A greenhouse study of northern red oak seedling growth on two forest soils at different stages of acidification

The objective of this study was to determine whether or not Ca and P in soils from two forested sites at two different stages of acidification were limiting growth of red oak seedlings. The A and E horizons of a Berks soil from Watershed 4 at the Fernow Experimental Forest (cation exchange buffer range) and a Hazelton/Dekalb soil from Pea Vine Hill in Southwestern Pennsylvania (Al buffer range) were placed in pots and utilized as the growth medium for northern red oak seedlings in a greenhouse environment. Soil water NO₃-N, Ca, Mg, and K concentrations were significantly higher (α≤0.05) on the Berks soil. Soil exchangeable P and soil solution TP (total phosphorus) were significantly higher (α≤0.10) on the Hazelton/Dekalb soil. Both soils were amended with bone meal (CaPO₄) to determine the effects of Ca and P addition on the growth and nutrient uptake of the seedlings. Height growth of the control red oak seedlings was significantly (α≤0.05) greater on the Berks soil after 45 d, but amendment of Hazelton/Dekalb soil with bone meal eliminated this difference. Bone meal addition to the Hazelton/Dekalb soil resulted in significantly greater (α≤0.05) height growth of red oak seedlings when compared to red oak seedlings grown on unamended Hazelton/Dekalb soil, but did not have a similar effect for red oak seedlings grown on Berks soil. Bone meal addition to Hazelton/Dekalb soil resulted in greater (α≤0.05) concentrations of Ca and Mg in red oak leaves. Unfertilized Berks red oak seedling leaves had significantly higher (α≤0.05) concentrations of Ca and K than their Hazelton/Dekalb counterparts. Al/Ca molar ratios were significantly lower on the Berks soil. Red oak height growth was increased significantly by Ca addition to the Hazelton/Dekalb soil.     

Determination of amino acids from the leaves of evergreen oak (Quercus ilex L.) at four different stages of decomposition

Summary It was established by weak ion exchange resin chromatography that 17 amino acids in proteins and 15 free amino acids account for almost all of the amino acids present in the leaves of evergreen oak (Quercus ilex L.) in four different stages of decomposition. No significant change in the amounts of these amino acids was observed in the course of decomposition. The amino acid content of evergreen oak leaves is comparable to that in pine needles and beech leaves.     

Time-dependent sorption of imidacloprid in two different soils

Time-dependent sorption of imidacloprid [1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine] was investigated with two German soils (sandy loam and silt loam). Soil batches containing the active ingredient (0.33 mg/kg) were incubated for 100 days. After selected aging periods, imidacloprid desorbed by 0.01 M CaCl(2) (soluble phase) and by organic solvents (methanol and acetonitrile) and reflux extraction with acidified methanol (sorbed phase) was determined. Calculated sorption coefficients K(d) and K(oc) increased by a factor of 3.2-3.8 during 100 days of aging. Additionally, the time-dependent sorption was verified by a column leaching experiment with the aged soil. The amount of imidacloprid in column eluates (0.01 M CaCl(2)) decreased compared to total recovered by a factor of approximately 2. Sorption of imidacloprid thus increased with residence time in soil, making it more resistant to leaching. These results are further information to explain the low leaching potential of imidacloprid in the field, despite its high water solubility.     

Nitrogen losses from two grassland soils with different fungal biomass

Nitrogen losses from agricultural grasslands cause eutrophication of ground- and surface water and contribute to global warming and atmospheric pollution. It is widely assumed that soils with a higher fungal biomass have lower N losses, but this relationship has never been experimentally confirmed. With the increased interest in soil-based ecosystem services and sustainable management of soils, such a relationship would be relevant for agricultural management. Here we present a first attempt to test this relationship experimentally. We used intact soil columns from two plots from a field experiment that had consistent differences in fungal biomass (68 ± 8 vs. 111 ± 9 μg C g⁻¹) as a result of different fertilizer history (80 vs. 40 kg N ha⁻¹ y⁻¹ as farm yard manure), while other soil properties were very similar. We performed two greenhouse experiments: in the main experiment the columns received either mineral fertilizer N or no N (control). We measured N leaching, N₂O emission and denitrification from the columns during 4 weeks, after which we analyzed fungal and bacterial biomass and soil N pools. In the additional ¹⁵N experiment we traced added N in leachates, soil, plants and microbial biomass. We found that in the main experiment, N₂O emission and denitrification were lower in the high fungal biomass soil, irrespective of the addition of fertilizer N. Higher ¹⁵N recovery in the high fungal biomass soil also indicated lower N losses through dentrification. In the main experiment, N leaching after fertilizer addition showed a 3-fold increase compared to the control in low fungal biomass soil (11.9 ± 1.0 and 3.9 ± 1.0 kg N ha⁻¹, respectively), but did not increase in high fungal biomass soil (6.4 ± 0.9 after N addition vs. 4.5 ± 0.8 kg N ha⁻¹ in the control). Thus, in the high fungal biomass soil more N was immobilized. However, the ¹⁵N experiment did not confirm these results; N leaching was higher in high fungal biomass soil, even though this soil showed higher immobilization of ¹⁵N into microbial biomass. However, only 3% of total ¹⁵N was found in the microbial biomass 2 weeks after the mineral fertilization. Most of the recovered ¹⁵N was found in plants (approximately 25%) and soil organic matter (approximately 15%), and these amounts did not differ between the high and the low fungal biomass soil. Our main experiment confirmed the assumption of lower N losses in a soil with higher fungal biomass. The additional ¹⁵N experiment showed that higher fungal biomass is probably not the direct cause of higher N retention, but rather the result of low nitrogen availability. Both experiments confirmed that higher fungal biomass can be considered as an indicator of higher nitrogen retention in soils.     

Phosphorus sorption kinetics in different types of alkaline soils

This study investigated phosphorus sorption kinetics of three different soils from three sites within the Sahel region of Tunisia; iso-humic soils from Chott-Mariem site, calcic-magnesic soils from Enfidha site and saline-sodic soils from Kondar site. Soils from all sites were sampled (0–25 cm) and analysed for their physico-chemical proprieties. In previous works, we determined the adsorption efficiency of these different soils. In this study, we focused on the influence of contact time on phosphorus adsorption by the different soils. The analytic data were approached from the following kinetics models: pseudo-first-order, pseudo- second-order and Elovich model. The second order model was shown to be the best fit for describing phosphorus adsorption by each soil sample, as seen from the correlation coefficient R² which ranged from 0.68 to 0.96 for the pseudo-first-order model, 0.91 to 0.99 for pseudo-second-order model and 0.84 to 0.94 for Elovich model.     

Carbon-nitrogen relationships during the humification of cellulose in soils containing different amounts of clay

¹⁴C-labelled cellulose and ¹⁵N-labelled (NH₄)₂SO₄ were added to four soils with clay contents of 4, 11, 18 and 34%, respectively. Labelled cellulose was added to each soil in amounts corresponding to 1, 2 and 4 mg C g^?1 soil, respectively, and labelled NH₄⁺ at the rate of 1 mg N per 25 mg labelled C.After the first month of incubation at temperatures of 10, 20 and 30°C, respectively, from 38 to 65% of the labelled C added in cellulose had disappeared from the soils as CO₂, and from 60 to nearly 100% of the labelled N added as NH₄⁺ were incorporated into organic forms. The ratio of labelled C remaining in the soils to labelled N in organic forms was close to 25 after 10 days of incubation, decreasing to about 15 after 1 month and about 10 after 4 yr.The retention of total labelled C was largest in the soil with the highest content of clay where after 4 yr it was 25% of that added, compared to 12 in the soil with the lowest content of clay. The incorporation of labelled N in organic forms and its retention in these forms was not directly related to the content of clay in the soils, presumably because the two soils with the high content of clay had a relatively high content of available unlabelled soil-N which was used for synthesis of metabolic material.The proportionate retention of labelled C for a given soil was largely independent of the size of the amendments, whereas the proportionate amount of labelled N incorporated into organic forms increased in the clay-rich soils with increasing size of amendments. Presumably this is because the dilution with unlabelled soil-N was less with the large amendments.From 50 to 70% of the total labelled C remaining in the soils after the first month of incubation was acid hydrolyzable, as compared to 80–100% of the total remaining labelled organic N. This relationship held throughout the incubation and was independent of the size of the amendment and of the temperature of incubation.During the second, third and fourth year of incubation the half-life of labelled amino acid-N in the soils was longer than the half-life of labelled amino acid-C, presumably due to immobilization reactions. Some of the labelled organic N when mineralized was re-incorporated into organic compounds containing increasing proportions of native soil-C. whereas labelled C when mineralized as CO₂ disappeared from the soils.In general, native C and native organic N were less acid hydrolyzable and were accounted for less in amino acid form than labelled C and N.The amount of labelled amino acid-C, formed during decomposition of the labelled cellulose, and retained in the soil, was proportional to the clay content. This amount was about three times as large in the soil with the highest content of clay as in the soil with the lowest content. This difference between the soils was established during the first 10 days of incubation when biological activity was most intense, and it held throughout the 4 yr of incubation; proportionally it was independent of the amount of cellulose added and the temperature.In contrast, the labelled amino acid-N content was not directly related to the amount of clay in the soil, presumably because more unlabelled soil-N was available for synthesis of metabolic material in the two clay-rich soils than in those soils with less clay. The wider ratio between labelled amino acid-C and labelled amino acid-N in the two clay-rich soils as compared with those obtained with the soils with less clay indicates this.The effect of clay in increasing the content of organic matter in soil is possibly caused by newly synthesized matter, extracellular metabolites, as well as cellular material, forming biostable complexes and aggregates with clay. The higher the concentration of clay the more readily the interactions take place. The presence of clay may also increase the efficiency of using substrate for synthesis.     

Fluctuations in microbial biomass indices at different sampling times in soils from tussock grasslands

Microbial biomass in four topsoils from New Zealand tussock grasslands was estimated by three biochemical procedures at five sampling times over a 15 month period. In Conroy, Cluden and Tima soils, biomass C content was high in two sets of March (summer-autumn) samples and low in October (early spring) samples; in Carrick soil from a wetter, cooler environment, it was similar at all sampling times. Significant time-of-sampling variations occurred with Min-N flush in Tima and Carrick soils, and with adenosine 5'-triphosphate (ATP) content in three of the soils. Generally, the ratios of these biomass indices also varied significantly at some sampling times. Because of this variability, common factors could not validly be used with these soils for estimating biomass C contents from Min-flush or ATP values.The contribution of bacteria and fungi to the respiratory activity of the microbial biomass was unsuccessfully investigated using streptomycin and actidione as differential inhibitors of anabolic metabolism in the presence of added glucose. In three of the soils, rates of O₂ uptake did not generally increase significantly during incubation, even with added N, P, K and S or prior incubation overnight. In Conroy soil, rates did increase significantly, but the effects of the antibiotics separately and together could not be satisfactorily balanced.     

不同有机废弃物对土壤磷吸附能力及有效性的影响

城郊农地是循环有机废弃物的重要场所,但长期施用畜禽粪和城市污泥可引起土壤磷素积累、磷饱和度提高,增加土壤向环境流失磷的风险。为了解施用不同来源的有机废弃物对城郊耕地土壤磷素化学行为的影响,选择4种不同磷含量的土壤,探讨在等量磷素情况下,施用KH2PO4、猪粪/稻草秸秆堆肥、沼渣、猪粪、鸡粪、生活垃圾堆肥和2种污泥等不同磷源时,土壤有效磷含量及磷吸附能力的差异。结果表明,施用有机废弃物增加了土壤有效磷和水溶性磷含量,降低了土壤对磷的吸附能力,但影响程度因有机废弃物来源而异。施用猪粪/稻草秸秆堆肥和猪粪降低土壤磷最大吸附量比例(9.03%~15.60%)与施KH2PO4(10.59%~16.63%)相当,但施用沼渣、鸡粪和生活垃圾堆肥降低土壤磷最大吸附量的比例(5.09%~9.84%)明显低于施KH2PO4;施用2种污泥降低土壤磷最大吸附量的比例(4.32%~6.77%)最小。不同有机废弃物对土壤有效磷的影响差异较小,但对水溶性磷的影响较大。施用有机废弃物后,土壤磷最大吸附量的下降值与施用有机废弃物中铁、铝、钙含量呈负相关;土壤水溶性磷的变化量与施用有机废弃物后土壤交换性钙的增加量呈负相关,表明有机废弃物中铁、铝和钙等矿质成分的增加,可在一定程度上减少有机废弃物在土壤循环处理时磷对环境的负影响。在农田施用有机废弃物时,不仅要考虑有机废弃物磷素状况,也应适当考虑其他矿质成分的组成特点。该研究可为城郊农地科学施用有机废弃物提供依据。     

Turnover time of microbial biomass carbon in Japanese upland soils with different textures

We investigated the turnover time of microbial biomass-C in Japanese upland soils with various textures and examined the soil physicochemical properties influencing their turnover time. Samples from five different soil types (sand-dune regosol, light-colored Andosol, humic Andosol, brown forest soil, and dark red soil) were taken from upland concrete-frame plots in the experimental field of Chiba University. Each soil amended with [U -¹³C] glucose was incubated for 80 d at 25°C. Microbial biomass-C and -¹³C in soil were periodically determined by the fumigation-extraction method. The longest turnover time of microbial biomass-C was observed in the dark red soil (215 d) followed by the humic Andosol (134 d), brown forest soil (97 d), and light-colored Andosol (83 d) and the shortest in the sand-dune regosol (45 d). The turnover time of microbial biomass-C was significantly correlated with the value of soil clay (R: 0.917*), CEC (R: 0.921*), and macroaggregate (R: 0.907*) contents, but not with the total-C content. The amount of microbial biomass-C showed a close correlation with the turnover time of microbial biomass-C, suggesting that the turnover time of microbial biomass-C is an important factor influencing the accumulation of microbial biomass-C in soil.     

Different sorption behaviors for wine polyphenols in contact with oak wood

The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contribution of sorption to oak wood in the disappearance phenomena, sorption kinetics were determined for trans-resveratrol and malvidin-3-glucoside through the extraction and the quantification of the fraction sorbed to wood. These curves showed that the wood intake of trans-resveratrol and malvidin-3-glucoside followed a two-step behavior, with a higher rate during the first 2 days, likely due to a surface sorption mechanism, and then a slower rate to reach the equilibrium, which could be related to a diffusion mechanism. The comparison of disappeared and sorbed amounts at equilibrium showed that a minor part of the disappeared monomeric anthocyanins were sorbed by wood. In contrast, half of the concentration decrease of trans-resveratrol in wine finds its origin in a sorption mechanism by oak wood. Results in real wine show similar sorption kinetics.     

Ciliates in coastal dune soils of different stages of development

Abundance and diversity of soil ciliates were studied in the dunes of the North Sea island Norderney (D). Live counts of ciliates were carried out in spring and fall 1999. The eight examined sites show a sequence from freshly thrown sand beach to heath, including primary dunes, white dunes, gray dunes, bushes and forest. Ciliate abundance was low (5–13 ind g^–1 dm) in the young sites without humus horizon (beach, primary and white dune), with dominance of hymenostomes and hypotrichs. The dune soils in older stages showed high abundance, between 39 and 264 ind g^–1 dm. Here, the Colpodea were the dominant group. Bacterial feeders were highly dominant at all sites. While in young sites nano- and microtrophic ciliates were important, in the older sites the community was much more diverse with fungivorous and omnivorous ciliates in addition. By using ordination methods, the young soil sites separated as a group, but the older sites, which differ clearly in community structure, did not. The results show the importance of organic matter as a factor for abundance and species richness of soil ciliates.     

Seasonal changes in the microbial biomass of Brazilian soils with different organic matter contents

Abstract

Carbon and nitrogen levels of microbial biomass were studied in four plots located in Rio de Janeiro State, Brazil. Two samplings were carried out, the first one, on November 1992 when rainfall was high which led the soil to high levels of moisture, and the second one on March 1993 when there was a decrease in rainfall coupled with high temperatures. Microbial carbon (MBC) and microbial nitrogen (MBN) assessments were done by the fumigation‐extraction method. The results showed significant differences for MBC and MBN between the sampling times and between different plots. Moreover, MBN showed differences as a function of sampling depth. In the 1993 sampling, developed under moisture conditions of soil which promoted the mineralization of organic matter, lesser values of MBC and MBN were found, whereas there was no difference in the organic carbon content. This fact shows a major sensitivity of biomass measurements to reflect changes which occur in the soil organic matter content. Significant correlations were obtained between MBC and organic carbon (r = 0.35, P < 0.01, n = 68), MBN and total N (r = 0.62; P < 0.07, n = 47), and MBC with NBM (r 0.74, P < 0.01, n = 54).     

Microbial biomass in soils under different tillage and crop rotation systems

A long-term study on the effect of different crop rotations [soybean/wheat, S/W; maize/wheat, M/W or cotton/wheat, C/W] and tillage regimes [no-tillage (NT) or conventional tillage (CT)] on microbial biomass and other soil properties is reported. The experiment was established in 1976 in southern Brazil as a split-plot experimental design in three replications. Soil samples were taken in 1997 and 1998 at 0- to 5-, 5- to 10- and 10- to 20-cm depths and evaluated for microbial biomass C, N, P and S by direct extraction methods. The NT system showed increases of 103%, 54%, 36%, and 44% for microbial biomass C, N, P, and C_mic:C_org percentage, respectively at the 0- to 5-cm depth. NT systems also increased the C to N:S:P ratios. These results provide evidence that tillage or crop rotation affect microbial immobilization of soil nutrients. The larger amount of C immobilized in microbial biomass suggests that soil organic matter under NT systems provides higher levels of more labile C than CT systems.     

磷肥和有机肥对不同磷水平土壤磷吸附-解吸的影响

采用培养试验结合Langmuir吸附等温方程进行拟合求出吸附、解吸的相关参数的方法,研究了磷肥和有机肥对不同磷水平土壤磷吸附和解吸特性的影响。结果表明,随土壤磷水平和磷肥和有机肥用量的增加,土壤最大吸磷量、土壤磷最大缓冲能力显著降低;土壤易解吸磷和土壤磷的解吸率显著增加。土壤易解吸磷和土壤磷的解吸率与土壤Olsen-P呈显著正相关;土壤最大吸磷量、土壤磷最大缓冲容量与土壤Olsen-P呈显著负相关。单位量磷肥所增加的土壤易解吸磷随着磷肥用量和土壤磷水平的增加而增大;土壤磷水平和磷用量是影响土壤磷最大吸磷量和土壤磷最大缓冲能力的重要因素。     

Gross nitrogen mineralization and nitrification rates and their relationships to enzyme activities and the soil microbial biomass in soils treated with dairy shed effluent and ammonium fertilizer at different water potentials

 Gross N mineralization and nitrification rates and their relationships to microbial biomass C and N and enzyme (protease, deaminase and urease) activities were determined in soils treated with dairy shed effluent (DSE) or NH₄ ⁺ fertilizer (NH₄Cl) at a rate equivalent to 200 kg N ha^–1 at three water potentials (0, –10 and –80 kPa) at 20  °C using a closed incubation technique. After 8, 16, 30, 45, 60 and 90 days of incubation, sub-samples of soil were removed to determine gross N mineralization and nitrification rates, enzyme activities, microbial biomass C and N, and NH₄ ⁺ and NO₃ ^– concentrations. The addition of DSE to the soil resulted in significantly higher gross N mineralization rates (7.0–1.7 μg N g^–1 soil day^–1) than in the control (3.8–1.2 μg N g^–1 soil day^–1), particularly during the first 16 days of incubation. This increase in gross mineralization rate occurred because of the presence of readily mineralizable organic substrates with low C : N ratios, and stimulated soil microbial and enzymatic activities by the organic C and nutrients in the DSE. The addition of NH₄Cl did not increase the gross N mineralization rate, probably because of the lack of readily available organic C and/or a possible adverse effect of the high NH₄ ⁺ concentration on microbial activity. However, nitrification rates were highest in the NH₄Cl-treated soil, followed by DSE-treated soil and then the control. Soil microbial biomass, protease, deaminase and urease activities were significantly increased immediately after the addition of DSE and then declined gradually with time. The increased soil microbial biomass was probably due to the increased available C substrate and nutrients stimulating soil microbial growth, and this in turn resulted in higher enzyme activities. NH₄Cl had a minimal impact on the soil microbial biomass and enzyme activities, possibly because of the lack of readily available C substrates. The optimum soil water potential for gross N mineralization and nitrification rates, microbial and enzyme activities was –10 kPa compared with –80 kPa and 0 kPa. Gross N mineralization rates were positively correlated with soil microbial biomass N and protease and urease activities in the DSE-treated soil, but no such correlations were found in the NH₄Cl-treated soil. The enzyme activities were also positively correlated with each other and with soil microbial biomass C and N. The forms of N and the different water potentials had a significant effect on the correlation coefficients. Stepwise regression analysis showed that protease was the variable that most frequently accounted for the variations of gross N mineralization rate when included in the equation, and has the potential to be used as one of the predictors for N mineralization. Received: 10 March 1998     

Structural diversity and enzyme activity of volcanic soils at different stages of development and response to experimental disturbance

We investigated the phospholipid fatty acid (PLFA) diversity and enzyme activities in soils from the volcano, Mt. Etna (Sicily). The soils were at sites which have been developing for different periods of time and have formed in volcanic lava of differing ages that have been supplemented with volcanic ejecta from subsequent eruptions. However, the plant communities indicated a marked successional difference between the sites and we have used this as a proxy for developmental stage. We have compared the structural and functional properties of the microbial communities in soils from the two sites and tested experimentally the hypothesis that the more diverse community was more resistant and resilient to disturbance. The experimental disturbance imposed was heating (60 °C for 48 h) and the recovery of enzyme activities (β-glucosidase, acid phosphatase and arylsulfatase) and structural properties (PLFA profiles) were then followed over six months. The microbial community in the soil from the older site was more structurally diverse and had a larger total PLFA concentration before disturbance than that of the soil from the younger site. The older soil community was not more resistant and resilient following an environmental disturbance as the younger soil community was equally or more resistant and resilient for all parameters. Changes in enzyme activities following disturbance were almost entirely attributable to changes in biomass (total PLFA).     

Phosphorus sorption capacities and saturation of soils in two regions with different livestock densities in northwest Germany

Abstract. Soils in areas with high livestock density contribute to the eutrophication of aquatic ecosystems through loss of nutrients, especially phosphorus (P). In order to identify the potential for P loss from such soils we determined phosphorus extracted by water (H₂O-P), by double lactate (DL-P), and P sorption capacity (PSC) and degree of P saturation (DPS) in soil samples from two counties, one with low (Harle-catchment) and the other with very high livestock density (Vechta). Both catchments are hydrologically connected with the tidal areas of the North Sea.
The mean concentrations of H₂O-P (0.4mmol/kg) and DL-P (3.9 mmol/kg) were lower in the Harle-catchment than in the Vechta area (1.2 mmol/kg, 6.8mmol/kg). Although oxalate-extractable Al (Al_ox) and Fe (Fe_ox) and the derived PSCs varied according to soil type and to land use, the livestock density and the resulting high concentrations of oxalate-extractable P (P_ox) were shown to be the main reason for the very high DPS of up to 179% in the county of Vechta. These values exceeded DPS reported from other intensive pig feeding areas in western Europe and indicate the potential for significant P loss. Less than 40% of the variation in P_ox could be explained by the routinely determined H₂O-Por DL-P. Geostatistical analyses indicated that the spatial variability of P_ox depended on manurial history of fields and Al_ox, showed still smaller-scale variability. These were the major constraints for regional assessments of P losses and eutrophication risk from agricultural soils using available soil P-test values, digital maps and geostatistical methods.