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1.
Previous studies have shown that carbon (C) mineralization in saline or sodic soils is affected by various factors including
organic C content, salt concentration and water content in saline soils and soil structure in sodic soils, but there is little
information about which soil properties control carbon dioxide (CO2) emission from saline-sodic soils. In this study, eight field-collected saline–sodic soils, varying in electrical conductivity
(ECe, a measure of salinity, ranging from 3 to 262 dS m−1) and sodium adsorption ratio (SARe, a measure of sodicity, ranging from 11 to 62), were left unamended or amended with mature wheat or vetch residues (2% w/w). Carbon dioxide release was measured over 42 days at constant temperature and soil water content. Cumulative respiration
expressed per gram SOC increased in the following order: unamended soil<soil amended with wheat residues (C/N ratio 122)<soil
with vetch residue (C/N ratio 18). Cumulative respiration was significantly (p < 0.05) negatively correlated with ECe but not with SARe. Our results show that the response to ECe and SARe of the microbial community activated by addition of organic C does not differ from that of the less active microbial community
in unamended soils and that salinity is the main influential factor for C mineralization in saline–sodic soils. 相似文献
2.
V. Acosta-Martínez D. Rowland R. B. Sorensen K. M. Yeater 《Biology and Fertility of Soils》2008,44(5):681-692
Little information is available on soil microbial and biochemical properties, important for understanding nutrient cycling
and organic matter dynamics, as affected by different peanut cropping systems and how they relate to soil functioning. Thus,
we studied a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) in Georgia, which is first in peanut
production in USA, after 5 and 8 years under continuous cotton (Gossypium hirsutum, L) (CtCtCt), cotton–cotton–peanut (CtCtPt), corn (Zea mays L.)–peanut–cotton (CrPtCt), peanut–peanut–cotton (PtPtCt), and continuous peanut (PtPtPt). Soil organic carbon (OC) at 0–20 cm
was already higher under PtPtPt (average, 8.7 g C kg−1 soil), PtPtCt (average, 7.7 g C kg−1 soil), and CrPtCt (average, 7.8 g C kg−1 soil) compared with CtCtPt (average, 4.7 g C kg−1 soil) and CtCtCt (average, 3.3 g C kg−1 soil). Similarly, alkaline phosphatase, acid phosphatase, and phosphodiesterase as a group showed higher activities under
PtPtPt, PtPtCt, and CrPtCt than under CtCtPt and CtCtCt. The activities of glycosidases (α-galactosidase, β-glucosidase, and
β-glucosaminidase) as a group were more sensitive to the cropping systems than phosphastases and showed a distinctive cropping
system separation as follows: PtPtPt = CrPtCt > PtPtCt > CtCtPt > CtCtCt. Similar to OC and microbial biomass C trends, distinctive
differences were found in the microbial community structure of this sandy soil after 8 years between peanut-based cropping
systems (CrPtCt, PtPtCt, and PtPtPt) and cotton-based cropping systems (CtCtCt and CtCtPt) as indicated by the fatty acid
methyl esters profiles.
Trade names and company names are included for the benefit of the reader and do not infer any endorsement or preferential
treatment of the product by USDA-ARS. 相似文献
3.
Giancarlo Renella Amar M. Chaudri Céline M. Falloon Loretta Landi Paolo Nannipieri Philip C. Brookes 《Biology and Fertility of Soils》2007,43(6):751-758
We investigated Cd, Zn, and Cd + Zn toxicity to soil microbial biomass and activity, and indigenous Rhizobium leguminosarum biovar trifolii, in two near neutral pH clay loam soils, under long-term arable and grassland management, in a 6-month laboratory incubation,
with a view to determining the causative metal. Both soils were amended with Cd- or Zn-enriched sewage sludge, to produce
soils with total Cd concentrations at four times (12 mg Cd g−1 soil), and total Zn concentrations (300 mg Zn kg−1 soil) at the EU upper permitted limit. The additive effects of Cd plus Zn at these soil concentrations were also investigated.
There were no significant differences in microbial biomass C (B
C), biomass ninhydrin N (B
N), ATP, or microbial respiration between the different treatments. Microbial metabolic quotient (defined as qCO2 = units of CO2–C evolved unit−1 biomass C unit−1 time) also did not differ significantly between treatments. However, the microbial maintenance energy (in this study defined
as qCO2-to-μ ratio value, where μ is the growth rate) indicated that more energy was required for microbial synthesis in metal-rich sludge-treated soils (especially
Zn) than in control sludge-treated soils. Indigenous R.
leguminosarum bv. trifolii numbers were not significantly different between untreated and sludge-treated grassland soils after 24 weeks regardless of
metal or metal concentrations. However, rhizobial numbers in the arable soils treated with metal-contaminated sludges decreased
significantly (P < 0.05) compared to the untreated control and uncontaminated sludge-treated soils after 24 weeks. The order of decreasing
toxicity to rhizobia in the arable soils was Zn > Cd > Cd + Zn. 相似文献
4.
A field experiment was conducted during 2003–2005 and 2004–2006 at the Indian Institute of Sugarcane Research, Lucknow, India
to study the effect of Trichoderma viride inoculation in ratoon sugarcane with three trash management practices, i.e. trash mulching, trash burning and trash removal.
Trichoderma inoculation with trash mulch increased soil organic carbon and phosphorus (P) content by 5.08 Mg ha−1 and 11.7 kg ha−1 over their initial contents of 15.75 Mg ha−1 and 12.5 kg ha−1, respectively. Soil compaction evaluated as bulk density in 0- to 15-cm soil layer, increased from 1.48 Mg m−3 at ratoon initiation (in April) to 1.53 Mg m−3 at harvest (in December) due to trash burning and from 1.42 Mg m−3 at ratoon initiation (in April) to 1.48 Mg m−3 at harvest (in December) due to trash mulching. The soil basal respiration was the highest during tillering phase and then
decreased gradually, thereafter with the advancement of crop growth. On an average, at all the stages of crop growth, Trichoderma inoculation increased the soil basal respiration over no inoculation. Soil microbial biomass increased in all plots except
in the plots of trash burning/removal without Trichoderma inoculation. The maximum increase (40 mg C kg−1 soil) in soil microbial biomass C, however, was observed in the plots of trash mulch with Trichoderma inoculation treatment which also recorded the highest uptake of nutrient and cane yield. On an average, Trichoderma inoculation with trash mulch increased N, P and K uptake by 15.9, 4.68 and 23.6 kg ha−1, respectively, over uninoculated condition. The cane yield was increased by 12.8 Mg ha−1 with trash mulch + Trichoderma over trash removal without Trichoderma. Upon degradation, trash mulch served as a source of energy for enhanced multiplication of soil bacteria and fungi and provided
suitable niche for plant–microbe interaction. 相似文献
5.
Osmotic potential (OP) of soil solution may be a more appropriate parameter than electrical conductivity (EC) to evaluate the effect of salts on plant growth and soil biomass.However,this has not been examined in detail with respect to microbial activity and dissolved organic matter in soils with different texture.This study evaluated the effect of salinity and sodicity on respiration and dissolved organic matter dynamics in salt-affected soils with different texture.Four non-saline and non-sodic soils differing in texture (S-4,S-13,S-24 and S-40 with 4%,13%,24% and 40% clay,respectively) were leached using combinations of 1 mol L-1 NaC1 and 1 mol L-1 CaC12 stock solutions,resulting in EC (1:5 soil:water ratio) between 0.4 and 5.0 dS m-1 with two levels of sodicity (sodium absorption ratio (SAR) < 3 (non-sodic) and 20 (sodic),1:5 soil:water ratio).Adjusting the water content to levels optimal for microbial activity,which differed among the soils,resulted in four ranges of OP in all the soils:from-0.06 to--0.24 (controls,without salt added),-0.55 to-0.92,-1.25 to-1.62 and-2.77 to-3.00 Mpa.Finely ground mature wheat straw (20 g kg-1) was added to stimulate microbial activity.At a given EC,cumulative soil respiration was lower in the lighter-textured soils (S-4 and S-13) than in the heavier-textured soils (S-24 and S-40).Cumulative soil respiration decreased with decreasing OP to a similar extent in all the soils,with a greater decrease on Day 40 than on Day 10.Cumulative soil respiration was greater at SAR =20 than at SAR < 3 only at the OP levels between-0.62 and-1.62 MPa on Day 40.In all the soils and at both sampling times,concentrations of dissolved organic C and N were higher at the lowest OP levels (from-2.74 to-3.0 MPa) than in the controls (from-0.06 to-0.24 MPa).Thus,OP is a better parameter than EC to evaluate the effect of salinity on dissolved organic matter and microbial activity in different textured soils. 相似文献
6.
Crop residues and fertilizer nitrogen influence residue decomposition and nitrous oxide emission from a Vertisol 总被引:2,自引:0,他引:2
Wisal Muhammad Sarah M. Vaughan Ram C. Dalal Neal W. Menzies 《Biology and Fertility of Soils》2011,47(1):15-23
Crop residues with high C/N ratio immobilize N released during decomposition in soil, thus reducing N losses through leaching,
denitrification, and nitrous oxide (N2O) emission. A laboratory incubation experiment was conducted for 84 days under controlled conditions (24°C and moisture content
55% of water-holding capacity) to study the influence of sugarcane, maize, sorghum, cotton and lucerne residues, and mineral
N addition, on N mineralization–immobilization and N2O emission. Residues were added at the rate of 3 t C ha−1 to soil with, and without, 150 kg urea N ha−1. The addition of sugarcane, maize, and sorghum residues without N fertilizer resulted in a significant immobilization of
soil N. Amended soil had significantly (P < 0.05) lower NO3−–N, which reached minimum values of 2.8 mg N kg−1 for sugarcane (at day 28), 10.3 mg N kg−1 for maize (day 7), and 5.9 mg N kg−1 for sorghum (day 7), compared to 22.7 mg N kg−1 for the unamended soil (day 7). During 84 days of incubation, the total mineral N in the residues + N treatments were decreased
by 45 mg N kg−1 in sugarcane, 34 mg kg−1 in maize, 29 mg kg−1 in sorghum, and 16 mg kg−1 in cotton amended soil compared to soil + N fertilizer, although soil NO3−–N increased by 7 mg kg−1 in lucerne amended soil. The addition of residues also significantly increased amended soil microbial biomass C and N. Maximum
emissions of N2O from crop residue amended soils occurred in the first 4–5 days of incubation. Overall, after 84 days of incubation, the
cumulative N2O emission was 25% lower with cotton + N fertilizer, compared to soil + N fertilizer. The cumulative N2O emission was significantly and positively correlated with NO3−–N (r = 0.92, P < 0.01) and total mineral N (r = 0.93, P < 0.01) after 84 days of incubation, and had a weak but significant positive correlation with cumulative CO2 in the first 3 and 5 days of incubation (r = 0.59, P < 0.05). 相似文献
7.
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
8.
Haiyan Chu Jianguo Zhu Xiangui Lin Rui Yin Zubin Xie Zhihong Cao Takeshi Fujii 《Biology and Fertility of Soils》2007,43(6):811-814
In this study, we investigated the effects of lanthanum (La), one of the rare earth elements (REEs), on microbial biomass
C as well as the decomposition of 14C-labelled glucose in a fluvo-aquic soil in 28 days. The soil was collected from the field plots under maize/wheat rotation
in Fengqiu Ecological Experimental Station of Chinese Academy of Sciences, Henan Province, China. Application of La decreased
soil microbial biomass C during the experimental period, and there was a negative correlation (P < 0.01) between microbial biomass and application rate of La. La increased microbial biomass 14C after 14C glucose addition, and the increase was significant (P < 0.05) at the rates of more than 160 mg kg−1 soil. La slightly increased 14CO2 evolution at lower rates of application but decreased it at higher rates 1 day after 14C glucose addition, while there was no significant effect from days 2 to 28. For the cumulative 14CO2 evolution during the incubation of 28 days, La slightly increased it at the rates of less than 120 mg kg−1 soil, while significantly decreased (P < 0.05) it at the rate of 200 mg kg−1 soil. The results indicated that agricultural use of REEs such as La in soil could decrease the amount of soil microbial
biomass and change the pattern of microbial utilization on glucose C source in a short period. 相似文献
9.
Combining field incubation with nitrogen-15 labelling to examine nitrogen transformations in low to high intensity grassland management systems 总被引:2,自引:0,他引:2
D. J. Hatch S. C. Jarvis R. J. Parkinson R. D. Lovell 《Biology and Fertility of Soils》2000,30(5-6):492-499
The 15N isotope dilution method was combined with a field incubation technique to provide simultaneous measurements of gross and
net rates of N turnover in three long-term swards: unfertilized (Z) or receiving N either from N fixation as clover (C), or
as 200 kg fertilizer N ha–1 year–1 (F). Uniform N enrichment of soil microplots was achieved with a multi-point soil injector to measure mineralization/immobilization
turnover and nitrification over a 4-day incubation. Net rates of mineralization ranged between 0.6 and 2.9 μg N g–1 day–1 and in all three treatments were approximately half the gross rates. Nitrification rates (gross) were between 1.0 and 1.6 μg
N g–1 day–1. In the F treatment, the turnover of NH4
+-N and NO3
–-N pools was on a 2- and 4-day cycle, respectively, whereas in the N-limited treatments (C and Z) turnover rates were faster,
with the NO3
–-N pools turning over twice as fast as the NH4
+-N pools. Therefore, available N was recycled more efficiently in the C and Z treatments, whereas in the F treatment a higher
N pool size was maintained which would be more vulnerable to leakage. A large proportion of the added 15N was recovered in the soil microbial biomass (SMB), which represented a 4–5 times larger sink for N than the plant biomass.
Although the C treatment had a significantly lower SMB than the grass-only treatments, there were no differences in microbial
activity. Gross rates of nitrification increased along the gradient of N input intensity (i.e. Z<C<F), and the addition of
a nitrification inhibitor (C2H2) tended to increase microbial immobilization, but did not influence plant N uptake. In this study, the value of combining
different techniques to verify net rates was demonstrated and the improved methodology for 15N labelling of soil enabled measurements to be obtained from relatively undisturbed soil under natural field conditions.
Received: 25 May 1999 相似文献
10.
We investigated some aspects of soil quality and community-level physiological profiles (CLPP) of bacteria in soil under a
long-term (37 years) trial with either exclusive inorganic fertilizers or fertilizers combined with farmyard manure cultivated
with jute–rice–wheat system. The treatments consisted of 100% recommended dose (RD) of NPK, 150% RD of NPK, 100% RD of N,
100% RD of NPK + FYM (10 t ha−1 year−1), and untreated control. Long-term application of 150% RD of NPK lowered the soil pH considerably while the soils in the
other treatments remained near neutral. The 100% RD of NPK + FYM treated plot showed significantly highest accumulation of
organic carbon, total nitrogen, microbial biomass carbon, basal soil respiration, and fluorescein diacetate hydrolyzing activity
among the treatments. CLPP analysis in Biolog Ecoplates revealed that utilization of carbohydrates was enhanced in all input
treated regimes, while the same for polymers, carboxylic acids, amino acids, and amines/amides were similar or less than the
untreated control. However, within these groups of carbon sources, heterogeneity of individual substrate utilization between
treatments was also noted. Taken together, addition of organic supplements showed significantly increased microbial biomass
carbon and microbial activity, but input of nutrient supplements, both inorganic and organic, only marginally affected the
overall substrate utilization pattern of soil microorganisms. 相似文献
11.
G. Sparling L. A. Schipper G. W. Yeates J. Aislabie M. Vojvodic-Vukovic J. Ryburn H. J. Di A. E. Hewitt 《Biology and Fertility of Soils》2008,44(4):633-640
The chemical, physical and biological conditions of a New Zealand Gley Soil was examined on matched sites under long-term
permanent pasture or used to grow blackcurrants (Ribes nigrum) for 2, 8, 10 or 20 years. The chemical and physical conditions of topsoils (0–10 cm) were assessed by soil pH, Olsen P,
total C, total N, mineralisable N, cation exchange, bulk density, porosity and moisture release characteristics. The biological
conditions were assessed from the microbial biomass, soil respiration, catabolic evenness and numbers and diversity of the
soil nematode populations. The ability of the soil populations to degrade the triazine herbicide simazine was tested. The
particle size distribution confirmed all the sites were very well matched, within 2%, in terms of percentage clay, silt and
sand contents, which were 36.5–40.5% clay and 59.5–62.5% silt. Compared with the soil under pasture, that under horticultural
use for 2, 8, 10 and 20 years had lower total C and N, lower mineralisable N, lower cation exchange and lower porosity but
higher bulk density and particle density. The differences were greater the longer the plots had been under blackcurrant production.
Olsen P content was greatest (58 μg P cm−3) under the 20-year blackcurrant plots. Changes in biological characteristics were greater than in physical or chemical characteristics.
Microbial biomass was 1.73 mg C cm−3 under pasture and decreased to 0.87 mg C cm−3 after 20 years of blackcurrants. Total nematode populations deceased from 3.89 million m−2 under pasture to 0.36 million m−2 after 2 years of blackcurrant production and to 108 000 m−2 after 20 years. There were similar proportional decreases in bacterial-feeding, fungal-feeding, plant-feeding and omnivore
nematodes; however, there was comparatively little change in nematode diversity (Shannon–Weiner) or in microbial catabolic
diversity or soil respiration. Despite the decreased microbial biomass, the microbial community under blackcurrant production
had enhanced capacity to degrade simazine, as compared with the pasture soil. That capacity to degrade simazine was similar
in soils that had grown blackcurrants for 2, 8, 10 or 20 years. Yield of blackcurrants had been maintained in the longer-term
sites, despite the marked changes in soil chemical, physical and biological conditions. 相似文献
12.
Immobilization and mineralization of nitrogen in a saline and alkaline soil during microbial use of sugarcane filter cake amended with glucose 总被引:1,自引:0,他引:1
Ghulam Rasul Ahtsham A. Khan Khalid S. Khan Rainer Georg Joergensen 《Biology and Fertility of Soils》2009,45(3):289-296
A 42-day incubation was conducted to study the effect of glucose and ammonium addition adjusted to a C/N ratio of 12.5 on
sugarcane filter cake decomposition and on the release of inorganic N from microbial residues formed initially. The CO2 evolved increased in comparison with the non-amended control from 35% of the added C with pure +5 mg g−1 soil filter cake amendment to 41% with +5 mg g−1 soil filter cake +2.5 mg g−1 soil glucose amendment to 48% with 5 mg g−1 soil filter cake +5 mg g−1 soil glucose amendment. The different amendments increased microbial biomass C and microbial biomass N within 6 h and such
an increase persisted. The fungal cell-membrane component ergosterol initially showed a disproportionate increase in relation
to microbial biomass C, which completely disappeared by the end of the incubation. The cellulase activity showed a 5-fold
increase after filter cake addition, which was not further increased by the additional glucose amendment. The cellulase activity
showed an exponential decline to values around 4% of the initial value in all treatments. The amount of inorganic N immobilized
from day 0 to day 14 increased with increasing amount of C added, in contrast to the control treatment. After day 14, the
immobilized N was re-mineralized at rates between 1.3 and 1.5 μg N g−1 soil d−1 in the treatments being more than twice as high as in the control treatment. This means that the re-mineralization rate is
independent of the actual size of the microbial residues pool and also independent of the size of the soil microbial biomass. 相似文献
13.
Ming-Xing Shen Lin-Zhang Yang Yue-Ming Yao Dong-Dong Wu Jianguo Wang Ruli Guo Shixue Yin 《Biology and Fertility of Soils》2007,44(1):187-200
The present paper summarizes the results from a long-term experiment setup in 1980 in the Taihu Lake region, China, to address
the yield sustainability, the dynamic changes of soil organic carbon (SOC) storage, and soil fertility in the rice–wheat ecosystem.
Treatments in three replicates comprising manure-treated and chemical fertilizer-treated groups (two factors), each having
seven sub-treatments of different combinations of inorganic nitrogen (N), phosphorus (P), potassium (K), and rice straw, were
randomly distributed. Results showed that the treatments of manure (pig manure from 1980 to 1996 and oil rape cake thereafter)
+ N + P + K (MNPK) and chemical fertilizer + N + P + K (CNPK) produced the highest and the most stable yields for both rice
and wheat within the respective fertilizer treatment group. Potassium fertilization was necessary for yield sustainability
in the ecosystem. Treatments of straw (as rice straw) + N (CRN) and manure + straw + N (MRN) produced more stable yield of
rice but less stable of wheat. It was therefore recommended that straw should be only incorporated during the rice season.
SOC contents in all treatments showed increasing trends over the period, even in the control treatment. Predicted SOC in chemical
fertilizer-treated plots (mostly yet attainable) ranged from 16 to 18 g C kg−1, indicating the high carbon (C) sequestration potential of the soil as compared to the initial SOC. SOC in manure- or straw-treated
plots ranged from 17 to 19 g C kg−1, which had been attained roughly 10 years after the experiment was initiated. Nutrient balance sheet showed that there was
P surplus in all P-treated plots and a steady increase in Olsen-P over a 24-year period in 0–15 cm soil, which contributed
little to crop yield increases. It was therefore suggested that P fertilization rate should be decreased to 30–40 kg P ha−1 year−1. Comparison of yields among the treatments showed that wheat was more responsive to P fertilizer than rice. Thus P fertilizer
should be preferably applied to wheat. Soil pH decrease was significant over the 24-year period and was not correlated with
fertilizer treatments. The overall recommendation is to incorporate straw at 4,500 kg ha−1 year−1 during the rice season only, with additional 190 kg N ha−1 year−1, 30–40 kg P ha−1 year−1 mainly during the rice season, and 150–160 kg K ha−1 year−1. Further research on the unusual P supply capacity of the soil is needed. 相似文献
14.
Sudipta Tripathi Ashis Chakraborty Bimal Kumar Bandyopadhyay 《Soil biology & biochemistry》2007,39(11):2840-2848
Soil salinity is a serious problem for agriculture in coastal regions, wherein salinity is temporal in nature. We studied the effect of salinity, in summer, monsoon and winter seasons, on microbial biomass carbon (MBC) and enzyme activities (EAs) of the salt-affected soils of the coastal region of the Bay of Bengal, Sundarbans, India. The average pH of soils collected from different sites, during different seasons varied from 4.8 to 7.8. The average organic C (OC) and total N (TN) content of the soils ranged between 5.2-14.1 and 0.6-1.4 g kg−1, respectively. The electrical conductivity of the saturation extract (ECe) of soils, averaged over season, varied from 2.2 to 16.3 dSm−1. The ECe of the soils increased five fold during the summer season (13.8 dSm−1) than the monsoon season (2.7 dSm−1). The major cation and anion detected were Na+ and Cl−, respectively. Seasonality exerted considerable effects on MBC and soil EAs, with the lowest values recorded during the summer season. The activities of β-glucosidase, urease, acid phosphatase and alkaline phosphatase were similar during the winter and monsoon season. The dehydrogenase activity of soils was higher in monsoon than in winter. Average MBC, dehydrogenase, β-glucosidase, urease, acid phosphatase and alkaline phosphatase activities of the saline soils ranged from 125 to 346 mg kg−1 oven dry soil, 6-9.9 mg triphenyl formazan (TPF) kg−1 oven dry soil h−1, 18-53 mg p-nitro phenol (PNP) kg−1 oven dry soil h−1, 38-86 mg urea hydrolyzed kg−1 oven dry soil h−1, 213-584 mg PNP kg−1 oven dry soil h−1 and 176-362 mg PNP g−1 oven dry soil h−1, respectively. The same for the non-saline soils were 274-446 mg kg−1 oven dry soil, 8.8-14.4 mg TPF kg−1 oven dry soil h−1, 41-80 mg PNP kg−1 oven dry soil h−1, 89-134 mg urea hydrolyzed kg−1 oven dry soil h−1, 219-287 mg PNP kg−1 oven dry soil h−1 and 407-417 mg PNP kg−1 oven dry soil h−1, respectively. About 48%, 82%, 48%, 63%, 40% and 48% variation in MBC, dehydrogenase activity, β-glucosidase activity, urease activity, acid phosphatase activity and alkaline phosphatase activity, respectively, could be explained by the variation in ECe of saline soils. Suppression of EAs of the coastal soils during summer due to salinity rise is of immense agronomic significance and needs suitable interventions for sustainable crop production. 相似文献
15.
Decomposition of maize straw in saline soil 总被引:3,自引:0,他引:3
Xiaogang Li Fengmin Li Bhupinderpal-Singh Zhijun Cui Zed Rengel 《Biology and Fertility of Soils》2006,42(4):366-370
The interactive effects of salinity and water on organic matter decomposition in soil are poorly known. A loamy topsoil adjusted
to five concentrations of salinity (0, 31, 62, 93 and 124 mmol Na kg−1 soil) using either NaCl or Na2SO4 was incubated at a water content of either 17 or 25% (w/w) in the dark at 28.5°C for 47 days, with maize straw added at 20 g
kg−1 soil. Comparing with non-saline soil, (1) NaCl salinity at all levels decreased cumulative CO2 evolved during days 1–3 (averaged across two water levels), increased in the period 4–32 days at both water contents, and
thereafter caused variable effects, depending upon water content and salinity; and (2) Na2SO4 salinity at various levels mainly caused no effect on cumulative CO2 evolved during days 1–3 (averaged across two water levels), and thereafter (i.e. in days 4–47) caused mainly positive effects
at 17% (w/w) water content and negative effects at 25% (w/w) water content. Cumulative CO2 evolved over 47 days for both types of salinities was mainly greater at 17% (w/w) and smaller at 25% (w/w) water content
compared with non-saline soil. Generally, at 25% (w/w) than at 17% (w/w) water content, there was a greater CO2 evolved over 47 days, and also during different incubation phases for both types of salinities; the difference at low salinity
levels was generally large and decreased as salinity increased. In conclusion, the salinity effect depends on soil water content
and incubation period or decomposition phase. 相似文献
16.
Wei Min Huijuan Guo Wen Zhang Guangwei Zhou Lijuan Ma Jun Ye 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(2):117-126
The scarcity of fresh water has forced farmers to use saline water (SW) for irrigation. It is important to understand the response of the soil microbial community and diversity to saline irrigation water. The objective of this study was to determine the effects of irrigation water salinity and nitrogen fertilization rates on soil physicochemical properties, microbial activity, microbial biomass, and microbial functional diversity. The field experiment consisted of a factorial design with three levels of irrigation water salinity (electrical conductivities (ECs) of 0.35, 4.61 or 8.04?dS?m?1) and two nitrogen rates (0 and 360?kg?N?ha?1). The results showed that the 4.61 and 8.04?dS?m?1 treatments both reduced soil microbial biomass C (MBC), microbial biomass N (MBN), basal respiration, total phospholipid fatty acid (PLFA), bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. In contrast, the SW treatments increased the MBC:MBN ratio. Nitrogen fertilization increased soil MBC, MBN, basal respiration, total PLFA, bacterial PLFA, and gram-negative bacterial PLFA. In contrast, N fertilization decreased gram-positive bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. Average well color development, Richness, and Shannon's Index were always lowest in the 8.04?dS?m?1 treatment. Carbon utilization patterns in the 8.04?dS?m?1 treatment were different from those in the 0.35?dS?m?1 treatment. In conclusion, five years of irrigation with brackish or SW reduced the soil microbial biomass, activity, and functional diversity, which may cause the deterioration of soil quality. Thus, the high-salinity water (EC?>?4.61?dS?m?1) is not appropriate as a single irrigation water resource. Proper N fertilizer input may overcome some of the negative effects of salinity on soil microbial. 相似文献
17.
Vermicomposting differs from conventional composting because the organic material is processed by the digestive systems of worms. The egested casts can be used to improve the fertility and physical characteristics of soil and potting media. In this study, the effects of earthworm casts (EW), conventional compost (CP) and NPK inorganic fertilizer (FT) amendments on N mineralization rates, microbial respiration, and microbial biomass were investigated in a laboratory incubation study. A bioassay with wheat (Triticum aestivium L.) was also conducted to assess the amendment effects on plant growth and nutrient uptake and to validate the nutrient release results from the incubation study. Both microbial respiration and biomass were significantly greater in the CP treatment compared to EW treatment for the initial 35 days of incubation followed by similar respiration rates and biomass to the end of the study at 70 days of incubation. Soil NO3− increased rapidly in the EW and CP treatments in the initial 30 days of incubation, attaining 290 and 400 mg N kg−1 soil, respectively. Nitrate in the EW treatment then declined to 120 mg N kg−1 soil by day 70, while nitrate in the CP treatment remained high. While ammonium levels decreased in the CP treatment as nitrate level increased with increasing incubation time, a low level of ammonium was maintained in the EW treatment throughout the incubation. The wheat bioassay study included two additional cast treatments (EW-N and EW2) to have treatments with higher levels of N input. Plants grown with CP or FT treatment had a lower shoot biomass and higher shoot N content than in EW-N and EW-2 treatments, and also showed symptoms of salinity stress. Ionic strength and other salinity indicators in the earthworm cast treatments were much lower than in the CP treatment, indicating a lower risk of salinity stress in casts than in compost. All cast and compost amendments significantly increased wheat P and K uptake compared to either the non-amended control or the mineral fertilizer treatment. The results show that casts are an efficient source of plant nutrients and that they are less likely to produce salinity stress in container as compared to compost and synthetic fertilizers. 相似文献
18.
C. Xiao R. Stevens M. Fauci R. Bolton M. Lewis W. T. McKean D. F. Bezdicek W. L. Pan 《Biology and Fertility of Soils》2007,43(6):709-719
The cereal and grass seed cropping systems of the Pacific northwestern USA generate a valuable fiber source for papermaking.
Pulping straw with KOH produces black liquor, an organic waste effluent with potential as a K source and soil amendment. The
objectives of this study were to determine if black liquor from wheat straw pulping with KOH improves soil quality including
soil aggregation, microbial biomass and microbial activity, and corn yield. A 2-year field trial with a randomized complete
block design was conducted with black liquor or KCl applied at 168 and 336 kg K ha−1 at two sites, respectively, planted to corn in Central Washington. Black liquor applied at rates of 168 and 336 kg K ha−1 slightly increased soil pH by 0.2 to 1.4 units and electrical conductivity by 0.0 to 0.8 dS m−1 at both sites, and significantly increased soil test K compared to the nonamended control by 199 to 368 mg K kg−1 soil in the top 5 cm at Paterson and by 44 to 200 mg K kg−1 soil in the top 5 cm at Prosser. Corn had no yield response to the application of either K sources, black liquor, or KCl
applied at both rates at both sites. Generally, black liquor applied at these rates increased soil dehydrogenase, β-glucosidase,
and arylsulfatase activities, microbial biomass C, and soil wet stable macroaggregates in the top 5-cm soil at both sites.
The results of this study suggest that the organic-rich waste liquor from wheat straw pulping with KOH may improve soil quality
and soil test K without reducing crop productivity. 相似文献
19.
Carbon fluxes in sodic and saline soils were investigated by measuring the soil microbial biomass (SMB) and soil respiration rates under controlled conditions over 12 weeks. Gypsum (10 t/ha) and organic material, as kangaroo grass (10 t/ha), were incorporated in an acidic and an alkaline saline–sodic soils. Cumulative soil respiration rates were lowest in the sodic and saline soils without amendment, while the highest rates were found in those soils that had organic material addition. The addition of gypsum decreased the cumulative respiration rates in the 0–5 cm layer compared to the addition of organic material and the addition of organic material and gypsum. Similarly, the SMB was lowest in the sodic and saline soils without amendment and highest in the soils which had organic material addition, while the effects of gypsum addition were not significant. The low levels of respiration and SMB were attributed to the low soil organic carbon (SOC) levels that result from little or no C input into the soils of these highly degraded landscapes as the high salinity and high sodicity levels have resulted in scarcity or absence of vegetation. Following the addition of organic material to the sodic and saline soils, SMB levels and respiration rates increased despite adverse soil environmental conditions. This suggests that a dormant population of salt-tolerant SMB is present in these soils, which has become adapted to such environmental conditions over time and multiplies rapidly when substrate is available. 相似文献
20.
Influence of soil phosphorus status and nitrogen addition on carbon mineralization from 14C-labelled glucose in pasture soils 总被引:2,自引:0,他引:2
This study examines the effect of soil P status and N addition on the decomposition of 14C-labelled glucose to assess the consequences of reduced fertilizer inputs on the functioning of pastoral systems. A contrast
in soil P fertility was obtained by selecting two hill pasture soils with different fertilizer history. At the two selected
sites, representing low (LF) and high (HF) fertility status, total P concentrations were 640 and 820 mg kg–1 and annual pasture production was 4,868 and 14,120 kg DM ha–1 respectively. Soils were amended with 14C-labelled glucose (2,076 mg C kg–1 soil), with and without the addition of N (207 mg kg–1 soil), and incubated for 168 days. During incubation, the amounts of 14CO2 respired, microbial biomass C and 14C, microbial biomass P, extractable inorganic P (Pi) and net N mineralization were determined periodically. Carbon turnover was greatly influenced by nutrient P availability.
The amount of glucose-derived 14CO2 production was high (72%) in the HF and low (67%) in the LF soil, as were microbial biomass C and P concentrations. The 14C that remained in the microbial biomass at the end of the 6-month incubation was higher in the LF soil (15%) than in the
HF soil (11%). Fluctuations in Pi in the LF soil during incubation were small compared with those in HF soil, suggesting that P was cycling through microbial
biomass. The concentrations of Pi were significantly greater in the HF samples throughout the incubation than in the LF samples. Net N mineralization and nitrification
rates were also low in the LF soils, indicating a slow turnover of microorganisms under limited nutrient supply. Addition
of N had little effect on biomass 14C and glucose utilization. This suggests that, at limiting P fertility, C turnover is retarded because microbial biomass becomes
less efficient in the utilization of substrates.
Received: 18 October 1999 相似文献