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1.
Long-term effects of mineral fertilization on microbial biomass C (MBC), basal respiration (R
B), substrate-induced respiration (R
S), β-glucosidase activity, and the r–K-growth strategy of soil microflora were investigated using a field trial on grassland established in 1969. The experimental
plots were fertilized at three rates of mineral N (0, 80, and 160 kg ha−1 year−1) with 32 kg P ha−1 year−1 and 100 kg K ha−1 year−1. No fertilizer was applied on the control plots (C). The application of a mineral fertilizer led to lower values of the MBC
and R
B, probably as a result of fast mineralization of available substrate after an input of the mineral fertilizer. The application
of mineral N decreased the content of C extracted by 0.5 M K2SO4 (C
ex). A positive correlation was found between pH and the proportion of active microflora (R
S/MBC). The specific growth rate (μ) of soil heterotrophs was higher in the fertilized than in unfertilized soils, suggesting the stimulation of r-strategists, probably as the result of the presence of available P and rhizodepositions. The cessation of fertilization with
320 kg N ha−1 year−1 (NF) in 1989 also stimulated r-strategists compared to C soil, probably as the result of the higher content of available P in the NF soil than in the C
soil. 相似文献
2.
Drought constraints on transpiration and canopy conductance in mature aspen and jack pine stands 总被引:3,自引:0,他引:3
P.Y. Bernier P. Bartlett T.A. Black A. Barr N. Kljun J.H. McCaughey 《Agricultural and Forest Meteorology》2006,140(1-4):64
Half-hourly mean values of transpiration measured by eddy covariance over the course of six growing seasons in two boreal forest sites were used to develop stand-level relationships between transpiration and soil water content. The two sites were an aspen site on fine-textured soil and over five growing seasons for a jack pine site on coarse-textured soil in Saskatchewan, Canada. About half of the data record covered a multi-year drought that was more severe at the aspen site than the jack pine site. Measurements of transpiration and environmental variables were used to adjust a transpiration model to each site, with environmental variables retained in the model based on their capacity to improve the model adjustment. The model was also used to produce estimates of maximum canopy conductance (gcMAX). The fit of the model to the aspen half-hourly transpiration is better than to the jack pine data (r2 of 0.86 versus 0.60). Relative soil water content explains more of the variability in half-hourly transpiration at the aspen site (46%) than at the jack pine site (10%). The relationships between transpiration and environmental variables are stable throughout the drought suggesting an absence of acclimation. Published soil water modifier curves for loamy clay soils compare well with the modifier function we obtained for a similar soil at the aspen site, but the agreement between the published curve and our curve is poor for the sandy soil of the jack pine site. Values of gcMAX computed at the half-hourly scale are greater at the aspen site (14.3 mm s−1) than at the jack pine site (10.2 mm s−1), but we hypothesize that the coarse soil and perennially lower water content of the jack pine site may cause this difference. Finally, we also present values of gcMAX computed at the daily and monthly scales for use in models that operate at these time steps. 相似文献
3.
Joseph C. Fetter Rebecca N. Brown Josef H. Görres Chong Lee José A. Amador 《Water, air, and soil pollution》2012,223(4):1531-1541
Consumer demand for cleaned squid generates a substantial amount of waste that must be properly disposed of, creating an economic
burden on processors. A potential solution to this problem involves converting squid by-products into an organic fertilizer,
for which there is growing demand. Because fertilizer application to lawns can increase the risk of nutrient contamination
of groundwater, we quantified leaching of NO3–N and PO4–P from perennial ryegrass turf (Lolium perenne L.) amended with two types of fertilizer: squid-based (SQ) and synthetic (SY). Field plots were established on an Enfield
silt loam, and liquid (L) and granular (G) fertilizer formulations of squid and synthetic fertilizers were applied at 0, 48,
146, and 292 kg N ha−1 year−1. Levels of NO3–N and PO4–P in soil pore water from a depth of 60 cm were determined periodically during the growing season in 2008 and 2009. Pore
water NO3–N levels were not significantly different among fertilizer type or formulation within an application rate throughout the
course of the study. The concentration of NO3–N remained below the maximum contaminant level (MCL) of 10 mg L−1 until midSeptember 2009, when values above the MCL were observed for SQG at all application rates, and for SYL at the high
application rate. Annual mass losses of NO3–N were below the estimated inputs (10 kg N ha−1 year−1) from atmospheric deposition except for the SQG and SYL treatments applied at 292 kg N ha−1 year−1, which had losses of 13.2 and 14.9 kg N ha−1 year−1, respectively. Pore water PO4–P levels ranged from 0 to 1.5 mg P L−1 and were not significantly different among fertilizer type or formulation within an application rate. Our results indicate
that N and P losses from turf amended with squid-based fertilizer do not differ from those amended with synthetic fertilizers
or unfertilized turf. Although organic in nature, squid-based fertilizer does not appear to be more—or less—environmentally
benign than synthetic fertilizers. 相似文献
4.
Application of feedlot manure (FLM) to cropping and grazing soils could provide a valuable N nutrient resource. However, because
of its high but variable N concentration, FLM has the potential for environmental pollution of water bodies and N2O emission to the atmosphere. As a potential management tool, we utilised the low-nutrient green waste compost (GWC) to assess
its effectiveness in regulating N release and the amount of N2O emission from two Vertisols when both FLM and GWC were applied together. Cumulative soil N2O emission over 32 weeks at 24°C and field capacity (70% water-filled pore space) for a black Vertisol (Udic Paleustert) was
45 mg N2O m−2 from unamended soil. This increased to 274 mg N2O m−2 when FLM was applied at 1 kg m−2 and to 403 mg N2O m−2 at 2 kg m−2. In contrast, the emissions of 60 mg N2O m−2 when the soil was amended with GWC 1 kg m−2 and 48 mg N2O m−2 at 2 kg m−2 were not significantly greater than the unamended soil. Emission from a mixture of FLM and GWC applied in equal amounts (0.5 kg m−2) was 106 mg N2O m−2 and FLM applied at 0.5 kg m−2 and GWC at 1.5 kg GWC m−2 was 117 mg N2O m−2. Although cumulative N2O emissions from an unamended grey Vertisol (Typic Chromustert) were only slightly higher than black Vertisol (57 mg N2O m−2), FLM application at 1 kg m−2 increased N2O emissions by 14 times (792 mg N2O m−2) and at 2 kg m−2 application by 22 times (1260 mg N2O m-2). Application of GWC did not significantly increase N2O emission (99 mg N2O m−2 at 1 kg m−2 and 65 mg N2O m−2 at 2 kg m−2) above the unamended soil. As observed for the black Vertisol, a mixture of FLM (0.5 kg m−2) and GWC (0.5 or 1.5 kg m−2) reduced N2O emission by >50% of that from the FLM alone, most likely by reducing the amount of mineral N (NH4+–N and NO3−–N) in the soil, as mineral N in soil and the N2O emission were closely correlated. 相似文献
5.
Nitrogen mineralisation in soils of various forest sites (pine plantation, natural and thinned oak) at Uluda? University campus in Bursa, Turkey was investigated continuously over a year by the field incubation method. Net nitrogen mineralisation and nitrification rates varied depending on sampling dates. Although nitrogen mineralisation and nitrification rates increased in the spring and summer months, there was no seasonal variation in the soils of the examined forests. Annual net nitrate (NO3?–N) accumulation in the upper soil layer (0–5 cm) was higher in Oak I and Oak II (14 kg ha y?1 and 12 kg ha y?1) than in the pine plantation (8 kg ha y?1). While annual net NO3?–N accumulation (0–5 cm) varied between the oak forests (possibly due to forest management practices), annual net Nmin values were similar in these forests. No significant correlation was found between the examined soil parameters and net nitrification and mineralisation rates in the soils (P > 0.05). These results indicate that tree species and forest management practices play important roles in N cycling in forest ecosystems. 相似文献
6.
Robert John Wilcock Karin Müller Gareth B. van Assema Margaret A. Bellingham Ron Ovenden 《Water, air, and soil pollution》2012,223(2):499-509
Water quantity and quality were monitored for 3 years in a 360-m-long wetland with riparian fences and plants in a pastoral
dairy farming catchment. Concentrations of total nitrogen (TN), total phosphorus (TP) and Escherichia coli were 210–75,200 g N m−3, 12–58,200 g P m−3 and 2–20,000 most probable number (MPN)/100 ml, respectively. Average retentions (±standard error) for the wetland over 3 years
were 5 ± 1%, 93 ± 13% and 65 ± 9% for TN, TP and E. coli, respectively. Retentions for nitrate–N, ammonium–N, filterable reactive P and particulate C were respectively −29 ± 5%,
32 ± 10%, −53 ± 24% and 96 ± 19%. Aerobic conditions within the wetland supported nitrification but not denitrification and
it is likely that there was a high conversion rate from dissolved inputs of N and P in groundwater, to particulate N and P
and refractory dissolved forms in the wetland. The wetland was notable for its capacity to promote the formation of particulate
forms and retain them or to provide conditions suitable for retention (e.g. binding of phosphate to cations). Nitrogen retention
was generally low because about 60% was in dissolved forms (DON and NOX–N) that were not readily trapped or removed. Specific yields for N, P and E. coli were c. 10–11 kg N ha−1 year−1, 0.2 kg P ha−1 year−1 and ≤109 MPN ha−1 year−1, respectively, and generally much less than ranges for typical dairy pasture catchments in New Zealand. Further mitigation
of catchment runoff losses might be achieved if the upland wetland was coupled with a downslope wetland in which anoxic conditions
would promote denitrification. 相似文献
7.
Harry H. Schomberg Dinku M. Endale Michael B. Jenkins Dwight S. Fisher 《Biology and Fertility of Soils》2011,47(7):823-831
Poultry (Gallus gallus domesticus L.) litter (PL) is a readily available nutrient source for crop production in the Southeast USA. Long-term PL application
may alter availability of N and the effect may be dependent on tillage practice. Tillage [no till (NT) vs. conventional (CT)]
and N source (PL vs. commercial fertilizer CF) effects on N availability and plant uptake were evaluated in years 9, 10, and
11 of a long-term cropping systems study at the United States Department of Agriculture, Agricultural Research Service, J.
Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA, USA. Mineral N in the top 10 cm, measured in situ,
varied each year and was influenced by time, tillage, and N source. In 2003 (year 9), soil mineral N content was greater in
CT–CF (100 kg ha−1) than in NT–PL (95 kg ha−1) but in 2004 (year 10) and 2005 (year 11) it was lower in CT–CF (93 and 60 kg ha−1) compared to NT–PL (140 and 71 kg ha−1). Nitrogen mineralization rates were generally greater for PL than for CF treatments with the difference being almost 1 kg ha−1 day−1 in 2003. Mineralization rates were greater for NT–PL compared to CT–CF in 2004 and 2005. Across the three growing seasons,
corn (Zea mays L.) aboveground biomass was consistently greater in the NT–PL treatment than in the NT–CF and CT–CF treatments. Correlation
between aboveground biomass and N mineralization was greater for PL than for CF (0.75 vs. 0.48). Patterns of N mineralization
and total soil mineral N indicated that the distribution of N through the growing season more closely matched corn N demand
in PL treatments. Results indicate that improved N availability through the growing season, by combining NT and PL, can result
in more profitable corn production in the southeast. 相似文献
8.
Kaiwen Pan Zhihong Xu Tim Blumfield Shane Totua Manxin Lu 《Journal of Soils and Sediments》2008,8(6):398-405
Background, aim, and scope Hoop pine (Araucaria cunninghamii) is a nitrogen (N) demanding indigenous Australia softwood species with plantations in Southeast Queensland, Australia. Soil
fertility has declined with increasing rotations and comparison study of N cycling between hoop pine plantations, and adjacent
native forest (NF) is required to develop effective forest management for enhancing sustainable forest production and promoting
environmental benefits. Field in situ mineral 15N transformations in these two forest ecosystems have not been studied. Hence, the present study was to compare the differences
in soil nutrients, N transformations, 15N fluxes, and fate between the hoop pine plantation and the adjacent native forest.
Materials and methods The study sites were in Yarraman State Forest (26°52′ S, 151°51′ E), Southeastern Queensland, Australia. The in situ core
incubation method was used in the field experiments. Mineral N was determined using a LACHAT Quickchem Automated Ion Analyzer.
15N were performed using an isotope ratio mass spectrometer with a Eurovector elemental analyzer. All statistical tests were
carried out by the SPSS 11.0 for Windows statistical software package.
Results Soil total C and N were significantly higher in the NF than in the 53-year-old hoop pine plantation. Concentrations of NO3
– were significantly higher in the NF soil than in the plantation soil. The plantation soil had significantly higher 15N and 13C natural abundances than the NF soil. The NF soil had significantly lower C/N ratios than the plantation soil. NO3
––N was dominated in mineral N pools in both NF and plantation soils, accounting for 91.6% and 70.3% of the total mineral N
pools, respectively. Rates of net nitrification and net N mineralization were, respectively, four and three times higher in
the NF soil than in the plantation soil. The 15NO3
––N and mineral 15N were significantly higher in the NF soil than in the plantation soil. Significant difference in 15NH4
+–N was found in the NF soil before and after the incubation.
Discussion The NF soil had significantly higher NO3
––N, mineral N, total N and C but lower δ15N, δ13C, and C/N ratios than the plantation soil. Moreover, the rates of soil net N mineralization and nitrification were significantly
higher, but ammonification rate was lower in the NF than in the plantation. The NF soil had many more dynamic N transformations
than the plantation soil due to the combination of multiple species and layers and, thus, stimulation of microbial activity
and alteration of C and N pool sizes in favor of the N transformations by soil microbes. The net rate of N and 15N transformation demonstrated differences in N dynamic related to the variation in tree species between the two ecosystems.
Conclusions The change of land use and trees species had significant impacts on soil nutrients and N cycling processes. The plantation
had larger losses of N than the NF. The NO3
––N and 15NO3
––N dominated in the mineral N and 15N pools in both forest ecosystems.
Recommendations and perspectives Native forest soil had strong N dynamic compared with the plantation soil. Composition of multiple tree species with different
ecological niches in the plantation could promote the soil ecosystem sustainability. The 15N isotope dilution technique in the field can be quite useful for studying in situ mineral 15N transformations and fate to further understand actual N dynamics in natural forest soils. 相似文献
9.
S. K. Tripathi A. Sumida H. Shibata K. Ono S. Uemura Y. Kodama T. Hara 《Biology and Fertility of Soils》2006,43(2):237-246
In many Japanese forests, the forest understory is largely dominated by dwarf bamboo (Sasa) species, which compete with overstory vegetation for soil nutrients. We studied the rate of leaf litterfall, and decomposition and mineralization of carbon (C) and nitrogen (N) from various components (leaf, root, wood, and rhizome) of overstory and understory vegetation in a young Betula ermanii forest from 2002 to 2004. Total litterfall was 377 g m−2 year−1, of which the overstory vegetation contributed about two thirds. A litter decomposition experiment conducted for 770 days indicated that mass loss of different litter components varied significantly, except for Sasa
kurilensis wood and rhizome. Relative decomposition rates were significantly greater in the first growth period (June to October) than the dormant period (November to May) in most cases. Rainfall was the most important abiotic variable, explaining 75–80% of the variability in mass loss rates. Concentrations of ethanol soluble substances and N were significantly positively correlated (r=0.77 to 0.97, P<0.05) with mass loss at an early stage (41 days). The ratios of lignin/N and C/N were found to be negatively correlated with mass loss rates at all stages of litter decomposition. C stock loss was similar to that of mass loss, whereas N stock loss was slower, except for S. kurilensis fine root litter. The evergreen understory species S. kurilensis exhibited greater N use efficiency than B. ermanii, suggesting better competitive ability that might favor the production of a high biomass and invasion under tree species like B. ermanii. 相似文献
10.
Background, aim, and scope
A large proportion of soil nitrogen (N; >80%) is present in organic form. Current research on plant N uptake in terrestrial ecosystems has focused mainly on inorganic N such as ammonium (NH4 +) and nitrate (NO3 −), while soluble organic N (SON) has received little attention. In recent years, the increasing evidence showing the direct uptake of various amino acids by plants and the predominance of the organic form in N loss by leaching in many forest ecosystems has drawn attention to critically re-examine the nature and the ecological role of soil SON in terrestrial N cycling. However, little is known about the sources and dynamics, chemical nature, and ecological functions of soil SON in forest ecosystems. This paper reviews recent advances in the areas of research on current techniques for characterizing soil SON and the size, nature, and dynamics of soil SON pools in forest ecosystems. 相似文献11.
In this study, 30 cowpea genotypes were assessed for symbiotic N2 fixation in 2005, and 15 of them were re-evaluated in 2006 using the 15N natural abundance technique. Shoot dry matter yield of cowpea genotypes increased significantly in cvs. Vuli-1, Glenda,
IT93K-2045-29, IT90K-59, Omondaw, Apagbaala, and IT84S-2246 in 2005 producing about 3.0 to 3.6-fold more biomass relative
to cv. Vallenga. In 2006, seven out of the 15 cowpea genotypes tested (namely, IT97K-499-39, TVu11424, Botswana White, IT84S-2246,
Sanzie, Brown Eye, and Glenda) also produced more dry matter than cv. CH14. Shoot δ15N values ranged from −0.58‰ to 1.49‰ in 2005, and −1.51‰ to 1.40‰ in 2006, and these resulted in %Ndfa values of 63.5–86.7%
and 56.2–96.3%, respectively. The amount of N-fixed was 49–178 kg N ha−1 in 2005 and 62–198 kg N ha−1 in 2006. Furthermore, there was a direct relationship between the level of symbiotic N nutrition and plant growth, and between
grain yield and amount of N-fixed in 2005 and 2006. As a result, genotypes that fixed the most N also produced the largest
biomass and the greatest amount of grain yield. The observed relationship between N2 fixation and biomass confirmed our view that cowpea (and other grain legumes) can be concurrently selected for higher N2 fixation, superior plant growth, and greater grain yield. The high levels of N-fixed by many of the cowpea genotypes in this
study suggest that they can contribute large amounts of N to cropping systems in African agriculture. 相似文献
12.
Balaji Anandha Rao Cameron P. Wake Todd Anderson William Andrew Jackson 《Water, air, and soil pollution》2012,223(1):181-188
Temporal depositional rates are important in order to understand the production and occurrence of perchlorate (ClO4−) as limited information exists regarding the impact of anthropogenic production or atmospheric pollution on ClO4− deposition. Perchlorate concentrations in discrete ice core samples from the Eclipse Icefield (Yukon Territory, Canada) and
Upper Fremont Glacier (Wyoming, USA) were analyzed using ion chromatography tandem mass spectrometry to evaluate temporal
changes in the deposition of ClO4
− in North America. The ice core samples cover a time period from 1726 to 1993 and 1970 to 2002 for the Upper Fremont Glacier
(UFG) and Eclipse ice cores, respectively. The average ClO4
− concentration in the Eclipse ice core for the time period from 1970 to 1973 was 0.6 ± 0.3 ng L−1, with higher values of 2.3 ± 1.7 and 2.2 ± 2.0 ng L−1 for the periods 1982–1986 and 1999–2002, respectively. All pre-1980 ice core samples from the UFG had ClO4
− concentrations <0.2 ng L−1, and the post-1980 samples ranged from <0.2 ng L−1 to a maximum of 2.6 ng L−1 for the year 1992. A significant positive correlation (R = 0.75, N = 15, p < 0.001) of ClO4− with SO42− was found for the annual UFG ice core layers and of ClO4
− with SO42− and NO3− in sub-annual Eclipse ice samples (R > 0.3, N = 121, p < 0.002). The estimated yearly ClO4− depositional flux for the Eclipse ice core ranged from 0.6 (1970) to 4.7 μg m−2 year−1 (1982) and the UFG from <0.1 (pre-1980) to 1.4 μg m−2 year−1 (1992). There was no consistent seasonal variation in the ClO4− depositional flux for the Eclipse ice core, in contrast to a previous study on the Arctic region. The presence of ClO4− in these ice cores might correspond to an intermittent source such as volcanic eruptions and/or any anthropogenic forcing
that may directly or indirectly aid in atmospheric ClO4− formation. 相似文献
13.
Fixation and defixation of ammonium in soils: a review 总被引:2,自引:0,他引:2
Fixed NH4+ (NH4+
f) and fixation and defixation of NH4+ in soils have been the subject of a number of investigations with conflicting results. The results vary because of differences
in methodology, soil type, mineralogical composition, and agro-climatic conditions. Most investigators have determined NH4+
f using strong oxidizing agents (KOBr or KOH) to remove organic N and the remaining NH4+
f does not necessarily reflect the fraction that is truly available to plants. The content of native NH4+
f in different soils is related to parent material, texture, clay content, clay mineral composition, potassium status of the
soil and K saturation of the interlayers of 2:1 clay minerals, and moisture conditions. Evaluation of the literature shows
that the NH4+
f-N content amounts to 10–90 mg kg−1 in coarse-textured soils (e.g., diluvial sand, red sandstone, granite), 60–270 mg kg−1 in medium-textured soils (loess, marsh, alluvial sediment, basalt) and 90–460 mg kg−1 in fine-textured soils (limestone, clay stone). Variable results on plant availability of NH4+
f are mainly due to the fact that some investigators distinguished between native and recently fixed NH4+ while others did not. Recently fixed NH4+ is available to plants to a greater degree than the native NH4+
f, and soil microflora play an important role in the defixation process. The temporal changes in the content of recently fixed
NH4+ suggest that it is actively involved in N dynamics during a crop growth season. The amounts of NH4+ defixed during a growing season varied greatly within the groups of silty (20–200 kg NH4+-N ha−1 30 cm−1) as well as clayey (40–188 kg NH4+-N ha−1 30 cm−1) soils. The pool of recently fixed NH4+ may therefore be considered in fertilizer management programs for increasing N use efficiency and reducing N losses from
soils. 相似文献
14.
Ilya Yevdokimov Andreas Gattinger Franz Buegger Jean Charles Munch Michael Schloter 《Biology and Fertility of Soils》2008,44(8):1103-1106
The changes in size, activity and structure of soil microbial community caused by N fertilization were studied in a laboratory
incubation experiment. The rates of N fertiliser applied (KNO3) were 0 (control), 100 and 2,000 μg N g−1 soil. Despite no extra C sources added, a high percentage of N was immobilized. Whereas no significant increase of microbial
C was revealed during incubation period, microbial growth kinetics as determined by the substrate-induced growth-response
method demonstrated a significant decrease in the specific growth rate of microbial community in soil treated with 2,000 μg
N g−1 soil. Additionally, a shift in microbial community structure resulting in an increase in fungal biomarkers, mainly in the
treatment with 2,000 μg N g−1 soil was visible. 相似文献
15.
Angela Y.Y. Kong Steven J. Fonte Chris van Kessel Johan Six 《Soil & Tillage Research》2009,104(2):256-262
Few studies address nutrient cycling during the transition period (e.g., 1–4 years following conversion) from standard to some form of conservation tillage. This study compares the influence of minimum versus standard tillage on changes in soil nitrogen (N) stabilization, nitrous oxide (N2O) emissions, short-term N cycling, and crop N use efficiency 1 year after tillage conversion in conventional (i.e., synthetic fertilizer-N only), low-input (i.e., alternating annual synthetic fertilizer- and cover crop-N), and organic (i.e., manure- and cover crop-N) irrigated, maize–tomato systems in California. To understand the mechanisms governing N cycling in these systems, we traced 15N-labeled fertilizer/cover crop into the maize grain, whole soil, and three soil fractions: macroaggregates (>250 μm), microaggregates (53–250 μm) and silt-and-clay (<53 μm). We found a cropping system effect on soil Nnew (i.e., N derived from 15N-fertilizer or -15N-cover crop), with 173 kg Nnew ha−1 in the conventional system compared to 71.6 and 69.2 kg Nnew ha−1 in the low-input and organic systems, respectively. In the conventional system, more Nnew was found in the microaggregate and silt-and-clay fractions, whereas, the Nnew of the organic and low-input systems resided mainly in the macroaggregates. Even though no effect of tillage was found on soil aggregation, the minimum tillage systems showed greater soil fraction-Nnew than the standard tillage systems, suggesting greater potential for N stabilization under minimum tillage. Grain-Nnew was also higher in the minimum versus standard tillage systems. Nevertheless, minimum tillage led to the greatest N2O emissions (39.5 g N2O–N ha−1 day−1) from the conventional cropping system, where N turnover was already the fastest among the cropping systems. In contrast, minimum tillage combined with the low-input system (which received the least N ha−1) produced intermediate N2O emissions, soil N stabilization, and crop N use efficiency. Although total soil N did not change after 1 year of conversion from standard to minimum tillage, our use of stable isotopes permitted the early detection of interactive effects between tillage regimes and cropping systems that determine the trade-offs among N stabilization, N2O emissions, and N availability. 相似文献
16.
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
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.
Roberto González-De Zayas Martín Merino-Ibarra Felipe Matos-Pupo Martín F. Soto-Jiménez 《Water, air, and soil pollution》2012,223(3):1125-1136
Nitrogen (N) deposition to the ocean is thought to be increasing worldwide, but the amount of coastal and open ocean measurements
is very limited. In this paper, we assess N deposition in the coastal zone of Cayo Coco, in central Cuba, during a multi-annual
period (2005–2007). Wet and dry N depositions were estimated based on the NH4+ and NOx– concentrations in the rain. Cold fronts and troughs, coming from the west, contributed most to rain (41%) and to N deposition,
followed by tropical waves and storms coming from the east, which caused 31% of the rain. Average concentrations of NH4+ and NOx– in the rain were 8.8 and 8.3 μM. NOx– presented a clearly decreasing trend (0.26 μM per month), decreasing by half during 2005–2007. Total N deposition averaged
3.23 kg N ha−1 year−1, similar to that found in Virgin Islands and Puerto Rico, but lower than previously measured in Cuba and in nearby areas
of the USA and than model predictions for the oceanic region around Cuba. These low values and the decreasing trend found
are attributed to drastic reduction of fossil fuel and fertilizer use in Cuba since 1990. Because land input has decreased
even more drastically, deposition seems to be nowadays the most important N source to the coastal zone of Cayo Coco. The δ15N range of seagrass (Thalassia testudinum) and macroalgae (Penicillus dumetosus) in the area (−1.83‰ to 3.02‰ and +1.02‰ to +4.17‰, respectively) sustain that atmospheric sources (deposition and N2 fixation) comprise 70–90% of the N budget. 相似文献
19.
Contribution of fine roots to ecosystem biomass and net primary production in black spruce, aspen, and jack pine forests in Saskatchewan 总被引:1,自引:0,他引:1
Fine root (<2 mm) processes contribute to and exhibit control over a large pool of labile carbon (C) in boreal forest ecosystems because of the high proportion of C allocated to fine root net primary production (NPP), and the rapid decomposition of fine roots relative to aboveground counterparts. The objective of this study was to determine the contribution of fine roots to ecosystem biomass and NPP in a mature black spruce (Picea mariana Mill.) (OBS), aspen (Populus tremuloides Michx.) (OA), and jack pine (Pinus banksiana Lamb.) (OJP) stand, and an 11-year-old harvested jack pine (HJP) stand in Saskatchewan. Estimates of fine root biomass and NPP were obtained from nine minirhizotron (MR) tubes at each of the four Boreal Ecosystem Research and Monitoring Sites (BERMS). Fine root data were collected once a month for May–September in 2003 and 2004. Additional C biomass and NPP data for various components of the forest stands were obtained from Gower et al. (1997) and Howard et al. (2004). Annual fine root biomass averaged 3.10 ± 0.89, 1.71 ± 0.49, 1.62 ± 0.32, and 2.96 ± 0.67 Mg C ha−1 (means ± S.D.) at OBS, OA, OJP, and HJP, respectively, comprising between 1 and 6% of total stand biomass. Annual fine root NPP averaged 2.66 ± 0.97, 2.03 ± 0.43, 1.44 ± 0.43, and 2.16 ± 0.81 Mg C ha−1 year−1 (means ± S.D.) at OBS, OA, OJP, and HJP, respectively, constituting between 41 and 71% of total stand NPP. Results of this study indicate that fine roots produce a large amount of C in boreal forests. It is speculated that fine root NPP may control a large amount of labile C-cycling in boreal forests and that fine root responses to environmental and anthropogenic stress may be an early indicator of impaired ecosystem functioning. 相似文献
20.
Impacts of 22-year organic and inorganic N managements on soil organic C fractions in a maize field,northeast China 总被引:1,自引:0,他引:1
Impacts of 22-year organic and inorganic N managements on total organic carbon (TOC), water-soluble organic C (WSOC), microbial biomass C (MBC), particulate organic C (POC) and KMnO4 oxidized organic C (KMnO4-C) concentrations, C management index (CMI), and C storage in surface soil (0–20 cm) were investigated in a maize (Zea may L.) field experiment, Northeast China. The treatments included, CK: unfertilized control, M: organic manure (135 kg N ha− 1 year− 1), N: inorganic N fertilizer (135 kg N ha− 1 year− 1) and MN: combination of organic manure (67.5 kg N ha− 1 year− 1) and inorganic N fertilizer (67.5 kg N ha− 1 year− 1). TOC concentration and C storage were significantly increased under the M and MN treatments, but not under the inorganic N treatment. The organic treatments of M and MN were more effective in increasing WSOC, MBC, POC and KMnO4-C concentrations and CMI than the N treatment. The M treatment was most effective for sequestrating SOC (10.6 Mg ha− 1) and showed similar increase in degree of grain yield to the N and MN treatments, therefore it could be the best option for improving soil productivity and C storage in the maize cropping system. 相似文献