. In this paper we present the results of a large scale inventory of the stone and boulder content of forest soils, which employed a surface penetration method (Viro's method) in 1943 plots across Sweden. The volume of stones and boulders was 43.4%, on average, although it was 47.6% for the most common soil type on glacial till parent material. The variation was spatially correlated and there were regional patterns, which were related to bedrock composition and Quaternary development. A stoniness function was developed for the upper 30 cm of the mineral soil and this was used to translate the penetration depths into stone and boulder content. The function was based on a reference data set of 200 soil pits. A relationship was found between stone and boulder content and surface boulder frequency, but the strength of the relationship varied regionally. In some regions surface boulders may provide an indicator of stone and boulder content in the soil.     

Gypsum amendment improves native grass establishment on saline-alkali soils in northeast China

Abstract. Soil salinity and alkalinity reduce plant production and alter species composition of meadow grasslands in western Jilin Province, China. This study was designed to compare the survival and growth of three grass species ( Aneumlepidium chinense, Puccinellia tenuijlora and Hordeum brevisubulatum ) transplanted into saline-alkali soils in the field, and to evaluate the effects of gypsum amendments on soil properties and growth of these species. Gypsum treatments decreased soil pH, electrical conductivity, and chloride and sodium levels; water infiltration and calcium levels were increased. Survival of grass transplants was increased by gypsum treatments. Tiller number and height, and grass yields were all increased by the application of gypsum. Improvements in plant growth and survival with gypsum treatment appeared to be due to reduced chloride levels and increased Ca availability in the soil, and to changes in soil structure leading to improved infiltration rates. Revegetation of salinelalkaline soils in this region would be improved by application of gypsum in the range of 14–19 t/ha.     

Short- and long-term effects of nitrogen fertilization on methane oxidation in three Swedish forest soils

 Under normal conditions, CH₄, one of the most important greenhouse gases, is subject to biological oxidation in forest soils. However, this process can be negatively affected by N amendment. The reported experiment was conducted in order to study the short- and long-term effects of N amendment on CH₄ oxidation in pine (Pinus sylvestris L.) forest soils. Soil samples were taken from three experimental sites, two of which had been amended with N once, over 20 years earlier, while the third had been amended 3 weeks earlier. The soil samples were incubated fresh at 15  °C at ambient CH₄ concentrations (ca. 1.8 ppmv CH₄). The variation in CH₄-turnover rates was high within the treatments: CH₄ was produced [up to 22.6 pmol CH₄ g dry wt. soil^–1 h^–1] in samples from the recently amended site, whereas it was consumed at high rates (up to 431 pmol CH₄ g dry wt. soil^–1 h^–1) in samples from the plot that had received the highest N amendment 27 years before sampling. Although no significant differences were found between N treatments, in the oldest plots there was a correlation between consumption of atmospheric CH₄ and the total C content at a depth of 7.5–15 cm in the mineral soil (r ²=0.74). This indicates that in the long-term, increased C retention in forest soils following N amendment could lead to increased CH₄ oxidation. Received: 3 September 1997     

The influence of rock powders on microbial activity of three forest soils

To improve the quality of forest soils by applying basic rock powders tests were carried out in Vorarlberg (Austria) in 1987: in the vicinity of Möggers on Stagno-Mollic Gleysol under Abieti-Fagetum luzuletosum, in Nenzing on Calcaric Regosol and Cambisol under Abieti-Fagetum luzuletosum and in Montafon on Stagno-Dystric Gleysol under Homogyno-Piceetum. The effects of a low dosage of rock powder application on nitrification, basal respiration, microbial biomass, xylanase, phosphatase and protease activities, the amount of nitrate nitrogen (NO₃^?-N), and the soil pH were investigated. Additions of rock powder increased protease, NO₃^?-N content and pH, but decreased phosphatase in the A_h-horizon of the Stagno-Mollic Gleysol. After 3 years the A_h-horizon from the experimental site Nenzing showed statistically verified differences of all investigated parameters except xylanase. In the acid spruce forest soils of the Montafon site the rock powder had no statistically significant effect on microbiological parameters. Only the soil pH increased. It can be postulated that the application of rock powders furthered C- and N-mineralization. In the long run this affects the turnover of mineral nutrients in forest ecosystems.     

Studies on the humus forms of forest soils

The results of elementary analysis of each fraction separated physically from each horizon of five forest soils were described.

The biggest fraction was Lf₂ (fresh litter) in L layers, Ff₂ (>2 mm) or Ff₂ (2-1 mm) is F layers and Hf₄ in H layers.

Of all the changes in various parameters which accompanied decomposition and humification, the change in C/N ratio was the most obvious; the C/N ratio for plant remains easily decreased to 25 or 30 during decomposition, but any further decrease in this value occurred with difficulty. It was specifically pointed out that Hf₇ and Hf₂ were fairly different materials from the other fractions.

As for A horizons, both carbon and nitrogen contents increased, and CIN ratios decreased in the order of sand, silt and clay fractions.     

Studies on the humus forms of forest soils

Samples described in the previous paper were analyzed for humus composition by the method of Kumada el al,, elementary composition of humic acids, nitrogen distribution among humic acid, fulvic acid, and humin, and organic matter composition by the modified Waksman method. The samples obtained by physical fractionation from each horizon of Higashiyama soil were as follows: f₁ and f₂ from the L layer, f₁, f₂ and f₃ from the F layer, f₁ f₂, sand, silt, and clay fractions from the H-A and A horizons.

With the progress of decomposition, the following tendencies were rather clearly observed.

The extraction ratio of soluble humus, amounts of humic acid and fulvic acid, and PQ, value tended to increase with some exceptions. The degree of humification of humic acid proceeded. Most humic acids belonged to the Rp type, but those of the clay fractions belonged to the B type.

As for the elementary composition of humic acid, transitional changes from the Lf₁ to the clay fraction of the A horizon were observed. But differences in elementary composition among humic acids were far less, compared with those among whole fractions.

Nitrogen contents in humic, fulvic, and humin fractions increased with the progress of decomposition and humiliation, and the largest relative increase was found in fulvic acid nitrogen.

According to the modified Waksman's method, the amounts of residues and protein increased, while the total amounts of each extract, except for the HCl extract, and the amounts of sugars and starch, phenolic substances, hemicelluloses and pectin, and cellulose decreased. Sugars and starch comprised only a small portion of the hot water extract, and polyphenols substances comparable to sugars and starch were also found in the extract. Hemicelluloses and pectin accounted for only about one-half of the HCl extract. Several characteristic differences in the elementary composition of extracts and residues were found.

Pheopigments existed in benzene-ethanol extracts and their amounts seemed to decrease from Lf₁ to Ff₂.     

Studies on the humus forms of forest soils

The results of humus composition analysis of each fraction separated physically from each horizon of the five forest soils used in the last paper (3) were presented.

Regular changes in humus composition were observed with the gradation of horizons and With the decrease in particle size. Most of the humic acids from plant residual fractions belonged to the Rp type; hurnic acids from the L layers showed a tannin-like character which disappeared with the progress of decomposition, and humic acids from the smaller particle fractions of the layers contained a Pg fraction.

As for humic acids from the A horizon, they all belonged to the P or B type and contained a Pg fraction. In addition, it was concluded that the humification process in the mineral layer Was clearly different from that in the organic layer.     

Phosphomonoesterase activity in forest soils

Phosphatases are important in the mineralization of organically-bound phosphorous. Although phosphatases have been studied extensively in agricultural soils, there are few reports on phosphatase activity in forest soils, and no information on the effect of forest management practices, such as thinning and N-fertilization, on phosphomonoesterase (PME) activities. In the present study, the (PME) activity of forest soils from Shawnigan Lake and Jordan River (mg p-nitrophenol released g⁻¹ dry soil h⁻¹ was highest in the forest floor horizon (L-H) and decreased with depth to 60 cm in mineral soil horizons. Addition of orthophosphate and urea during the assay of PME demonstrated these chemicals competitively depressed PME activity. With Shawnigan Lake soil (L-H), the minimum rate (V_max) of PME activity was 5.71 mg p-nitrophenol released g⁻¹ dry soil h⁻¹. For Jordan River, V_max was 3.33 mg p-nitrophenol released g⁻¹h⁻¹. Incubation of L-H horizon of both soils, fumigated or non-fumigated, at 30°C for up to 40 days after rewetting resulted in an initial reduction in PME activity. Comparatively, the PME activity of Jordan River soil recovered faster than that of the Shawnigan Lake soil whose activity remained very low at the end of the incubation. In field plots where trees were thinned and urea and ammonium nitrate fertilizers had been applied 2 yr previously, assays for PME demonstrated that urea fertilization and thinning depressed PME activity while ammonium nitrate did not. This study demonstrated (1) PME activity depended on soil geographic location and depth, and (2) fertilization of forests with phosphates and urea appeared to reduce PME activity and thus may have the potential to depress the mineralization of organic-P.     

不同改良剂对镉污染土壤中小白菜吸收镉的影响

采用盆栽试验, 研究了施用石灰、钙镁磷肥、泥炭、碱渣4种土壤改良剂对外加镉污染的赤红壤上小白菜产量、镉吸收量、土壤有效态镉及pH的影响。结果表明: 外加1 mg·kg^-1和5 mg·kg^-1镉对小白菜生物量无显著影响, 且1 mg·kg^-1镉对小白菜生长有一定的促进作用; 施用改良剂对镉污染土壤上小白菜无显著增产效果。施用4种改良剂均能降低小白菜地上部镉含量, 作用效果为石灰≈泥炭>碱渣>钙镁磷肥。不同改良剂对小白菜根部镉含量影响不同, 泥炭和石灰在所有镉浓度下、钙镁磷肥在0和1 mg·kg^-1镉浓度下可显著降低根部镉含量, 而碱渣无明显作用, 种植两茬规律一致。土壤有效态镉含量与pH呈显著负相关; 施用石灰、碱渣、钙镁磷肥使土壤pH显著升高, 有效态镉含量显著降低, 从而降低小白菜对镉的吸收; 泥炭可显著提高土壤pH, 虽降低土壤有效态镉作用效果不显著, 但显著降低小白菜体内镉含量, 这可能与土壤中形成难以被植物吸收的镉有机结合物有关。两茬蔬菜种植结果显示, 施用后期改良剂对镉污染的抑制效果也较明显。     

Interactive effects of charcoal and earthworm activity increase bioavailable phosphorus in sub-boreal forest soils

The purpose of this study was to assess the effects of charcoal and earthworm presence in contrasting soil types of northern Japan using the biologically based phosphorus (BBP) extraction method, which employs a variety of plant P acquisition strategies. Using soils developed in serpentine and sedimentary parent materials, we tested the interactive effects of Eisenia japonica (Michaelsen) earthworms and 500 kg ha^?1 of dwarf bamboo charcoal (Sasa kurilensis (Rupr.) Makino et Shibata) in a microcosm incubation that lasted four weeks. Soils were extracted in parallel after the incubation with the BBP method using 0.01 M CaCl₂ (soluble P), 0.01 M citric acid (chelate-extractable P), 0.02 phosphatase enzyme units ml^?1 (enzyme-extractable organic P), and 1.0 M HCl (mineral occluded P). Dwarf bamboo charcoal alone contained up to 444 mg total BBP kg^?1 prior to application to soil microcosms. Treatment effects in soil microcosms were highest in sedimentary soil types and where charcoal was combined with earthworms (15.97 mg P kg^?1 ± SE 1.23 total inorganic BBP). Recalcitrant inorganic P (HCl extracted) in combination treatments yielded the highest single inorganic BBP measure (12.41 mg kg^?1 ± SE 1.11). Our findings suggest that charcoal, as a legacy of wildfire, and native earthworm activity may help stimulate cycling of recalcitrant inorganic BBP pools.     

有机-无机复合改良剂对滨海盐碱地的改良效应研究

针对河北中捷农场滨海盐碱地所具有的盐碱化程度高、单盐毒害突出的特点,选取园林废弃物堆肥和惰化产品,并结合磷石膏对该地区的土壤进行改良研究.以大田条件下的实际应用为基础,设置不同处理,进行田间对比试验,定期取样,对土壤盐分指标进行测定分析.结果表明:1)施入有机改良剂和磷石膏,既能有效降低土壤pH值,又能避免单独施人磷石膏后,土壤pH值变化过大,对植物产生不利影响.2)从单因素试验分析,土壤的SAR随着有机改良剂和磷石膏施入量的提高而显著降低,磷石膏的改良效果优于有机改良剂;从2种改良剂的交互作用来看,有机-无机改良剂配施的效果优于改良剂的单施效果.3)随着有机-无机改良剂施人量的增加,土壤中的C1-质量分数呈显著降低,而SO42-质量分数呈显著增加趋势.4)根据试验结果,推荐施入1 kg/m2的磷石膏及5％的有机改良剂(体积比,约3.35 kg/m2),能够取得较好的改良效果,此时的改良成本约为6.70元/m2.研究结果以期为滨海盐碱地区城市绿化,提供理论依据.     

Acidity of open and intercepted precipitation in forests and effects on forest soils in Alberta,Canada

Emissions of SO₂ appear to have an acidifying effect on grossfall (open rainfall), throughfall, stemflow and soil solution at sites near major sources. Resulting effects on soil chemistry include elevated extractable acidity and aluminum and depressed exchangeable bases, especially Ca and Mg. These changes are mostly in the incipient phases in the study area.     

微生物改良基质对新围垦海涂盐土改良的初步研究

海涂围垦区是陆海过渡带,围垦区土壤的传统洗盐和培肥技术易威胁近海生态环境,因此,探索新型、生态的盐土改良技术十分重要。该研究初步研究了新型微生物改良基质的盐土改良功能,结果表明微生物改良基质效果显著。相较于对照处理,微生物改良基质处理水稻产量增加了83.2%(P<0.05);土壤饱和含水率、田间持水量、总孔隙度、有机质、全氮、速效钾分别增加了13.80%、20.00%、6.80%、2.30倍、53.00%、31.00%(P<0.05);土壤容重降低了6.90%;土壤细菌、真菌和放线菌数量分别增加了10.30、11.20和3.18倍;水稻生育期累积灌溉水量减少了35.20%;0~10和>10~20cm土层可溶性盐质量分数分别降低了61.10%和54.40%。微生物改良基质能够在短期内加速盐分洗脱,提升土壤质量,是海涂新围垦区盐土改良的生态高效措施。