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1.
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
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.
P. F. A. M. Römkens Johannes van der Plicht Jan Hassink 《Biology and Fertility of Soils》1999,28(3):277-284
Conversion of arable land (maize) to pasture will affect the soil organic matter (SOM) content. Changes in the SOM content
were studied using a size- and density-fractionation method and 13C analysis. Twenty-six years of maize cropping had resulted in a depletion of carbon stored in the macro-organic fractions
(>150 μm) and an increase in the <20 μm fraction. Maize-derived carbon in the upper 20 cm increased from 10% in the finest
fraction (<20 μm) to 91% in the coarse (>250 μm), light (b.d. <1.13 g cm–3) fractions. Pasture installation resulted in a rapid recovery of the total SOM content. Up to 90% of the pasture-derived
carbon that was mineralized during maize cropping was replaced within 9 years. Especially the medium and coarse size (>150
μm) and light (b.d. <1.13 g cm–3) fractions were almost completely regenerated by input of root-derived SOM. The amount of medium-weight and heavy macro-organic
fractions (>150 μm; b.d. >1.13 g cm–3) in the 0- to 20-cm layer was still 40–50% lower than in the continuous pasture plots. Average half-life times calculated
from 13C analyses ranged from 7 years in the light fractions to 56 years in heavy fractions. Fractionation results and 13C data indicated that mechanical disturbance (plowing) during maize cropping had resulted in vertical displacement of dispersed
soil carbon from the 0- to 20-cm layer down to 60–80 cm. Conversion of arable land to pasture, therefore, not only causes
a regeneration of the soil carbon content, it also reduces the risk of contaminant transport by dispersed soil carbon.
Received: 10 March 1998 相似文献
4.
In grazed pasture systems, a major source of N2O is nitrogen (N) returned to the soil in animal urine. We report in this paper the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), applied in a fine particle suspension (FPS) to reduce N2O emissions from dairy cow urine patches in two different soils. The soils are Lismore stony silt loam (Udic Haplustept loamy skeletal) and Templeton fine sandy loam (Udic Haplustepts). The pasture on both soils was a mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). Total N2O emissions in the Lismore soil were 23.1–31.0 kg N2O-N ha−1 following the May (autumn) and August (late winter) urine applications, respectively, without DCD. These were reduced to 6.2–8.4 kg N2O-N ha−1 by the application of DCD FPS, equivalent to reductions of 65–73%. All three rates of DCD applied (7.5, 10 and 15 kg ha−1) were effective in reducing N2O emissions. In the Templeton soil, total N2O emissions were reduced from 37.4 kg N2O-N ha−1 without DCD to 14.6–16.3 kg N2O-N ha−1 when DCD was applied either immediately or 10 days after the urine application. These reductions are similar to those in an earlier study where DCD was applied as a solution. Therefore, treating grazed pasture soils with an FPS of DCD is an effective technology to mitigate N2O emissions from cow urine patch areas in grazed pasture soils. 相似文献
5.
An understanding of the effects of salinity and sodicity on soil carbon (C) stocks and fluxes is critical in environmental
management, as the areal extents of salinity and sodicity are predicted to increase. The effects of salinity and sodicity
on the soil microbial biomass (SMB) and soil respiration were assessed over 12weeks under controlled conditions by subjecting
disturbed soil samples from a vegetated soil profile to leaching with one of six salt solutions; a combination of low-salinity
(0.5dSm−1), mid-salinity (10dSm−1), or high-salinity (30dSm−1), with either low-sodicity (sodium adsorption ratio, SAR, 1), or high-sodicity (SAR 30) to give six treatments: control (low-salinity
low-sodicity); low-salinity high-sodicity; mid-salinity low-sodicity; mid-salinity high-sodicity; high-salinity low-sodicity;
and high-salinity high-sodicity. Soil respiration rate was highest (56–80mg CO2-C kg−1 soil) in the low-salinity treatments and lowest (1–5mg CO2-C kg−1 soil) in the mid-salinity treatments, while the SMB was highest in the high-salinity treatments (459–565mg kg−1 soil) and lowest in the low-salinity treatments (158–172mg kg−1 soil). This was attributed to increased substrate availability with high salt concentrations through either increased dispersion
of soil aggregates or dissolution or hydrolysis of soil organic matter, which may offset some of the stresses placed on the
microbial population from high salt concentrations. The apparent disparity in trends in respiration and the SMB may be due
to an induced shift in the microbial population, from one dominated by more active microorganisms to one dominated by less
active microorganisms. 相似文献
6.
A. de Varennes M. O. Torres C. Cunha-Queda M. J. Goss C. Carranca 《Biology and Fertility of Soils》2007,44(1):49-58
We investigated conservation and cycling of N under oat–oat and lupine–oat rotations in disturbed and undisturbed soil, when
roots or roots plus aboveground residues were retained. Crop residues were labelled with 15N in Year 1, and differential soil disturbance was imposed after harvest. In Year 2, plant growth, N transfer from residue
into the various sinks of the second crop (plant, soil, and residual residues), and changes in microbial activity and numbers
were determined. Oat biomass was greater after lupine than after oat due to differences in supply of N from these residues.
Buried residues of both crops appeared to decompose faster than when left on the soil surface. Lupine residues decomposed
faster than oat residues. Oat biomass was not affected by soil disturbance if grown after lupine but decreased when oat straw
was buried in the soil. More residue N was recovered from soil than from the crop. Most 15N was recovered from disturbed soil, which also had greater dehydrogenase activity and more culturable fungi. At the end of
the oat–oat rotation, 20 and 5 kg N ha−1 were derived from the roots of the first crop in undisturbed or disturbed soil, respectively. Equivalent values for the lupine–oat
rotation were 18 and 44 kg N ha−1. Returning aboveground residues provided an extra 52–80 kg N ha−1 for oat and 61–63 kg N ha−1 for lupine relative to treatments where they were removed. Over a year, lupine contributed 9 to 20 kg N ha−1 more to the agroecosystem than did oat. 相似文献
7.
Water and N availability are the major limiting factors of primary production in desert ecosystems, and the response of soil
biota to these two factors is of great importance. We examined the immediate response of soil nematodes and the microbial
biomass to a single pulse of water amendment in N-treated plots in the Israeli Negev desert. Plots were treated with 0, 50
and 100 kg NH4NO3 ha–1 in December 1992, and at the end of the summer period (August 1993) the plots were exposed to a 15 mm water. Soil samples
from the 0–10 cm layer were collected daily and analysed soil moisture, total soluble N, nematode populations and microbial
biomass. Soil moisture increased to 8.5%, then gradually decreased to 2% during the 11 days of the study. Microbial biomass,
soil respiration and metabolic quotient values did not exhibit any significant correlation with soil N levels. Free-living
nematode population levels in the different plots were found to increase from a mean level of 45 500 to a mean level of 92 300
individuals m–2. N treatment was found to affect the patterns of free-living nematode population dynamics. The results of this study demonstrated
the importance of moisture availability levels and the ability to mobilize previous N inputs into available N which, occurring
in pulses, can affect the microbial ecophysiological status, nematode population dynamics and the interrelationship between
these two important components in the desert soil milieu.
Received: 5 November 1998 相似文献
8.
Pinus radiata was planted in a grazed pasture at Tikitere, New Zealand in 1973; final tree stocking rates were 0, 50, 100, 200 and 400 stems
ha–1; trees were harvested in 1999. We sampled the loamy sand for chemistry, earthworms, enchytraeids and nematodes during crop
growth. There were no visible changes in the soil profile between years 2 and 25 of the P. radiata rotation, but marked changes in soil chemistry with pH declining at all depths. Topsoil pH declined but plant-available P
and the soil C : N ratio increased. That similar trends occurred in pasture may have reflected reduced inputs. Lumbricid earthworms
declined with increasing time and tree stocking rate; significant populations were found only in pasture at 25 years; no related
changes in soil bulk density were detected. Enchytraeids were abundant but declined in the plots with 200 and 400 stems ha–1. The composition of the nematode fauna at a soil depth of 0–10 cm varied, and there were changes in the “control” pasture.
Pratylenchus sp. and Pungentus sp. were characteristic of pasture;Diphtherophora sp. appeared at higher tree stocking rates. In addition to changes related to the change in landuse there were temporal changes
that affected faunal composition across tree stocking rates: Heterodera sp. and Paratylenchus sp. were rare after year 6;Prismatolaimus sp. was most abundant in years 2, 13 and 25;Axonchium sp. occurred in year 6 and Alaimus sp. mainly in year 25. Overall, the changes in soil chemistry reflected the change from pasture to forest. Parallel changes
in soil microfauna and macrofauna also reflected the change in landuse, from fertilised pasture to coniferous forest, and
are considered reversible.
Received: 5 July 1999 相似文献
9.
R. W. McDowell J. T. Scott I. Stewart L. M. Condron 《Biology and Fertility of Soils》2007,43(4):409-415
A pot trial using wet-sieved soil aggregates (>4, 4–2, 2–1, 1–0.5, 0.5–25, and remaining soil <0.25 mm) from a soil that had
been cultivated out of permanent pasture and used for winter forage crops for 2 years examined changes in P forms before and
after 35 weeks when resown with perennial ryegrass. Soil analyses showed that P was depleted after 35 weeks growth. Changes
in P forms were analyzed by 31P nuclear magnetic resonance of soil NaOH-EDTA extracts, which removed 98–96% of total P (about 1,080 mg kg−1 in unsieved soil before pasture growth). This indicated that aggregate size influenced the concentrations and forms of P
probably via a combination of physical protection and moisture status: orthophosphate, monoesters, diesters and pyrophosphate
increased with decreasing size, while phosphonates and polyphosphates were unaffected. The increase in pyrophosphate was attributed
to fungal growth, while decreases in orthophosphate and labile organic P (diesters) decreased due to either leaching or mineralisation
and plant uptake. The largest decrease was associated with orthophosphate, which could be replenished by fertiliser. However,
given the soil’s high potential for P loss, this should only be done to meet conditions for optimal plant growth as any excess
would increase the risk of loss. To further minimise P loss without affecting pasture yield, management should maintain or
improve soil structure. 相似文献
10.
Significant changes in soil microfauna in grazed pasture under elevated carbon dioxide 总被引:1,自引:0,他引:1
Soil microfauna in 0- to 10-cm soil under grazed pasture on a sand (Mollic Psammaquent) was assessed quarterly in free air CO2 enrichment (FACE) rings that were at either ambient CO2 or had been exposed to 475 l l–1 CO2 for 4–5 years. There were significant increases in nematode (1.5×) and rotifer (4.1×) abundance in soils subjected to elevated CO2. Ten nematode taxa were significantly more abundant under elevated CO2. The greatest increase was 4.3× in root-feeding Longidorus; three other root-feeders showed no increase in population densities at elevated CO2. Bacterial-feeding Cervidellus
was the only nematode with a significant decrease (0.4×). The abundance of all nematode feeding groups increased significantly in soils subjected to elevated CO2. The relative increases in abundance of feeding groups (bacterial-feeders 1.3×, root-feeders 1.3×, plant-associated 1.5×, fungal-feeders 1.6×, omnivores 2.0×, predators 2.1×) suggest marked increases in fluxes through microbial-feeding nematodes and a multitrophic response among the soil biota to the increase in atmospheric CO2 above ambient. Data from the site suggest soil microbial biomass C and N pools were unchanged over the sampling period. Of eight nematode indices only total maturity index increased (2.9 to 3.2), reflecting the increased proportion of the large Longidorus. Further work on microbial-microfaunal interactions and their micro-scale relation to roots is needed to better understand the impact of increasing atmospheric CO2 on soil processes. 相似文献
11.
The critical S concentration and S requirement of the soil microbial biomass of a granitic regosol was examined. S was applied
at the rate of 0, 5, 10, 20, 30 and 50 μg S as MgSO4·7H2O, together with either 3000 μg glucose-C or 3333 μg cellulose-C, 400 μg N, and 200 μg P g –1 soil and 200 μg K g–1 soil. Microbial biomass, inorganic SO4
2–-S, and CO2 emission were monitored over 30 days during incubation at 25 °C. Both glucose and cellulose decomposition rates responded
positively to the S made available for microbial cell synthesis. The amounts of microbial biomass C and S increased with the
level of applied S up to 10 μg S g–1 soil and 30 μg S g–1 soil in the glucose- and cellulose-amended soil, respectively, and then declined. Incorporated S was found to be concentrated
within the microbial biomass or partially transformed into soil organic matter. The concentration of S in the microbial biomass
was higher in the cellulose- (4.8–14.2 mg g–1) than in the glucose-amended soil (3.7–10.9 mg g–1). The microbial biomass C:S ratio was higher in the glucose- (46–142 : 1) than in the cellulose-amended soil (36–115 : 1).
The critical S concentration in the microbial biomass (defined as that required to achieve 80% of the maximum synthesis of
microbial biomass C) was estimated to be 5.1 mg g–1 in the glucose- and 10.9 mg g–1 in the cellulose-amended soil. The minimum requirement of SO4
2–-S for microbial biomass formation was estimated to be 11 μg S g–1 soil and 21 μg S g–1 soil for glucose- and cellulose-amended soil, respectively. The highest levels of activity of the microbial biomass were
observed at the SO4
2–-S concentrations of 14 μg S g–1 soil and 17 μg S g–1 soil, for the glucose and cellulose amendments, respectively, and were approximately 31–54% higher during glucose than cellulose
decomposition.
Received: 20 October 1999 相似文献
12.
Large amounts of C and N are returned to pasture soils by grazing animals in the form of urine and dung. Therefore, a field
trial was carried out to investigate the mid-term effects of 15N-labeled excrements, produced by feeding a cow with 15N-labeled grass silage, on the soil microbial biomass. Simulating the deposition of excrements, 15N-labeled urine and dung were applied to a 0.09-m2 area of a sandy pasture soil in October 2000 and 2001. Applied amounts
of N were 1,030 and 1,052 kg ha−1, respectively. Soil was sampled at 0–15 cm depth, three times over 7 months and analyzed for total C and N, and microbial
biomass C and N. Recovery of urine and dung N in microbial biomass was determined by 15N analysis of K2SO4 extracts of pre-extracted fumigated and unfumigated soils. Under dung patches, microbial biomass C was 16% and 45% higher,
and microbial biomass N was 24% and 57% higher than under the untreated soil in 2001 and 2002, respectively. Under urine patches,
microbial biomass C was increased after 12 weeks and decreased after 27 weeks. Microbial biomass assimilated 7% to 17% and
10% to 21% of the 15N applied initially as urine and dung, respectively. These percentages were considerably higher than those for artificially
with spiked 15N urea-created and labeled manures reported in previous experiments. An important reason may be that the naturally 15N-labeled N components behave differently in soil than urea spikes. 相似文献
13.
Roberta Gentile Mike Dodd Mark Lieffering Shona C. Brock Phil W. Theobald Paul C. D. Newton 《Biology and Fertility of Soils》2012,48(3):357-362
Altered soil nutrient cycling under future climate scenarios may affect pasture production and fertilizer management. We conducted
a controlled-environment study to test the hypothesis that long-term exposure of pasture to enriched carbon dioxide (CO2) would lower soil nutrient availability. Perennial ryegrass was grown for 9 weeks under ambient and enriched (ambient + 120 ppm)
CO2 concentrations in soil collected from an 11.5-year free air CO2 enrichment experiment in a grazed pasture in New Zealand. Nitrogen (N) and phosphorus (P) fertilizers were applied in a full
factorial design at rates of 0, 12.5, 25 or 50 kg N ha−1 and 0, 17.5 or 35 kg P ha−1. Compared to ambient CO2, under enriched CO2 without P fertilizer, total plant biomass did not respond to N fertilizer, and tissue N/P ratio was increased indicating
that P was co-limiting. This limitation was alleviated with the lowest rate of P fertilizer (17.5 kg P ha−1). Plant biomass in both CO2 treatments increased with increasing N fertilizer when sufficient P was available. Greater inputs of P fertilizer may be
required to prevent yield suppression under enriched CO2 and to stimulate any response to N. 相似文献
14.
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
15.
S. Kundu Ranjan Bhattacharyya Ved Prakash H. S. Gupta H. Pathak J. K. Ladha 《Biology and Fertility of Soils》2007,43(3):271-280
A long-term (30 years) soybean–wheat experiment was conducted at Hawalbagh, Almora, India to study the effects of organic
and inorganic sources of nutrients on grain yield trends of rainfed soybean (Glycine
max)–wheat (Triticum
aestivum) system and nutrient status (soil C, N, P and K) in a sandy loam soil (Typic Haplaquept). The unfertilized plot supported
0.56 Mg ha−1 of soybean yield and 0.71 Mg ha−1 of wheat yield (average yield of 30 years). Soybean responded to inorganic NPK application and the yield increased significantly
to 0.87 Mg ha−1 with NPK. Maximum yields of soybean (2.84 Mg ha−1) and residual wheat (1.88 Mg ha−1) were obtained in the plots under NPK + farmyard manure (FYM) treatment, which were significantly higher than yields observed
under other treatments. Soybean yields in the plots under the unfertilized and the inorganic fertilizer treatments decreased
with time, whereas yields increased significantly in the plots under N + FYM and NPK + FYM treatments. At the end of 30 years,
total soil organic C (SOC) and total N concentrations increased in all the treatments. Soils under NPK + FYM-treated plots
contained higher SOC and total N by 89 and 58% in the 0–45 cm soil layer, respectively, over that of the initial status. Hence,
the decline in yields might be due to decline in available P and K status of soil. Combined use of NPK and FYM increased SOC,
oxidizable SOC, total N, total P, Olsen P, and ammonium acetate exchangeable K by 37.8, 42.0, 20.8, 30.2, 25.0, and 52.7%,
respectively, at 0–45 cm soil layer compared to application of NPK through inorganic fertilizers. However, the soil profiles
under all the treatments had a net loss of nonexchangeable K, ranging from 172 kg ha−1 under treatment NK to a maximum of 960 kg ha−1 under NPK + FYM after 30 years of cropping. Depletion of available P and K might have contributed to the soybean yield decline
in treatments where manure was not applied. The study also showed that although the combined NPK and FYM application sustained
long-term productivity of the soybean–wheat system, increased K input is required to maintain soil nonexchangeable K level. 相似文献
16.
Land use effects on microbial biomass C, β-glucosidase and β-glucosaminidase activities,and availability,storage, and age of organic C in soil 总被引:1,自引:0,他引:1
David Sotomayor-Ramírez Yusmary Espinoza Veronica Acosta-Martínez 《Biology and Fertility of Soils》2009,45(5):487-497
Microbial biomass, β-glucosidase and β-glucosaminidase activities, and availability, storage, and age of soil organic C were
investigated after 26 years of conversion from sugarcane (Saccharum officinarum) to forest (Eucaliptus robusta or Leucaena leucocephala), pasture (mixture of tropical grasses), and to vegetable cropping (agriculture) in a vertisol in Puerto Rico. Soil organic
C (SOC) at 0–100 cm was similar under Leucaena (22.8 kg C/m2), Eucalyptus (18.6 kg C/m2), and pasture (17.2 kg C/m2), which were higher than under agriculture (13.0 kg C/m2). Soil organic N (SON) at 0–100 cm was similar under the land uses evaluated which ranged from 1.70 (under agriculture) to
2.28 kg N/m2 (under Leucaena forest). Microbial biomass C (MBC) and N (MBN) of the 0–15-cm soil layer could be ranked as: pasture > Leucaena = Eucalyptus > agriculture. The percentages of SOC and SON present as MBC and MBN, respectively, were nearly 1% in pasture and less than
0.50% in forest under Leucaena or Eucalyptus and agricultural soil. The activity of β-glucosidase of the 0–15-cm soil layer could be ranked as: Leucaena = Eucalyptus > pasture > agriculture; while β-glucosaminidase activity was ranked as: Eucalyptus > Leucaena = pasture > agriculture. The soil δ
13C changed from 1996 to 2006 in forest under Eucalyptus (18.7‰ to 21.2‰), but not under Leucaena (20.7‰ to 20.8‰). The soil under Leucaena preserved a greater proportion of old C compared to the forest under Eucalyptus; the former had an increased soil mineralizable C from the current vegetation inputs. The soil under agriculture had the
lowest enzyme activities associated with C cycling, lowest percentage of SOC as MBC, highest percentage of SOC present as
mineralizable C, and highest percentage of MBC present as mineralizable C compared to the other land uses. 相似文献
17.
Zhihong Xu Sally Ward Chengrong Chen Tim Blumfield Nina Prasolova Juxiu Liu 《Journal of Soils and Sediments》2008,8(2):99-105
Background, Aims, and Scope An improved understanding of important soil carbon (C) and nutrient pools as well as microbial activities in forest ecosystems
is required for developing effective forest management regimes underpinning forest productivity and sustainability. Forest
types and management practices can have significant impacts on soil C and nutrient pools as well as biological properties
in forest ecosystems. Soil C and nutrient pools were assessed for adjacent natural forest (NF), first rotation (1R) (50-year-old),
and second rotation (2R) (1-year-old) hoop pine (Araucaria cunninghamii Ait. ex D. Don) plantations in southeast Queensland of subtropical Australia.
Materials and Methods Five transects spaced 3 m apart with 9 sampling points along each transect were selected (9.6 m × 12.0 m each site), with
45 soil cores (7.5 cm in diameter) collected and separated into 0–10 and 10–20 cm depths. These soils were analysed for total
C, total nitrogen (N), C (δ13C) and N (δ15N) isotope composition. The 0–10 cm soils were analysed for pH, CEC, exchangeable cations, total P and total K, and assayed
for microbial biomass C and N, respiration, metabolic quotient, potential mineralizable N (PMN), gross N mineralization (M) and immobilization (I).
Results Total C and N in 0–10 cm soils were higher under NF and 1R plantation than under 2R plantation, while they were highest in
10–20 cm soils under NF, followed by the 1R and then 2R plantation. δ13C was lower under NF than under the plantations, while δ15N was higher under NF than under the plantations. Total P was the highest under NF, followed by the 1R and then 2R plantation,
while total K was higher under the 2R plantation. No significant differences were detected for pH, CEC, exchangeable cations,
microbial C and N, respiration and metabolic quotient among the 3 sites. PMN and M were higher under NF, while I was the highest under the 2R plantation, followed by the NF and then 1R plantation.
Discussion Soil total C and N in 0–10 cm depth were significantly lower under 2R hoop pine plantation than those under NF and 1R hoop
pine plantation. There were significant reductions in soil total C and N from NF to 1R and from 1R to 2R hoop pine plantations
in 10–20 cm depth. This highlights potential N deficiency in the 2R hoop pine plantations, and application of N fertilizers
may be required to improve the productivity of 2R hoop pine plantations.
There were no significant differences in other soil chemical and physical properties in 0–10 cm depth among the 3 sites under
NF, 1R and 2R hoop pine plantations, except for soil total P and K.
Soil microbial biomass C, CO2 respiration and metabolic quotient did not differ among the 3 sites assessed, perhaps mainly due to these biological variables
being too sensitive to variations in soil chemical and physical properties and thereby being associated with a larger variability
in the soil biological properties. However, soil potential mineralizable N, gross N mineralization and immobilization were
rather sensitive to the conversion of NF to hoop pine plantation and forest management practices.
Conclusions Total C and N in the top 20 cm soil were highest under NF, followed by 1R and then 2R hoop pine plantations, indicating that
N deficiency may become a growth-limiting factor in the 2R hoop pine plantations and subsequent rotations of hoop pine plantation.
The sample size for soil δ13C seems to be much smaller than those for soil total C and N as well as δ15N. The significant reductions in soil total P from NF to 1R and then from 1R to 2R hoop pine plantations highlight that P
deficiency might become another growth-limiting factor in the second and subsequent rotations of hoop pine plantations. Soil
microbial properties may be associated with large spatial variations due to these biological properties being too sensitive
to the variations in soil chemical and physical properties in these forest ecosystems.
Recommendations and Perspectives Soil potential mineralizable N, gross N mineralization and immobilization were useful indices of soil N availability in response
to forest types and management practices. The sampling size for soil δ13C was much smaller than the other soil chemical and biological properties due to the different patterns of spatial variation
in these soil properties. 相似文献
18.
Richard W. Todd N. Andy Cole R. Nolan Clark William C. Rice Wen-Xuan Guo 《Biology and Fertility of Soils》2008,44(8):1099-1102
Cattle feedyards can impact local environments through emission of ammonia and dust deposited on nearby land. Impacts range
from beneficial fertilization of cropland to detrimental effects on sensitive ecosystems. Shortgrass prairie downwind from
an adjacent feedyard on the southern High Plains of Texas, USA changed from perennial grasses to annual weeds. It was hypothesized
that N enrichment from the feedyard initiated the cascade of negative ecological change. Objectives were to determine the
distribution of soil nitrogen and estimate N loading to the pasture. Soil samples were collected from 119 locations across
the pasture and soil total N (TN), nitrate-N and ammonium-N (AN) determined in the top 30 cm. Soil TN concentration decreased
with distance downwind from the feedyard from 1.6 ± 0.2 g kg−1 at 75 m to 1.2 ± 0.05 g kg−1 at 582 m. Nitrate-N concentration decreased within 200 m of the feedyard and changed little at greater distances. Ammonium-N
concentration decreased linearly (P < 0.001) with increasing distance from the feedyard from 7.9 ± 1.7 mg kg−1 within 75 m from the feedyard to 5.8 ± 1.5 mg kg−1 at more than 550 m from the feedyard; however, distance only explained 12% of the variability in AN concentration. Maximum
nitrogen loading, from 75 to 106 m from the feedyard, was 49 kg ha−1 year−1 over 34 years and decreased with distance from the feedyard. An estimate of net dry deposition of ammonia indicated that
it contributed negligibly to N loading to the pasture. Nitrogen enrichment that potentially shifted vegetation from perennial
grasses to annual weeds affected soil N up to 500 m from the feedyard; however, measured organic and inorganic N beyond that
returned to typical and expected levels for undisturbed shortgrass prairie.
相似文献
Richard W. ToddEmail: |
19.
Kannan Iyyemperumal James GreenJr. Daniel W. Israel Noah N. Ranells Wei Shi 《Biology and Fertility of Soils》2008,44(3):425-434
This study characterized soil chemical and microbiological properties in hay production systems that received from 0 to 600 kg
plant-available N (PAN) ha−1 year−1 from either swine lagoon effluent (SLE) or ammonium nitrate (AN) from 1999 to 2001. The forage systems contained plots planted
with bermudagrass (Cynodon dactylon L.) or endophyte-free tall fescue (Festuca arundinaceae Schreb.). In March 2004, the plots were sampled for measurements of a suite of soil chemical and microbiological properties.
Nitrogen fertilization rates were significantly correlated with soil pH and K2SO4-extractable soil C but not with total soil C, soil C/N ratio, electrical conductivity, or Mehlich-3-extractable nutrients.
Soil supplied with SLE had significantly lower Mehlich-3-extractable nutrients than the soil supplied with AN. Two indicators
of soil N-supplying capacity (potentially mineralizable N and amino sugar N) varied with plant species and the type of N fertilizer.
However, they generally peaked at an application rate of 200 or 400 kg PAN ha−1 year−1. Soil microbial biomass C also peaked at an application rate of 200 or 400 kg PAN ha−1 year−1. Nitrification potential was significantly higher in soil supplied with AN than in the unfertilized control but was similar
between SLE-fertilized and unfertilized soils. Our results indicated that an application rate as high as 600 kg PAN ha−1 year−1 did not benefit soil microbial biomass, microbial activity, and N transformation processes in these forage systems. 相似文献
20.
Stylianos Liodakis Charalampos Michalopoulos Elpida Efthymiou Georgios Katsigiannis 《Water, air, and soil pollution》2012,223(1):169-179
One of the main environmental impacts of concentrated animal feeding operations is the soil degradation in vicinity with the
livestock breeding facilities due to substances such as ammonia emitted from the various stages of the process. Owing to the
high temperatures of the Mediterranean ecosystems, the evolution of gasses is more extensive and the soil degradation is consequently
more severe than those obtained in northern Europe. In this research, the soil degradation effects of a large meat-producing,
processing, and packaging unit have been investigated. The investigated intensive hog farming operation (IHFO) is located
at a limestone soil coastal area with sea to the north and hills to the south. Soil samples of the upper mineral soil were
taken in various distances and directions from the IHFO boundaries. Thirteen experimental cycles were carried out in the duration
of 1.5 years starting in March 2009 until October 2010. The soil samples were analyzed on pH and electrical conductivity (EC)
values as well as NH4
+ and NO3
− concentrations. Significantly higher concentrations of the two nitrogen forms were observed on samples at increasing proximity
downwind from the farm (south). Southern soil average NH4
+ and NO3
− concentrations ranged between 0.4–118 μg NH4
+-N g−1 soil and 6.1–88.4 μg NO3
−-N g−1 soil, respectively. The variation of emitted gasses depositions was clearly reflected in the average pH and EC values. Average
pH and EC values downwind from IHFO boundaries varied between 7.1–8.2 and 140–268 μS/cm, respectively. 相似文献