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1.
Yong-Shan Li Liang-Huan Wu Xing-Hua Lu Li-Mei Zhao Qiao-Lan Fan Fu-Suo Zhang 《Biology and Fertility of Soils》2006,43(1):107-111
The long-term field experiments were initiated in 2001 on five sites in Zhejiang province of China to monitor the impacts of non-flooded plastic mulching management on rice soil microbial biomass for sustainable agro-ecosystem. The three treatments were plastic film mulching with no flooding (PM), no plastic film mulching and no flooding (UM), and the traditional flooding management (TF). Microbial biomass C accounted for 0.3–2.4% of the soil total organic C, microbial biomass N for 0.79–4.3% of the soil total N, and microbial biomass P for 0.1–1.6% of the soil total P. Three years of non-flooded plastic film mulching reduced microbial biomass C and N and increased microbial biomass P in rice soil. 相似文献
2.
Dwipendra Thakuria Narayan C. Talukdar Chandan Goswami Samarendra Hazarika Mohan C. Kalita Gary D. Bending 《Biology and Fertility of Soils》2009,45(3):237-251
To achieve higher yields and better soil quality under rice–legume–rice (RLR) rotation in a rainfed production system, we
formulated integrated nutrient management (INM) comprised of Azospirillum (Azo), Rhizobium (Rh), and phosphate-solubilizing bacteria (PSB) with phosphate rock (PR), compost, and muriate of potash (MOP). Performance
of bacterial bioinoculants was evaluated by determining grain yield, nitrogenase activity, uptake and balance of N, P, and
Zn, changes in water stability and distribution of soil aggregates, soil organic C and pH, fungal/bacterial biomass C ratio,
casting activities of earthworms, and bacterial community composition using denaturing gradient gel electrophoresis (DGGE)
fingerprinting. The performance comparison was made against the prevailing farmers’ nutrient management practices [N/P2O5/K2O at 40:20:20 kg ha−1 for rice and 20:30:20 kg ha−1 for legume as urea/single super-phosphate/MOP (urea/SSP/MOP)]. Cumulative grain yields of crops increased by 7–16% per RLR
rotation and removal of N and P by six crops of 2 years rotation increased significantly (P < 0.05) in bacterial bioinoculants-based INM plots over that in compost alone or urea/SSP/MOP plots. Apparent loss of soil
total N and P at 0–15 cm soil depth was minimum and apparent N gain at 15–30 cm depth was maximum in Azo/Rh plus PSB dual
INM plots. Zinc uptake by rice crop and diethylenetriaminepentaacetate-extractable Zn content in soil increased significantly
(P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Total organic C content in
soil declined at 0–15 cm depth and increased at 15–30 cm depth in all nutrient management plots after a 2-year crop cycle;
however, bacterial bioinoculants-based INM plots showed minimum loss and maximum gain of total organic C content in the corresponding
soil depths. Water-stable aggregation and distribution of soil aggregates in 53–250- and 250–2,000 μm classes increased significantly
(P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Fungal/bacterial biomass
C ratio seems to be a more reliable indicator of C and N dynamics in acidic soils than total microbial biomass C. Compost
alone or Azo/Rh plus PSB dual INM plots showed significantly (P < 0.05) higher numbers of earthworms’ casts compared to urea/SSP/MOP alone and bacterial bioinoculants with urea or SSP-applied
plots. Hierarchical cluster analysis based on similarity matrix of DGGE profiles revealed changes in bacterial community composition
in soils due to differences in nutrient management, and these changes were seen to occur according to the states of C and
N dynamics in acidic soil under RLR rotation. 相似文献
3.
Long-term experiments on different crop management systems provide essential information about turnover of soil organic matter
and changes in microbial properties over a period of time. A long-term field site trial, which was established in 1967 near
Vienna, Austria, to document the fate of 14C-labelled manure (straw and farmyard) under different crop management systems (crop rotation, spring wheat and bare fallow),
was investigated. Soil samples were taken in 1997 and separated into size fractions (>250 μm, 250–63 μm, 63–2 μm, 2–0.1 μm
and <0.1 μm) after aggregate dispersion using low-energy sonication. Organic C, total N and 14C content were measured in the bulk soil and the size fractions and microbial properties were analysed in the bulk soil. Additionally,
C mineralization in bulk soil samples was monitored at 20 °C over a period of 28 days, and subsequently 14C-CO2 content was analysed. The distribution of organic C and N within the size fractions was similar between crop rotation and
spring wheat; the highest amounts of organic C and N were found in the clay-sized fraction. The amounts of C and N were significantly
smaller in the bare fallow, which was depleted of organic matter in the coarse-sized fractions. 14C distribution differed significantly from unlabelled C distribution, labelled C was accumulated in the silt-sized fraction,
indicating weak humification of the applied manure C. The highest rate of C mineralization was measured in the crop rotation
and spring wheat, whereas the emission rate of the bare fallow was about 40% lower. The higher 14C:C ratio of the bulk soil in comparison to the emitted CO2 indicated that labelled C compounds still remained mineralizable after a period of 30 years. Microbial properties showed
a great difference between crop management systems and bare fallow, particularly regarding urease and xylanase activity.
Received: 31 May 1999 相似文献
4.
R. Roscoe C. A. Vasconcellos A. E. Furtini-Neto G. A. A. Guedes L. A. Fernandes 《Biology and Fertility of Soils》2000,32(1):52-59
We studied the relationship between urease activity (UA) and soil organic matter (SOM), microbial biomass N (Nbiom) content, and urea-N fertilizer assimilation by maize in a Dark Red Latosol (Typic Haplustox) cultivated for 9 years under
no-tillage (NT), tillage with a disc plough (DP), and tillage with a moldboard plough (MP). Two soil depths were sampled (0–7.5 cm
and 7.5–15 cm) at 4 different times during the crop cycle. Urea was applied at four different rates, ranging from 0 to 240 kg
N ha–1. The levels of fertilizer N did not affect the UA, SOM content, and Nbiom content. No significant difference between the treatments (NT, DP, and MP) was observed for SOM during the experiment, probably
because the major part of the SOM was in recalcitrant pools, since the area was previously cultivated (conventional tillage)
for 20 years. The Nbiom content explained 97% and 69% of the variation in UA in the upper and deeper soil layer, respectively. UA and biomass N were
significantly higher in the NT system compared to the DP and MP systems. The highest maize productivity and urea-N recovery
was also observed for the NT system. We observed that the increase in urea-N losses under NT, possibly as a consequence of
a higher UA, was compensated for by the increase in N immobilized in the biomass.
Received: 2 July 1999 相似文献
5.
Organic matter, microbial biomass and enzyme activity of soils under different crop rotations in the tropics 总被引:8,自引:0,他引:8
Soil organic matter level, soil microbial biomass C, ninhydrin-N, C mineralization, and dehydrogenase and alkaline phosphatase
activity were studied in soils under different crop rotations for 6 years. Inclusion of a green manure crop of Sesbania aculeata in the rotation improved soil organic matter status and led to an increase in soil microbial biomass, soil enzyme activity
and soil respiratory activity. Microbial biomass C increased from 192 mg kg–1 soil in a pearl millet-wheat-fallow rotation to 256 mg kg–1 soil in a pearl millet-wheat-green manure rotation. Inclusion of an oilseed crop such as sunflower or mustard led to a decrease
in soil microbial biomass, C mineralization and soil enzyme activity. There was a good correlation between microbial biomass
C, ninhydrin-N and dehydrogenase activity. The alkaline phosphatase activity of the soil under different crop rotations was
little affected. The results indicate the green manuring improved the organic matter status of the soil and soil microbial
activity vital for the nutrient turnover and long-term productivity of the soil.
Received: 7 January 1996 相似文献
6.
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
7.
Effects of N fertilizer treatments on biologically active N pools in soils under plow and no tillage 总被引:2,自引:0,他引:2
Studies assessing the effects of different tillage and N fertilizer management practices on distributions and amounts of
various C and N pools in soil can provide information about the influence of such management on the quality of organic matter
in agricultural soils. To assess the influence of management on soil quality, we characterized the organic matter by measurements
of total N, organic C, microbial biomass N and active N in the 0–20cm profiles of soil from long-term field experiments containing
plots under treatments of plow or no tillage and 0, 135, or 270kgNha–1 fertilizer. Previous work had established that on the basis of the crop growth requirement of maize, these application rates
of fertilizer N provide amounts of N that are deficient, sufficient, and excessive, respectively. The studies reported provide
evidence that the sufficient amount of fertilizer N stimulated formation of the biologically active pools of N (biomass N
and active N) in soils under no tillage treatments, but the excessive amount of fertilizer N tended to suppress these pools.
The results demonstrated that these influences of excessive N fertilization were not reflected in distributions of total N
or total organic C in soil profiles but became evident with the measurements of biologically active N. This suggests that
such measurements can provide information related to the influence of different management practices on soil quality.
Received: 30 November 1995 相似文献
8.
J. R. Salinas-García J. de J. Velzquez-García M. Gallardo-Valdez P. Díaz-Mederos F. Caballero-Hernndez L. M. Tapia-Vargas E. Rosales-Robles 《Soil & Tillage Research》2002,66(2):177-152
Quantifying how tillage systems affect soil microbial biomass and nutrient cycling by manipulating crop residue placement is important for understanding how production systems can be managed to sustain long-term soil productivity. Our objective was to characterize soil microbial biomass, potential N mineralization and nutrient distribution in soils (Vertisols, Andisols, and Alfisols) under rain-fed corn (Zea mays L.) production from four mid-term (6 years) tillage experiments located in central-western, Mexico. Treatments were three tillage systems: conventional tillage (CT), minimum tillage (MT) and no tillage (NT). Soil was collected at four locations (Casas Blancas, Morelia, Apatzingán and Tepatitlán) before corn planting, at depths of 0–50, 50–100 and 100–150 mm. Conservation tillage treatments (MT and NT) significantly increased crop residue accumulation on the soil surface. Soil organic C, microbial biomass C and N, potential N mineralization, total N, and extractable P were highest in the surface layer of NT and decreased with depth. Soil organic C, microbial biomass C and N, total N and extractable P of plowed soil were generally more evenly distributed throughout the 0–150 mm depth. Potential N mineralization was closely associated with organic C and microbial biomass. Higher levels of soil organic C, microbial biomass C and N, potential N mineralization, total N, and extractable P were directly related to surface accumulation of crop residues promoted by conservation tillage management. Quality and productivity of soils could be maintained or improved with the use of conservation tillage. 相似文献
9.
Soil management systems can have great effect on soil chemical, physical and biological properties. Conversion of forest to grassland and cropland can alter C and N dynamics. The objective of this study was to evaluate the changes in aggregate‐associated and labile soil organic C and N fractions after conversion of a natural forest to grassland and cropland in northern Turkey. This experiment was conducted on plots subject to three different adjacent land uses (forest, grassland and cropland). Soil samples were taken from 0–5, 5–15 and 15–30 cm depths from each land use. Some soil physical (soil texture, bulk density), chemical (soil pH, soil organic matter, lime content, total organic C and N, inorganic N, free and protected organic C) and biological (microbial biomass C and N, mineralizable C and N) properties were measured. The highest and lowest bulk densities were observed in grassland (1.41 g cm−3) and cropland (1.14 g cm−3), respectively. Microbial biomass C and total organic C in forest were almost twice greater than grassland and four‐times greater than cropland. Cultivation of forest reduced total organic N, mineralizable N and microbial biomass N by half. The great portion of organic C was stored in macroaggregates (>250 µm) in all the three land uses. Free organic C comprised smaller portion of soil organic C in all the three land uses. Thus, this study indicated that long‐term conversion of forest to grassland and cropland significantly decreased microbial biomass C, mineralizable C and physically protected organic C and the decreases were the greatest in cropland. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Sukhdev S. Malhi Marvin Nyborg Elston D. Solberg Brian McConkey Miles Dyck Dick Puurveen 《Biology and Fertility of Soils》2011,47(7):785-800
Crop residue and fertilizer management practices alter some soil properties, but the magnitude of change depends on soil type
and climatic conditions. Field experiments with mainly barley (and canola, wheat, triticale, or pea in a few years) under
conventional tillage were conducted from 1983 to 2009 at Breton (Gray Luvisol (Typic Haplocryalf) loam) and Ellerslie (Black
Chernozem (Albic Argicryoll) clay loam), Alberta, Canada, to determine the effects of straw management (straw removed (S
Rem) and straw retained (S
Ret)) and N fertilizer rate (0, 25, 50, and 75 kg N ha−1) on total organic C (TOC) and N (TON), light fraction organic C (LFOC), and N (LFON) in the 0–7.5 and 7.5–15 cm, pH in the
0–7.5, 7.5–15, and 15–20 cm and extractable P, ammonium-N, and nitrate-N in the 0–15, 15–30, 30–60, and 60–90 cm soil layers.
The S
Ret and N fertilizer treatments usually had higher mass of TOC, TON, LFOC, and LFON in soil at Breton, but only of LFOC and LFON
in soil at Ellerslie compared with the corresponding S
Rem and zero-N control treatments. The responses of soil organic C and N to management practices were more pronounced for N fertilization
than straw management. There were significant correlations among most soil organic C or N fractions, especially at Breton.
Linear regressions between crop residue C or N input, or rate of fertilizer N applied and soil organic C or N were significant
in most cases at Breton, but only for LFOC and LFON at Ellerslie. At Breton, compared with zero-N rate, the C sequestration
efficiency of additional crop residue C input was 5.8%, 20.1%, and 20.4% in S
Ret and 17.2%, 28.0%, and 30.1% in S
Rem treatments at the 25, 50, and 75 kg N ha−1 rates, respectively. The effects of crop residue management and N fertilization on chemical properties were generally similar
for both contrasting soil types. There was no effect of crop residue management on soil pH, extractable P and residual nitrate-N.
Extractable P and pH in the top 0–15 cm soil decreased significantly with N application in both soil types. Residual nitrate-N
(though quite low in Breton soil) increased with application of N and also indicated some downward movement in the soil profile
up to 90 cm depth in Ellerslie soil. There was generally no effect of any treatment on ammonium-N in soil. In conclusion,
straw retention and N application improved organic C and N in soil, and generally differences were more pronounced for light
fraction than total organic C and N, and between the most extreme treatments (S
Rem0 vs. S
Ret75). Application of N fertilizer reduced extractable P and pH in the surface soil, and showed accumulation and downward leaching
of nitrate-N in the soil profile. 相似文献
11.
Effects of 17-year fertilization on soil microbial biomass C and N and soluble organic C and N in loessial soil during maize growth 总被引:2,自引:0,他引:2
As labile organic pools, soluble organic matter and soil microbial biomass are sensitive to changes in soil management and
therefore good indicators of soil quality. Effects of a 17-year long-term fertilization on soil microbial biomass C (SMBC)
and N (SMBN), soluble organic C, and soluble organic N during the maize growing season were evaluated in a loess soil (Eum-Orthic
Anthrosol) in northwest China. The fertilization treatments included no fertilizer (CK), inorganic N, P, and K fertilizer
(NPK), cattle manure plus NPK fertilizer (MNPK), and straw plus NPK fertilizer (SNPK). Our results showed that C storage in
the 0–20 cm soil layer was 28% to 81% higher in the fertilized treatments compared to the unfertilized treatment. In the 0–10 cm
soil layer, SMBC and SMBN in the three fertilized treatments were higher than in the unfertilized treatment on all sampling
dates, while microbial biomass C and N in the 0−10 cm soil layers were the highest at grain filling. In the same soil layer,
soil-soluble organic C generally decreased in the order MNPK > SNPK > NPK > CK, while soluble organic N was the highest in
the MNPK followed by the SNPK treatment. There was no significant difference in soluble organic N in the NPK and CK treatments
throughout most of the maize growing season. Changes in soluble organic N occurred along the growing season and were more
significant than those for soluble organic C. Soluble organic N was the highest at grain filling and the lowest at harvest.
Overall, our results indicated that microbial biomass and soluble organic N in the surface soil were generally the highest
at grain filling when maize growth was most vigorous. Significant positive relationships were found between soluble organic
C and SMBC and between soluble organic N and SMBN. 相似文献
12.
Tillage and cropping effects on soil quality indicators in the northern Great Plains 总被引:9,自引:5,他引:9
The extreme climate of the northern Great Plains of North America requires cropping systems to possess a resilient soil resource in order to be sustainable. This paper summarizes the interactive effects of tillage, crop sequence, and cropping intensity on soil quality indicators for two long-term cropping system experiments in the northern Great Plains. The experiments, located in central North Dakota, were established in 1984 and 1993 on a Wilton silt loam (FAO: Calcic Siltic Chernozem; USDA1: fine-silty, mixed, superactive frigid Pachic Haplustoll). Soil physical, chemical, and biological properties considered as indicators of soil quality were evaluated in spring 2001 in both experiments at depths of 0–7.5, 7.5–15, and 15–30 cm. Management effects on soil properties were largely limited to the surface 7.5 cm in both experiments. For the experiment established in 1984, differences in soil condition between a continuous crop, no-till system and a crop–fallow, conventional tillage system were substantial. Within the surface 7.5 cm, the continuous crop, no-till system possessed significantly more soil organic C (by 7.28 Mg ha−1), particulate organic matter C (POM-C) (by 4.98 Mg ha−1), potentially mineralizable N (PMN) (by 32.4 kg ha−1), and microbial biomass C (by 586 kg ha−1), as well as greater aggregate stability (by 33.4%) and faster infiltration rates (by 55.6 cm h−1) relative to the crop–fallow, conventional tillage system. Thus, soil from the continuous crop, no-till system was improved with respect to its ability to provide a source for plant nutrients, withstand erosion, and facilitate water transfer. Soil properties were affected less by management practices in the experiment established in 1993, although organic matter related properties tended to be greater under continuous cropping or minimum tillage than crop sequences with fallow or no-till. In particular, PMN and microbial biomass C were greatest in continuous spring wheat (with residue removed) (22.5 kg ha−1 for PMN; 792 kg ha−1 for microbial biomass C) as compared with sequences with fallow (SW–S–F and SW–F) (Average=15.9 kg ha−1 for PMN; 577 kg ha−1 for microbial biomass C). Results from both experiments confirm that farmers in the northern Great Plains of North America can improve soil quality and agricultural sustainability by adopting production systems that employ intensive cropping practices with reduced tillage management. 相似文献
13.
Elcio L. Balota Arnaldo Colozzi-Filho Diva S. Andrade Richard P. Dick 《Biology and Fertility of Soils》2003,38(1):15-20
A long-term study on the effect of different crop rotations [soybean/wheat, S/W; maize/wheat, M/W or cotton/wheat, C/W] and tillage regimes [no-tillage (NT) or conventional tillage (CT)] on microbial biomass and other soil properties is reported. The experiment was established in 1976 in southern Brazil as a split-plot experimental design in three replications. Soil samples were taken in 1997 and 1998 at 0- to 5-, 5- to 10- and 10- to 20-cm depths and evaluated for microbial biomass C, N, P and S by direct extraction methods. The NT system showed increases of 103%, 54%, 36%, and 44% for microbial biomass C, N, P, and Cmic:Corg percentage, respectively at the 0- to 5-cm depth. NT systems also increased the C to N:S:P ratios. These results provide evidence that tillage or crop rotation affect microbial immobilization of soil nutrients. The larger amount of C immobilized in microbial biomass suggests that soil organic matter under NT systems provides higher levels of more labile C than CT systems. 相似文献
14.
Long-term effect of chemical fertilizer,straw, and manure on labile organic matter fractions in a paddy soil 总被引:2,自引:0,他引:2
To assess the effect of long-term fertilization on labile organic matter fractions, we analyzed the C and N mineralization
and C and N content in soil, particulate organic matter (POM), light fraction organic matter (LFOM), and microbial biomass.
Results showed that fertilizer N decreased or did not affect the C and N amounts in soil fractions, except N mineralization
and soil total N. The C and N amounts in soil and its fractions increased with the application of fertilizer PK and rice straw.
Generally, there was no significant difference between fertilizer PK and rice straw. Furthermore, application of manure was
most effective in maintaining soil organic matter and labile organic matter fractions. Soils treated with manure alone had
the highest microbial biomass C and C and N mineralization. A significant correlation was observed between the C content and
N content in soil, POM, LFOM, microbial biomass, or the readily mineralized organic matter. The amounts of POM–N, LFOM–N,
POM–C, and LFOM–C closely correlated with soil organic C or total N content. Microbial biomass N was closely related to the
amounts of POM–N, LFOM–N, POM–C, and LFOM–C, while microbial biomass C was closely related to the amounts of POM–N, POM–C,
and soil total N. These results suggested that microbial biomass C and N closely correlated with POM rather than SOM. Carbon
mineralization was closely related to the amounts of POM–N, POM–C, microbial biomass C, and soil organic C, but no significant
correlation was detected between N mineralization with C or N amounts in soil and its fractions. 相似文献
15.
Transformations and recovery of residue and fertilizer nitrogen-15 in a sandy Lixisol of West Africa
The fate of 15N-labeled plant residues from different cover-cropping systems and labeled inorganic N fertilizer in the organic, soil mineral,
microbial biomass and soil organic matter (SOM) particle-size fractions was investigated in a sandy Lixisol. Plant residues
were from mucuna (legume), lablab (legume), imperata (grass), maize (cereal) and mixtures of mucuna or lablab with imperata
or maize, applied as a surface mulch. Inorganic N fertilizer was applied as 15N-(NH4)2SO4 at two rates (21 and 42 mg N kg–1 soil). Total N release from mucuna or lablab residues was 2–3 times higher than from the other residues, whereas imperata
immobilized N throughout the study period. In contrast, 15N was mineralized from all the plant residues irrespective of the mineralization–immobilization pattern observed for total
N. After 168 days, 69% of soil mineral N in mucuna- or lablab-mulched soils was derived from the added residues, representing
4–8% of residue N, whereas 9–30% of inorganic N was derived from imperata, maize and the mixed residues. At the end of the
study, 4–19% of microbial biomass N was derived from the added residue/fertilizer-N, accounting for 1–3% of added residue-N.
Averaged across treatments, particulate SOM fractions accounted for less than 1% of the total soil by weight but contained
20% of total soil C and 8% of soil N. Soils amended with mucuna or lablab incorporated more N in the 250–2000 μm SOM pool,
whereas soil amended with imperata or the mixed residues incorporated similar proportions of labeled N in the 250–2000 μm
and 53–250 μm fractions. In contrast, in soils receiving the maize or inorganic fertilizer-N treatments, higher proportions
of labeled N were incorporated into the 53–250 μm than the 250–2000 μm fractions. The relationship between these differences
in residue/fertilizer-N partitioning into different SOM particle-size fractions and soil productivity is discussed.
Received: 12 March 1999 相似文献
16.
Soil microbiological properties and its stratification ratios for soil quality assessment under different cover crop management systems in a semiarid vineyard
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In vineyards in Spain, tillage and semiarid Mediterranean climatic conditions accelerate organic matter loss from the soil. Cover crops are a conservation management practice that can provoke changes in soil quality which requires evaluation. Stratification ratios of soil properties such as soil organic C and labile C fractions have been proposed for the assessment of soil quality under different soil management systems. Our objective was to study the effect of different cover crop management on various soil parameters and their stratification ratios. We evaluated three different soil managements in a Typic Haploxerept from NE Spain: conventional tillage (CT); 5‐y continuous cover crop of resident vegetation (RV); and 4‐y continuous cover crop of Festuca longifolia Thuill., followed by 1‐y Bromus catharticus L. after resowing (BV). We monitored soil organic C, particulate organic C, water soluble C, potentially mineralizable N, microbial biomass C, β‐glucosidase and urease enzymatic activities, and water stable aggregates at 0–2.5, 2.5–5, 5–15, 15–25, and 25–45 cm soil depths. We calculated soil depth stratification ratios of those soil properties. Resident cover crop increased microbiological properties, labile C fractions, and aggregation with respect to conventional tillage at 0–2.5 and 2.5–5 cm soil depths. However, for Bromus cover crop the same soil properties were lower than for the resident cover crop at 0–2.5 cm depth. Stratification ratios of β‐glucosidase and urease enzymatic activities, and particulate organic C showed a higher sensitivity than other soil properties; therefore, they would be the best indicators for soil quality assessment in semiarid Mediterranean vineyards. 相似文献
17.
Soil microbial biomass and nitrogen supply in an irrigated lowland rice soil as affected by crop rotation and residue management 总被引:5,自引:0,他引:5
C. Witt Kenneth G. Cassman Johannes C. G. Ottow Ulrich Biker 《Biology and Fertility of Soils》1998,28(1):71-80
Processes that govern the soil nitrogen (N) supply in irrigated lowland rice systems are poorly understood. The objectives
of this paper were to investigate the effects of crop rotation and management on soil N dynamics, microbial biomass C (CBIO) and microbial biomass N (NBIO) in relation to rice N uptake and yield. A maize-rice (M-R) rotation was compared with a rice-rice (R-R) double-cropping
system over a 2-year period with four cropping seasons. In the M-R system, maize (Zea mays L.) was grown in aerated soil during the dry season (DS) followed by rice (Oryza sativa L.) grown in flooded soil during the wet season (WS). In the R-R system, rice was grown in flooded soil in both the DS and
WS. Three fertilizer N rates (0, 50 or 100 kg urea-N ha–1 in WS) were assigned to subplots within the cropping system main plots. Early versus late crop residue incorporation following
DS maize or rice were established as additional treatments in sub-subplots in the second year. In the R-R system, the time
of residue incorporation had a large effect on NO3
–-N accumulation during the fallow period and also on extractable NH4
+-N, rice N uptake and yield in the subsequent cropping period. In contrast, time of residue incorporation had little influence
on extractable N in both the fallow and rice-cropping periods of the M-R system, and no detectable effects on rice N uptake
or yield. In both cropping systems, CBIO and NBIO were not sensitive to residue incorporation despite differences of 2- to 3-fold increase in the amount of incorporated residue
C and N, and were relatively insensitive to N fertilizer application. Extractable organic N was consistently greater after
mid-tillering in M-R compared to the R-R system across N rate and residue incorporation treatments, and much of this organic
N was α-amino N. We conclude that N mineralization-immobilization dynamics in lowland rice systems are sensitive to soil aeration
as influenced by residue management in the fallow period and crop rotation, and that these factors have agronomically significant
effects on rice N uptake and yield. Microbial biomass measurements, however, were a poor indicator of these dynamics.
Received: 31 October 1997 相似文献
18.
The proportion of N from crop residues entering the light-fraction organic matter (LFOM) pool was investigated in soils with
contrasting soil organic matter and microbial characteristics arising from different management histories. A laboratory experiment
was conducted in which 15N-labelled sugar beet, Brussels sprout or ryegrass shoots, which possessed a range of C/N contents, and hence different biochemical
qualities, were incorporated into a sandy–loam soil collected from within a field (FC) or from the field margin (FM). Amounts
of C and N incorporated into LFOM were determined after 112 days. The FC and FM soils had organic C contents of 0.9% and 2.5%,
respectively. Addition of crop residues increased total LFOM N content and reduced its C/N in FC soil but had no effect on
total LFOM N or its C/N in FM soil. Ryegrass incorporation into FC was the only treatment in which there was a net increase
in LFOM C. Isotopic analysis indicated that more crop-residue-derived N became incorporated into the LFOM N pool in FM relative
to FC soil, with per cent crop residue N incorporated ranging from 25.9% to 35.3% in FC and between 38.9 and 68.5 in FM. Incorporation
of crop residues had a positive priming effect on pre-existing LFOM N in FM but not FC soil. We conclude that the characteristics
of plant material, together with differences in soil organic matter and microbiology resulting from contrasting management,
determined the amount of crop residue C and N incorporated into both HFOM and LFOM. 相似文献
19.
Anja Nüsse Deborah Linsler Michael Kaiser Dorothee Ebeling Bettina Tonn Johannes Isselstein 《Archives of Agronomy and Soil Science》2017,63(12):1776-1783
The effects of different grazing pressures (GPs) on soil properties are not sufficiently understood. The objectives were to analyse the effects of three different extensive GPs on stocks of soil organic C and total N, soil microbial biomass C, basal respiration and mineral N in three different soil depths of a long-term pasture in Central Germany (FORBIOBEN field trial). No significant (p ≤ 0.05) effects of GP on weighted stocks of soil organic C, total N, soil microbial biomass C, mineral N and basal respiration rate were observed, suggesting that the C and N cycles are coupled in the three grazing treatments. Oxalate soluble Fe contents explained a marked part of the variation of soil organic C (multiple linear regression: R2 = 0.64) and total N contents (R2 = 0.64) in the soils, whereas almost all of the variability of soil microbial biomass C contents and basal respiration was explained by soil organic C contents. Overall, variabilities of soil organic C and N contents were largely explained by oxalate soluble Fe contents, whereas grazing intensity did not affect the C and N dynamics. 相似文献
20.
Gross N mineralization and nitrification rates and their relationships to microbial biomass C and N and enzyme (protease,
deaminase and urease) activities were determined in soils treated with dairy shed effluent (DSE) or NH4
+ fertilizer (NH4Cl) at a rate equivalent to 200 kg N ha–1 at three water potentials (0, –10 and –80 kPa) at 20 °C using a closed incubation technique. After 8, 16, 30, 45, 60 and
90 days of incubation, sub-samples of soil were removed to determine gross N mineralization and nitrification rates, enzyme
activities, microbial biomass C and N, and NH4
+ and NO3
– concentrations. The addition of DSE to the soil resulted in significantly higher gross N mineralization rates (7.0–1.7 μg
N g–1 soil day–1) than in the control (3.8–1.2 μg N g–1 soil day–1), particularly during the first 16 days of incubation. This increase in gross mineralization rate occurred because of the
presence of readily mineralizable organic substrates with low C : N ratios, and stimulated soil microbial and enzymatic activities
by the organic C and nutrients in the DSE. The addition of NH4Cl did not increase the gross N mineralization rate, probably because of the lack of readily available organic C and/or a
possible adverse effect of the high NH4
+ concentration on microbial activity. However, nitrification rates were highest in the NH4Cl-treated soil, followed by DSE-treated soil and then the control. Soil microbial biomass, protease, deaminase and urease
activities were significantly increased immediately after the addition of DSE and then declined gradually with time. The increased
soil microbial biomass was probably due to the increased available C substrate and nutrients stimulating soil microbial growth,
and this in turn resulted in higher enzyme activities. NH4Cl had a minimal impact on the soil microbial biomass and enzyme activities, possibly because of the lack of readily available
C substrates. The optimum soil water potential for gross N mineralization and nitrification rates, microbial and enzyme activities
was –10 kPa compared with –80 kPa and 0 kPa. Gross N mineralization rates were positively correlated with soil microbial biomass
N and protease and urease activities in the DSE-treated soil, but no such correlations were found in the NH4Cl-treated soil. The enzyme activities were also positively correlated with each other and with soil microbial biomass C and
N. The forms of N and the different water potentials had a significant effect on the correlation coefficients. Stepwise regression
analysis showed that protease was the variable that most frequently accounted for the variations of gross N mineralization
rate when included in the equation, and has the potential to be used as one of the predictors for N mineralization.
Received: 10 March 1998 相似文献