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241.
不同时期施用生物炭对稻田N_2O和CH_4排放的影响 总被引:7,自引:0,他引:7
通过分别在水稻季(R)和小麦季(W)设置对照(RB0-N0、WB0-N0)、单施氮肥(RB0-N1、WB0-N1)、20 t hm-2生物炭与氮配施(RB1-N1、WB1-N1)、40 t hm-2生物炭与氮配施(RB2-N1、WB2-N1)等8个处理,研究稻麦轮作周年系统N2O和CH4排放规律及其引起的综合温室效应(Global warming potential,GWP)和温室气体强度(Greenhouse gas intensity,GHGI)特征。结果表明:稻季配施20 t hm-2生物炭对N2O和CH4的排放、作物产量及GWP和GHGI均都无明显影响;稻季配施40 t hm-2生物炭能显著降低8.6%的CH4的排放和9.3%的GWP,显著增加作物产量17.2%。麦季配施20 t hm-2生物炭虽然对温室气体及GWP影响不明显,但显著增加21.6%的作物产量,从而显著降低21.7%的GHGI;麦季配施40 t hm-2生物炭能显著降低20.9%和11.3%的N2O和CH4排放,显著降低15.7%和23.5%的GWP和GHGI。因此麦季配施生物炭对减少N2O和CH4的排放、增加稻麦轮作产量及降低GWP和GHGI的效果较稻季配施生物炭效果更好。 相似文献
242.
中国农业能源消耗碳排放变化驱动因素及其贡献研究*——基于Kaya恒等扩展与LMDI指数分解方法 总被引:4,自引:1,他引:4
农业低碳化发展方式是农业现代化背景下农业可持续发展的有效实现途径。判断农业碳排放影响因素的驱动力、驱动方向等对有的放矢地制定低成本、高效率低碳农业发展策略与措施意义重大。在前人研究的基础上,为探讨常规因素之外还有哪些其他因素对农业碳排放有所影响,本研究以Kaya恒等式为基础,利用Kaya恒等式的数学性质将中国农业碳排放的影响因素分解为一般技术因素、农业低碳技术因素、农村生活水平因素、间接城镇化因素以及人口规模因素等5个因素,并利用LMDI指数分解方法对这些因素进行了驱动强度与贡献率的分析。研究发现:农村生活水平提高是促成农业碳排放的最主要因素;一般技术因素与农业低碳技术因素都负向地驱动农业碳排放,相比较而言,农业低碳技术变动比一般技术变动的碳排放驱动力更为强劲;总人口变动因素对农业碳排放呈现出正向驱动力,但无论从整个长跨度区间还是细分区间来看,其正向驱动力都不强;由扩展的Kaya恒等式得出的间接城镇化指标与一般城镇化指标之间关于50%的水平在坐标系中对称,经转换与修正发现城镇化水平对农业碳排放表现出温和的正向驱动力。1990—2013年中国总的农业碳排放中一般技术因素贡献为?25.85%,农业低碳技术因素贡献率为?166.55%,农村生活水平因素贡献率为220.65%,城镇化水平贡献率为57.63%,人口规模因素的贡献率则为14.12%。文章建议在发展农业现代化过程中,通过发展通用和低碳农业技术,合理有序推进城镇化进程以及营造低碳发展的社会氛围等方面创造更适宜的环境,以达到农业低碳化发展与可持续发展目标。 相似文献
243.
An experiment was performed to examine the chemical and biological effects on high clay sodic subsoil following the incorporation and incubation with organic amendments. The main treatments consisted of amendments with wheat shoots, lucerne pellets and peat, and these were compared to gypsum addition. Additional treatments were residues of chickpea and canola, chicken manure and sawdust. All materials were finely ground and added to crushed and sieved soil at the rate of 1% by weight. Wheat, canola and chickpea residues and chicken manure resulted in modest reductions in soil sodicity. Carbon and N mineralization were related to the soluble C/total N ratio in the amendment. The initial mineralization of wheat amendment was rapid due to its soluble C content, but then slowed to have the lowest loss, of around one third of added C, of all the plant residues after 174 days. In comparison, lucerne-amended soil increased total N and lost almost half of its C after the 174-day incubation. The canola stubble amendment showed the highest carbon loss, losing 64% of its added C. The addition of gypsum resulted in high soil electrical conductivity which suppressed respiration, compared to the control soil, indicating a detrimental effect on microbial activity due to the high electrolyte concentration in the soil. The peat amendment, with a low-soluble C content, showed a similar respiration rate to the control soil, confirming that a source of soluble C is important for the initiation of rapid biological activity. Soil pH was significantly increased (by 0.6 of a pH unit) with addition of chicken manure, and still remained higher than control soil after 174 days of incubation. Lucerne was the only plant residue to increase soil pH, with the effect being sustained for 56 days. The study demonstrated how some organic amendments can improve chemical fertility and biological activity in high clay sodic subsoil, and at the same time contribute, after 25 weeks incubation, to an increase in carbon content. 相似文献
244.
245.
Simon Bilodeau-Gauthier Daniel Houle Christian GagnonBenoît Côté Christian Messier 《Forest Ecology and Management》2011,261(1):95-104
Partitioning of elements in tree xylem is being increasingly studied, as it suggests that elements are potentially mobile within the xylem long after their uptake. A recent study revealed that only the most mobile xylem fraction (water-soluble) of base cations (calcium [Ca], magnesium [Mg], and potassium [K]) increased at higher soil acidity, while the two mobile fractions (water- and acid-soluble) of acidic metals—potentially phytotoxic aluminium (Al), cadmium (Cd) and manganese (Mn)—were significantly enhanced on very acid soils. The current paper presents an investigation of soil-wood chemistry relationships with basal area tree growth. It was hypothesized that the growth of sugar maple would be reduced by low base cation and high acidic metal concentrations in the xylem mobile fractions. Sugar maple trees (n = 55) from six watersheds in southern Quebec, Canada were analysed by sequential chemical extractions for the water-soluble, acid-soluble and residual fractions of base cations (Ca, K, Mg) and acidic metals (Al, Cd, Mn) in xylem. Generally, tree growth was positively correlated to concentrations of base cations in wood (ρ = 0.27-0.50) and soil (ρ = 0.41-0.67), and negatively correlated to concentrations of acidic metals in wood (ρ = −0.33 to −0.52) and soil (ρ = −0.67). However, these relations differed depending on the element fraction considered. Water- and acid-soluble xylem concentrations of base cations and Al were among the best predictors of growth trends (R2 = 0.46-0.51). The relationship between acidic metals and tree growth is further discussed. 相似文献
246.
不同利用方式红壤反硝化势和气态产物排放特征 总被引:1,自引:1,他引:1
采用厌氧培养-乙炔抑制法测定了4种不同利用方式红壤的反硝化势和气态产物N2O和N2的排放速率。结果表明,不同利用方式红壤反硝化势和N2O和N2的排放速率差异明显,土壤反硝化势强弱顺序依次为:竹林>茶园>林地>旱地。反硝化势与土壤有机碳(P<0.05)、厌氧培养期间土壤CO2累积排放量(P<0.01)、nirS基因丰度( P<0.05)和nirK基因丰度(P<0.05) 呈显著正相关关系。逐步回归分析结果表明,CO2累积排放量表征的易矿化碳是造成不同利用方式红壤反硝化势差异的主要原因,可以解释反硝化势变化的66%(P<0.01)。不同利用方式红壤N2O和N2排放速率差异明显,旱地红壤N2O和N2排放速率均最低,表明土壤pH的提升并没有增加旱地红壤的反硝化损失风险和N2O排放速率。土壤易矿化有机碳含量也是影响不同利用方式红壤N2O和N2排放速率的主要因素。反硝化功能基因nirS、nirK和nosZ的丰度均与CO2累积排放量呈显著正相关关系,进一步支持了土壤易矿化有机碳含量是影响不同利用方式红壤反硝化势和气态产物排放的主要因子。土壤pH是影响不同利用方式红壤反硝化气态产物N2/N2O的主要因素,但是pH影响红壤N2/N2O的微生物机制仍需要进一步研究。 相似文献
247.
248.
菜地土壤中氮肥的反硝化损失和N2O排放 总被引:4,自引:0,他引:4
A field experiment was conducted on Chinese cabbage (Brassica campestris L. ssp. pekinensis (Lour.) Olsson) in a Nanjing suburb in 2003. The experiment included 4 treatments in a randomized complete block design with 3 replicates: zero chemical fertilizer N (CK); urea at rates of 300 kg N ha^-1 (U300) and 600 kg N ha^-1 (U600), both as basal and two topdressings; and polymer-coated urea at a rate of 180 kg N ha^-1 (PCU180) as a basal application. The acetylene inhibition technique was used to measure denitrification (N2 + N2O) from intact soil cores and N2O emissions in the absence of acetylene. Results showed that compared to (3K total denitrification losses were significantly greater (P ≤ 0.05) in the PCU180, U300, and U600 treatments,while N2O emissions in the U300 and U600 treatments were significantly higher (P ≤ 0.05) than (3K. In the U300 and U600 treatments peaks of denitrification and N2O emission were usually observed after N application. In the polymer-coated urea treatment (PCU180) during the period 20 to 40 days after transplanting, higher denitrification rates and N2O fluxes occurred. Compared with urea, polymer-coated urea did not show any effect on reducing denitrification losses and N2O emissions in terms of percentage of applied N. As temperature gradually decreased from transplanting to harvest, denitrification rates and N2O emissions tended to decrease. A significant (P ≤0.01) positive correlation occurred between denitrification (r = 0.872) or N2O emission (r = 0.781) flux densities and soil temperature in the CK treatment with a stable nitrate content during the whole growing season. 相似文献
249.
250.
Determinants of annual fluxes of CO2 and N2O in long-term no-tillage and conventional tillage systems in northern France 总被引:2,自引:1,他引:2
Katrien Oorts Roel Merckx Eric Grhan Jrme Labreuche Bernard Nicolardot 《Soil & Tillage Research》2007,95(1-2):133-148
The greenhouse gases CO2 and N2O emissions were quantified in a long-term experiment in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated during 32 years in plots under a maize–wheat rotation. Continuous CO2 and periodical N2O soil emission measurements were performed during two periods: under maize cultivation (April 2003–July 2003) and during the fallow period after wheat harvest (August 2003–March 2004). In order to document the dynamics and importance of these emissions, soil organic C and mineral N, residue decomposition, soil potential for CO2 emission and climatic data were measured. CO2 emissions were significantly larger in NT on 53% and in CT on 6% of the days. From April to July 2003 and from November 2003 to March 2004, the cumulated CO2 emissions did not differ significantly between CT and NT. However, the cumulated CO2 emissions from August to November 2003 were considerably larger for NT than for CT. Over the entire 331 days of measurement, CT and NT emitted 3160 ± 269 and 4064 ± 138 kg CO2-C ha−1, respectively. The differences in CO2 emissions in the two tillage systems resulted from the soil climatic conditions and the amounts and location of crop residues and SOM. A large proportion of the CO2 emissions in NT over the entire measurement period was probably due to the decomposition of old weathered residues. NT tended to emit more N2O than CT over the entire measurement period. However differences were statistically significant in only half of the cases due to important variability. N2O emissions were generally less than 5 g N ha−1 day−1, except for a few dates where emission increased up to 21 g N ha−1 day−1. These N2O fluxes represented 0.80 ± 0.15 and 1.32 ± 0.52 kg N2O-N ha−1 year−1 for CT and NT, respectively. Depending on the periods, a large part of the N2O emissions occurred was probably induced by nitrification, since soil conditions were not favorable for denitrification. Finally, for the period of measurement after 32 years of tillage treatments, the NT system emitted more greenhouses gases (CO2 and N2O) to the atmosphere on an annual basis than the CT system. 相似文献