Nitrous oxide emissions from fertilized upland fields in Thailand

Nitrous oxide (N₂O) emission from fertilized maize fields was measured using a closed chamber at four experimental sites in Thailand. The average measured N₂O flux from unfertilized plots through crop season was 4.16 ± 1.52, 5.05 ± 1.65, 5.25 ± 1.68 and 6.74 ± 2.95 g N₂O-N m^-2 h^-1, at Nakhon Sawan, Phra Phutthabat, Khon Kaen and Chiang Mai, respectively. Increased N₂O emissions by the application of nitrogen fertilizer were 0.22–0.44, 0.19–0.38%, 0.12–0.24 and 0.08–0.15% of the applied N, respectively. Compared to other data, N₂O emission rate to applied nitrogen was not significantly different between the data of Thailand and the Temperate Zone.     

Methane Emission from Irrigated and Intensively Managed Rice Fields in Central Luzon (Philippines)

Methane (CH₄) emissions were measured with an automated system in Central Luzon, the major rice producing area of the Philippines. Emission records covered nine consecutive seasons from 1994 to 1998 and showed a distinct seasonal pattern: an early flush of CH₄ before transplanting, an increasing trend in emission rates reaching maximum toward grain ripening, and a second flush after water is withdrawn prior to harvesting. The local practice of crop management, which consists of continuous flooding and urea application, resulted in 79–184 mg CH₄ m^–2 d^–1 in the dry season (DS) and 269–503 mg CH₄ m^–2 d^–1 in the wet season (WS). The higher emission in the WS may be attributed to more labile carbon accumulation during the dry fallow period before the WS cropping as shown by higher % organic C. Incorporation of sulfate into the soil reduced CH₄ emission rates. The use of ammonium sulfate as N fertilizer in place of urea resulted in a 25–36% reduction in CH₄ emissions. Phosphogypsum reduced CH₄ emissions by 72% when applied in combination with urea fertilizer. Midseason drainage reduced CH₄ emission by 43%, which can be explained by the influx of oxygen into the soil. The practice of direct seeding instead of transplanting resulted in a 16–54% reduction in CH₄ emission, but the mechanisms for the reducing effect are not clear. Addition of rice straw compost increased CH₄ emission by only 23–30% as compared with the 162–250% increase in emissions with the use of fresh rice straw. Chicken manure combined with urea did not increase CH₄ emission. Fresh rice straw has wider C/N (25 to 45) while rice straw compost has C/N = 6 to 10 and chicken manure has C/N = 5 to 8. Modifications in inorganic and organic fertilizer management and water regime did not adversely affect grain yield and are therefore potential mitigation options. Direct seeding has a lower yield potential than transplanting but is getting increasingly popular among farmers due to labor savings. Combined with a package of technologies, CH₄ emission can best be reduced by (1) the practice of midseason drainage instead of continuous flooding, (2) the use of sulfate-containing fertilizers such as ammonium sulfate and phosphogypsum combined with urea; (3) direct seeding crop establishment; and (4) use of low C/N organic fertilizer such as chicken manure and rice straw compost.     

我国2000年化肥市场漫谈

对最近几年我国氮肥主要品种、尿素产量、进出口及表观消费量进行了分析 ,指出 2 0 0 0年氮肥供大于求的格局不会有大的改变。通过对影响化肥价格因素的探讨 ,分析了 2 0 0 0年化肥市场启动的有利因素和不利条件 ,结论是 2 0 0 0年化肥市场启动难度大 ,但在有利因素促使下 ,化肥市场有可能好于去年     

包裹型缓释/控制释放肥料专题报告

阐述了包膜肥料、包裹肥料、涂层肥料、缓释肥料、控制释放肥料以及肥效调节肥料在概念上的区别 ,并讨论了以水中氮溶出率测定缓释氮肥释放期不能反映缓释氮肥的实际肥效期。根据分析肥料—土壤—作物的相互关系以及多年在美国草坪上施 LUXACOTE的观察 ,提出了评判缓释性能的新标准。     

Nitrification of fertilizer wastewaters in a biofilm reactor

The nitrification characteristics of fertilizer wastes were investigated in a biofilm system using a submerged aerated filter. The attachment of biomass on packing media was studied. Supplement of organic carbon in the form of glucose and yeast extract enhanced biofilm formation although the nitrifiers did not require organic carbon for growth. After an attachment period, continuous operation of the reactor at different loading rates and dissolved oxygen levels was investigated. The maximum achievable nitrification rate was strongly dependent on the dissolved oxygen. In the dissolved oxygen range of 3·2–3·5 mg dm⁻³, the maximum ammonia removal rate was about 0·17 kg NH₄ N m⁻³ day⁻¹. When the dissolved oxygen was increased to 4·9 mg dm⁻³, removal rates as high as 0·41 kg NH₄ N m⁻³ day⁻¹ could be obtained. Nitrite accumulation depended on the bulk nitrogen and dissolved oxygen concentrations.     

园林绿化废弃物在污泥好氧发酵上的应用

园林绿化废弃物是一种绿色废弃物,由于其组成及结构的特殊性,园林绿化废弃物是作为污泥好氧发酵的良好结构剂调理剂,有着一定的优缺点,能够很好地提高堆肥效率。同时经过二次发酵堆肥腐熟后的物料,其品质优良,是作为生产有机肥的良好原材料,能够更好地提高作物产量与品质。     

Thermodynamics of metal reactants for ammonia synthesis from steam,nitrogen and biomass at atmospheric pressure

Catalytic ammonia synthesis at approximately 30 MPa and 800 K consumes about 5% of the global annual natural gas production causing significant CO₂ emissions. A conceptual solar thermochemical reaction cycle to produce NH₃ at near atmospheric pressure without natural gas is explored here and compared to solar thermochemical steam/air reforming to provide H₂ used in the Haber‐Bosch process for NH₃ synthesis. Mapping of Gibbs free energy planes quantifies the tradeoff between the yield of N₂ reduction via metal nitridation, and NH₃ liberation via steam hydrolysis vs. the temperatures required for reactant recovery from undesirably stable metal oxides. Equilibrium composition simulations suggest that reactants combining an ionic nitride‐forming element (e.g., Mg or Ce) with a transition metal (e.g., MgCr₂O₄, MgFe₂O₄, or MgMoO₄) may enable the concept near 0.1 MPa (at maximum 64 mol % yield of Mg₃N₂ through nitridation of MgFe₂O₄ at 1,300 K, and 72 mol % of the nitrogen in Mg₃N₂ as NH₃ during hydrolysis at 500 K). © 2011 American Institute of Chemical Engineers AIChE J, 58: 3203–3213, 2012     

以紫茎泽兰沼渣制作腐殖酸肥料的实验研究

以制作农残降解剂后紫茎泽兰的残渣残叶为原料,通过对其进行不同TS浓度的发酵实验,探究其适用于发酵的最佳浓度;并对发酵后沼渣的氮、磷、钾、腐殖酸等成分进行测定。结果表明,TS浓度为11.25%时产气较多;残渣腐殖酸含量与市场腐殖酸复合肥相近,但氮、钾元素相比含量较少。该实验可以为资源化利用紫茎泽兰、制作新型腐殖酸肥料提供参考依据。     

塔式熔体复合肥造粒工艺物料泵送方案设想和探讨

阐述塔式熔体复合肥造粒工艺在塔顶完成的制浆和造粒工序所存在的问题.设想并介绍采用塔下制浆,然后用液下泵通过管道输送至塔上进行喷淋造粒的方案.     

水溶肥发展现状及市场前景

水溶肥是近年来在国内发展起来的一种可以完全溶于水的新型肥料,通过地埋或滴灌来完成施肥,具有肥效显著、省工省肥、增产增效等特点,被誉为中国化肥产业和有机、生态、高效农业发展的新方向。目前国内水溶肥行业进入加速成长期,其发展前景十分广阔。介绍了水溶肥的性能特点、制取工艺、生产现状及市场前景,并对国内今后水溶肥产业的发展提出了一些建议。