Apparent variations in nitrogen runoff and its uptake in paddy rice under straw incorporation

Straw incorporation is a widespread practice to promote agricultural sustainability.However,the potential effects of straw incorporation with the prolonged time on nitrogen(N)runoff loss from paddy fields are not well studied.The current study addresses the knowledge gap by assessing the effects of straw incorporation on the processes influencing N runoff patterns and its impacts on crop yield,N uptake,total N(TN),and soil organic matter(SOM).We conducted field experiments with rice(Oryza sativa L.)–wheat(Triticum aestivum L.)rotation,rice–tobacco(Nicotiana tabacum L.)rotation,and double-rice cropping in subtropical China from 2008 to 2012.Each rotation had three N treatments:zero N fertilization(CK),chemical N fertilization(CF),and chemical N fertilization combined with straw incorporation(CFS).The treatment effects were assessed on TN runoff loss,crop yield,N uptake,soil TN stock,and SOM.Results showed that TN runoff was reduced by substituting part of the chemical N fertilizer with straw N in the double rice rotation,while crop N uptake was significantly(P<0.05)decreased due to the lower bioavailability of straw N.In contrast,in both rice–wheat and rice–tobacco rotations,TN runoff in CFS was increased by 0.9–20.2%in the short term when straw N was applied in addition to chemical N,compared to CF.However,TN runoff was reduced by 2.3–19.3%after three years of straw incorporation,suggesting the long-term benefits of straw incorporation on TN loss reduction.Meanwhile,crop N uptake was increased by 0.8–37.3%in the CFS of both rotations.This study demonstrates the challenges in reducing N runoff loss while improving soil fertility by straw incorporation over the short term but highlights the potential of long-term straw incorporation to reduce N loss and improve soil productivity.

Reducing nitrogen runoff from paddy fields with arbuscular mycorrhizal fungi under different fertilizer regimes

Nitrogen（N） runoff from paddy fields serves as one of the main sources of water pollution. Our aim was to reduce N runoff from paddy fields by fertilizer management and inoculation with arbuscular mycorrhizal fungi（AMF）. In northeast China, Shuangcheng city in Heilongjiang province, a field experiment was conducted, using rice provided with 0%, 20%, 40%, 60%, 80%,and 100% of the local norm of fertilization（including N, phosphorus and potassium）, with or without inoculation with Glomus mosseae. The volume, concentrations of total N（TN）,dissolved N（DN） and particulate N（PN） of runoff water were measured. We found that the local norm of fertilization led to 18.9 kg/ha of N runoff during rice growing season, with DN accounting for 60%–70%. We also found that reduction in fertilization by 20% cut down TN runoff by 8.2% while AMF inoculation decreased N runoff at each fertilizer level and this effect was inhibited by high fertilization. The combination of inoculation with AMF and 80% of the local norm of fertilization was observed to reduce N runoff by 27.2%. Conclusively, we suggested that the contribution of AMF inoculation combined with decreasing fertilization should get more attention to slow down water eutrophication by reducing N runoff from paddy fields.

Spatial and temporal variation of nitrogen exported by runoff from sandy agricultural soils

The eutrophication problem has drawn attention to nutrient leaching from agricultural soils, and an understanding of spatial and temporal variability is needed to develop decision-making tools. Thus, eleven sites were selected to monitor, over a two-year period, spatial and temporal variation of runoff discharge and various forms of N in surface runoff in sandy agricultural soils. Factors influencing the variation of runoff discharge and various forms of N in surface runoff were analyzed. Variation of annual rainfall was small among 11 sites, especially between 2001 and 2002. However, variation of annual discharge was significant among the sites. The results suggest that rainfall patterns and land use had significant effect on discharge. The concentrations of total N, total kjeldahl N （TKN）, organic matter-associated N （OM-N）, NO3- -N, and NHn＋-N in the runoff ranged widely from 0.25 to 54.1, 0.15 to 20.3, 0.00 to 14.6, 0.00 to 45.3, and 0.00 to 19.7 mg/L, respectively. Spatial and temporal variations in the N concentration and runoff discharge were noted among the different sites. Annual loads of N in the runoff varied widely among monitoring sites and depend mainly on runoff discharge. High loads of total N, OM-N, NO3--N, and NHn＋-N in the runoff either in citrus groves or on vegetable farms occurred from June to October for each year, which coincided with the rainy season in the region. This study found that N in surface runoff was related to rainfall intensity, soil N level, and fertilizer use.

Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application

The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.

Nitrogen export by runoff and sedimentunder different types of land use inWest Tiaoxi catchment

Five typical land covers in West Tiaoxi catchment of China, including mulberry garden, bamboo forest, pinery, vegetable plot and paddy field, were studied on nitrogen loss in artificial rainstorm runoff and sediment. Triple duplication experiments have been carried out under the artificial rain condition with an intensity of 2 mm.mm?1 and lasting 32 minutes in 3 m2 field. Export of various species of nitrogen in runoff and sediment were investigated. The results show that nitrogen loss amount and rate are quite different among five kinds of land covers. The loss of total nitrogen in runoff of mulberry is the largest and that of paddy field is the smallest. Particle nitrogen accounts for 70–90% of total nitrogen in runoff of various kinds of land covers. Loss of dissolved nitrogen in pinery is much higher than in other kinds of land covers, which are similar among them. More detailed species of dissolved nitrogen show their respective features among various land covers. Total amounts of nitrogen loss from the top 10 cm layer of 5 kinds of soils are estimated as high as 4.66–9.40 g.m?2, of which nitrogen loss through sediment of runoff accounts for more than 90%. The rate of total nitrogen losses are ranged in 2.68–14.48 mg.m?2.min?1 in runoff, which is much lower than that of 100.01–172.67 mg.m?2.min?1 in sediment of runoff.

冬春季生态沟渠对农田径流污染物的净化效果分析

为有效提高冬春季沟渠的净化效率,在原有土质沟渠中增设耐寒植物黑麦草浮毯与填料透水坝构建生态沟渠,分析生态沟渠对农田径流中主要污染物的削减率,对比沿程不同处理段对污染物的净化效果,估算植物吸收对于污染通量降低总量的贡献。结果显示:在冬春季节,生态沟渠对总氮(TN)、硝氮(NO_(3)^(-)-N)、总磷(TP)、化学需氧量(COD)和悬浮物(SS)的总削减率均值分别为29.06%、54.93%、20.76%、54.08%和49.85%。透水坝段的TN和NO_(3)^(-)-N沿程削减率最高;植物浮毯+透水坝段的TP和COD沿程削减率最高;植物浮毯段的SS沿程削减率最高,其对NO_(3)^(-)-N、TP和COD也有较好的净化效果。在降水量达到10 mm以上的9 d内,TN和TP的污染通量降低总量分别为11.43和0.27 kg;黑麦草吸收的氮、磷量分别约占污染通量降低总量的20.6%和55.6%。大雪融化后气温降至0℃以下,可能引起土壤冻融作用,雪水径流中的氮、磷浓度显著升高,此时生态沟渠对径流中氮、磷的净化效果不明显,可利用周边河塘暂存雪水径流,后续结合生态措施对污染物实施强化处理。

不同配置乡村植被缓冲带阻控径流污染特征研究

植被缓冲带是河湖的重要生态空间屏障,对于减缓人类活动对河湖的直接干扰、阻隔农业面源污染等具有重要意义。为系统研究不同类型缓冲带对农田氮磷等污染物的拦截功效,本研究在定远张山设计8个缓冲带小区,结合自然降雨方式,持续两年观测不同缓冲带对地表径流及其主要污染物(TN、TP、COD)的削减效果。结果表明:林地和3°、8°横垄耕地缓冲带对径流的拦截效率较高,减流率分别达到了62.4%、52.0%和60.6%,径流量随雨强增大先升高后下降。与8°坡耕地缓冲带相比,降坡(3°)处理竖垄、横垄缓冲带泥沙流失量分别降低53.3%、50.9%。降雨产流的养分流失以氮素和有机质为主,林地缓冲带对径流NH4+-N的拦截率平均高达95.2%,此外降坡和横垄耕作措施也能有效减少径流冲刷的氮素流失。不同处理缓冲带对径流TP均有较好的拦蓄效果。3°、8°横垄耕地缓冲带CODMn流失量较低,拦截率达到53.0%、58.6%。林地缓冲带中高覆盖度的植被和发达的根系能够有效减缓降雨对地表的冲刷,减少径流和养分流失。在南方丘陵山地的乡村地区实施横坡垄作是拦蓄径流、降低面源污染风险的有效措施。

南方校园降雨径流特性与植草沟净化效果研究

为研究植草沟对降雨径流污染的削减效果,于校园绿化带路段建立植草沟示范点,并在研究校园总体降雨水质和不同下垫面降雨径流特性基础上,开展植草沟对屋面雨水和地表径流中污染物的控制效果研究。结果表明,校园降雨径流中COD和NH_(3)-N浓度较高,需进行控制;且屋面雨水相较于道路径流水质污染更为严重,可能的原因是沥青油毡屋面材料中有机物的释出增加了径流水质的有机物污染程度;屋面雨水降雨初期污染较为严重,但屋面雨水与道路径流各污染物浓度随着降雨历时的延长均呈现逐渐下降并趋于稳定的变化规律;植草沟对屋面雨水COD的去除率为59%~98%,浊度的去除率为50%~83%,TP的去除率为59%~93%,NH_(3)-N的去除率为49%~88%。可见,渗透型生态植草沟作为一种植被生态排水沟渠,有助于减少不透水下垫面的覆盖程度,对控制城市面源污染效果十分显著。

基于SWAT模型的武强溪流域非点源污染关键源区界定与控制策略

随着点源污染的控制与处理技术日趋完善,非点源污染成为重要的水污染源。武强溪作为流入千岛湖的第二大支流,量化武强溪流域非点源污染负荷,解析非点源污染时空分布特征,提出适合削减武强溪流域污染物的最佳管理措施(best management practices,BMPs)对千岛湖水污染高效治理至关重要。该研究基于土壤水分评估工具(Soil and water assessment tool,SWAT)分析了武强溪流域径流量、总氮输出负荷量的时空分布特征,探究了不同管理措施及组合的削减效果,提出了武强溪流域非点源污染针对性的治理措施。结果表明:1)SWAT模型对于武强溪流域径流量和总氮输出负荷量的模拟具有较好的适用性,径流量校准期和验证期的决定系数(coefficient of determination,R^(2))分别为0.86、0.97,纳什系数(nash-sutcliffe coefficient,NSE)分别为0.83、0.96,百分比偏差(percent bias,PBIAS)分别为15.8%、-6.3%,总氮校准期和验证期的决定系数分别为0.87、0.74,纳什系数分别为0.63、0.66,百分比偏差分别为31.6%、21.2%;2)该流域径流量和总氮负荷主要集中在3—7月,分别占全年输出量的71.67%和75.76%。综合考虑氮的来源和流失途径,将耕地和林地面积占比大、坡度陡的子流域设置为总氮的关键污染源区。考虑调整化肥施用量/配方、改变耕作方式和设置植被缓冲带等削减非点源污染的手段,进行总氮输出负荷削减效率的情景模拟,表明10 m植被缓冲带是减少总氮输出负荷的最佳单一控制策略,总氮削减率可达到69.90%;实施综合管理措施对总氮的污染削减效果更佳,10 m植被缓冲带与施肥量减少20%可使总氮削减率达到74.79%。研究结果可为千岛湖水质管理与控制提供理论基础。

不同农作措施下紫色土坡耕地氮磷流失特征

为揭示不同农作措施下径流氮磷流失变化特征,基于2020年12场次的自然降雨产流事件,分析了顺坡无施肥(对照,CK)、顺坡混合施用有机肥和化肥(T1)、顺坡单施化肥(T2)、顺坡单施化肥增量(T3)、横坡单施化肥(T4)5种处理下径流量及径流中总氮(TN)、总磷(TP)质量浓度与流失量、氮磷比(TN/TP)的变化特征.结果表明:①各处理径流TN,TP最高质量浓度均发生在施肥后的前6次降雨,其中的4次降雨事件造成了超50%的总氮、总磷流失.②与单施化肥相比,有机肥化肥配施的径流TN,TP流失量没有显著差异,且径流TN,TP质量浓度与施肥后天数都呈极显著线性负相关(p<0.01).③和顺坡耕作相比,横坡垄作可以显著削减76.85%的径流量、75.12%的径流总氮流失量和87.97%的径流总磷流失量.④CK处理的TN/TP显著高于T2和T3(p<0.05),但与T1,T4差异无统计学意义(p>0.05),所有处理下全年超50%的TN/TP≥50,表现为磷限制.

降雨事件下洱海北部主要入湖河流污染物特征分析

通过研究2019年雨季(7—9月)洱海最主要的入湖河流污染物特征,对流域内6场次降雨下的污染物浓度与负荷进行监测,阐述6种污染物特征,计算入湖负荷,并评估对洱海的水质影响。结果表明:弥苴河是北三江流域径流与污染物入湖的主要贡献来源,径流量占北三江流域入湖总径流量的47%,氨氮、硝态氮、可溶性总氮(TDN)、正磷酸盐、可溶性总磷(TDP)和化学需氧量(COD)入湖负荷分别占总负荷的40.5%、65.0%、55.0%、55.0%、54.1%、57.1%;TDN、TDP、氨氮、COD污染负荷之间都存在着不同程度的相关性,降雨是影响氮磷等典型污染物负荷入湖的主要因素。雨季径流携带大量养分入湖使水体养分浓度升高,导致水体环境质量下降。因此在雨季控制径流携带污染物入湖,对防控洱海水质持续下降具有重要意义。

不同厚度降解地膜对坡耕地溶解态氮磷流失的影响

[目的]为探究降解地膜覆盖对径流及溶解态氮磷流失的影响。[方法]利用野外原位径流小区,以覆膜垄作花生种植为研究对象,设置0.003 mm厚聚乙烯普通地膜覆盖处理(PF)和厚度为0.006 mm(BF1),0.008 mm(BF2),0.010 mm(BF3),0.012 mm(BF4)的降解地膜覆盖处理及未覆膜处理(CK),测定不同处理在自然降雨条件下的径流量及径流中铵态氮(NH_(4)^(+)-N)、硝态氮(NO_(3)^(-)-N)、速效磷(PO_(4)^(3-)-P)浓度,分析不同厚度降解地膜覆盖条件下径流及养分流失特征。[结果](1)降解地膜降解所需时间随地膜厚度的增加而增加。(2)各处理的累积径流量由小到大为BF1<BF2<BF3<PF<CK<BF4,BF1与BF4之间差异显著(p<0.05)。(3)与CK相比,各覆膜处理均能不同程度减少氮磷累积流失量。其中,BF1处理对NH_(4)^(+)-N和NO_(3)^(-)-N流失量的削减效果较好,而BF2处理对PO_(4)^(3-)-P流失量的削减效果较好。(4)在5个覆膜处理中,BF4处理的NO_(3)^(-)-N和PO_(4)^(3-)-P流失量最高,而BF3处理的NH_(4)^(+)-N流失量最高。[结论]研究结果可为防治覆膜坡耕地水土及养分流失、解决农业面源污染等问题提供理论基础,对绿色农业发展和生态可持续发展具有重要意义。

马尾松改造成香榧林对地表径流及氮磷流失的影响

掌握马尾松Pinus massoniana林转换为香榧Torreya grandis林对地表径流及氮磷流失的影响,可为人工林经营管理提供一定的基础。在浙江省东阳市林业总场设置马尾松林、香榧幼龄林和香榧中龄林3种处理径流小区,全面监测2023年地表径流量,分析径流水中不同形态氮、磷浓度,并计算养分流失量。结果表明:地表径流量大小为马尾松林(218.0 m^(3)·hm^(−2))>香榧幼龄林(206.0 m^(3)·hm^(−2))>香榧中龄林(157.0 m^(3)·hm^(−2));地表氮流失量大小为香榧幼龄林(806.56 g·hm^(−2))>香榧中龄林(582.80 g·hm^(−2))>马尾松林(159.89 g·hm^(−2)),磷流失量大小为香榧幼龄林(265.55 g·hm^(−2))>香榧中龄林(183.57 g·hm^(−2))>马尾松林(48.72 g·hm^(−2))。与马尾松林相比,香榧幼、中龄林地表径流量分别减少了5.5%和22.5%,而氮流失量增加了4.04倍和2.65倍,磷流失量增加了4.45倍和2.77倍。综上,马尾松林改造成香榧林后降低了地表径流,但增加氮、磷流失量,随着香榧林龄的增大,地表径流及氮、磷流失量随之降低。

自然红壤坡地氮素在地表径流-土壤水系统迁移转化规律试验研究

目前对红壤坡地氮素流失的试验研究主要集中在人工土槽装置中监测径流和壤中流氮素,缺乏在野外自然坡情况下氮素在径流-壤中流及土壤中迁移转化过程的整体研究。为了探究天然红壤坡地氮素在地表径流-土壤水系统中的迁移转化规律,在江西水土保持生态科技园开展了3次坡地人工降雨氮素流失试验,对不同坡面及土壤初始条件下人工降雨过程中地表径流、壤中流及土壤水分状况与氮素(硝态氮和铵态氮)浓度进行了监测和分析。结果表明,初始坡面粗糙截流能力强,能减少地表径流产流量,但会导致硝态氮大量渗入土壤,造成硝态氮随土壤水的下移。自然坡地土壤中的大孔隙和土壤空间变异性是导致壤中流的主要原因,壤中流硝态氮浓度显著高于地表径流硝态氮浓度,导致壤中流硝态氮流失占比较高,第一次试验中硝态氮壤中流流失占比超过50%。相比较而言,壤中流与地表径流铵态氮浓度均较小,与铵态氮在土壤中较强的吸附能力有关。历次试验中,土壤硝态氮和铵态氮沿顺坡方向空间变异性较大,随时间变化无一致性规律,除受到坡面水力特征影响外,还受到土壤温度的影响。

碎石含量对三峡库区坡耕地土壤氮磷流失特征的影响

坡耕地是三峡库区水土流失的主要来源,导致土壤养分的损失,严重影响库区生态环境建设与社会经济可持续发展。库区坡耕地土壤浅薄化和砾质化特征明显,但目前对含碎石坡耕地土壤侵蚀和养分流失特征的研究尚不多见。该研究通过设置3个降雨梯度(60、90、120 mm/h)和4种碎石含量(0、10%、20%、30%),开展人工模拟降雨试验,分析各试验条件下含碎石土壤产流产沙和氮磷流失特征。结果表明:1)碎石主要通过改变土壤结构以增大产流产沙量来促进氮磷流失,而对相应流失速率与流失浓度的变化规律影响较小,不同碎石含量下泥沙产量的变异系数更高,且泥沙中不同碎石含量下的氮磷流失量显著性差异更强(P<0.05);2)泥沙中累计磷流失量略微大于氮流失量,有效磷几乎不随泥沙流失,有效氮约占全氮流失量的15%;径流中氮素流失量几乎为磷素的10倍且以有效氮为主,占总氮流失量的75%,有效磷占总磷流失量的25%;3)不同碎石含量下有效氮流失规律大致相同,径流中硝态氮约占有效氮流失量的70%,而泥沙中则以铵态氮为主,约占65%;4)不同碎石含量下土壤中氮磷元素均以随侵蚀产沙流失为主,累计产沙量与氮磷元素随侵蚀产沙流失量均在20%碎石含量下达到极大值,10%碎石含量下流失量相对较小,因此泥沙库区坡耕地氮磷流失防治应以减少侵蚀产沙为主,注意大雨暴雨多发季节的水质监测与施肥控制。同时可对土中碎石进行清除使其保持在不高于10%水平。研究结果可为三峡库区含碎石坡耕地水土流失防治和氮磷流失治理提供科学参考。

The Impact of Hula Project (1993-2018) on Nutrient Migrations

During the 1950s the Hula wetlands and old lake were drained and the land converted utilization to agriculture and ecotourism. As a result of the drainage, the Peat Soil was exposed to atmospheric oxygen. The geochemical environment was modified from reductive to oxidative and the Nitrogen in it was converted from Ammonium to Nitrate. Intensive migration of Nitrate from the Hula Valley induced a national concern of water quality deterioration in the lake which was dissipated when Nitrogen deficiency was developed in Lake Kinneret. Forty years after drainage the ecosystem structure was renovated (Hula Project, HP) aimed at agricultural management and nutrient migration reduction. The paper examines through evaluation of the ecological data record (1993-2018) the impact of hydrological changes, attributed to the HP implementation on nutrient dynamics within surface waters in the Hula Valley. It is suggested that soil moisture elevation by irrigation in summer reduced Phosphorus and enhanced Nitrate concentrations.

我国中部水网区茭白潜流湿地进出水质和净化性能时变特征

本研究从小集水区角度研究了茭白潜流湿地进出水氮、磷、COD_(Cr)污染和净化性能的时变特征,结果表明,茭白潜流湿地进水氮、磷、COD_(Cr)季节波动大,其中春节期间湿地进水总氮(TN)和总磷(TP)最高,其次是农田施用化肥后产生地表径流的首月,中等降雨量下湿地进水COD_(Cr)浓度高于强暴雨下的浓度。受沉淀池的调节缓冲,湿地进水氨氮(NH_(3)-N)和硝态氮(NO_(x)^(-)-N)秋季最高,其次是春节后。湿地对小集水区氮、磷、COD_(Cr)冲击负荷均具有良好的缓冲能力和净化性能,TP、TN和COD_(Cr)平均去除率分别为(82.1±10.5)%、(72.9±8.1)%和(65.6±6.2)%;秋冬季过渡期间,因微生物降解和基质吸附的协同作用使得植物吸收氮磷的季节拐点不明显;冬季湿地具有耐受中部水网区低温的能力。不过冬季低温易于引起潜流湿地内有机氮分解转变为NH_(3)-N后被沸石等基质吸附而发生积聚,同时较长水力停留时间(HRT)下因有机质分解耗氧引起环境厌氧的加剧。此外,冬季出水溶解有机磷(DOP)比例增加。该潜流湿地可有效提升村镇面源污染排水水质,改善乡村水环境,但对上述受季节影响较大的时变因素应加强管控。

自然降雨和施用缓释肥对北运河上游大田氮磷径流流失的影响

在北运河上游流域,通过大田监测试验,研究了自然降雨条件下不施肥(T_(1))、传统施肥(T_(2))、缓释肥(T_(3))3种不同施肥处理玉米生长季氮磷径流流失的影响。结果表明:当流域内12 h内降雨量超过30 mm时,土壤含量水呈饱和状态,由此地表径流液产生;若在1 h内降雨量超过30 mm,则会加剧径流的产出。与T_(2)处理相比,T_(3)处理的总氮、总磷、铵态氮、硝态氮流失量均偏低,分别低15.3%、24.2%、10%和12%,但未达到显著性差异。T_(3)处理的总氮流失率为0.07%,较T_(2)处理减少46.2%;T_(3)处理的总磷流失率为0.13%,较T_(2)处理减少71.7%;T_(3)处理的硝态氮流失率为0.06%,较T_(2)处理减少25%。综上,与传统施肥相比,施用缓释肥在减少氮磷流失方面能起到一定的减排作用,对科学推广缓释肥和评估缓释肥对氮磷流失的减排效果提供了数据支撑。

Change trend analysis of ammonia nitrogen in Nenjiang River main stream under fluctuating precipitation

将2004-2010年嫩江流域沿途13个气象站的降水量作为径流的主要考察因子，以嫩江最下游的自沙滩水环境监测站获得的氨氮监测数据为流域总体氨氮污染水平表征，分析了降水波动对嫩江流域氨氮污染变化的影响。结果表明，嫩江流域在年度内的氨氮质量浓度以枯水期最高，平均为（0．99±0．48）mg／L，在丰水期最低，平均为（O．58±0．08）mg／L。从年际总体变化趋势来看，2004-2010年嫩江流域氨氮浓度总体呈增加趋势。降水量的年内分布格局对嫩江流域氨氮浓度的影响在不同时期略有差别。在平水期，降水量变化对氨氮浓度的影响不显著；但在枯水期、丰水期，降水量的波动对氨氮浓度有较显著（Sig．〈O．05）的影响。从年尺度上看，随降水量增加，嫩江流域中氨氮浓度总体呈下降趋势。

Discharge Water Quality Models of Storm Runoff in a Catchment

The relationships between the water qualities of nitrogen and phosphorous contents in the discharge water and the discharge of storm runoff of an experimental catchment including terraced paddy field are analyzed based on experiment results of the catchment. By summarizing the currently related research on water quality models, the water quality models of different components of storm runoff of the catchment are presented and verified with the experiment data of water quality analyses and the corresponding discharge of the storm runoffs during 3 storms. Through estimating the specific discharge of storm runoff, the specific load of different components of nitrogen and phosphorus in the discharge water of the catchment can be forecasted by the models. It is found that the mathematical methods of linear regression are very useful for analysis of the relationship between the concentrations of nitrogen and phosphorus and the water discharge of storm runoff. It is also found that the most content of the nitrogen (75%) in the discharge water is organic, while half of the content (49%) of phosphorus in the discharge water is inorganic.