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1.
Biological and chemical properties of arable soils affected by long-term organic and inorganic fertilizer applications 总被引:17,自引:0,他引:17
M. Šimek D. W. Hopkins J. Kalčík T. Picek H. Šantrůčková J. Staňa K. Trávník 《Biology and Fertility of Soils》1999,29(3):300-308
Using soils from field plots in four different arable crop experiments that have received combinations of manure, lime and
inorganic N, P and K for up to 20 years, the effects of these fertilizers on soil chemical properties and estimates of soil
microbial community size and activity were studied. The soil pH was increased or unaffected by the addition of organic manure
plus inorganic fertilizers applied in conjunction with lime, but decreased in the absence of liming. The soil C and N contents
were greater for all fertilized treatments compared to the control, yet in all cases the soil samples from fertilized plots
had smaller C:N ratios than soil from the unfertilized plots. The soil concentrations of all the other inorganic nutrients
measured were greater following fertilizer applications compared with the unfertilized plots, and this effect was most marked
for P and K in soils from plots that had received the largest amounts of these nutrients as fertilizers. Both biomass C determined
by chloroform fumigation and glucose-induced respiration tended to increase as a result of manure and inorganic fertilizer
applications, although soils which received the largest additions of inorganic fertilizers in the absence of lime contained
less biomass C than those to which lime had been added. Dehydrogenase activity was lower in soils that had received the largest
amounts of fertilizers, and was further decreased in the absence of lime. This suggests that dehydrogenase activity was highly
sensitive to the inhibitory effects associated with large fertilizer additions. Potential denitrification and anaerobic respiration
determined in one soil were increased by fertilizer application but, as with both the microbial biomass and dehydrogenase
activity, there were significant reductions in both N2O and CO2 production in soils which received the largest additions of inorganic fertilizers in the absence of lime. In contrast, the
size of the denitrifying component of the soil microbial community, as indicated by denitrifying enzyme activity, was unaffected
by the absence of lime at the largest rate of inorganic fertilizer applications. The results indicated differences in the
composition or function of microbial communities in the soils in response to long-term organic and inorganic fertilization,
especially when the soils were not limited.
Received: 10 March 1998 相似文献
2.
Influence of soil properties on microbial populations, activity and biomass in humid subtropical mountainous ecosystems of India 总被引:1,自引:0,他引:1
Microbial populations, biomass, soil respiration and enzyme activities were determined in slightly acid organic soils of
major mountainous humid subtropical terrestrial ecosystems, along a soil fertility gradient, in order to evaluate the influence
of soil properties on microbial populations, activity and biomass and to understand the dynamics of the microbial biomass
in degraded ecosystems and mature forest. Although the population of fungi was highest in the undisturbed forest (Sacred Grove),
soil respiration was lowest in the 7-year-old regrowth and in natural grassland (approximately 373 μg g–1 h–1). Dehydrogenase and urease activities were high in "jhum" fallow, and among the forest stands they were highest in the 7-year-old
regrowth. Microbial biomass C (MBC) depended mainly on the organic C status of the soil. The MBC values were generally higher
in mature forest than in natural grassland, 1-year-old jhum fallow and the 4-year-old alder plantation. The MBC values obtained
by the chloroform-fumigation-incubation technique (330–1656 μg g–1) did not vary significantly from those obtained by the chloroform-fumigation-extraction technique (408–1684 μg g–1), however, the values correlated positively (P<0.001). The enzyme activities, soil respiration, bacterial and fungal populations and microbial biomass was greatly influenced
by several soil properties, particularly the levels of nutrients. The soil nutrient status, microbial populations, soil respiration
and dehydrogenase activity were greater in Sacred Grove, while urease activity was greater in grassland.
Received: 14 October 1998 相似文献
3.
N. D. Ananyeva T. S. Demkina W. J. Jones M. L. Cabrera W. C. Steen 《Biology and Fertility of Soils》1999,29(3):291-299
Non-tilled and tilled plots on a spodosol (Corg 0.65–1.70%; pH 4.1–4.5) and a mollisol (Corg 3.02–3.13%, pH 4.9–5.3), located in the European region of Russia, were investigated to determine variances in soil microbial biomass and microbial community composition. Continuous, long-term management practices, including tillage and treatment with inorganic fertilizers or manure, were used on the spodosol (39 years) and mollisol (22 years). Total microbial biomass (Cmic), estimated by the substrate-induced respiration (SIR) method, and total fungal hyphae length (membrane filter technique) were determined seasonally over a 3-year period. Long-term soil management practices (primarily tillage and fertilizer application) led to decreases in total microbial biomass (80–85% lower in spodosol and 20–55% lower in mollisol), decreases in the contribution of Cmic to Corg (2.3- to 3.5-fold lower in spodosol and 1.2- to 2.3-fold lower in mollisol), and 50–87% decreases in total fungal hyphae length compared to non-tilled control plots. The contribution of fungi to total SIR in virgin mollisol and fallow spodosol plots was approximately 30%. However, the contribution of fungi to SIR was approximately two times greater in tilled spodosol plots compared to a fallow plot. In contrast, the contribution of fungi to SIR in tilled plots of mollisol was less (1.4–4.7 times) than for a virgin plot. In summary, long-term soil management practices such as tillage and treatment with organic or inorganic fertilizers are important determinants of soil microbial biomass and the contribution of fungi to total SIR. Received: 28 April 1998 相似文献
4.
Effects of increasing periods under intensive arable vegetable production on biological, chemical and physical indices of soil quality 总被引:6,自引:0,他引:6
The effects on soil condition of increasing periods under intensive cultivation for vegetable production on a Typic Haplohumult
were compared with those of pastoral management using soil biological, physical and chemical indices of soil quality. The
majority of the soils studied had reasonably high pH, exchangeable cation and extractable P levels reflecting the high fertilizer
rates applied to dairy pasture and more particularly vegetable-producing soils. Soil organic C (Corg) content under long-term pasture (>60 years) was in the range of 55 g C kg–1 to 65 g C kg–1. With increasing periods under vegetable production soil organic matter declined until a new equilibrium level was attained
at about 15–20 g C kg–1 after 60–80 years. The loss of soil organic matter resulted in a linear decline in microbial biomass C (Cmic) and basal respiratory rate. The microbial quotient (Cmic/Corg) decreased from 2.3% to 1.1% as soil organic matter content declined from 65 g C kg–1 to 15 g C kg–1 but the microbial metabolic quotient (basal respiration/Cmic ratio) remained unaffected. With decreasing soil organic matter content, the decline in arginine ammonification rate, fluorescein
diacetate hydrolytic activity, earthworm numbers, soil aggregate stability and total clod porosity was curvilinear and little
affected until soil organic C content fell below about 45 g C kg–1. Soils with an organic C content above 45 g C kg–1 had been under pasture for at least 30 years. At the same Corg content, soil biological activity and soil physical conditions were markedly improved when soils were under grass rather
than vegetables. It was concluded that for soils under continuous vegetable production, practices that add organic residues
to the soil should be promoted and that extending routine soil testing procedures to include key physical and biological properties
will be an important future step in promoting sustainable management practices in the area.
Received: 18 November 1997 相似文献
5.
Summary Conditions for a rapid, precise [100 g iodonitrotetrazolium chloride (INT)-formazan ml-1 assay mixture], and easily reproducible assay of potential soil dehydrogenase activity are described, using 2(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (iodonitrotetrazolium chloride, INT) as the substrate. Reduced iodonitrotetrazolium formazan (INTF) was measured by spectrophotometry (464 nm) after extraction with N,N-dimethylformamide and ethanol. With this method, the coloured complex formed is highly stable. The effects of pH, buffer concentration, temperature, substrate concentration, amount of soil weight, and reaction time on dehydrogenase activity were investigated. The rate of substrate hydrolysis was proportional to soil weight; the optimal INT reduction was achieved with 1 M TRIS buffer (pH 7.0) at 40 °C. It was possible to determine the biotic and abiotic substrate reduction by comparing assays of autoclaved and unsterile soil samples. Different investigations have confirmed that the intracellular enzyme is highly correlated with the microbial biomass, and indicate that this activity is suitable as an indirect parameter of microbial biomass, measurement. 相似文献
6.
Phosphorus mineralization and microbial biomass were measured in the surface 5 cm of a Spodosol (sandy, siliceous hyperthermic Ultic Alaquod) from north-central Florida. Soils from fertilized and unfertilized plantations of loblolly pine (Pinus taeda L.) were incubated at a range of water potentials (∼0, –3, –8, –10 and –1500 kPa) and temperatures (15 °C, 25 °C and 38 °C) for 14 days and 42 days. Increasing water potential and temperature increased specific P mineralization (mineralization expressed as a percentage of total P) regardless of fertilizer treatment. An increase in water potential from –10 kPa to –0.1 kPa resulted in an increase of between 38% and 239% in the concentration of KCl-extractable inorganic P, depending on incubation temperature and time. An increase in incubation temperature from 15 °C to 38 °C resulted in an increase of between 13% and 53% in KCl-extractable inorganic P. Changes in specific P mineralization with change in water potential or temperature were not affected by fertilizer application. This suggests that, although specific P mineralization was greater in the fertilized soils, environmental control of P mineralization was the same for both treatments. Specific P mineralization was most sensitive when soils were at higher water potentials, and decreased logarithmically to water potentials of between –3 kPa and –8 kPa. Specific P mineralization was relatively insensitive to changes in water potential when water potential was lower than –8 kPa. Microbial biomass C showed no consistent responses to changes of temperature or water potential and was not significantly correlated with specific P mineralization. Our results suggest that field estimates of P mineralization in these Spodosols may be improved by accounting for changes in soil water potential and temperature. Received: 30 October 1997 相似文献
7.
R. J. Haynes 《Biology and Fertility of Soils》1999,30(3):210-216
The effects of 5 years of continuous grass/clover (Cont grass/clover) or grass (Cont grass) pasture or 5 years of annual grass under conventional (Ann grass CT) or zero tillage (Ann grass ZT) were compared with that of 5 years of continuous barley (LT arable) on a site which had previously been under arable crops for 11 years. For added comparison, a long-term grass/clover pasture site (LT past) nearby was also sampled. Soil organic C (Corg) content followed the order LT arable=Ann grass CT<Ann grass ZT<Cont grass=Cont grass/clover<LTpast. Trends with treatment for microbial biomass C (Cmic), basal respiration, flourescein diacetate (FDA) hydrolytic activity, arginine ammonification rate and the activities of dehydrogenase, protease, histidase, acid phosphatase and arylsulphatase enzymes were broadly similar to those for Corg. For Cmic, FDA hydrolysis, arginine ammonification and the activities of histidase, acid phosphatase and arylsulphatase, the percentage increase caused by 5 years of continuous pasture (in comparison with LT arable) was 100–180%, which was considerably greater than that for organic C (i.e. 60%). The microbial metabolic quotient (qCO2) was higher for the two treatments which were mouldboard ploughed annually (LT arable and Ann grass CT) than for the undisturbed sites. At the undisturbed sites, Corg declined markedly with depth (0–15 cm) and there was a similar stratification in the size and activity of Cmic and enzyme activity. The microbial quotient (Cmic/Corg) declined with depth whilst qCO2 tended to increase, reflecting a decrease in the proportion of readily available substrate with depth. Received: 7 July 1998 相似文献
8.
Effects of long-term waste water irrigation on soil organic matter, soil microbial biomass and its activities in central Mexico 总被引:4,自引:0,他引:4
The effect of long-term waste water irrigation (up to 80 years) on soil organic matter, soil microbial biomass and its activities
was studied in two agricultural soils (Vertisols and Leptosols) irrigated for 25, 65 and 80 years respectively at Irrigation
District 03 in the Valley of Mezquital near Mexico City. In the Vertisols, where larger amounts of water have been applied
than in the Leptosols, total organic C (TOC) contents increased 2.5-fold after 80 years of irrigation. In the Leptosols, however,
the degradability of the organic matter tended to increase with irrigation time. It appears that soil organic matter accumulation
was not due to pollutants nor did microbial biomass:TOC ratios and qCO2 values indicate a pollutant effect. Increases in soil microbial biomass C and activities were presumably due to the larger
application of organic matter. However, changes in soil microbial communities occurred, as denitrification capacities increased
greatly and adenylate energy charge (AEC) ratios were reduced after long-term irrigation. These changes were supposed to be
due to the addition of surfactants, especially alkylbenzene sulfonates (effect on denitrification capacity) and the addition
of sodium and salts (effect on AEC) through waste water irrigation. Heavy metals contained in the sewage do not appear to
be affecting soil processes yet, due to their low availability. Detrimental effects on soil microbial communities can be expected,
however, from further increases in pollutant concentrations due to prolonged application of untreated waste water or an increase
in mobility due to higher mineralization rates.
Received: 28 April 1999 相似文献
9.
Soil organic carbon stocks, storage profile and microbial biomass under different crop management systems in a tropical agricultural ecosystem 总被引:3,自引:0,他引:3
We investigated the soil organic C and N stocks, storage profiles and microbial biomass as influenced by different crop management
systems in a tropical agricultural ecosystem. The different crop management systems significantly affected the C and N stocks
and microbial biomass C and N at different soil depths. Amongst the systems evaluated, the rice-wheat system maintained a
higher soil organic C content. Inclusion of legumes in the system improved the soil organic matter level and also soil microbial
biomass activity, vital for the nutrient turnover and long-term productivity of the soil. Irrespective of the cropping system,
approximately 58.4%, 25.7% and 15.9% of the C was distributed in 0–15, 15–30 and 30–60 cm depths, respectively.
Received: 10 October 1999 相似文献
10.
This paper reports the effect of the addition of the organic fraction of municipal solid waste at two different rates on the microbiological and biochemical properties of an arid soil after 8 years. The vegetation that appeared spontaneously just after the amendment was still present 8 years later. The organic matter fractions were higher in the amended soil than in the control soil. Amended soil showed higher values of microbial biomass C, soil basal respiration and dehydrogenase activity than control soil, which reached values near to those of the natural soils in the area. The organic amendment had a positive effect on the activity of enzymes related with C, N, P cycles, particularly when the amendment was at the highest dose. This effect could be also observed on the activity of extracted enzymes. The results indicated that the addition of urban waste could be a suitable technique with which to restore soil quality. Received: 3 July 1998 相似文献
11.
Estimation of the capacity of soils to supply N for crop growth requires estimates of the complex interactions among organic
and inorganic N components as a function of soil properties. Identification and measurement of active soil N forms could help
to quantify estimates of N supply to crops. Isotopic dilution during incubation of soils with added 15NH4
+ compounds could identify active N components. Dilution of 15N in KCl extracts of mineral and total N, non-exchangeable NH44
+, and N in K2SO4 extracts of fumigated and non-fumigated soil was measured during 7-week incubation. Samples from four soils varying in clay
content from 60 to 710 g kg–1 were used. A constant level of 15N enrichment within KCl and K2SO4 extracted components was found at the end of the incubation period. Total N, microbial biomass C and non-exchangeable NH4
+ contents of the soils were positively related to the clay contents. The mineralized N was positively related to the silt
plus clay contents. The active soil N (ASN) contained 28–36% mineral N, 29–44% microbial biomass N, 0.3–5% non-exchangeable
NH4
+ with approximately one third of the ASN unidentified. Assuming that absolute amounts of active N are related to N availability,
increasing clay content was related to increased N reserve for crop production but a slower turnover.
Received: 7 July 1998 相似文献
12.
Influence of stock camping behaviour on the soil microbiological and biochemical properties of grazed pastoral soils 总被引:3,自引:0,他引:3
The size and activity of the soil microbial biomass in grazed pastures was compared on the main grazing area and on stock
camp areas where animals congregate. Two sites were on hill country and three on gently sloping border-dyke irrigated land.
Due to the transfer of nutrients and organic matter to the camp areas via dung and urine there was an accumulation of soil
organic C, organic and inorganic P and S and soluble salts in the camp areas. Soil pH also tended to be higher in camp areas
due to transfer of alkalinity by the grazing animals. Water soluble organic C, microbial biomass C and basal respiration were
all higher in soils from camp areas but the proportion of organic C present as microbial C and the microbial respiratory quotient
were unaffected. Microbial activity as quantified by arginine ammonification rate and fluorescein diacetate (FDA) hydrolysis
was higher in camp than non-camp soils but dehydrogenase activity remained unaffected. Activities of protease, histidase,
urease, acid phosphatase and aryl-sulphatase were all higher in stock camp soils. The activities of both histidase and aryl-sulphatase
were also higher when expressed per unit of microbial biomass C, indicating that the increased activity was the result of
increased enzyme production by the microbial community. Prolonged regular applications of dairy shed effluent (diluted dung
and urine from cattle) to a field had a similar effect to stock camping in increasing soil organic matter content, nutrient
accumulation and soil biological activity. It was concluded that the stock camping activity of grazing animals results in
an increase in both the fertility and biological activity in soils from camp areas at the expense of these properties on the
main grazing areas.
Received: 20 October 1997 相似文献
13.
Flushes of C and N from fumigation-extraction (FE-C and FE-N, respectively), substrate-induced respiration (SIR), denitrification enzyme activity (DEA) and numbers of NH4 + and NO2 – oxidizers were studied in the rhizospheres of Scots pine (Pinus sylvestris L.), Norway spruce [(Picea abies (L.) Karsten] and silver birch (Betula pendula Roth) seedlings growing in soil from a field afforestation site. The rhizosphere was defined as the soil adhering to the roots when they were carefully separated from the rest of the soil in the pots, termed as \"planted bulk soil\". Soil in unplanted pots was used as control soil. All seedlings had been grown from seed and had been infected by the natural mycorrhizas of soil. Overall, roots of all tree species tended to increase FE-C, FE-N, SIR and DEA compared to the unplanted soil, and the increase was higher in the rhizosphere than in the planted bulk soil. In the rhizospheres tree species did not differ in their effect on FE-C, FE-N and DEA, but SIR was lowest under spruce. In the planted bulk soils FE-C and SIR were lowest under spruce. The planted bulk soils differed probably because the roots of spruce did not extend as far in the pot as those of pine and birch. The numbers of both NH4 + and NO2 –oxidizers, determined by the most probable number method, were either unaffected or decreased by roots, with the exception of the spruce rhizosphere, where numbers of both were increased. Received: 26 August 1998 相似文献
14.
Conservation tillage, and especially no-tillage, induce changes in the distribution of organic pools in the soil profile.
In long-term field experiments, marked stratification of the total soil microbial biomass and its activity have been observed
as consequence of the application of no-tillage to previously tilled soils. Our objective was to study the evolution of the
total and active soil microbial biomass and mineralized C in vitro during the first crop after the introduction of no-tillage
to an agricultural soil. The experiment was performed on a Typic Hapludoll from the Argentinean Pampa. Remaining plant residues,
total and active microbial biomass and mineralized C were determined at 0–5 cm and 5–15 cm depths, at three sampling times:
wheat tilling, silking and maturity. The introduction of no-tillage produced an accumulation of plant residues in the soil
surface layer (0–5 cm), showing stratification with depth at all sampling dates. Active microbial biomass and C mineralization
were higher under no-tillage than under conventional tillage in the top 5 cm of the profile. The total soil microbial biomass
did not differ between treatments. The active soil biomass was highly and positive correlated with plant residues (r
2=0.617;P<0.01) and with mineralized C (r
2=0.732;P<0.01). Consequently, the active microbial biomass and mineralized C reflected immediately the changes in residue management,
whereas the total microbial biomass seemed not to be an early indicator of the introduction of a new form of soil management
in our experiment.
Received: 23 February 1999 相似文献
15.
Soil microbial and extractable C and N after wildfire 总被引:12,自引:0,他引:12
The effect of wildfire on soil microbes and extractable C (Cext) and N (Next) changed with respect to the time from burning and soil depth. Initially, microbial biomass C (Cmic) and N (Nmic) were drastically reduced in the soil surface layer (0–5 cm) and reduced by 50% in the subsurface (5–10 cm), whereas Cext increased by 62% in the surface layer and did not significantly change in the subsurface. These parameters were affected
for the following 4 years, during which the average reductions in the soil surface and subsurface layers were, respectively,
60% and 50% for Cmic, 70% and 45% for Nmic, 60% and 40% for the ratio Cmic: organic C (Corg) and 70% and 30% for the ratio Nmic: total N (Ntot), while for Cext the surface layer was the only zone consistently affected and Cext decreased by up to 59%. Immediately after a fire, the Cext : Corg ratio increased by 3.5-fold and 2-fold in the surface and subsurface layers, respectively; thereafter for 2 years, it decreased
in the surface layer (by up to 45%) while the effect on the subsurface layer was not consistent. The effect of burning on
Next lasted 1 year, in which Next increased by up to 7- and 3-fold in the surface and subsurface layers, respectively, while the average Next : Ntot ratio doubled in the surface layer and increased by 34% in the subsurface. During the time in which each parameter was affected
by burning, the soil factor explained a high percentage of variance in the fluctuations of Cmic, Nmic, Cmic : Corg and Nmic : Ntot, while those of Next and Next : Ntot, but not those of Cext and Cext : Corg depended on both the soil and its depth. In the burned soils similar patterns of response were found between the following
parameters listed in pairs: Cmic and Nmic; Cmic : Corg and Nmic : Ntot; Cext and Next; and Cext : Corg and Next : Ntot. However, after the fire relationships found previously between the parameters studied and many other soils properties were
either no longer evident, or were inverted. Although the addition of cellulose to the burned soil favoured fungal mycelium
development and increased Cmic and Cext contents, the negative effect of burning on the microbial biomass and the Cext was not counteracted even under incubation conditions suitable for both microbial growth and C mineralization.
Received: 28 May 1997 相似文献
16.
C. Witt J. L. Gaunt C. C. Galicia J. C. G. Ottow H.-U. Neue 《Biology and Fertility of Soils》2000,30(5-6):510-519
A chloroform-fumigation extraction method with fumigation at atmospheric pressure (CFAP, without vacuum) was developed for measuring microbial biomass C (CBIO) and N (NBIO) in water-saturated rice soils. The method was tested in a series of laboratory experiments and compared with the standard chloroform-fumigation extraction (CFE, with vacuum). For both methods, there was little interference from living rice roots or changing soil water content (0.44–0.55 kg kg–1 wet soil). A comparison of the two techniques showed a highly significant correlation for both CBIO and NBIO (P<0.001) suggesting that the simple and rapid CFAP is a reliable alternative to the CFE. It appeared, however, that a small and relatively constant fraction of well-protected microbial biomass may only be lysed during fumigation under vacuum. Determinations of microbial C and N were highly reproducible for both methods, but neither fumigation technique generated NBIO values which were positively correlated with CBIO. The range of observed microbial C:N ratios of 4–15 was unexpectedly wide for anaerobic soil conditions. Evidence that this was related to inconsistencies in the release, degradation, and extractability of NBIO rather than CBIO came from the observation that increasing the fumigation time from 4 h to 48 h significantly increased NBIO but not CBIO. The release pattern of CBIO indicated that the standard fumigation time of 24 h is applicable to water-saturated rice soils. To correct for the incomplete recovery of CBIO, we suggest applying the k C factor of 2.64, commonly used for aerobic soils (Vance et al. 1987), but caution is required when correcting NBIO data. Until differences in fumigation efficiencies among CFE and CFAP are confirmed for a wider range of rice soils, we suggest applying the same correction factor for both methods. Received: 1 June 1999 相似文献
17.
P. M. Groffman 《Biology and Fertility of Soils》1999,29(4):430-433
The effects of acetate additions to northern hardwood forest soils on microbial biomass carbon (C) and nitrogen (N) content,
soil inorganic N levels, respirable C and potential net N mineralization and nitrification were evaluated. The experiment
was relevant to a potential watershed-scale calcium (Ca) addition that aims to replace Ca depleted by long-term exposure to
acid rain. One option for this addition is to use calcium-magnesium (Mg) acetate, a compound that is inexpensive and much
more readily soluble than the Ca carbonate that is generally used for large-scale liming. Field plots were treated with sodium
(NA) acetate, Na bicarbonate or water (control) and were sampled (forest floor – Oe and Oa combined) 2, 10 and 58 days following
application. It was expected that the addition of C would lead to an increase in biomass C and N and a decrease in inorganic
N. Instead, we observed no effect on biomass C, a decline in biomass N and an increase in N availability. One possible explanation
for our surprising results is that the C addition stimulated microbial activity but not growth. A second, and more likely,
explanation for our results is that the C addition did stimulate microbial growth and activity, but there was no increase
in microbial biomass due to predation of the new biomass by soil fauna. The results confirm the emerging realization that
the effects of increases in the flow of C to soils, either by deliberate addition or from changes in atmospheric CO2, are more complex than would be expected from a simple C : N ratio analysis. Evaluations of large-scale manipulations of
forest soils to ameliorate effects of atmospheric deposition or to dispose of wastes should consider microbial and faunal
dynamics in considerable detail.
Received: 13 March 1998 相似文献
18.
Effect of rotation, nitrogen fertilization and management of crop residues on some chemical, microbiological and biochemical properties of soil 总被引:4,自引:0,他引:4
P. Perucci U. Bonciarelli R. Santilocchi A. A. Bianchi 《Biology and Fertility of Soils》1997,24(3):311-316
A long-term experiment, which started in 1971 near Perugia, central Italy, was performed to investigate the effect of different
crop residue management practices and rotation systems on some soil properties. Twenty years after the beginning of the experiment,
chemical (organic C, total N, humified organic C, humic and fulvic acids), microbiological and biochemical parameters (microbial
biomass, global hydrolase activity, dehydrogenase and catalase activities) were investigated. Two crop residue management
practices were used in the experiment, i.e. removal (RCR soils) and burial (BCR soils). These treatments were factorially
combined with eight rotation systems, i.e. five maize-wheat rotations of different lengths (M-1W, M-2W, M-3W, M-4W and M-5W)
and three continuous wheat systems with different fertilization inputs, from 150 to 250 kg N ha–1. Soil samples were collected in the spring of 1991 for chemical determinations, and in the spring and autumn of 1992, 1993
and 1994, for microbiological and biochemical determinations. All soil chemical, microbiological and biochemical parameters
investigated showed significant differences depending on the management of the crop residues. The BCR soils showed more favourable
characteristics. In contrast, few significant effects were observed in relation to rotation and N-fertilization treatment.
Significant correlations were found between organic-C content and all microbiological and biochemical parameters, as well
as between the microbiological and biochemical parameters themselves, indicating that organic-C content plays an important
role in determining the level of soil enzyme activity and, consequently, of soil fertility. This experiment showed that burying
crop residues in soil can be considered good agronomic practice, which may help limit the gradual depletion of soil organic
matter and improve the chemical properties of the soil.
Received: 11 January 1996 相似文献
19.
M. V. Cheshire C. N. Bedrock B. L. Williams B. T. Christensen I. Thomsen P. Alpendre 《Biology and Fertility of Soils》1999,28(3):306-312
Wheat straw enclosed in mesh bags was buried for periods up to 1 year over two seasons in Scottish, Danish and Portuguese
soils treated with 15NH4NO3 or NH4
15NO3. Scottish soils were: Terryvale, a poorly drained sandy loam; and Tipperty, an imperfectly drained brown forest soil with
a higher clay content. The Danish soil (Foulum) was a freely drained sandy loam and the Portuguese soils were a sandy soil
(Evora) and a clay soil (Beja). During the first month, 15N was being incorporated into the straw in the Tipperty, Terryvale and Foulum soils simultaneously as the total N content
was decreasing. Subsequently, the straws began to show net immobilization and the total N content of the original straw was
exceeded in Tipperty and Foulum soils after 4 months and 8 months, respectively. Net immobilization in Terryvale was detected
only in the second season and did not occur in the first because of high soil moisture content. The rates of 15N incorporation were similar in the two Portuguese soils, and a loss of N was only detected after 8 months. After 1 month,
in the two clay soils, Beja and Tipperty, 15NO3
– was incorporated into straw to a greater extent than 15NH4
+ and this was attributed to 15NH4
+ fixation by clay minerals. In contrast, 15NH4
+ was more efficiently incorporated than 15NO3
– under waterlogged conditions (Terryvale) and NO3
– loss could be attributed to denitrification. The proportion of added 15N in the straw residue after 1 month varied between 6% and 18% for 15NH4
+ and 2% and 23% for 15NO3
– and immobilization of N in the longer term tended to be greater in soils from northern Europe than from Portugal.
Received: 19 January 1998 相似文献
20.
Inhibitory effects of the total and water-soluble concentrations of nine different metals on the dehydrogenase activity of a loess soil 总被引:8,自引:0,他引:8
G. Welp 《Biology and Fertility of Soils》1999,30(1-2):132-139
This study focuses on a comparison of the microbial toxicity of nine metals, including As as a metalloid and two species
of Cr. A loess soil [Ap horizon, clay 15.2%, organic C 1.12%, pH(CaCl2) 7.02] was spiked with 8–12 geometrically increasing doses of the metals. The dehydrogenase assay (2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazoliumchloride method) was combined with sorption and solubility experiments. The resulting dose-response
curves and sorption isotherms were used to derive total doses that caused definite percentage inhibitions [i.e. effective
doses (ED) causing a 10–90% reduction in dehydrogenase activity (dha)] as well as the corresponding toxic solution concentrations
causing the same reductions in dha (i.e. effective concentrations; EC10–EC90). Based on total doses, the toxicity decreased in the following order with ED50 values (mg kg–1) given in brackets: Hg (2.0)>Cu (35)>Cr(VI) (71)>Cr(III) (75)>Cd (90)>Ni (100)>Zn (115)>As (168)>Co (582)>Pb (652). With
regard to solution concentrations, toxicity decreased in the order (EC50 in mg l–1): Hg (0.003)>Pb (0.04)>Cu (0.05)>Cd (0.14)>Zn (0.19)>Cr(III) (0.62)>Ni (0.69)>Co (30.6)>As (55.5)>Cr(VI) (78.1). The retention
of the metals by the soil differed strongly. Pb, Cu, and Hg exhibited the highest and Ni, As, and Cr(VI) the lowest sorption
constants (Freundlich K values: 2455, 724, 348, 93, 13, and 0.06 mg kg–1, respectively). The sorptivity of the metals and their microbial toxicity in the aqueous phase were characteristically related:
metals with a strong toxic action in the soil solution were adsorbed by the soil to a high degree and vice versa. Therefore,
especially for metals with a high inherent toxicity, sorption is an effective way of immobilizing them and temporarily detoxifying
soil.
Received: 2 July 1998 相似文献