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1.
Aims
Decomposition of leaf litterfall plays a major role for nitrogen (N) dynamics in soils. However, little is known as to which extent beech leaf litter contributes to N turnover and nitrous oxide (N2O) emissions within one decade after litterfall.Methods
In 1997, we exchanged recently fallen leaf litter by 15N-labelled litter in a beech stand (Fagus sylvatica) at the Solling, Germany. Measurements were conducted 2–3 and 10–11 years after litter exchange.Results
Two years after litter exchange, 92 % of added 15N was recovered in the surface 10 cm of the soil. The labelled N was primarily found in the upper part of the F layer of the moder type humus. Eleven years after litter exchange, 73 % of the added 15N was lost and the remaining 27 % was mainly recovered in the lower part of the F layer indicating N sequestration. The remaining leaf litter N was subject to measurable N mineralisation (2–3 % of litter N) and N2O production (0.02 %). Between 0.3 % (eleventh year) and 0.6 % (second year) of total annual N2O emissions were attributed to beech leaf litter of a single year.Conclusions
Most of the annual N2O emissions (1.33–1.54 kg N ha?1 yr?1) were probably derived from older soil N pools. 相似文献2.
Background and purpose
Rapid increases in atmospheric carbon dioxide concentration ([CO2]) may increase crop residue production and carbon: nitrogen (C:N) ratio. Whether the incorporation of residues produced under elevated [CO2] will limit soil N availability and fertilizer N recovery in the plant is unknown. This study investigated the interaction between crop residue incorporation and elevated [CO2] on the growth, grain yield and the recovery of 15N-labeled fertilizer by wheat (Triticum aestivum L. cv. Yitpi) under controlled environmental conditions.Methods
Residue for ambient and elevated [CO2] treatments, obtained from wheat grown previously under ambient and elevated [CO2], respectively, was incorporated into two soils (from a cereal-legume rotation and a cereal-fallow rotation) 1 month before the sowing of wheat. At the early vegetative stage 15N-labeled granular urea (10.22 atom%) was applied at 50 kg?N ha?1 and the wheat grown to maturity.Results
When residue was not incorporated into the soil, elevated [CO2] increased wheat shoot (16 %) and root biomass (41 %), grain yield (19 %), total N uptake (4 %) and grain N removal (8 %). However, the positive [CO2] fertilization effect on these parameters was absent in the soil amended with residue. In the absence of residue, elevated [CO2] increased fertilizer N recovery in the plant (7 %), but when residue was incorporated elevated [CO2] decreased fertilizer N recovery.Conclusions
A higher fertilizer application rate will be required under future elevated [CO2] atmospheres to replenish the extra N removed in grains from cropping systems if no residue is incorporated, or to facilitate the [CO2] fertilization effect on grain yield by overcoming N immobilization resulting from residue amendment. 相似文献3.
Background and aims
As low initial uptake and essentially zero later uptake limit efficacy of N fertilization for temperate conifers, we investigated factors limiting long-term tree uptake of residual 15?N-labeled fertilizer.Methods
We used a pot bioassay to assess availability of 15?N from soil sampled 10 years after fertilization of a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand with 15?N-urea (200 kg N ha?1). Douglas-fir seedlings were grown for 2 years in organic (designated LFH) and mineral soil (0–10 cm) layers reconstructed from control and fertilized plots; residual fertilizer N amounted to 10 % of LHF and 5 % of MIN N.Results
Percentage recovery of residual 15?N in seedlings was not affected by the original season of fertilization (spring vs. fall), but differed by the source of 15?N excess. LFH was a better source of residual 15?N; 12.4 % of residual LFH 15?N was taken up by seedlings and 7.6 % transferred to soil, whereas mineral soil yielded only 8.3 % of residual 15?N to seedling uptake and 2.4 % to LFH. Extractable inorganic N was 2–3 orders of magnitude higher in fallow pots.Conclusions
Ten-year residual fertilizer 15?N was clearly cycling between LFH and mineral soil and available to seedlings, indicating that other factors such as denitrification, leaching, and asynchrony of soil N mineralization and tree uptake limit long-term residual N fertilizer uptake in the field. 相似文献4.
German Andres Estrada Vera Lúcia Divan Baldani Danilo Messias de Oliveira Segundo Urquiaga José Ivo Baldani 《Plant and Soil》2013,369(1-2):115-129
Background and Aims
Plant growth-promoting bacteria, mainly diazotrophs and phosphate solubilizers, can reduce the use of chemical fertilizers for rice crops. Here, diazotrophic bacteria isolated from rice were screened for their ability to solubilize inorganic P (Pi) in vitro and in association with rice plants cultivated in pots.Methods
Forty-nine isolates were tested for the ability to solubilize Pi on NBRIP and GL agar plate media and seven selected strains were further evaluated in NBRIP liquid medium. Three of these strains were inoculated in rice plants grown in soil pots containing 15N-labeled fertilizer and two sources of P: tricalcium phosphate (TCP) or simple superphosphate (SSP). The dry matter, yield, N, P, and the 15N content accumulated in plant tissues were measured at 135 days after planting.Results
Seven strains belonging to the genera Herbaspirillum and Burkholderia formed a halo of solubilized Pi on agar plates. The Burkholderia strains showed peak soluble P (around 200 mg P L?1) on the fifth day when grown in NBRIP liquid medium for 14 days. Inoculation of Herbaspirillum strains (H18, ZA15) and a Burkholderia vietaminensis strain (AR114) increased rice grain yield from 33 to 47 % with TCP and 18 to 44 % with TSS, respectively. The bacterial inoculation led to enhanced N-use efficiency of the 15N-labeled fertilizer.Conclusion
These results suggest that the selection and use of P-solubilizing diazotrophic bacteria are a good strategy to promote P solubilization and/or N use efficiency in rice plants. 相似文献5.
Nitrogen dynamics following field application of biochar in a temperate North American maize-based production system 总被引:5,自引:0,他引:5
David Güereña Johannes Lehmann Kelly Hanley Akio Enders Charles Hyland Susan Riha 《Plant and Soil》2013,365(1-2):239-254
Background and aims
Biochar additions to tropical soils have been shown to reduce N leaching and increase N use efficiency. No studies exist verifying reduced N leaching in field experiments on temperate agricultural soils or identifying the mechanism for N retention.Methods
Biochar derived from maize stover was applied to a maize cropping system in central New York State at rates of 0, 1, 3, 12, and 30 t?ha-1 in 2007. Secondary N fertilizer was added at 100, 90, 70, and 50 % of the recommended rate (108 kg N ha-1). Nitrogen fertilizer enriched with 15?N was applied in 2009 to the 0 and 12 t?ha-1 of biochar at 100 and 50 % secondary N application.Results
Maize yield and plant N uptake did not change with biochar additions (p?>?0.05; n?=?3). Less N (by 82 %; p?<?0.05) was lost after biochar application through leaching only at 100 %?N fertilization. The reason for an observed 140 % greater retention of applied 15?N in the topsoil may have been the incorporation of added 15?N into microbial biomass which increased approximately three-fold which warrants further research. The low leaching of applied fertilizer 15?N (0.42 % of applied N; p?<?0.05) and comparatively high recovery of applied 15?N in the soil (39 %) after biochar additions after one cropping season may also indicate greater overall N retention through lower gaseous or erosion N losses with biochar.Conclusions
Addition of biochar to fertile soil in a temperate climate did not improve crop growth or N use efficiency, but increased retention of fertilizer N in the topsoil. 相似文献6.
Fertilizer N uptake of paddy rice in two soils with different fertility under experimental warming with elevated CO2 总被引:1,自引:0,他引:1
Hong-Shik Nam Jin-Hyeob Kwak Sang-Sun Lim Woo-Jung Choi Sun-Il Lee Dong-Suk Lee Kwang-Seung Lee Han-Yong Kim Sang-Mo Lee Miwa Matsushima 《Plant and Soil》2013,369(1-2):563-575
Background and aims
Only limited information is available in the research area on the effect of elevated CO2 concentration ([CO2]) and air temperature (Tair) on the fertilizer N uptake by rice. This study was conducted to investigate changes in rice uptake of N derived from fertilizer (NDFF) and soil (NDFS) as well as fertilizer N uptake efficiency (FUE) with elevated [CO2] and Tair in two soils with different fertility.Methods
Rice (Oryza sativa L.) plants were grown with 15N-urea for two growing seasons (2007 in the less fertile and 2008 in the more fertile soil) in temperature gradient chambers under two (ambient and elevated) levels of [CO2] and Tair regimes. At harvest, dry matter (DM) and N uptake amount of rice compartments (root, shoot, and grain) were determined.Results
The DM of whole rice increased (P?<?0.01) with co-elevation of [CO2] and Tair in both years (by 28.0 % in 2007 and by 27.4 % in 2008). The DM in 2008 was greater than that in 2007 by 48.1 to 63.1 % probably due to better soil fertility as well as longer sunshine hours (456 h vs. 568 h). Co-elevation of [CO2] and Tair increased total N uptake, NDFF, and NDFS by 19.4 to 29.1 % in general compared to the ambient conditions. The FUE increased with co-elevation of [CO2] and Tair from 46.5 to 59.5 % in 2007 and from 36.7 to 43.8 % in 2008.Conclusions
The projected global warming with elevated [CO2] is expected to increase FUE via enhanced DM accumulation with less increments in the soils that have higher indigenous soil N availabilities. 相似文献7.
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8.
Purpose
This study investigated the residual contribution of legume and fertilizer nitrogen (N) to a subsequent crop under the effect of elevated carbon dioxide concentration ([CO2]).Methods
Field pea (Pisum sativum L.) was labeled in situ with 15N (by absorption of a 15N-labeled urea solution through cut tendrils) under ambient and elevated (700 μmol mol–1) [CO2] in controlled environment glasshouse chambers. Barley (Hordeum vulgare L.) and its soil were also labeled under the same conditions by addition of 15N-enriched urea to the soil. Wheat (Triticum aestivum L.) was subsequently grown to physiological maturity on the soil containing either 15N-labeled field pea residues (including 15N-labeled rhizodeposits) or 15N-labeled barley plus fertilizer 15N residues.Results
Elevated [CO2] increased the total biomass of field pea (21 %) and N-fertilized barley (23 %), but did not significantly affect the biomass of unfertilized barley. Elevated [CO2] increased the C:N ratio of residues of field pea (18 %) and N-fertilized barley (19 %), but had no significant effect on that of unfertilized barley. Elevated [CO2] increased total biomass (11 %) and grain yield (40 %) of subsequent wheat crop regardless of rotation type in the first phase. Irrespective of [CO2], the grain yield and total N uptake by wheat following field pea were 24 % and 11 %, respectively, higher than those of the wheat following N-fertilized barley. The residual N contribution from field pea to wheat was 20 % under ambient [CO2], but dropped to 11 % under elevated [CO2], while that from fertilizer did not differ significantly between ambient [CO2] (4 %) and elevated [CO2] (5 %).Conclusions
The relative value of legume derived N to subsequent cereals may be reduced under elevated [CO2]. However, compared to N fertilizer application, legume incorporation will be more beneficial to grain yield and N supply to subsequent cereals under future (elevated [CO2]) climates. 相似文献9.
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10.
Assessment of carbon sustainability under different tillage systems in a double rice cropping system in Southern China 总被引:1,自引:0,他引:1
Jian-Fu Xue Sheng-Li Liu Zhong-Du Chen Fu Chen Rattan Lal Hai-Ming Tang Hai-Lin Zhang 《The International Journal of Life Cycle Assessment》2014,19(9):1581-1592
Purpose
Adoption of the carbon (C)-friendly and cleaner technology is an effective solution to offset some of the anthropogenic emissions. Conservation tillage is widely considered as an important sustainable technology and for the development of conservation agriculture (CA). Thus, the objective of this study was to assess the C sustainability of different tillage systems in a double rice (Oryza sativa L.) cropping system in southern China.Methods
The experiment was established with no-till (NT), rotary tillage (RT), and conventional tillage (CT) treatments since 2005. Emission of greenhouse gasses (GHG), C footprint (CF), and ecosystem service through C sequestration in different tillage systems were compared.Result and discussion
Emission of GHG from agricultural inputs (Mg CO2-eq ha?1 year?1) ranged from 1.81 to 1.97 for the early rice, 1.82 to 1.98 for the late rice, and 3.63 to 3.95 for the whole growing season, respectively. The CF (kg CO2-eq kg?1 of rice year?1) in the whole growing seasons were 1.27, 1.85, and 1.40 [excluding soil organic carbon (SOC) storage] and 0.54, 1.20, and 0.72 (including SOC storage) for NT, RT, and CT, respectively. The value of ecosystem services on C sequestration for the whole growing seasons ranged from ¥3,353 to 4,948 ha?1 year?1 and followed the order of NT > CT > RT. The C sustainability under NT was better than that under RT for the late, but reversed for the early rice. However, NT system had better C sustainability for the whole cropping system compared with CT.Conclusions
Therefore, NT is a preferred technology to reduce GHG emissions, increase ecosystem service functions of C sequestration, and improve C sustainability in a double rice cropping region of Southern China. 相似文献11.
Background and aims
Knowledge about the effects of water and fertilizer on soil CO2 efflux (SCE) and Q 10 is essential for understanding carbon (C) cycles and for evaluating future global C balance. A two-year field experiment was conducted to determine the effects of water, fertilizer, and temperature on SCE in semiarid grassland in northern China.Methods
SCE, as well as environmental factors was measured in two grasslands, one with bunge needlegrass (BNE, Stipa bungeana) and one with purple alfalfa (ALF, Medicago sativa), with four treatments: CK (unwatered and unfertilized); W (50 mm water addition yr?1); F (50 kg phosphorus (P) fertilizer ha?1 yr?1 for ALF, 100 kg nitrogen (N)?+?50 kg P fertilizer ha?1 yr?1 for BNE); and W + F.Results
During the 11-month experimental period from July 2010 to October 2011, the addition of water consistently stimulated mean SCE in BNE and ALF, and the positive effects were relatively stronger during dry seasons. P fertilization consistently enhanced SCE in ALF, and the positive effect was strongly dependent on the availability of soil water. The effects of N plus P fertilization on SCE in BNE varied seasonally from significant increases to small reductions to no response. Water addition increased the Q 10 of SCE in ALF by 11 % but had no effect in BNE. Fertilization, however, reduced the Q 10 of SCE by 21 % and 13 % for BNE and ALF, respectively. Models that rely only on Q 10 underestimated the emissions of soil CO2 by 8–15 % at the study site, which was mediated by species and treatment.Conclusions
Responses of SCE and its temperature sensitivity to water and fertilizer may vary with species and depend on the period of measurement. Models of SCE need to incorporate the availability of ecosystemic water and nutrients, as well as species, and incorporate different environmental factors when determining the impact of water, nutrients, and species on SCE. 相似文献12.
Sharing N resources in the early growth of rapeseed intercropped with faba bean: does N transfer matter? 总被引:1,自引:0,他引:1
Background and aims
Legume-brassica intercrops may help to reduce N fertilizer input. We tested whether (i) intercropping with faba bean can improve N status of rapeseed, and (ii) root complementarity and/or N transfer is involved in such performance.Methods
Pre-germinated rapeseed and faba bean were grown either together or in monospecific rhizotrons (2 plants per rhizotron). Root growth was recorded. N rhizodeposition of the crops and N transferred between species were assessed using a 15N stem-labelling method.Results
Intercropped rapeseeds accumulated 20 % higher amounts of N per plant than monocultures. Up to 32 days after sowing, root distribution in the rhizotrons was favourable to physical sharing of the soil N: 64 % of faba bean root length was located in the upper part, as 70 % was in the lower part for rapeseed. At late flowering of the faba bean (52 days after sowing), N rhizodeposition of the two crops were similar and reached 8 to 9 % of the plant N. N transferred from the faba bean to the rapeseed was similar to that transferred from the rapeseed to the faba bean.Conclusions
Niche complementarity benefits more intercropped rapeseed than net N fluxes between species in the early growth. 相似文献13.
Nitrous oxide emissions and nitrate leaching from a rain-fed wheat-maize rotation in the Sichuan Basin, China 总被引:3,自引:0,他引:3
Minghua Zhou Bo Zhu Klaus Butterbach-Bahl Xunhua Zheng Tao Wang Yanqiang Wang 《Plant and Soil》2013,362(1-2):149-159
Aims
A 3-year field experiment (October 2004–October 2007) was conducted to quantify N2O fluxes and determine the regulating factors from rain-fed, N fertilized wheat-maize rotation in the Sichuan Basin, China.Methods
Static chamber-GC techniques were used to measure soil N2O fluxes in three treatments (three replicates per treatment): CK (no fertilizer); N150 (300 kg N fertilizer ha?1 yr?1 or 150 kg N?ha?1 per crop); N250 (500 kg N fertilizer ha?1 yr?1 kg or 250 kg N?ha?1 per crop). Nitrate (NO 3 ? ) leaching losses were measured at nearby sites using free-drained lysimeters.Results
The annual N2O fluxes from the N fertilized treatments were in the range of 1.9 to 6.7 kg N?ha?1 yr?1 corresponding to an N2O emission factor ranging from 0.12 % to 1.06 % (mean value: 0.61 %). The relationship between monthly soil N2O fluxes and NO 3 - leaching losses can be described by a significant exponential decaying function.Conclusions
The N2O emission factor obtained in our study was somewhat lower than the current IPCC default emission factor (1 %). Nitrate leaching, through removal of topsoil NO 3 ? , is an underrated regulating factor of soil N2O fluxes from cropland, especially in the regions where high NO 3 - leaching losses occur. 相似文献14.
Contribution of winter cover crop amendments on global warming potential in rice paddy soil during cultivation 总被引:3,自引:0,他引:3
Background and aims
Winter cover crop cultivation during the fallow season has been strongly recommended in mono-rice paddy soil to improve soil quality, but its impact in increasing the greenhouse gases (GHGs) emissions during rice cultivation when applied as green manure has not been extensively studied. In order to recommend a preferable cover crop which can increase soil productivity and suppress GHG emission impact in paddy soil, the effect of winter cover crop addition on rice yield and total global warming potential (GWP) was studied during rice cultivation.Methods
Two cover crops (Chinese milk vetch, Astragalus sinicus L., hereafter vetch, and rye, Secale cerealis) having different carbon/nitrogen (C/N) ratios were cultivated during the rice fallow season. The fresh above-ground biomasses of vetch [25 Mg fresh weight (FW) ha?1, moisture content (MC) 86.9 %, C/N ratio 14.8] and rye (29 Mg rye FW ha?1, MC 78.0 %, C/N ratio 64.3) were incorporated as green manure 1 week before rice transplanting (NPK + vetch, and NPK + rye). The NPK treatment was installed for comparison as the control. During the rice cultivation, methane (CH4) and nitrous oxide (N2O) gases were collected simultaneously once a week using the closed-chamber method, and carbon dioxide (CO2) flux was estimated using the soil C balance analysis. Total GWP impact was calculated as CO2 equivalents by multiplying the seasonal CH4, CO2, and N2O fluxes by 25, 1, and 298, respectively.Results
Methane mainly covered 79–81 % of the total GWP, followed by CO2 (14–17 %), but the N2O contribution was very small (2–5 %) regardless of the treatment. Seasonal CH4 fluxes significantly increased to 61 and 122 % by vetch and rye additions, respectively, compared to that of the NPK treatment. Similarly, the estimated seasonal CO2 fluxes increased at about 197 and 266 % in the vetch and rye treatments, respectively, compared with the NPK control plots. Based on these results, the total GWP increased to 163 and 221 % with vetch and rye applications, respectively, over the control treatment. Rice productivity was significantly increased with the application of green manure due to nutrient supply; however, vetch was more effective. Total GWP per grain yield was similar with the vetch (low C/N ratio) and NPK treatments, but significantly increased with the rye (high C/N ratio) application, mainly due to its higher CH4 emission characteristic and lower rice productivity increase.Conclusions
A low C/N ratio cover crop, such as vetch, may be a more desirable green manure to reduce total GWP per grain yield and to improve rice productivity. 相似文献15.
Effects of seeding ratios and nitrogen fertilizer on ecosystem respiration of common vetch and oat on the Tibetan plateau 总被引:1,自引:0,他引:1
Zhenhua Zhang Jichuang Duan Shiping Wang Caiyun Luo Xiaoxue Zhu Burenbayin Xu Xiaofeng Chang Shujuan Cui 《Plant and Soil》2013,362(1-2):287-299
Background and aims
Few studies have investigated the effect of nitrogen (N) fertilizer on ecosystem respiration (Re) under mixed legume and grass pastures sown at different seeding ratios,and data are almost entirely lacking for alpine meadow of the Tibetan Plateau. Our aim was to test the hypothesis that although a combination of legumes with grass and N fertilizer increases Re the combination decreases Re intensity (i.e. Re per unit of aboveground biomass) due to greater increases in aboveground biomass compared to increases in Re.Methods
This hypothesis was tested using different seeding ratios of common vetch (Vicia sativa L.) and oat (Avena sativa L.) with and without N fertilizer on the Tibetan plateau in 2009 and 2010. Re was measured using a static closed opaque chamber. Re intensity was estimated as the ratio of seasonal average Re during the growing season to aboveground biomass.Results
Compared with common vetch monoculture pasture, mixed legume-grass pastures only significantly decreased Re intensity (with a decrease of about 75 %–87 %) in the drought year 2009 due to greater increases in aboveground biomass compared to increases in Re. There were no significant differences in Re and Re intensity among different seeding ratios of oat and common vetch in either year. N fertilizer significantly decreased Re intensity for common vetch monoculture pasture by 24.5 % in 2009 and 69.5 % in 2010 although it did not significantly affect plant production and Re.Conclusions
From the perspective of forage yield and Re, planting mixed legume-grass pastures without N fertilizer is a preferable way to balance the twin objectives of forage production and mitigation of atmospheric greenhouse gas emissions in alpine regions. 相似文献16.
Aims
Two pot experiments in a “walk-in” growth chamber with controlled day and night temperatures were conducted to investigate the influence of elevated temperatures along with rice straw incorporation on methane (CH4) and nitrous oxide (N2O) emissions as well as rice yield.Methods
Three temperature regimes–29/25, 32/25, and 35/30 °C (Exp. I) and 29/22, 32/25, and 35/28 °C (Exp. II), representing daily maxima/minima were used in the study. Two amounts of rice straw (0 and 6 t ha?1) were applied with four replications in each temperature regime. CH4 and N2O emissions as well as soil redox potential (Eh) were monitored weekly throughout the rice-growing period.Results
Elevated temperatures increased CH4 emission rates, with a more pronounced effect from flowering to maturity. The increase in emissions was further enhanced by incorporation of rice straw. A decrease in soil Eh to <?100 mV and CH4 emissions was observed early in rice straw–incorporated pots while the soil without straw did not reach negative Eh levels (Exp. I) or showed a delayed decrease (Exp. II). Moreover, soil with high organic C (Exp. II) had higher CH4 emissions. In contrast to CH4 emissions, N2O emissions were negligible during the rice-growing season. The global warming potential (GWP) was highest at high temperature with rice straw incorporation compared with low temperature without rice straw. On the other hand, the high temperature significantly increased spikelet sterility and reduced grain yield (p?<?0.05).Conclusions
Elevated temperature increased GWP while decreased rice yield. This suggests that global warming may result in a double negative effect: higher emissions and lower yields. 相似文献17.
Background and aims
A critical soil mineral nitrogen concentration (Nmin) for guiding fertilizer application and maximizing maize grain yield is needed.Methods
A three-year field experiment with three N regimes, unfertilized (N0), optimized N management (Opt.) and conventional N practice (Con.) was performed in maize.Results
The mean soil Nmin in 0–60 cm soil profile for N0, Opt. and Con. treatments was 2.0, 6.7 and 8.9 mg?kg–1 at V8–VT growth stages and 2.2, 6.1 and 11.2 mg?kg–1 on average over the whole growth season, respectively. Correspondingly, the soil N supplying capacity (soil Nmin content?+?fertilizer N) of the three N treatments was smaller, identical or greater than the plant N accumulation at different growth stages. The Opt. treatment had significantly higher N use efficiency, N recovery efficiency and N partial factor productivity compared with the Con. treatment, while it did not cause maize yield loss.Conclusions
Compared with the insensitivity of the critical shoot N dilution curve to excessive N application, soil Nmin showed strong response to all treatments. We propose a minimum of soil Nmin of 6.1 mg?kg–1 at the sowing–V8, 6.7 mg?kg–1 at the V8–VT, and 5.5 mg?kg–1 at the VT–R6 growing stages with an average of about 6 mg?kg–1 of soil Nmin in the 0–60 soil depth for maximizing maize yield and N use efficiency in northern China. To maintain this critical Nmin value over the whole growth period, N topdressing at V8 and V12 stages was recommended. 相似文献18.
E. D. Schulze D. Nicolle A. Boerner M. Lauerer G. Aas I. Schulze 《Trees - Structure and Function》2014,28(4):1125-1135
Key message
Eucalyptus and Acacia species were surprisingly similar with respect to variations in δ 13 C, δ 15 N. Both genera respond with speciation and associated changes in leaf structure to drought.Abstract
Stable carbon and nitrogen isotope ratios (δ13C and δ15N) in leaves of eucalypts (Corymbia and Eucalyptus) and Acacia (and some additional Fabaceae) species were investigated together with specific leaf area (SLA), leaf nitrogen (N) and leaf phosphorous (P) concentration along a north–south transect through Western Australia covering winter- and summer-dominated rainfall between 100 and 1,200 mm annually. We investigated 62 eucalypts and 78 woody Fabaceae species, mainly of the genus Acacia. Leaf δ13C values of Eucalyptus and Acacia species generally increased linearly with latitude from ?29.5 ± 1.3 ‰ in the summer-dominated rainfall zone (15°S–18°S) to about ?25.7 ± 1.1 ‰ in the winter-dominated rainfall zone (29°S–31°S). δ15N increased initially with southern latitudes (0.5 ± 1.6 ‰ at 15°S; 5.8 ± 3.3 ‰ at 24–29°S) but decreased again further South (4.6 ± 3.5 ‰ at 31°S). The variation in δ13C and δ15N was probably due to speciation of Eucalyptus and Acacia into very local populations. There were no species that were distributed over the whole sampling area. The variation in leaf traits was larger between species than within species. Average nitrogen concentrations were 11.9 ± 1.05 mg g?1 in Eucalyptus, and were 18.7 ± 4.1 mg g?1 in Acacia. Even though the average nitrogen concentration was higher in Acacia than Eucalyptus, δ15N gave no clear indication for N2 fixation in Acacia. In a multiple regression, latitude (as a surrogate for rainfall seasonality), mean rainfall, leaf nitrogen concentration, specific leaf area and nitrogen fixation were significant and explained 69 % of the variation of δ13C, but only 36 % of the variation of δ15N. Higher nitrogen and phosphorus concentration could give Acacia an advantage over Eucalyptus in arid regions of undefined rainfall seasonality. 相似文献19.
Thiem Thi Tran Mana Kano-Nakata Moe Takeda Daniel Menge Shiro Mitsuya Yoshiaki Inukai Akira Yamauchi 《Plant and Soil》2014,378(1-2):139-152
Background
The promoted root growth under developmental plasticity triggered specifically by mild drought stress (MDS) is known to contribute to maintained water uptake and dry matter production (DMP).Aims
To examine whether the expression of developmental plasticity of root systems and its contribution to DMP would be affected by the levels of nitrogen (N) application.Methods
Two genotypes (CSSL50 derived from Nipponbare/Kasalath cross and Nipponbare) were grown under soil moisture gradients with a line source sprinkler system. Three N fertilizer treatments were used; 25 (low), 75 (standard) and 150 kg N ha?1 (high) in 2009 and 60 (low), 120 (standard) and 180 kg N ha?1 (high) in 2011.Results
Across varying N level treatments, there were no significant differences in any of the traits examined between the two genotypes under well-watered and severe drought stress conditions. In contrast, under MDS conditions (15–25 % w/w of soil moisture content (SMC) in 2009 and 17–25 % w/w of SMC in 2011), CSSL50 showed greater DMP than Nipponbare. The difference, however, varied with N level treatments since CSSL50’s greater root system development under MDS, was more pronounced at standard and high N levels than at low N level than it was for Nipponbare.Conclusions
N application enhanced the expression of plasticity in root system development at standard and high N levels as compared with low N level under MDS conditions, which contributed to the maintenance of DMP. 相似文献20.
Fang Zhang Xue-Neng Wu Hong-Min Zhou Dan-Feng Wang Ting-Ting Jiang Ya-Fei Sun Yue Cao Wen-Xia Pei Shu-Bin Sun Guo-Hua Xu 《Plant and Soil》2014,384(1-2):259-270