改性尿素追施对冬小麦和夏玉米季氮素挥发和淋溶的影响

以NBPT(N-丁基硫代磷酰三胺)和DMPP(3,4-二甲基吡唑磷酸盐)为复合抑制剂,利用转鼓喷涂工艺,开发出新型复合型抑制剂涂覆尿素肥料,采用扫描电镜和能谱仪分析其涂覆效果。通过田间试验系统对比评价了追施不同氮肥对调控氮素的特征效果。试验设置5个处理:(1)不施氮肥(CK);(2)农民习惯追施尿素(CU);(3)优化追施尿素(CUU);(4)优化追施抑制剂涂覆尿素(CUY1);(5)优化追施抑制剂涂覆尿素(CUY2)。在夏玉米喇叭口期、冬小麦拔节期追施氮肥后的15天内进行田间原位连续动态观测。电镜和能谱结果表明,复合抑制剂均匀涂覆于尿素表面,形成薄而致密、光滑的涂覆层,该涂覆层均匀分布有磷和硫2种元素,表明复合抑制剂与尿素已有效结合。田间试验结果表明,在同等优化施氮量下与普通尿素相比,夏玉米和冬小麦季追肥后CUY1和CUY2处理氨挥发分别降低55.19%,32.15%和52.46%,39.43%。夏玉米季追肥后,0-20 cm土层CU、CUU处理土壤硝态氮含量于第5天达到峰值,到后期已显著低于CUY1、CUY2处理,CUY2处理稳定硝态氮的效果更好。冬小麦季追肥后,0-20 cm土壤硝态氮含量CU、CUU处理分别在第5,3天达到峰值,CUY1、CUY2处理于第11天达到峰值后,硝态氮含量已显著高于相同施氮量的CUU处理。在保证产量和净收益的同时,抑制剂涂覆尿素显著降低了追施氮素的氨挥发和淋溶损失浓度,其中冬小麦季CUY1处济效益较好,夏玉米季CUY2调控氮素的效果最佳,减少向下淋溶的效果明显。     

含DMPP抑制剂尿素的氨挥发特性及阻控对策研究

采用原状土柱模拟方法,探讨了施肥水平、添加不同碳氮比（C／N）有机物、不同类型土壤、土壤水分含量及温度对含3,4-二甲基吡唑磷酸盐（3,4－dimethyl pyrazole phosphate,DMPP）硝化抑制剂的尿素（DMPP尿素）氨挥发损失的影响。结果表明,施肥水平对DMPP尿素的氨挥发损失有显著影响,随着DMPP尿素施用量的增加,土壤氨挥发损失量呈显著上升的趋势;DMPP尿素配施低C／N比的有机物鸡粪,氨挥发损失增加6．0％;而配施高C／N比的生物秸秆,则表现为可抑制78．2％的氨挥发损失;DMPP尿素的氨挥发损失受土壤理化性质影响很大,在肥力高的碱性土壤中氨挥发损失严重,而在酸性红壤和阳离子交换量高的青紫泥中挥发损失量较低;在土壤含水量为田间饱和持水量时,氨挥发损失表现为急剧增加;随着土壤温度的升高,氨挥发损失的量快速递增。合理控制施肥量、选择配施高C／N比的生物秸秆和适宜的水分管理方式是减少农田氨挥发损失的重要对策。     

控/缓释肥料减少氨挥发和氮淋溶的效果研究

采用“静态吸收法”和“土柱淋溶法”室内模拟实验,分别研究了6种控／缓释肥料施入土壤中的氨挥发和氮淋溶情况。结果表明：6种控／缓释肥料处理都不同程度的降低了氨挥发量和N素淋溶量。与尿素比较,6种控／缓释肥料氨挥发量分别较普通尿素减少16．62％,23．78％,32．15％,0．11％,16．59％和37、78％,氮淋溶量分别较普通尿素减少15．84％,38．27％,68．87％,46．17％,52．51%和62．01％。试验还表明控／缓释氮肥氨挥发量与不同氮肥引起的土壤脲酶活性、pH值有密切关系。     

改性尿素施用对氨挥发量及无机氮变化的影响

采用室内土壤培养和玉米幼苗盆栽试验的方法,研究了改性尿素施用后的氨挥发量及其对土壤无机氮和pH值的影响。结果表明:(1)表施改性尿素比表施普通尿素的氨挥发量显著减少,从而降低氮素的损失;在一定范围内,土壤含水量越大,氨挥发量越低。(2)硝化抑制剂双氰胺(DCD)能够抑制土壤硝化作用,使NH+4-N能较长时间存在土壤中,从而减少NO-3-N的损失;在一定范围内,DCD施用浓度越大,抑制效果越好。(3)土壤pH值与铵态氮呈极显著指数正相关,与硝态氮呈极显著线性负相关,与无机氮呈多项式相关。因此,改性尿素能够显著减少氨挥发量,抑制土壤硝化作用,从而降低尿素的氮素损失。     

缓释尿素与普通尿素配施对氨挥发和土壤氮素动态变化过程的影响

通过室内模拟试验,采用\"静态吸收法\"和\"土壤培养法\",研究了缓释尿素与普通尿素混施条件下,氨挥发和土壤中氮素的动态变化特征。结果表明:缓释掺混肥处理能减少氨挥发损失氮量;与普通尿素处理(SRU0)相比,25%缓释尿素+75%普通尿素(SRU25)、45%缓释尿素+55%普通尿素(SRU45)、65%缓释尿素+35%普通尿素(SRU65)、100%缓释尿素(SRU100)处理的氨挥发量分别降低19.88%、25.94%、42.84%和46.13%。在培养前期,普通尿素处理的土壤全氮、碱解氮和铵态氮含量明显高于缓释尿素处理,随着培养时间延长,普通尿素处理降低幅度最大,缓释掺混肥处理的全氮、碱解氮和铵态氮含量明显高于普通尿素处理;而硝态氮含量随培养时间延长逐渐升高。其中,以45%缓释尿素+55%普通尿素配比最佳,既能满足植物全生育期对养分的需求,又能减少氨挥发损失,节省经济成本。     

不同肥料运筹对夏玉米田间土壤氮素淋溶与挥发影响的原位研究

运用排水采集器法和通气法结合田间原位试验,研究了不同肥料运筹对夏玉米田间土壤氮素淋溶与挥发的影响。结果表明,在夏玉米生长季节,田间土壤水分淋溶体积达63.49～7.L/hm2,且表现与灌溉水量和降雨量正相关。与单施氮肥相比,有机肥配施氮肥在夏玉米生长发育前期易加剧水分的淋溶;氮素淋溶损失量明显高于氨挥发损失量,且二者均随施氮量的增加而升高;与单施氮肥相比,有机肥配施氮肥极显著地增大了氮素淋失量,减少氮素的氨挥发损失量,总体分析显示,有机肥配施氮肥极显著增大了氮素净损失量和氮素损失率;在夏玉米生长期内,施肥运筹的田间土壤淋溶水硝态氮浓度均呈现双峰趋势,以硝态氮形式淋失是田间土壤氮素淋失的主要形式,铵态氮浓度则呈现先升后降的趋势,铵态氮的累计淋失量很少。同时发现,大口期夏玉米生长旺盛,对氮素的需求强烈可以减少氮素的淋失和氨挥发损失,适量增加夏玉米大口期的追肥量,是提高氮肥利用效率的有效途径。     

控释与稳定尿素配施对土壤氮素迁移及冬小麦-夏玉米产量的影响

控释与稳定尿素配施,可通过双重调控作用增强对氮素的高效管理。本文以聚氨酯包膜控释尿素和新型复合型抑制剂涂覆尿素为试材,研究了二者配施条件下,调控冬小麦-夏玉米季施肥后氮素的动态迁移转化的效果,为开发高效专用肥和农业面源污染治理提供新的思路和技术手段。试验设置不施氮肥(CK)、农民习惯施用尿素[CV,冬小麦和夏玉米习惯施氮量分别为285 kg(N)·hm~(-2)和225 kg(N)·hm~(-2)]、优化施用尿素(OPT,冬小麦和夏玉米优化施氮量分别为199.50 kg(N)·hm~(-2)和157.50 kg(N)·hm~(-2))、优化施氮量下控释尿素+普通尿素(CRF1,冬小麦和夏玉米控释氮分别占40%和30%)和2个优化施氮量下控释尿素+抑制剂涂覆尿素(CRF2,冬小麦季和夏玉米季控释氮分别占30%和20%; CRF3,冬小麦季和夏玉米季控释氮分别占50%和30%)。试验测定了氨挥发和土壤硝态氮及作物产量。结果表明:在同等施氮量条件下,与OPT相比,CRF1、CRF2和CRF3在夏玉米、冬小麦季分别显著降低累积氨挥发量24.90%～57.00%和10.20%～27.80%,CRF2、CRF3比CRF1分别显著降低33.30%～42.80%和12.20%～19.60%。施肥后土壤表层硝态氮含量升高和降低速率由快至慢依次为CV、OPT、CRF1、CRF2和CRF3。夏玉米收获期土壤剖面残留硝态氮淋失风险由大到小依次是CV、OPT、CRF1、CRF2和CRF3,而冬小麦则为CV、OPT、CRF2、CRF1和CRF3。与CV和OPT处理相比,一次性优化施氮CRF1、CRF2和CRF3处理冬小麦、夏玉米产量没有显著差异。CRF2和CRF3净收入与其他施氮处理相比略有增加,与CRF1相比在夏玉米季增加639元·hm~(-2)和859元·hm~(-2),在冬小麦季降低1 196元·hm~(-2)和增加61元·hm~(-2)。控释氮和稳定氮为5︰5(冬小麦)和3︰7(夏玉米)表现效果最佳。     

改性尿素的肥效及淋溶特性研究初探

在普遍尿素的生产工艺中分别加入一定比例的无机矿物改性剂,研制出３种改性尿素。盆栽结果显示,在等质量及等Ｎ施肥条件下,３种改性尿素均有较大幅度的增产,淋溶实验表明,改性尿素与德国缓释尿素的淋溶曲线相似。     

典型双季稻田基施碳酸氢铵和尿素的氨挥发损失研究

采用密闭室连续抽气法研究了湖南典型双季稻田,尿素和碳酸氢铵基施后的氨挥发特征。结果表明,基施碳酸氢铵(NC)稻田初始氨挥发强度和氨挥发总量大于基施尿素(UR)稻田。早稻季NC处理稻田氨挥发排放量为45.19 kg·hm-2,损失率达30.12%,UR处理氨挥发排放量为32.93 kg·hm-2,损失率达21.95%;晚稻季NC处理稻田氨挥发排放量为70.91 kg·hm-2,损失率达31.93%,UR处理氨挥发排放量为61.78 kg·hm-2,损失率达27.04%。基施尿素能够显著降低稻田氨挥发排放,减少氮素损失。     

追施猪粪沼液对菜地氨挥发的影响

氨挥发是肥料氮素损失的主要途径之一。以厌氧发酵后的猪粪沼液为研究对象,通过蔬菜大棚小区试验,分析其作为追肥表施于冬季菜地(水芹(Oenanthe clecumbens L.)和扬花萝卜(Raphanus sativusL.Var.Radiculus pers.);追施氮量分别为72 kg hm-2和54 kg hm-2)及夏季菜地(小白菜(Brassica chinensisL.)和大叶茼蒿(Chrysanthemum carinatum Schousb.);追施氮量分别为42 kg hm-2和63 kg hm-2)后的氨排放特征及其影响因子。研究结果表明:(1)施用猪粪沼液后菜地氨挥发激增,沼液中氮素以氨挥发形态损失较快,通常发生在施入后48 h内;(2)冬季芹菜地和萝卜地施用沼液后的累积氨排放量分别为8.68 kg hm-2和9.90 kg hm-2,显著高于化肥处理(4.06 kg hm-2和5.59 kg hm-2);而夏季白菜地和茼蒿地则分别为10.40kg hm-2和11.61 kg hm-2,与化肥处理间差异不显著(9.81 kg hm-2和10.09 kg hm-2);(3)冬季菜地施用沼液后氨挥发损失率分别达到11.7%和17.7%,显著低于夏季菜地(23.3%和26.8%);(4)0～10 cm土层土壤温度、水分含量、可溶性有机碳含量、氮素水平及形态、微生物生物量及活性,均与菜地氨挥发有较高的关联度。沼液作为追肥施入农田后会因其自身氨挥发和激发效应而使氨排放增加,在施用过程中应特别注意温度的影响,同时应选择合适的施用方式。     

华北农田土壤氨挥发原位测定研究

通过系数矫正后的双层海绵吸收法对不同N肥处理和NPK配施下氨气挥发损失特征研究结果表明,N肥施用方式、土壤温度以及灌溉是影响氨挥发的重要因素。施肥后氨挥发损失量为0.67~9.91kg/hm2,占施N量的0.41%~5.0%。玉米季氨挥发量占全年挥发损失的80%以上。尿素与过磷酸钙配施可显著降低氨挥发,在此基础上施用KCl,尿素氨挥发损失变化不明显。     

Ammonia volatilization following surface application of urea to tilled and no-till soils: A laboratory comparison

Broadcasting of urea to agricultural soils can result in considerable losses by NH₃ volatilization. However, it is unclear if the impact of this practice on NH₃ emissions is further enhanced when performed on no-till (NT) soils. The objective of this study was to compare NH₃ volatilization following broadcasting of urea to NT and moldboard plowed (MP) soils. Intact soil cores were taken shortly after harvest from NT and MP plots of three long-term tillage experiments in Québec (Canada) and stored for 4.5 months prior to incubation. Urea (14 g N m⁻²) was applied at the soil surface and NH₃ volatilization was measured for 30 d using an open incubation system. Mean cumulative NH₃ losses were greater (P < 0.001) in NT (3.00 g N m⁻²) than in MP (0.52 g N m⁻²). Several factors may have contributed to the higher emissions from the NT soils. Urease activity in the top 1 cm of soils was on average 4.2 times higher in NT than in MP soils. As a result, hydrolysis of urea occurred very rapidly in NT soils as indicated by enhanced NH₃ emissions 4 h after application of urea. The presence of crop residues at the surface of NT soils also decreased contact of the urea granules with the soil, possibly reducing adsorption of NH₄⁺ on soil particles. Lower volatilization on the MP soils may also have partly resulted from a fraction of urea granules falling into shallow cracks. Field trials are needed to confirm our finding that NT soils bear greater potential for NH₃ volatilization following surface application of urea than MP soils.     

藻类在稻田生态系统中的作用及其对氨挥发损失的影响

本文在总结已有稻田藻类研究结果的基础上,结合温室盆栽试验的初步结果,阐述了藻类对稻田氨挥发损失过程的影响,及其在稻田土壤N素转化、供应与调节中所起的重要作用。提出了减少N素氨挥发损失和合理利用稻田藻类的方法。     

Reducing ammonia loss from urea and improving soil-exchangeable ammonium retention through mixing triple superphosphate, humic acid and zeolite

Ammonia losses from soil following fertilization with urea may be large. This laboratory study compared the effect of four different, urea–triple superphosphate (TSP)–humic acid–zeolite, mixtures on NH₃ loss, and soil ammonium and nitrate contents, with loss from surface‐applied urea without additives. The soil was a sandy clay loam Typic Kandiudult (Bungor Series). The mixtures significantly reduced NH₃ loss by between 32 and 61% compared with straight urea (46% N) with larger reductions with higher rates of humic acid (0.75 and 1 g kg^?1 of soil) and zeolite (0.75 and 1 g kg^?1 of soil). All the mixtures of acidic P fertilizer, humic acid and zeolite with urea significantly increased soil NH₄ and NO₃ contents, increased soil‐exchangeable Ca, K and Mg, and benefited the formation of NH₄ over NH₃ compared with urea without additives. The increase in soil‐exchangeable cations, and temporary reduction of soil pH may have retarded urea hydrolysis in the microsite immediately around the fertilizer. It may be possible to improve the efficiency of urea surface‐applied to high value crops by the addition of TSP, humic acid and zeolite.     

太湖地区稻田氨挥发及影响因素的研究

应用微气象学方法研究太湖地区水稻三个不同施肥期施用尿素后的氨挥发损失 ,并对其影响因素 (气候、田面水中NH 4 N浓度和作物覆盖等 )的作用进行了分析研究。结果表明 ,水稻施用尿素后的氨挥发损失为各时期施氮量的 18 6 %～ 38 7% ,其中以分蘖肥时期损失最大 ,其次为基肥 ,穗肥氨挥发损失最小。氨挥发损失主要时期是在施肥后 7d内。在水稻不同生长期 ,各因素对氨挥发的影响能力大小并不一样 ,三个施肥期的氨挥发损失通量与施肥后田面水中铵态氮浓度呈显著正相关。     

红壤不同含水量对尿素氨挥发的影响

根据第四纪红壤水分特征设计160、200、240、280、320、360g/kg6个土壤含水量处理,通过温室模拟,研究了红壤不同含水量对尿素氨挥发的影响。结果表明,等量尿素施入红壤后,氨挥发通量与土壤含水量之间无显著相关性,而高含水量(280、320、360g/kg)处理氨挥发通量峰值较低含水量(160、200g/kg)处理提前10天。氨挥发过程可分为快速-慢速2个阶段,氨累积挥发量(y)与对应时间(t)符合Elovish动力学方程(y=a blnt)。第1～10天,氨挥发累积量随红壤含水量的增加而递增;第11天后,以含水量为240g/kg处理的氨挥发累积N量最低。试验期间,氨挥发累积总N量,以含水量240g/kg时最低(0.90gN),含水量320g/kg时最高(1.16gN),分别占尿素施入N量的9.0%和11.6%。     

太湖地区氮磷肥施用对稻田氨挥发的影响

在太湖地区乌栅土上,采用田间小区试验连续两年研究了施氮(N)量为0、180、255、330kg hm-2,施磷(P2O5)量为0、309、0、180 kg hm-2的6个组合(对照N0P0、低氮N180P90、优化N255P90、低磷N255P30、高磷N255P180、高氮N330P90)以及三个施肥时期对稻田氨挥发损失的影响,氨挥发采用密闭室间歇通气法测定。结果表明,稻田氨挥发损失主要发生在施肥后6d内,基肥和第一次追肥后各处理氨挥发量占施氮量的0.4%~11.5%,而第二次追肥后氨挥发损失比例较大,对照、低氮、优化、低磷、高磷和高氮处理的氨挥发在2002年稻季分别占施氮量的5.8%、9.7%、25.6%、15.6%和11.6%,在2003年稻季则分别为27.4%、26.2%、30.0%、35.1%和27.6%。若施肥后遇阴雨天气或正值水稻拔节孕穗期,氨挥发量便降低。田面水中的NH4 -N浓度是氨挥发的决定因素之一,与氨挥发通量呈正相关。施磷量相同时,氨挥发随施氮量增加而增加;施氮量相同时,高磷和低磷处理氨挥发均高于优化处理,表明在氮磷不平衡施用时,氮肥氨挥发损失会加剧,从氨挥发损失方面考虑,稻田推荐施磷量不宜超过P2O590 kg hm-2。     

Effects of some environmental factors on ammonia volatilization from simulated livestock urine applied to soil

Summary The proportion of the N that was volatilized as ammonia during 8 days, following the application of simulated livestock urine to soil, increased from 25 to 38% as the temperature of incubation was increased from 4° to 20°C in a system with a continuous flow of air at 70% relative humidity. However, volatilization was reduced if the application was followed by simulated rain; the reduction was greater as the amount of rain increased (up to at least 16 mm) and became less with an increasing length of time (up to 2–3 days) after the application of the urine. The effects of the soil water content before application of the urine, and of the relative humidity of the air, were generally small but volatilization was reduced by a combination of air-dry soil with a low relative humidity. Volatilization was slight (7%) when the flow of air was restricted to 0.5 h in every 12 h but, with an air flow for 12 h in every 24 h, the volatilization was much closer to that with a continuous flow for the whole 8-day period. When cool or dry conditions were imposed for 8 days and then more favourable conditions were instituted for a second period of 8 days, there was a substantial increase in volatilization following the change.