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1.
Impacts of greenwaste biochar on ammonia volatilisation from bauxite processing residue sand 总被引:7,自引:0,他引:7
C. R. Chen I. R. Phillips L. M. Condron J. Goloran Z. H. Xu K. Y. Chan 《Plant and Soil》2013,367(1-2):301-312
Background and Aims
The objective of this study was to test the suitability of greenwaste biochar to aid nitrogen (N) retention in rehabilitated bauxite-processing residue sand (BRS).Methods
Bauxite residue sand was collected from the Alcoa of Australia Pinjarra refinery. The pH of BRS was adjusted to values of 5, 7, 8 and 9 and subsequently amended with different rates (1, 5, 10 and 20 %, w/w) of greenwaste biochar. The loss of N via NH3 volatilization following addition of di-ammonium phosphate (DAP) was determined using an acid trapping method.Results
At low pH (5), increasing pH rather than adsorption capacity, resulting from biochar addition, caused greater losses of N through volatilization from BRS. In BRS with medium pH (7, 8), increasing adsorption capacity, induced by biochar addition, played the more dominant role in enhancing adsorption of NH 4 + -N /NH3-N and lowering NH3 volatilization. In the BRS with high pH (9), the majority of NH 4 + -N /NH3-N pools was lost via NH3 volatilization due to the strong acid-base reaction at this pH.Conclusions
It is concluded that the interaction of changes in pH and adsorption capacity induced by greenwaste biochar addition affects the availability and dynamics of NH 4 + -N/ NH3-N in BRS amended with DAP. 相似文献2.
Responses of CO2 efflux from an alpine meadow soil on the Qinghai Tibetan Plateau to multi-form and low-level N addition 总被引:1,自引:0,他引:1
Huajun Fang Shulan Cheng Guirui Yu Jiaojiao Zheng Peilei Zhang Minjie Xu Yingnian Li Xueming Yang 《Plant and Soil》2012,351(1-2):177-190
Aims
To assess the effects of atmospheric N deposition on the C budget of an alpine meadow ecosystem on the Qinghai–Tibetan Plateau, it is necessary to explore the responses of soil-atmosphere carbon dioxide (CO2) exchange to N addition.Methods
Based on a multi-form, low-level N addition experiment, soil CO2 effluxes were monitored weekly using the static chamber and gas chromatograph technique. Soil variables and aboveground biomass were measured monthly to examine the key driving factors of soil CO2 efflux.Results
The results showed that low-level N input tended to decrease soil moisture, whereas medium-level N input maintained soil moisture. Three-year N additions slightly increased soil inorganic N pools, especially the soil NH 4 + -N pool. N applications significantly increased aboveground biomass and soil CO2 efflux; moreover, this effect was more significant from NH 4 + -N than from NO 3 ? -N fertilizer. In addition, the soil CO2 efflux was mainly driven by soil temperature, followed by aboveground biomass and NH 4 + -N pool.Conclusions
These results suggest that chronic atmospheric N deposition will stimulate soil CO2 efflux in the alpine meadow on the Qinghai–Tibetan Plateau by increasing available N content and promoting plant growth. 相似文献3.
Reductive soil disinfestation (RSD) alters gross N transformation rates and reduces NO and N2O emissions in degraded vegetable soils 总被引:1,自引:0,他引:1
Background and aims
Continuous vegetable cultivation in greenhouses can easily induce soil degradation, which considerably affects the development of sustainable vegetable production. Recently, the reductive soil disinfestation (RSD) is widely used as an alternative to chemical soil disinfestations to improve degraded greenhouse vegetable soils. Considering the importance of nitrogen (N) for plant growth and environment effect, the internal N transformation processes and rates should be well investigated in degraded vegetable soils treated by RSD, but few works have been undertaken.Methods
Three RSD-treated and three untreated degraded vegetable soils were chosen and a 15?N tracing incubation experiment differentially labeled with 15NH4NO3 or NH4 15NO3 was conducted at 25 °C under 50 % water holding capacity (WHC) for 96 h. Soil gross N transformation rates were calculated using a 15?N tracing model combined with Markov Chain Monte Carlo Metropolis algorithm (Müller et al. 2007), while the emissions of N2O and NO were also measured.Results
RSD could significantly enhance the soil microbial NH4 + immobilization rate, the heterotrophic and autotrophic nitrification rates, and the NO3 ? turnover time. The ratio of heterotrophic nitrification to total inorganic N supply rate (mineralization + heterotrophic nitrification) increased greatly from 5.4 % in untreated vegetable soil to 56.1 % in treated vegetable soil. In addition, low release potential of NO and N2O was observed in RSD-treated vegetable soil, due to the decrease in the NO and N2O product ratios from heterotrophic and autotrophic nitrifications. These significant differences in gross N transformation rates, the supply processes and capacity of inorganic N, and the NO and N2O emissions between untreated and treated vegetable soils could be explained by the elimination of accumulated NO3 ?, increased pH, and decreased electrical conductivity (EC) caused by RSD. Noticeably, the NO3 ? consumption rates were still significantly lower than the NO3 ? production rates in RSD-treated vegetable soil.Conclusions
Except for improving soil chemical properties, RSD could significantly alter the supply processes of inorganic N and reduce the release potential of N2O and NO in RSD-treated degraded vegetable soil. In order to retard the re-occurrence of NO3 ? accumulation, acidification and salinization and to promote the long-term productivity of greenhouse vegetable fields, the rational use of N fertilizer should be paid great attention to farmers in vegetable cultivation. 相似文献4.
Fabiano Daniel De Bona Fabiana Schmidt Francisco Antonio Monteiro 《Plant and Soil》2013,373(1-2):201-216
Background and aims
Plant responses to S supply are highly dependent on N nutrition. We investigated the effect of S status on metabolic, nutritional, and production variables in Brachiaria brizantha treated with different N forms. Additionally, 15N and 34S root influx were determined in plants under short- and long-term S deprivation.Methods
Plants were submitted to soil fertilization treatments consisted of combinations of N forms [without N, ammonium (NH4 +), nitrate (NO3 ?) or NH4 ++NO3 ?] at S rates (0, 15, 30, or 45 mg dm?3). N and S influx capacity was determined in hydroponically-grown plants.Results
Shoot production due to S supply increased 53, 145 and 196 % with NH4 +, NH4 ++NO3 ? and NO3 ? treatments, respectively. No or low S impaired protein synthesis and led to high accumulation of N-NO3 ? and asparagine in NO3 ?-fed plants, both alone and with NH4 +. Proline accumulation was observed in NH4 +-fed plants. Short- and long-term S deprivation did not promote considerable changes in 15N influx. 34S absorption decreased depending on the N form provided: NH4 ++NO3 ? > only NH4 + > only NO3 ? > low N.Conclusions
Including both NH4 + and NO3 ? forms in fertilizer increases N and S intake potential and thereby enhances plant growth, nutritional value and production. 相似文献5.
Background and aims
The impacts of atmospheric nitrogen (N) deposition on terrestrial ecosystem processes remain controversial, mostly because of the uncertainty regarding the fates of deposited N. We conducted a 16-week simulated deposition study to experimentally trace N in a greenhouse plant-soil system.Methods
Using a two-way factorial design, we added (15NH4)2SO4 solution twice a week to pots containing different soil organic matter (SOM) content and with or without a live plant (Salix dasyclados). The recoveries of 15N in soil, plant biomass, and leaching solution were quantified.Results
We found most 15N was retained in soil (18.0–59.2%), with significantly more 15N recovered from high-SOM soils than from low-SOM soils. Plant presence significantly increased 15N retention in soil. Plant biomass accounted for 10–20% of the 15N input, with proportionally more 15N assimilated when plants were grown in low-SOM soils. Leaching loss of 15N was relatively low (10–17%).Conclusion
Our study suggests that SOM content and plant presence significantly affect the fates of deposited N. Indeed, N would be preferentially retained in soils with high SOM content and live plant, while plants would assimilate more deposited N when grown in low SOM soils. Global biogeochemical models thus need to incorporate such soil-specific N retention and plant N assimilation. 相似文献6.
Composts are considered low analysis fertilizers because their nitrogen and phosphorus content are around 1% and the organic nitrogen mineralization rate is near 10%. If compost is added to agricultural land at the N requirement of grain crops (40 – 100 kg N ha–1), application rates approach 40–100 mg ha–1. Much lower rates may be advisable to avoid rapid accumulation of growth limiting constituents such as heavy metals found in some composts. Combining low amendment rates of composts with sufficient fertilizer to meet crop requirements is an appealing alternative which (a) utilizes composts at lower rates than those needed to supply all the crop N requirement, (b) reduces the amount of inorganic fertilizer applied to soils, and (c) reduces the accumulation of non-nutrient compost constituents in soils. A study was conducted to compare the effects of blends of biosolids compost (C) with 15N urea(U) or 15NH4 15NO3 (N) fertilizers to fertilizer alone on tall fescue (Festuca arundinacea L.) growth and N uptake. Blends which provided 0, 20, 40 or 60 mg N kg–1 application rate as compost N and 120, 100, 80 or 60 mg N kg–1 as fertilizer N, respectively, were added to Sassafras soil (Typic Hapludults). Fescue was grown on the blends in a growth chamber for 98 days. Fescue yields recorded by clippings taken at 23, 46 and 98 days and roots harvested after the 98-day clipping increased with increasing fertilizer level for both NH4NO3 and urea and with or without compost. Nitrogen uptake by fescue responded similarly to yield with increases recorded with increasing fertilizer levels with or without compost. Paired comparisons based on cumulative 98-day clippings data showed that yields from blends were equal to yields from fertilizer treatments containing the same percentage of fertilizer as the blends. These data indicated that compost did not provide sufficient plant-available N to increase yields or N uptake. None of the blends equaled 120 mg N kg–1 fertilizer rate except for 100 mg NH4NO3-or urea-N kg–1 –20 mg compost-N kg–1blends. The data suggest that biosolids compost blended with fertilizer at a rate of 2–6 mg ha –1 did not supply sufficient additional available N to increase yields or N uptake over those of fertilizer alone. 相似文献
7.
The role of ammonia volatilization in controlling the natural 15N abundance of a grazed grassland 总被引:1,自引:0,他引:1
Although the variation in natural 15N abundance in plants and soils is well characterized, mechanisms controlling N isotopic composition of organic matter are still poorly understood. The primary goal of this study was to examine the role of NH3 volatilization from ungulate urine patches in determining 15N abundance in grassland plants and soil in Yellowstone National Park. We additionally used isotopic measurements to explore the pathways that plants in urine patches take up N. Plant, soil, and volatilized NH315N were measured on grassland plots for 10 days following the addition of simulated urine. Simulated urine increased 15N of roots and soil and reduced 15N of shoots. Soil enrichment was due to the volatilization of isotopically light NH3. Acid-trapped NH315N increased from –28 (day 1) to –0.3 (day 10), and was lighter than the original urea-N added (1.2). A mass balance analysis of urea-derived N assimilated by plants indicated that most of the N taken up by plants was in the form of ammonium through roots. However, isotope data also showed that shoots directly absorbed 15N – depleted NH3-N that was volatilized from simulated urine patches. These results indicate that NH3 volatilization from urine patches enriches grassland soil with 15N and shoots are a sink for volatilized NH3, which likely leads to accelerated cycling of excreted N back to herbivores. 相似文献
8.
Rodrigo M. Boaretto Dirceu Mattos Jr. José A. Quaggio Heitor Cantarella Paulo C. O. Trivelin 《Plant and Soil》2013,365(1-2):283-290
Background and aims
Gaseous losses of ammonia (NH3) have been observed in citrus orchards when urea is surface-applied to the soils, and this loss might significantly limit the effectiveness of the nitrogen (N) fertilizer. However, a portion of the volatilized NH3 might be absorbed by the plants through the leaves. To quantify the contribution of the leaf absorption of 15NH3, a study with sweet oranges was conducted in two field areas where trees were grown at standard (480 trees ha?1) and high densities (617 trees ha?1).Methods
Plastic trays were filled with soil, covered with mown grass to simulate field management conditions, fertilized with 15N labeled urea (12 atom % excess) and placed under each of three trees in the orchards. This experimental procedure prevented the uptake of N from the labeled urea by the roots. Two weeks after 15N fertilization, the trays were removed from the field, and the soil was homogenized and sampled for chemical analyses. The citrus trees under which the trays were placed were destructively harvested, and the total N concentrations and 15N/14N ratios were determined.Results
After urea application, the NH3 losses peaked within three days and subsequently decreased to negligible amounts after 10 days. The total NH3 losses accounted for 55–82 % of the applied N. Although the NH3 absorption by the citrus leaves was proportional to the tree density in the field, only 3–7 % of the 15NH3 volatilized from the soil was recovered by the citrus trees, and the NH3 absorption was also influenced by the proximity of citrus trees to the site of urea application and the leaf areas of the trees.Conclusions
The citrus trees can absorb the NH3 volatilized from urea, even though, the amount recovered by the trees is small and does not represent a significant proportion of total gaseous N losses, what demonstrates the importance of enhanced N use efficiency practices in field to reduce losses of NH3 when urea is applied to soil surfaces. 相似文献9.
Characterization of ammonium and nitrate uptake and assimilation in roots of tea plants 总被引:3,自引:0,他引:3
Y. Y. Yang X. H. Li R. G. Ratcliffe J. Y. Ruan 《Russian Journal of Plant Physiology》2013,60(1):91-99
It has been pointed out that tea (Camellia sinensis (L.) O. Kuntze) prefers ammonium (NH 4 + ) over nitrate (NO 3 ? ) as an inorganic nitrogen (N) source. 15N studies were conducted using hydroponically grown tea plants to clarify the characteristics of uptake and assimilation of NH 4 + and NO 3 ? by tea roots. The total 15N was detected, and kinetic parameters were calculated after feeding 15NH 4 + or 15NO 3 ? to tea plants. The process of N assimilation was studied by monitoring the dynamic 15N abundance in the free amino acids of tea plant roots by GC-MS. Tea plants supplied with 15NH 4 + absorbed significantly more 15N than those supplied with 15NO 3 ? . The kinetics of 15NH 4 + and 15NO 3 ? influx into tea plants followed a classic biphasic pattern, demonstrating the action of a high affinity transport system (HATS) and a low affinity transport system (LATS). The V max value for NH 4 + uptake was 54.5 nmol/(g dry wt min), which was higher than that observed for NO 3 ? (39.3 nmol/(g dry wt min)). KM estimates were approximately 0.06 mM for NH 4 + and 0.16 mM for NO 3 ? , indicating a higher rate of NH 4 + absorption by tea plant roots. Tea plants fed with 15NH 4 + accumulated larger amounts of assimilated N, especially glutamine (Gln), compared with those fed with 15NO 3 ? . Gln, Glu, theanine (Thea), Ser, and Asp were the main free amino acids that were labeled with 15N under both conditions. The rate of N assimilation into Thea in the roots of NO 3 ? -supplied tea plants was quicker than in NH 4 + -supplied tea plants. NO 3 ? uptake by roots, rather than reduction or transport within the plant, seems to be the main factor limiting the growth of tea plants supplied with NO 3 ? as the sole N source. The NH 4 + absorbed by tea plants directly, as well as that produced by NO 3 ? reduction, was assimilated through the glutamine synthetase-glutamine oxoglutarate aminotransferase pathway in tea plant roots. The 15N labeling experiments showed that there was no direct relationship between the Thea synthesis and the preference of tea plants for NH 4 + . 相似文献
10.
Ingeborg Callesen Lars Ola Nilsson Inger Kappel Schmidt Lars Vesterdal Per Ambus Jesper Riis Christiansen Peter Högberg Per Gundersen 《Plant and Soil》2013,368(1-2):375-392
Aims
We investigated the influence of tree species on the natural 15N abundance in forest stands under elevated ambient N deposition.Methods
We analysed δ15N in litter, the forest floor and three mineral soil horizons along with ecosystem N status variables at six sites planted three decades ago with five European broadleaved tree species and Norway spruce.Results
Litter δ15N and 15N enrichment factor (δ15Nlitter–δ15Nsoil) were positively correlated with N status based on soil and litter N pools, nitrification, subsoil nitrate concentration and forest growth. Tree species differences were also significant for these N variables and for the litter δ15N and enrichment factor. Litter from ash and sycamore maple with high N status and low fungal mycelia activity was enriched in 15N (+0.9 delta units) relative to other tree species (European beech, pedunculate oak, lime and Norway spruce) even though the latter species leached more nitrate.Conclusions
The δ15N pattern reflected tree species related traits affecting the N cycling as well as site fertility and former land use, and possibly differences in N leaching. The tree species δ15N patterns reflected fractionation caused by uptake of N through mycorrhiza rather than due to nitrate leaching or other N transformation processes. 相似文献11.
Labeled nitrogen (15?N) was applied to a soil-based substrate in order to study the uptake of N by Glomus intraradices extraradical mycelium (ERM) from different mineral N (NO 3 ? vs. NH 4 + ) sources and the subsequent transfer to cowpea plants. Fungal compartments (FCs) were placed within the plant growth substrate to simulate soil patches containing root-inaccessible, but mycorrhiza-accessible, N. The fungus was able to take up both N-forms, NO 3 ? and NH 4 + . However, the amount of N transferred from the FC to the plant was higher when NO 3 ? was applied to the FC. In contrast, analysis of ERM harvested from the FC showed a higher 15?N enrichment when the FC was supplied with 15NH 4 + compared with 15NO 3 ? . The 15?N shoot/root ratio of plants supplied with 15NO 3 ? was much higher than that of plants supplied with 15NH 4 + , indicative of a faster transfer of 15NO 3 ? from the root to the shoot and a higher accumulation of 15NH 4 + in the root and/or intraradical mycelium. It is concluded that hyphae of the arbuscular mycorrhizal fungus may absorb NH 4 + preferentially over NO 3 ? but that export of N from the hyphae to the root and shoot may be greater following NO 3 ? uptake. The need for NH 4 + to be assimilated into organically bound N prior to transport into the plant is discussed. 相似文献
12.
Segundo Urquiaga Rogério P. Xavier Rafael F. de Morais Rafael B. Batista Nivaldo Schultz José M. Leite Jerusa Maia e Sá Karolina P. Barbosa Alexander S. de Resende Bruno J. R. Alves Robert M. Boddey 《Plant and Soil》2012,356(1-2):5-21
Aims
In Brazil N fertilization of sugarcane (Saccharum spp.) is low compared to most other countries. 15N-aided studies and the occurrence of many N2-fixing bacteria associated with cane plants suggest significant contributions from biological N2 fixation (BNF). The objective of this study was to evaluate BNF contributions to nine cane varieties under field conditions using N balance and 15N natural abundance techniques.Methods
The field experiment was planted near Rio de Janeiro in 1989, replanted in 1999 and harvested 13 times until 2004. Soil total N was evaluated at planting and again in 2004. Samples of cane leaves and weeds for the evaluation of 15N natural abundance were taken in 2000, 2003 and 2004.Results
N accumulation of the commercial cane varieties and a variety of Saccharum spontaneum were persistently high and N balances (60 to 107?kg?N ha?1?yr?1) significantly (p?<?0.05) positive. The δ15N of leaf samples were lower than any of the weed reference plants and data obtained from a greenhouse study indicated that this was not due to the cane plants tapping into soil of lower 15N abundance at greater depth.Conclusion
The results indicate that the Brazilian varieties of sugarcane were able to obtain at least 40?kg?N ha?1?yr?1 from BNF. 相似文献13.
Arezoo Taghizadeh-Toosi Tim J. Clough Robert R. Sherlock Leo M. Condron 《Plant and Soil》2012,353(1-2):73-84
Aims
Ammonia (NH3) can be volatilised from the soil surface following the surface application of nitrogenous fertilisers or ruminant urine deposition. The volatilisation of NH3 is of agronomic and environmental concern, since NH3-N is a form of reactive nitrogen. Ammonia adsorption onto biochar has the potential to mitigate NH3 losses, but to date no studies have examined the potential for reducing NH3 losses when biochar is present in the soil matrix.Methods
We used 15N-enriched urine to examine the effect of incorporating a wood based low-temperature biochar into soil on NH3 volatilisation. Then, we extracted the urine-treated biochar and compared its potential to act as a plant N source with fresh biochar, while growing ryegrass (Lolium perenne).Results
The NH3 volatilisation from 15N-labelled ruminant urine, applied to soil, was reduced by 45% after incorporating either 15 or 30?t ha?1 of biochar. When the urine-treated biochar particles were transferred into fresh soil, subsequent plant growth was not affected but the uptake of 15N in plant tissues increased, indicating that the adsorbed-N was plant available.Conclusions
Our results show that incorporating biochar into the soil can significantly decrease NH3 volatilisation from ruminant urine and that the NH3-N adsorbed onto the biochar is bioavailable. Further studies are now required to assess the temporal dynamics of the N pools involved. 相似文献14.
Dynamics of fertilizer-derived organic nitrogen fractions in an arable soil during a growing season 总被引:8,自引:0,他引:8
Huijie Lü Hongbo He Jinsong Zhao Wei Zhang Hongtu Xie Guoqing Hu Xiao Liu Yeye Wu Xudong Zhang 《Plant and Soil》2013,373(1-2):595-607
Background
Inorganic fertilizer is one of the most important anthropogenic inputs which influences soil nutrient turnover in agricultural ecosystems. However, as the key process involved in the maintenance, transformation and stability of soil nitrogen (N), the incorporation and allocation of fertilizer N between different soil organic N (SON) fractions in a growing season remains largely unknown.Methods
In this study, a field experiment was conducted in triplicate of micro-plots and a total of 200 kg N ha?1 (15?N-labeled (NH4)2SO4, 98 atom %) was applied as a basal dressing and two top dressings, at jointing and filling stages, respectively, to a maize crop during one growing season. The distribution and seasonal dynamics of fertilizer N in different SON fractions (i.e., amino acids, amino sugars, hydrolyzable ammonium N and acid insoluble-N) were measured by liquid/gas chromatography–mass spectrometry (LC/GC-MS) and element analysis-combustion-isotope ratio mass spectrometry (EA-C-IRMS) techniques. Path analysis was used to evaluate the transformation processes between organic N fractions derived from fertilizer and N supply strategy in soil-plant system.Results
The accumulation of fertilizer-derived N in different organic fractions was season-specific. At jointing stage, preferential enrichment of 15?N was found in soil amino acids plus amino sugars, indicating the active biological immobilization of basal dressing fertilizer N. Nevertheless, there is still a small proportion of fertilizer N stabilized in the acid insoluble fraction. The accumulation of the residual fertilizer N in hydrolyzable ammonium N reached a maximum at filling stage and then declined significantly, implying the rapid release of the fertilizer N remained in mineral forms. The contents of amino acids changed slightly, but they played a very important role in mediating SON transformation.Conclusion
The hydrolyzable ammonium N was a temporary pool for rapid fertilizer N retention and simultaneously was apt to release N for crop uptake in the current season. In contrast, the amino acids could serve as a transitional pool of available N in the soil-crop system, while the acid insoluble fraction was as a stable pool of fertilizer N. Importantly, there is an interim shift among different pools to maintain soil N turnover; hence N in the amino acid fraction mediates N supply and the depolymerization of SON constituents controls the proceeding of fertilizer N cycling in the soil-plant system. 相似文献15.
Aims
Effects of different soil amendments were investigated on methane (CH4) emission, soil quality parameters and rice productivity in irrigated paddy field of Bangladesh.Methods
The experiment was laid out in a randomized complete block design with five treatments and three replications. The experimental treatments were urea (220 kg ha?1) + rice straw compost (2 t ha?1) as a control, urea (170 kg ha?1) + rice straw compost (2 t ha?1) + silicate fertilizer, urea (170 kg ha?1) + sesbania biomass (2 t ha?1 ) + silicate fertilizer, urea (170 kg ha?1) + azolla biomass (2 t ha?1) + cyanobacterial mixture 15 kg ha?1 silicate fertilizer, urea (170 kg ha?1) + cattle manure compost (2 t ha?1) + silicate fertilizer.Results
The average of two growing seasons CH4 flux 132 kg ha?1 was recorded from the conventional urea (220 kg ha?1) with rice straw compost incorporated field plot followed by 126.7 (4 % reduction), 130.7 (1.5 % reduction), 116 (12 % reduction) and 126 (5 % reduction) kg CH4 flux ha?1 respectively, with rice straw compost, sesbania biomass, azolla anabaena and cattle manure compost in combination urea and silicate fertilizer applied plots. Rice grain yield was increased by 15 % and 10 % over the control (4.95 Mg ha?1) with silicate plus composted cattle manure and silicate plus azolla anabaena, respectively. Soil quality parameters such as soil organic carbon, total nitrogen, microbial biomass carbon, soil redox status and cations exchange capacity were improved with the added organic materials and azolla biofertilizer amendments with silicate slag and optimum urea application (170 kg ha?1) in paddy field.Conclusion
Integrated application of silicate fertilizer, well composted organic manures and azolla biofertilizer could be an effective strategy to minimize the use of conventional urea fertilizer, reducing CH4 emissions, improving soil quality parameters and increasing rice productivity in subtropical countries like Bangladesh. 相似文献16.
Zubin Xie Yanping Xu Gang Liu Qi Liu Jianguo Zhu Cong Tu James E. Amonette Georg Cadisch Jean W. H. Yong Shuijin Hu 《Plant and Soil》2013,370(1-2):527-540
Aims
Two field microcosm experiments and 15N labeling techniques were used to investigate the effects of biochar addition on rice N nutrition and GHG emissions in an Inceptisol and an Ultisol.Methods
Biochar N bioavailability and effect of biochar on fertilizer nitrogen-use efficiency (NUE) were studied by 15N-enriched wheat biochar (7.8803 atom% 15N) and fertilizer urea (5.0026 atom% 15N) (Experiment I). Corn biochar and corn stalks were applied at 12 Mg?ha?1 to study their effects on GHG emissions (Experiment II).Results
Biochar had no significant impact on rice production and less than 2 % of the biochar N was available to plants in the first season. Biochar addition increased soil C and N contents and decreased urea NUE. Seasonal cumulative CH4 emissions with biochar were similar to the controls, but significantly lower than the local practice of straw amendment. N2O emissions with biochar were similar to the control in the acidic Ultisol, but significantly higher in the slightly alkaline Inceptisol. Carbon-balance calculations found no major losses of biochar-C.Conclusion
Low bio-availability of biochar N did not make a significantly impact on rice production or N nutrition during the first year. Replacement of straw amendments with biochar could decrease CH4 emissions and increase SOC stocks. 相似文献17.
Rafael F. de Morais Diego M. Quesada Veronica M. Reis Segundo Urquiaga Bruno J. R. Alves Robert M. Boddey 《Plant and Soil》2012,356(1-2):23-34
Aims
Because of its high dry matter (DM) productivity, elephant grass (Pennisetum purpureum) is an ideal candidate for biomass production for biofuel production if low N fertilizer rates are used to avoid high fossil fuel inputs. The objective of this study was to investigate the potential of different elephant grass genotypes to obtain contributions of plant-associated biological N2 fixation (BNF).Methods
Three field experiments with 4 or 5 different genotypes were conducted on low-fertility Acrisols, two in Rio de Janeiro State and one in Espirito Santo for the evaluation of DM and N accumulation and 15N abundance.Results
DM and N accumulation rates of four genotypes in the two experiments in Rio State stabilized at high levels after 2?years of growth. In all experiments the spontaneously-occurring weeds in the plots were significantly higher in 15N abundance than the elephant grass genotypes. The lower 15N abundance of the elephant grass was shown not to be due to lower δ15N abundance at depth in the soil.Conclusions
Four of the grass genotypes obtained between 18 and 70% of their N from BNF amounting to inputs of between 36 and 132?kg N ha?1?yr?1. 相似文献18.
Mona N. Högberg Róbert Blaško Lisbet Holm Bach Niles J. Hasselquist Gustaf Egnell Torgny Näsholm Peter Högberg 《Plant and Soil》2014,381(1-2):45-60
Background and aims
To find out how N-saturated forests can return to an N-limited state, we examined the recovery of biotic N sinks under decreasing N supply.Methods
. We studied a 40-year-old experiment in Pinus sylvestris forest, with control plots, N0, three N treatments, N1-N3, of which N3 was stopped after 20 years, allowing observation of recovery.Results
In N3, the N concentration in foliage was still slightly elevated, but the N uptake capacity of ectomycorrhizal (ECM) roots in N3 was no longer lower than in N0. Per area the amount of a biomarker for fungi, here mainly attributed ECM, was higher in N3 and N0 than in N1 and N2. Retention of labeled 15NH4 + by the soil was greater in the control (99 %) and N3 (86 %), than in N1 (45 %) and N2 (29 %); we ascribe these differences to biotic retention because cation exchange capacity did not vary. Gross N mineralisation and retention of N correlated, negatively and positively, respectively, with abundance of ECM fungal biomarker.Conclusions
. The results suggest a key role for ECM fungi in regulating the N cycle. We propose, in accordance with plant C allocation theory, that recovery is driven by increased tree below-ground C allocation to ECM roots and fungi. 相似文献19.
Carbon footprint of spring barley in relation to preceding oilseeds and N fertilization 总被引:3,自引:0,他引:3
Yantai Gan Chang Liang William May Sukhdev S. Malhi Junyi Niu Xiaoyu Wang 《The International Journal of Life Cycle Assessment》2012,17(5):635-645
Purpose
Carbon footprint of field crops can be lowered through improved cropping practices. The objective of this study was to determine the carbon footprint of spring barley (Hordeum vulgare L.) in relation to various preceding oilseed crops that were fertilized at various rates of inorganic N the previous years. System boundary was from cradle-to-farm gate.Materials and methods
Canola-quality mustard (Brassica juncea L.), canola (Brassica napus L.), sunflower (Helianthus annuus L.), and flax (Linum usitatissimum L.) were grown under the N fertilizer rates of 10, 30, 70, 90, 110, 150, and 200?kg?N?ha?1 the previous year, and spring barley was grown on the field of standing oilseed stubble the following year. The study was conducted at six environmental sites; they were at Indian Head in 2005, 2006 and 2007, and at Swift Current in 2004, 2005 and 2006, Saskatchewan, Canada.Results and discussion
On average, barley grown at humid Indian Head emitted greenhouse gases (GHGs) of 1,003?kg?CO2eq?ha?1, or 53% greater than that at the drier Swift Current site. Production and delivery of fertilizer N to farm gate accounted for 26% of the total GHG emissions, followed by direct and indirect emissions of 28% due to the application of N fertilizers to barley crop. Emissions due to N fertilization were 26.6 times the emission from the use of phosphorous, 5.2 times the emission from pesticides, and 4.2 times the emission from various farming operations. Decomposition of crop residues contributed emissions of 173?kg?CO2eq?ha?1, or 19% of the total emission. Indian Head-produced barley had significantly greater grain yield, resulting in about 11% lower carbon footprint than Swift Current-produced barley (0.28 vs. 0.32?kg?CO2eq?kg?1 of grain). Emissions in the barley production was a linear function of the rate of fertilizer N applied to the previous oilseed crops due to increased emissions from crop residue decomposition coupled with higher residual soil mineral N.Conclusions
The key to lower the carbon footprint of barley is to increase grain yield, make a wise choice of crop types, reduce N inputs to crops grown in the previous and current growing seasons, and improved N use efficiency. 相似文献20.