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1.
探究施用生物炭和脲酶抑制剂/硝化抑制剂对亚热带水稻土氮素硝化过程的调控作用、氨挥发和N 2O排放的温室效应潜能的影响,确定生物炭与硝化和脲酶抑制剂的最佳组合,可为削减施用氮肥带来的活性氮气体排放对环境的负面风险提供理论依据。本研究采用室内好气培养试验方式,以单施尿素(N)为对照,设置7个试验处理[尿素+生物炭(NB),尿素+硝化抑制剂(N+NI),尿素+脲酶抑制剂(N+UI),尿素+硝化抑制剂+脲酶抑制剂(N+NIUI),尿素+硝化抑制剂+生物炭(NB+NI),尿素+脲酶抑制剂+生物炭(NB+UI),尿素+硝化抑制剂+脲酶抑制剂+生物炭(NB+NIUI)],观测生物炭与脲酶抑制剂(NBPT)/硝化抑制剂(DMPP)配施下土壤无机氮含量、N 2O排放及氨挥发的变化动态。结果表明: 1)培养期间,与N处理(5.11 mg N·kg -1·d -1)相比,NB处理的土壤硝化速率常数显著增加33.9%,N+NI处理显著降低22.9%;NB处理显著提高了氨氧化细菌(AOB)丰度,增幅达56.0%。2)与N处理相比,N+NI和NB+NI处理的NH 3累积排放量均显著增加约49%;N+UI处理降低了NH 3累积损失量,NB+UI处理抑制效果更明显。3)各处理的N 2O排放速率高峰均出现在施肥后前10 d;NB处理的N 2O排放高峰出现最早,N处理排放速率最高(5.87 μg·kg -1·h -1);硝化抑制剂与脲酶抑制剂配施减少土壤N 2O排放的效果最佳。综合计算各处理直接N 2O和间接N 2O(NH 3)排放产生的温室效应潜能(GWP)发现,N+NI和NB+NI处理较N处理分别增加了34.8%和40.9%,而NB和NB+UI处理的GWP显著降低了45.9%和60.5%。因此,生物炭与脲酶抑制剂配施对降低土壤活性氮气体排放所产生的温室效应潜能效果最佳。 相似文献
2.
Nitrification, a microbial process, is a key component and integral part of the nitrogen (N) cycle. Soil N is in a constant state of flux, moving and changing chemical forms. During nitrification, a relatively immobile N-form (NH 4 +) is converted into highly mobile nitrate-N (NO 3 ?). The nitrate formed is susceptible to losses via leaching and conversion to gaseous forms via denitrification. Often less than 30% of the applied N fertilizer is recovered in intensive agricultural systems, largely due to losses associated with and following nitrification. Nitrogen-use efficiency (NUE) is defined as the biomass produced per unit of assimilated N and is a conservative function in most biological systems. A better alternative is to define NUE as the dry matter produced per unit N applied and strive for improvements in agronomic yields through N recovery. Suppressing nitrification along with its associated N losses is potentially a key part in any strategy to improve N recovery and agronomic NUE. In many mature N-limited ecosystems, nitrification is reduced to a relatively minor flux. In such systems there is a high degree of internal N cycling with minimal loss of N. In contrast, in most high-production agricultural systems nitrification is a major process in N cycling with the resulting N losses and inefficiencies. This review presents the current state of knowledge on nitrification and associated N losses, and discusses strategies for controlling nitrification in agricultural systems. Limitations of the currently available nitrification inhibitors are highlighted. The concept of biological nitrification inhibition (BNI) is proposed for controlling nitrification in agricultural systems utilizing traits found in natural ecosystems. It is emphasized that suppression of nitrification in agricultural systems is a critical step required for improving agronomic NUE and maintaining environmental quality. 相似文献
3.
A field experiment was carried out at the Shenyang Experimental Station of Ecology (CAS) in order to study the effects of slow-release urea fertilizers high polymer-coated urea (SRU1), SRU1 mixed with dicyandiamide DCD (SRU2), and SRU1 mixed with calcium carbide CaC 2 (SRU3) on urease activity, microbial biomass C and N, and nematode communities in an aquic brown soil during the maize growth period. The results demonstrated that the application of slow-release urea fertilizers inhibits soil urease activity and increases the soil NH 4 +-N content. Soil available N increment could promote its immobilization by microorganisms. Determination of soil microbial biomass N indicated that a combined application of coated urea and nitrification inhibitors increased the soil active N pool. The population of predators/omnivores indicated that treatment with SRU2 could provide enough soil NH 4 +-N to promote maize growth and increased the food resource for the soil fauna compared with the other treatments. 相似文献
4.
Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have doubled global annual reactive N inputs in the past 50–100 years, causing deleterious effects on the environment through increased N leaching and nitrous oxide (N 2O) and ammonia (NH 3) emissions. Leaching and gaseous losses of N are greatly controlled by the net rate of microbial nitrification. Extensive experiments have been conducted to develop ways to inhibit this process through use of nitrification inhibitors (NI) in combination with fertilizers. Yet, no study has comprehensively assessed how inhibiting nitrification affects both hydrologic and gaseous losses of N and plant nitrogen use efficiency. We synthesized the results of 62 NI field studies and evaluated how NI application altered N cycle and ecosystem services in N‐enriched systems. Our results showed that inhibiting nitrification by NI application increased NH 3 emission (mean: 20%, 95% confidential interval: 33–67%), but reduced dissolved inorganic N leaching (?48%, ?56% to ?38%), N 2O emission (?44%, ?48% to ?39%) and NO emission (?24%, ?38% to ?8%). This amounted to a net reduction of 16.5% in the total N release to the environment. Inhibiting nitrification also increased plant N recovery (58%, 34–93%) and productivity of grain (9%, 6–13%), straw (15%, 12–18%), vegetable (5%, 0–10%) and pasture hay (14%, 8–20%). The cost and benefit analysis showed that the economic benefit of reducing N's environmental impacts offsets the cost of NI application. Applying NI along with N fertilizer could bring additional revenues of $163 ha ?1 yr ?1 for a maize farm, equivalent to 8.95% increase in revenues. Our findings showed that NIs could create a win‐win scenario that reduces the negative impact of N leaching and greenhouse gas production, while increases the agricultural output. However, NI's potential negative impacts, such as increase in NH 3 emission and the risk of NI contamination, should be fully considered before large‐scale application. 相似文献
5.
Nitrification inhibitors show promise in decreasing nitrous oxide (N 2O) emission from agricultural systems worldwide, but they may be much less effective than previously thought when both direct and indirect emissions are taken into account. Whilst nitrification inhibitors are effective at decreasing direct N 2O emission and nitrate (NO 3–) leaching, limited studies suggest that they may increase ammonia (NH 3) volatilization and, subsequently, indirect N 2O emission. These dual effects are typically not considered when evaluating the inhibitors as a climate change mitigation tool. Here, we collate results from the literature that simultaneously examined the effects of nitrification inhibitors on N 2O and NH 3 emissions. We found that nitrification inhibitors decreased direct N 2O emission by 0.2–4.5 kg N 2O‐N ha ?1 (8–57%), but generally increased NH 3 emission by 0.2–18.7 kg NH 3‐N ha ?1 (3–65%). Taking into account the estimated indirect N 2O emission from deposited NH 3, the overall impact of nitrification inhibitors ranged from ?4.5 (reduction) to +0.5 (increase) kg N 2O‐N ha ?1. Our results suggest that the beneficial effect of nitrification inhibitors in decreasing direct N 2O emission can be undermined or even outweighed by an increase in NH 3 volatilization. 相似文献
6.
A field experiment was carried out at the Shenyang Experimental Station of Ecology (CAS) in order to study the effects of slow-release urea fertilizers high polymer-coated urea (SRU1), SRU1 mixed with dicyandiamide DCD (SRU2), and SRU1 mixed with calcium carbide CaC2 (SRU3) on urease activity, microbial biomass C and N, and nematode communities in an aquic brown soil during the maize growth period. The results demonstrated that the application of slow-release urea fertilizers inhibits soil urease activity and increases the soil NH4
+-N content. Soil available N increment could promote its immobilization by microorganisms. Determination of soil microbial biomass N indicated that a combined application of coated urea and nitrification inhibitors increased the soil active N pool. The population of predators/omnivores indicated that treatment with SRU2 could provide enough soil NH4
+-N to promote maize growth and increased the food resource for the soil fauna compared with the other treatments. 相似文献
7.
In rice cultivation, there are controversial reports on net impacts of nitrogen (N) fertilizers on methane (CH 4) emissions. Nitrogen fertilizers increase crop growth as well as alter CH 4 producing (Methanogens) and consuming (Methanotrophs) microbes, and thereby produce complex effects on CH 4 emissions. Objectives of this study were to determine net impact of N fertilizers on CH 4 emissions and to identify their underlying mechanisms in the rice soils. Database was obtained from 33 published papers that contained CH 4 emissions observations from N fertilizer (28–406 kg N ha ?1) treatment and its control. Results have indicated that N fertilizers increased CH 4 emissions in 98 of 155 data pairs in rice soils. Response of CH 4 emissions per kg N fertilizer was significantly ( P < 0.05) greater at < 140 kg N ha ?1 than > 140 kg N ha ?1 indicating that substrate switch from CH 4 to ammonia by Methanotrophs may not be a dominant mechanism for increased CH 4 emissions. On the contrary, decreased CH 4 emission in intermittent drainage by N fertilizers has suggested the stimulation of Methanotrophs in rice soils. Effects of N fertilizer stimulated Methanotrophs in reducing CH 4 emissions were modified by the continuous flood irrigation due to limitation of oxygen to Methanotrophs. Greater response of CH 4 emissions per kg N fertilizer in urea than ammonia sulfate probably indicated the interference of sulfate in the CH 4 production process. Overall, response of CH 4 emissions to N fertilizers was correlated with N‐induced crop yield ( r = +0.39; P < 0.01), probably due to increased carbon substrates for Methanogens. Using CH 4 emission observations, this meta‐analysis has identified dominant microbial processes that control net effects of N fertilizers on CH 4 emissions in rice soils. Finally, we have provided a conceptual model that included microbial processes and controlling factors to predict effects of N fertilizers on CH 4 emissions in rice soils. 相似文献
8.
Background. To investigate whether the Helicobacter pylori status influences levels of antibodies against mycobacterial heat shock protein (hsp) 65 and human hsp60 in systemic autoimmune diseases and to study the concentration of anti‐ H. pylori antibodies in autoimmune patients and healthy controls. Materials and Methods. Antibodies against human heat‐shock protein hsp60, mycobacterial heat‐shock protein hsp65 were analyzed by ELISA. Anti‐Helicobacter antibodies were determined by enzyme immunoassay. Results. There was a markedly higher prevalence of H. pylori infection in undifferentiated connective tissue disease (82%) (n = 33) and systemic sclerosis (78%) (n = 55) but not in systemic lupus erythematosus (n = 49), polymyositis/dermatomyositis (n = 14), rheumatoid arthritis (n = 21) or primary Raynaud's syndrome (n = 26) compared with controls (59%) (n = 349). In autoimmune diseases H. pylori infection was associated with elevated levels of antihsp65 ( p = .008) but not of antihsp60. Anti‐hsp65 levels were significantly higher in H. pylori‐infected (n = 129) than in uninfected patients (n = 69) ( p = .0007). Conclusions. These findings indicate that in autoimmune diseases the infection with the H. pylori bacterium is associated with increased concentration of antimycobacterial hsp65. 相似文献
9.
Aim. To compare the short‐term (7‐day) safety and efficacy of two triple‐therapy regimens using pantoprazole with those of two dual‐therapy regimens (one with pantoprazole and one without), for Helicobacter pylori eradication in patients with peptic ulcer disease. Methods. H. pylori infection was identified by rapid urease (CLOtest), and confirmed by histology and culture. Patients were enrolled into one of two randomized, double‐blind, multicenter, parallel‐group studies. In study A, patients received oral pantoprazole 40 mg, clarithromycin 500 mg, and metronidazole 500 mg (PCM); pantoprazole, clarithromycin and amoxicillin 1000 mg (PCA); or pantoprazole and clarithromycin (PC). In study B, patients received PCM, PCA, PC, or clarithromycin and metronidazole without pantoprazole (CM). Treatments were given twice daily for 7 days. H. pylori status after therapy was assessed by histology and culture at 4 weeks after completing the course of study treatment. Modified intent‐to‐treat (MITT; each study: n = 424, n = 512) and per‐protocol (PP; each study: n = 371, n = 454) populations were analyzed. The MITT population comprised all patients whose positive H. pylori status was confirmed by culture and histology; the PP population comprised patients who also complied with ≥ 85% of study medication doses. Results. A total of 1016 patients were enrolled. Cure rates among patients with clarithromycin‐susceptible H. pylori strains were 82 and 86% for PCM, and 72 and 71% for PCA, in studies A and B, respectively. Cure rates among patients with metronidazole‐susceptible H. pylori strains were 82 and 87% for PCM, and 71 and 69% for PCA, in studies A and B, respectively. The combined eradication rates observed with the PCM regimen were superior to those of all other regimens tested. Side‐effects were infrequent and mild. Conclusions. PCM had the highest overall eradication rate in these two studies examining 7‐day treatment regimens. All regimens were safe and well tolerated. 相似文献
11.
The agriculture sector has historically been a major source of greenhouse gas (GHG) emissions into the atmosphere. Although the use of synthetic fertilizers is one of the most common widespread agricultural practices, over-fertilization can lead to negative economic and environmental consequences, such as high production costs, depletion of energy resources, and increased GHG emissions. Here, we provide an analysis to understand the evolution of cereal production and consumption of nitrogen (N) fertilizers in Brazil and to correlate N use efficiency (NUE) with economic and environmental losses as N 2O emissions. Our results show that the increased consumption of N fertilizers is associated with a large decrease in NUE in recent years. The CO 2 eq. of N 2O emissions originating from N fertilization for cereal production were approximately 12 times higher in 2011 than in 1970, indicating that the inefficient use of N fertilizers is directly related to environmental losses. The projected N fertilizer forecasts are 2.09 and 2.37 million ton for 2015 and 2023, respectively. An increase of 0.02% per year in the projected NUE was predicted for the same time period. However, decreases in the projected CO 2 eq. emissions for future years were not predicted. In a hypothetical scenario, a 2.39% increase in cereal NUE would lead to $ 21 million savings in N fertilizer costs. Thus, increases in NUE rates would lead not only to agronomic and environmental benefits but also to economic improvement. 相似文献
12.
Agricultural fields are an important anthropogenic source of atmospheric nitrous oxide (N 2O) and nitric oxide (NO). Although many field studies have tested the effectiveness of possible mitigation options on N 2O and NO emissions, the effectiveness of each option varies across sites due to environmental factors and field management. To combine these results and evaluate the overall effectiveness of enhanced‐efficiency fertilizers [i.e., nitrification inhibitors (NIs), polymer‐coated fertilizers (PCFs), and urease inhibitors (UIs)] on N 2O and NO emissions, we performed a meta‐analysis using field experiment data (113 datasets from 35 studies) published in peer‐reviewed journals through 2008. The results indicated that NIs significantly reduced N 2O emissions (mean: ?38%, 95% confidential interval: ?44% to ?31%) compared with those of conventional fertilizers. PCFs also significantly reduced N 2O emissions (?35%, ?58% to ?14%), whereas UIs were not effective in reducing N 2O. NIs and PCFs also significantly reduced NO (?46%, ?65% to ?35%; ?40%, ?76% to ?10%, respectively). The effectiveness of NIs was relatively consistent across the various types of inhibitors and land uses. However, the effect of PCFs showed contrasting results across soil and land‐use type: they were significantly effective for imperfectly drained Gleysol grassland (?77%, ?88% to ?58%), but were ineffective for well‐drained Andosol upland fields. Because available data for PCFs were dominated by certain regions and soil types, additional data are needed to evaluate their effectiveness more reliably. NIs were effective in reducing N 2O emission from both chemical and organic fertilizers. Moreover, the consistent effect of NIs indicates that they are potent mitigation options for N 2O and NO emissions. 相似文献
13.
Nitrogen (N) fertilizers are a major input cost in rice production, and its excess application leads to major environmental pollution. Development of rice varieties with improved nitrogen use efficiency (NUE) is essential for sustainable agriculture. Here, we report the results of field evaluations of marker‐free transgenic NERICA4 (New Rice for Africa 4) rice lines overexpressing barley alanine amino transferase ( HvAlaAT) under the control of a rice stress‐inducible promoter (pOsAnt1). Field evaluations over three growing seasons and two rice growing ecologies (lowland and upland) revealed that grain yield of pOsAnt1: HvAlaAT transgenic events was significantly higher than sibling nulls and wild‐type controls under different N application rates. Our field results clearly demonstrated that this genetic modification can significantly increase the dry biomass and grain yield compared to controls under limited N supply. Increased yield in transgenic events was correlated with increased tiller and panicle number in the field, and evidence of early establishment of a vigorous root system in hydroponic growth. Our results suggest that expression of the HvAlaAT gene can improve NUE in rice without causing undesirable growth phenotypes. The NUE technology described in this article has the potential to significantly reduce the need for N fertilizer and simultaneously improve food security, augment farm economics and mitigate greenhouse gas emissions from the rice ecosystem. 相似文献
14.
Eggplant ( Solanum melongena L.) yield is highly sensitive to N fertilization, the excessive use of which is responsible for environmental and human health damage. Lowering N input together with the selection of improved Nitrogen‐Use‐Efficiency (NUE) genotypes, more able to uptake, utilize, and remobilize N available in soils, can be challenging to maintain high crop yields in a sustainable agriculture. The aim of this study was to explore the natural variation among eggplant accessions from different origins, in response to Low (LN) and High (HN) Nitrate (NO 3‐) supply, to identify NUE‐contrasting genotypes and their NUE‐related traits, in hydroponic and greenhouse pot experiments. Two eggplants, AM222 and AM22, were identified as N‐use efficient and inefficient, respectively, in hydroponic, and these results were confirmed in a pot experiment, when crop yield was also evaluated. Overall, our results indicated the key role of N‐utilization component (NUtE) to confer high NUE. The remobilization of N from leaves to fruits may be a strategy to enhance NUtE, suggesting glutamate synthase as a key enzyme. Further, omics technologies will be used for focusing on C‐N metabolism interacting networks. The availability of RILs from two other selected NUE‐contrasting genotypes will allow us to detect major genes/quantitative trait loci related to NUE. 相似文献
15.
Cytosolic glutamine synthetase (GS1) plays a central role in nitrogen (N) metabolism. The importance of GS1 in N remobilization during reproductive growth has been reported in cereal species but attempts to improve N utilization efficiency (NUE) by overexpressing GS1 have yielded inconsistent results. Here, we demonstrate that transformation of barley ( Hordeum vulgare L.) plants using a cisgenic strategy to express an extra copy of native HvGS1‐1 lead to increased HvGS1.1 expression and GS1 enzyme activity. GS1 overexpressing lines exhibited higher grain yields and NUE than wild‐type plants when grown under three different N supplies and two levels of atmospheric CO 2. In contrast with the wild‐type, the grain protein concentration in the GS1 overexpressing lines did not decline when plants were exposed to elevated (800–900 μL/L) atmospheric CO 2. We conclude that an increase in GS1 activity obtained through cisgenic overexpression of HvGS1‐1 can improve grain yield and NUE in barley. The extra capacity for N assimilation obtained by GS1 overexpression may also provide a means to prevent declining grain protein levels under elevated atmospheric CO 2. 相似文献
16.
Increased use of nitrogen fertilizers has deleterious impact on the environment. Increase in yield potential at low nitrogen supply is regarded as a cereal breeding goal for future agricultural sustainability. Although natural variations of nitrogen transporters have been investigated, key genes associated with assimilation remain largely unexplored for nitrogen use efficiency (NUE) enhancement. Here, we identified a NIN‐like protein NLP4 associated with NUE through a GWAS in rice. We found that OsNLP4 transactivated OsNiR encoding nitrite reductase that was critical in nitrogen assimilation in rice. We further constructed quadrupling NREs (Nitrate‐responsive cis‐elements) in the promoter of OsNiR ( p4xNRE:OsNiR) and enhanced nitrogen assimilation significantly. We demonstrated that OsNLP4‐OsNiR increased tiller number and yield through enhancing nitrogen assimilation and NUE. Our discovery highlights the genetic modulation of OsNLP4‐OsNiR signalling cascade as a strategy for high NUE and yield breeding in rice. 相似文献
17.
Knowledge‐based nitrogen (N) management, which is designed for a better synchronization of crop N demand with N supply, is critical for global food security and environmental sustainability. Yet, a comprehensive assessment on how these N management practices affect food production, greenhouse gas emission (GHG), and N pollution in China is lacking. We compiled the results of 376 studies (1166 observations) to evaluate the overall effects of seven knowledge‐based N management practices on crop productivity, nitrous oxide (N 2O) emission, and major reactive N (Nr) losses (ammonia, NH 3; N leaching and runoff), for staple grain (rice, wheat, and corn) production in China. These practices included the application of controlled‐release N fertilizer, nitrification inhibitor (NI) and urease inhibitor (UI), higher splitting frequency of fertilizer N application, lower basal N fertilizer (BF) proportion, deep placement of N fertilizer, and optimal N rate based on soil N test. Our results showed that, compared to traditional N management, these knowledge‐based N practices significantly increased grain yields by 1.3–10.0%, which is attributed to the higher aboveground N uptake (5.1–12.1%) and N use efficiency in grain (8.0–48.2%). Moreover, these N management practices overall reduced GHG emission and Nr losses, by 5.4–39.8% for N 2O emission, 30.7–61.5% for NH 3 emission (except for the NI application), 13.6–37.3% for N leaching, and 15.5–45.0% for N runoff. The use of NI increased NH 3 emission by 27.5% (9.0–56.0%), which deserves extra‐attention. The cost and benefit analysis indicated that the yield profit of these N management practices exceeded the corresponding input cost, which resulted in a significant increase of the net economic benefit by 2.9–12.6%. These results suggest that knowledge‐based N management practice can be considered an effective way to ensure food security and improve environmental sustainability, while increasing economic return. 相似文献
18.
Cultivation of bioenergy crops has been suggested as a promising option for reduction of greenhouse gas (GHG) emissions from arable organic soils (Histosols). Here, we report the annual net ecosystem exchange (NEE) fluxes of CO 2 as measured with a dynamic closed chamber method at a drained fen peatland grown with reed canary grass (RCG) and spring barley (SB) in a plot experiment ( n = 3 for each cropping system). The CO 2 flux was partitioned into gross photosynthesis (GP) and ecosystem respiration ( RE). For the data analysis, simple yet useful GP and RE models were developed which introduce plot‐scale ratio vegetation index as an active vegetation proxy. The GP model captures the effect of temperature and vegetation status, and the RE model estimates the proportion of foliar biomass dependent respiration ( Rfb) in the total RE. Annual RE was 1887 ± 7 (mean ± standard error, n = 3) and 1288 ± 19 g CO 2‐C m ?2 in RCG and SB plots, respectively, with Rfb accounting for 32 and 22% respectively. Total estimated annual GP was ?1818 ± 42 and ?1329 ± 66 g CO 2‐C m ?2 in RCG and SB plots leading to a NEE of 69 ± 36 g CO 2‐C m ?2 yr ?1 in RCG plots (i.e., a weak net source) and ?41 ± 47 g CO 2‐C m ?2 yr ?1 in SB plots (i.e., a weak net sink). Standard errors related to spatial variation were small (as shown above), but more significant uncertainties were related to the modelling approach for establishment of annual budgets. In conclusion, the bioenergy cropping system was not more favourable than the food cropping system when looking at the atmospheric CO 2 emissions during cultivation. However, in a broader GHG life‐cycle perspective, the lower fertilizer N input and the higher biomass yield in bioenergy cropping systems could be beneficial. 相似文献
19.
Intensive vegetable production exhibits contrasting characteristics of high nitrous oxide (N 2O) emissions and low nitrogen use efficiency (NUE). In an effort to mitigate N 2O emissions and improve NUE, a field experiment with nine consecutive vegetable crops was designed to study the combined effects of nitrogen (N) and biochar amendment and their interaction on soil properties, N 2O emission and NUE in an intensified vegetable field in southeastern China. We found that N application significantly increased N 2O emissions, N 2O–N emission factors and yield‐scaled N 2O emissions by 51–159%, 9–125% and 14–131%, respectively. Moreover, high N input significantly decreased N partial factor productivity (PFPN) and even yield during the seventh to ninth vegetable crops along with obvious soil degradation and mineral N accumulation. To the contrary, biochar amendment resulted in significant decreases in cumulative N 2O emissions, N 2O–N emission factor and yield‐scaled N 2O emissions by 5–39%, 16–67% and 14–53%, respectively. In addition, biochar significantly increased yield, PFPN and apparent recovery of N (ARN). Although without obvious influence during the first to fourth vegetable crops, biochar amendment mitigated N 2O emissions during the fifth to ninth vegetable crops. The relative effects of biochar amendments were reduced with increasing N application rate. Hence, while high N input produced adverse consequences such as mineral N accumulation and soil degradation in the vegetable field, biochar amendment can be a beneficial agricultural strategy to mitigate N 2O emissions and improve NUE and soil quality in vegetable field. 相似文献
20.
Laboratory incubation and field experiments were conducted to evaluate thiourea, ATC (4-amino-1, 2, 4 triazole hydrochloride)
and N-Serve 24 E (2-chloro-6-trichloromethyl-pyridine) as inhibitors of nitrification of fertilizer N. In the incubation experiment,
most of the added aqueous NH 3 or urea was nitrified at 14 days on both soils, but addition of the inhibitors to fertilizer N decreased the conversion of
NH 4−N to NO 3−N markedly. There was less nitrification for ATC and thiourea but not for N-Serve 24 E when the fertilizers and the inhibitors
were placed at a point as opposed to when mixed into soil. After 28 days, ATC and N-Serve 24 E were more effective in inhibiting
nitrification than thiourea. ATC and N-Serve 24 E also inhibited release of mineral N (NH 4−N+NO 3−N) from native soil N. In the uncropped field experiment, which received N fertilizers in the fall, nitrification of fall-applied
N placed in the 15-cm bands was almost complete by early May in the Malmo soil, but not in the Breton soil. When ATC or thiourea
had been applied with urea, nitrification of fall-applied N was depressed by May and the recovery of applied N as NH 4−N was greater with increasing band spacing to 60 cm or placing N fertilizer in nests (a method of application where urea
prills were placed at a point in the soil in the center of 60×60 cm area). In late June, the percentage recovery of fall-applied
N in soil as NH 4−N or mineral N increased with wide band spacing, or nest placement, or by adding ATC to fertilizer N on both soils. These
results indicate that placing ammonium-based N fertilizers in widely-spaced bands or in nests with low rates of inhibitors
slows nitrification enough to prevent much of the losses from fall-applied N.
Scientific Paper No. 552, Lacombe Research Station, Research Branch, Agric, Can. 相似文献
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