滴灌施氮肥对盆栽玉米生长的影响

本研究通过滴灌施氮肥与常规的基施氮肥进行比较试验,以了解两种不同的施肥方式下施用不同品种氮肥对氮肥利用率的影响。试验设10个处理,所选用的氮肥品种有:尿素、硝酸铵、硝酸钙、硫酸铵。试验结果表明,同基施氮肥+滴灌处理相比,滴灌施氮肥处理能显著提高氮肥的利用率,其增幅达8.75%～21.50%,有利于玉米对氮肥的吸收及生物量的积累;在同一灌溉施肥条件下施用不同品种的氮肥时,各处理间的氮肥利用率表现出一定的差异性,其中硝酸钙处理的氮肥利用率显著低于另外3种氮肥处理。     

包膜脲酶抑制剂增效尿素对小麦生长的影响及其机理研究

为有效提高尿素氮利用率,促进新型缓/控释氮肥的研发。在盆栽试验条件下,研究了脲酶抑制剂氢醌(HQ)部分或全部包膜与尿素掺混施用对小麦生长及土壤不同形态氮素含量和脲酶活性的影响。试验共设5个处理:对照(CK)、普通尿素(U)、U+普通HQ(SRU1)、U+包膜HQ(SRU2)和U+30%普通HQ+70%包膜HQ(SRU3)。结果表明:与SRU1相比,包膜HQ能够促进小麦生长,改善小麦产量构成,增加小麦产量,并提高氮素利用率,其中SRU2、SRU3分别增加了小麦产量的34.71%,56.54%;与SRU2相比,SRU3处理中普通HQ与包膜HQ配合施用前期能够有效抑制尿素水解,维持土壤中NH_4~+—N的适宜浓度,后期能增加土壤NH_4~+—N含量,保证土壤有效氮的持续供应,减少氮素损失,使小麦整个生育期内土壤脲酶活性维持在较低水平。综上,HQ部分包膜与尿素掺混施用的SRU3处理土壤氮的供应能力最强,氮素利用率最高,对小麦生长的促进作用最显著。     

控释氮肥对土壤酶活性与土壤养分利用的影响

为探明控释氮肥施用对土壤环境和土壤肥力的影响,通过小麦盆栽试验研究不同施氮量控释氮肥和普通尿素对小麦土壤酶活性、土壤养分利用及产量的影响。结果表明,推荐施氮量及减氮30%控释氮肥施用显著提高土壤酶活性和无机氮含量;推荐施氮量控释氮肥和普通尿素处理土壤有效磷含量显著降低;减氮50%控释氮肥处理土壤速效钾含量显著降低;土壤酶之间及土壤酶与土壤养分之间表现出显著的相关性。推荐施氮量控释氮肥处理较等氮量普通尿素处理籽粒产量显著提高14.06%,但减氮30%及减氮50%控释氮肥处理与推荐施氮量普通尿素处理籽粒产量差异不显著。推荐施氮量控释氮肥处理较其他施氮处理氮、磷、钾吸收总量分别显著增加20.83%~37.63%,32.86%~55.00%和11.20%~21.82%。推荐施氮量、减氮30%及减氮50%控释肥处理较推荐施氮量普通尿素处理氮素利用率分别显著提高40.42%,46.05%和65.73%。控释氮肥施用有利于提高土壤酶活性、土壤养分利用及小麦籽粒产量,是优化农业施肥管理的有效措施。     

氮肥施用对直播冬油菜产量及氮肥利用率的影响

为探明安徽省直播冬油菜种植中适宜的氮肥用量、氮肥种类和施氮方式,通过田间小区试验,研究尿素不同用量及等氮量尿素和控释尿素不同施用方式对直播冬油菜产量、氮肥累积量及氮肥利用率的影响。结果表明:施氮水平和施氮方式对直播冬油菜产量具有显著影响,成株率与产量之间呈显著正相关,施氮量180 kg N·hm~(-2)条件下,尿素分次施用处理(N180)和控释尿素一次性施用处理(CRU180)在生育中后期能有效提高直播冬油菜密度。施氮量240 kg N·hm~(-2)、尿素分次施用处理(N240)角壳和茎秆氮素累积量分配比例增加,籽粒分配比例减少,氮肥表观利用率、氮肥农学效率、氮肥生理效率和氮肥偏生产力显著降低,籽粒产量不增反降,较CRU180和N180分别降低2.87%和9.67%。各施氮处理中,N180处理产量最高,较其他施氮处理显著增产7.53%～82.15%。施氮量180 kg N·hm~(-2)条件下,相比尿素一次性施用处理(U180),CRU180和N180显著增产8.53%和16.69%,籽粒氮素累积量显著增加8.80%和16.02%,氮肥表观利用率显著增加11.68%和14.30%,氮素农学效率显著增加12.53%和24.46%,氮素生理效率增加0.74%和9.13%,氮肥偏生产力显著增加8.59%和16.76%。综合本试验直播冬油菜产量、氮素累积量和氮肥利用率结果来看,合理的氮肥用量和氮肥品种可以有效增加直播冬油菜的成株率和氮素累积量,进而增加产量、提高氮肥利用率。安徽省直播冬油菜施氮量180 kg N·hm~(-2),尿素分次施用和控释尿素一次性施用,均能达到产量和氮肥利用率的双向提升。考虑到直播冬油菜轻简化发展大趋势,建议采用控释尿素一次性基施。     

包膜控释掺混尿素对双季稻生长及氮素利用率的影响

为了比较常规分次施肥和包膜控释掺混尿素对双季稻生长及氮素利用率的影响,在田间条件下,研究了不同施肥处理对双季稻分蘖数、叶绿素含量、各个生育期植株含氮量、稻草稻谷产量及氮素利用率等因素的影响。结果表明：（1）在早稻上,控释掺混尿素处理的以上各测试指标均高于常规分次施氮肥处理,各指标两处理之间差异均不显著（P〈0.05）。控释掺混尿素的氮肥利用率为40.08%,显著高于常规分次施氮肥的32.47%,而一次基施氮肥的利用率只有19.50%。（2）在晚稻上,常规分次施氮肥处理的稻谷产量高于控释掺混尿素处理,差异不显著（P〈0.05）,其他各项测试指标均低于控释掺混尿素处理。控释掺混尿素和常规分次施氮肥的氮素利用率分别为39.91%、39.58%,二者显著高于一次基施氮肥的28.14%。由此可见,科学合理的施用包膜控释掺混尿素可以提高双季稻生产的经济效益,提高氮素利用率,减少资源的浪费,保护土壤生态环境。     

不同控释氮肥减量施用对双季水稻产量和氮素利用的影响

研究不同控释氮肥在减氮量施用条件下早、晚稻产量效应、氮素吸收利用、土壤氮素养分特性和养分释放规律的差异,为南方双季稻区控释氮肥在水稻高产节肥栽培上的应用提供参考。采用静水溶解试验和田间小区试验研究了2种控释氮肥(树脂包膜尿素和硫包膜尿素)的养分释放特性和在常规尿素施氮量基础上节氮15%和30%对早、晚稻产量、产量构成因素、氮素养分吸收利用及土壤氮养分含量的影响。结果表明,2种控释氮肥的氮素累积释放曲线均为"S"形,但在培养期间硫包膜尿素氮素累积释放率均高于树脂包膜尿素。在田间条件下,与常规尿素处理相比,早稻减氮15%和30%施用硫包膜尿素和树脂包膜尿素均表现为增产,而晚稻施硫包膜尿素增产,施树脂包膜尿素减产。株高、每穗实粒数、结实率和千粒重的增加是早、晚稻增产的主要原因。施用2种控释氮肥均能促进早、晚稻水稻植株氮素养分的吸收积累,施用相同种类控释氮肥早晚稻稻谷、稻草和植株氮养分积累量随施氮量提高而提高。减氮15%和30%施用2种控释氮肥有利于氮肥回收利用率、氮肥偏生产力和氮肥农学效率的提高,在同一施氮水平下,硫包膜尿素的提高效果优于树脂包膜尿素。常规尿素处理、减15%氮的2种控释氮肥处理均能保持较高的土壤氮素水平,减30%氮的控释氮肥处理土壤氮素肥力较试验前有所降低。适当降低氮用量施用控释氮肥,能促进双季水稻增产、增加氮素利用效率、维持或提高土壤氮素肥力和可持续生产力,控释氮肥养分释放规律的差异是导致其作用效应不同的主要原因。     

氮素抑制剂对双季稻产量、氮素利用效率及土壤氮平衡的影响

【目的】 了解氮素抑制剂对双季稻产量、氮素利用效率及氮素在土壤中转化的影响,旨在为制定科学合理的农田氮素管理措施及节肥增效策略提供依据。 【方法】 以湘早籼45号和荆楚优148为材料,于2015年早、晚稻期间进行田间试验。试验设5个处理:不施肥 (CK);100%尿素 (100%U);80%尿素 (减氮20%,80%U);80%尿素+脲酶抑制剂NBPT (80%U+NBPT);80%尿素+硝化抑制剂DCD (80%U+DCD)。研究尿素减施条件下添加硝化抑制剂 (NBPT) 和脲酶抑制剂 (DCD) 对双季水稻产量、氮素养分吸收利用效率、土壤硝态氮、铵态氮、微生物量氮及土壤氮平衡的影响。 【结果】 NBPT和DCD均有利于提高早、晚稻产量、植株氮吸收量和氮素利用效率。减氮20%条件下添加NBPT(80%U+NBPT)处理早、晚稻稻谷较100%尿素处理 (100%U) 分别增产5.0%和6.1%,较施用80%尿素 (80%U) 分别增产8.0%和14.0%;80%U+DCD与100%U处理的早、晚稻稻谷产量差异不显著,较80%U处理分别增产6.0%和4.2%。80%U+NBPT较100%U处理早、晚稻植株氮吸收量分别增加4.5%和9.4%,较80%U处理分别增加10.3%和16.2%。80%U+NBPT和80%U+DCD处理氮肥表观利用率、氮肥农学效率、氮肥偏生产力和氮素吸收效率均较100%U和80%U处理提高。添加NBPT和DCD降低了早、晚稻收获后土壤硝态氮和铵态氮残留量,显著提高土壤微生物量氮积累量,降低氮表观损失,有利于维持作物-土壤体系氮素平衡。早、晚稻收获后80%U+NBPT较100%U处理氮表观损失降低42.2%和44.6%,较80%U处理降低27.5%和29.2%,80%U+DCD较100%U处理降低23.7%和31.6%,较80%U处理降低4.2%和12.6%。 【结论】 在该区域双季稻种植体系中,氮肥减量20%条件下添加NBPT和DCD能增加或维持水稻产量,提高氮素利用效率。供试条件下,添加NBPT提高氮素持续供应能力和保持土壤氮素平衡的效果好于DCD。      

控释尿素对小麦-玉米产量及土壤氮素的影响

利用田间试验研究了包膜控释尿素对小麦-玉米产量、氮素利用效率、土壤氮素积累及移动的影响。结果表明,与施用普通尿素比较,小麦-玉米周年施用包膜控释尿素,在肥料用量减少20%和40%情况下,小麦-玉米总产量分别是100%普通尿素处理的97.4%和97.7%;控释尿素施氮量为60%处理的肥料农艺利用率和偏生产力分别比普通尿素提高11.57%和54.14%。控释尿素施氮量为80%处理的肥料农艺利用率和偏生产力分别提高6.40%和22.09%。施用控释尿素显著增加了0-20 cm土层的碱解氮和0～40cm土层的硝态氮含量;60-100 cm土层中,控释氮肥处理土壤硝态氮含量与不施氮肥处理差异不显著,普通尿素处理小麦收获后60～80 cm土层、玉米收获后60～100 cm土壤硝态氮显著高于不施氮肥处理,肥料氮素下移明显。试验结果显示,施用控释尿素增加了耕层（0～20 cm）土壤的氮素积累,减少了氮素向土壤深层移动的数量,有利于减少施肥对环境的不利影响。     

3,5-二甲基吡唑对铵态氮硝化及作物生长的影响

采用室内培养试验和盆栽试验相结合的方法,以春小麦和水稻为供试作物,初步探讨不同用量的3,5-二甲基吡唑(DMP)对土壤铵态氮硝化、作物产量及氮素利用的影响。结果表明,在本试验条件下,施用占尿素N量0.6%～1.0%的DMP(折合0.8～0.9g/g,干土),可显著抑制土壤硝化作用的进行,其抑制效应随抑制剂用量的增加逐渐增强。与对照单施尿素相比,施用1.0%DMP可使土壤NH4+-N含量提高30%以上,NO3--N含量降低20%左右。施用占尿素N量0.8%～1.0%的DMP对春小麦产量影响不大,但能显著提高水稻产量和两种作物的氮肥表观利用率,促进植株体内的氮素向子粒中的转移。与等量DCD(双氰胺)比较,DMP处理的水稻子粒粗蛋白含量和氮肥表观利用率显著提高,但产量差异不显著。     

冬小麦上短控释期尿素的适宜施用量与施用方法研究

【目的】控释尿素受土壤温度、 水分等环境条件的影响,应用效果不一。对比相同施氮量下一次性基施控释尿素与尿素分期施用,以及控释尿素和普通尿素追施对冬小麦籽粒产量、 品质, 氮肥利用率及综合经济效益的影响,可为控释尿素的合理施用提供理论和技术依据。【方法】采用大田试验,选用新麦26为供试材料,随机区组试验设计,调查了冬小麦籽粒产量、 主要品质性状、 氮肥利用率及经济效益。设两个试验,试验1: 控释尿素和普通尿素各设5个氮肥水平,即N 0、 120、 160、 200和240 kg/hm2; 试验2: 设不施氮肥、 N 200 kg/hm2总氮量下普通尿素和控释尿素均40%返青期追施3个处理。【结果】 1)与不施氮(CK)相比,控释尿素和普通尿素均可显著提高小麦籽粒产量,且随着施氮量的增加而增加,其中以分期施用普通尿素N 240 kg/hm2处理籽粒产量最高。相同施氮量下,分期施用普通尿素处理小麦籽粒产量显著高于一次性基施控释尿素处理(N 160 kg/hm2除外)。然而,返青期追施控释尿素处理小麦籽粒产量显著高于同期追施普通尿素处理,增产率达15.8%; 2)相同施氮量下,分期施用普通尿素处理较一次性基施控释尿素处理的小麦籽粒容重、 蛋白质含量、 水分含量、 湿面筋含量均有所提高,且两种尿素处理间籽粒容重在N 160 kg/hm2和N 200 kg/hm2时差异达显著水平。然而,返青期追施控释尿素处理小麦籽粒容重、 湿面筋含量、 蛋白质含量等品质指标显著高于同期追施普通尿素处理; 3)两种尿素处理氮肥农学利用率和氮肥偏生产力随施氮量的增加而降低,在相同施氮量下分期施用普通尿素处理显著高于一次性基施控释尿素处理。此外,与分期施用普通尿素处理相比,一次性基施控释尿素处理减少了小麦拔节期追肥人工成本投入,但由于一次性基施控释尿素处理籽粒产量较低和氮肥价格较高,导致经济效益相对较低。然而,试验2结果表明,返青期追施控释尿素处理氮素利用率(氮肥农学效率、 氮肥偏生产力及氮素回收率)和经济效益显著高于同期追施普通尿素处理。【结论】本研究地区较适宜的推荐氮肥施用量为N 200 kg/hm2,一次性基施控释尿素较适宜于劳力欠缺的农户,而对于个别劳力充足的农户则适宜采用分期追施普通尿素或者小麦返青期追施控释尿素的氮肥管理技术。因此,在当前农村劳动力日益减少,用工成本日益增加以及种粮比较效益持续降低的大环境下,氮素肥料合理选择和施用技术要依据实际情况而定。     

覆膜栽培及抑制剂施用对稻田N2O排放的影响

采用静态箱-气相色谱法研究脲酶抑制剂氢醌(Hydroquinone, HQ)与硝化抑制剂双氰胺(Dicyandiamide, DCD)配合施用(HQ/DCD)对常规栽培和水稻覆膜节水高产栽培下四川丘陵地区稻田的N2O排放的影响。结果表明,水稻生长期,常规栽培和水稻覆膜节水高产栽培稻田N2O排放总量分别为41.8 mg/m2 和506.9 mg/m2。HQ/DCD施用减少常规栽培与水稻覆膜节水高产栽培稻田N2O季节总排放,降幅分别为25.2% 和48.5%。常规栽培和水稻覆膜节水高产栽培N2O季节总排放占施氮量的0.3% 和3.4%,施入HQ与DCD后,其N2O季节总排放分别降为施氮量的0.2% 和1.7%,HQ/DCD施用对水稻覆膜节水高产栽培下的N2O减排更为有效。各处理N2O排放与5 cm土壤温度、土壤Eh无显著相关性。     

Water management for maize grown in sandy soil under climate change conditions

To reduce climate change risks on maize yield grown in sandy soil, agricultural management practices must be studied. The aim of the study was to determine whether improved water management practices could reduce the vulnerability of maize to drought stress by climate change. Eight fertigation treatments in addition to farmer irrigation (control treatment) were tested. Two climate change scenarios were incorporated in the CropSyst model to assess maize yield responses to variable fertigation regimes under different climate change conditions. The results showed that under current climate, the highest and lowest water productivity (WP) values were obtained when irrigation was applied using 0.8 and 0.6 potential crop evapotranspiration (ETc) with fertigation application in 80% and 60% of application time, respectively. The highest WP under the tested climate change scenarios was obtained when irrigation was applied using 1.2 and 0.8 of ETc with fertigation application in 80% of application time, respectively, in 2009 and 2010 growing seasons. Irrigating maize grown in sandy soil under drip irrigation with an amount of either 1.2 or 0.8 of ETc with fertigation application in 80% of application time are recommended to enhance the WP and reduce maize’s damage caused by extreme climate change.     

不同滴灌施肥策略对棉花氮素吸收和氮肥利用率的影响

在温室条件下应用^15N标记尿素进行了不同滴灌施肥策略对棉花氮素吸收和氮肥利用率影响的盆栽试验.根据滴灌灌水施肥时段的分配,设置四种不同氮肥滴灌施肥策略.研究结果表明,不同滴灌施肥策略显著影响棉花的干物质重和氮素吸收量,棉花的氮素吸收量明显受到根系生长的影响,整株氮素吸收量与根干物质重之间呈显著的正相关关系.在一次灌溉过程中先滴1/2时间的肥液,然后再滴1/2时间清水的施肥策略可显著促进棉花根系的生长,增加棉花的氮素吸收量,减少氮肥在土壤中的残留,提高氮肥利用率.因此,在膜下滴灌条件下采用合适的施肥策略有助于提高肥料的利用效率.     

滴灌施肥机灌水与施肥均匀性试验

为了研究滴灌施肥机在不同压力条件下灌水流量和溶液浓度的时空变化以及水力要素对灌溉均匀性的影响,该文以荧光示踪剂溶液模拟肥料,并以比例混合泵滴灌施肥机为研究对象,通过连续均匀采样的试验方法分析其灌水和施肥均匀性。结果表明：比例混合泵施肥机在不同压力条件下灌水和施肥均匀性都很好,但在施肥过程中存在施肥滞后时间和停肥延时时间,这两个时间决定施肥机灌溉的最小时间及最佳施肥方式,同时受这两个时间的影响,选择不同滴灌施肥测试时间得到的施肥均匀性分析结果存在着差别。     

棉花高产和磷高效的磷肥基施追施配合技术研究

【目的】 本文比较了不同磷肥基施、追施比例对棉花生物量、产量及养分吸收的影响，以优化新疆膜下滴灌棉花的磷肥施用技术。 【方法】 2009—2011年连续三年进行了田间试验。试验共设3个处理:不施磷肥，磷肥全部基施，磷肥滴灌追施 (2009、2010年为磷肥50%基施和50%滴灌追施，2011年为磷肥65%基施和35%滴灌追施)，追施的磷肥分2次在棉花蕾期和初花期随水施入。各处理的氮、钾肥用量相同，氮肥全部滴灌追施，钾肥全部基施。棉花成熟期测定了棉株生物量、籽棉产量和磷肥的利用率。 【结果】 施用磷肥显著提高了棉花地上部生物量，与不施磷肥相比，磷肥基施显著增加了棉花的叶、茎、籽和纤维的生物量，分别增加15%、9%、9%和11%，磷肥滴灌追施显著增加了叶、茎、壳、籽和纤维的生物量，分别增加21%、23%、21%、12%和13%。施用磷肥能够显著提高棉花产量，与不施磷肥相比，磷肥全部基施籽棉平均增产8%，磷肥滴灌追施籽棉平均增产13%，而磷肥滴灌追施的产量比磷肥全部基施提高5%。施用磷肥显著增加了棉花的磷素吸收量，磷肥全部基施的磷肥平均利用率为18%，而磷肥滴灌追施的磷肥平均利用率为23%。磷肥35%滴灌追施的增产率和磷肥利用率分别为18%和24%，50%滴灌追施处理两者分别为11%和22%。 【结论】 与不施磷肥相比，磷肥全部基施与部分磷肥滴灌追施都能显著提高棉花生物量和产量，增加磷素吸收量，而磷肥部分滴灌追施的效果优于磷肥全部基施，磷肥65%基施和35%滴灌追施的增产效果好于50%基施和50%滴灌追施。      

Efficiency of Nitrogen Fertilizer for Potato under Fertigation Utilizing a Nitrogen Tracer Technique

Abstract

Efficient crop use of nitrogen (N) fertilizer is critical from economic and environmental viewpoints, especially under irrigated conditions. Nitrogen fertilizer (¹⁵N‐labeled urea) and irrigation methods (drip and furrow) were evaluated on spring and fall potato cultivars under Syrian Mediterranean climatic conditions. Field experiments were conducted in the El‐Ghab Valley near Hama in fall 2000 and spring 2001 on a heavy clay soil. Four N‐fertilizer applications (70, 140, 210, and 280 kg N/ha) were applied in five equally split treatments for both irrigation methods. Potato was irrigated when soil moisture in the specified active root depth reached 80% of the field capacity as indicated by the neutron probe.

Higher marketable tuber yield of spring potato was obtained by fertigation compared to furrow irrigation; the magnitude of tuber yield increases was 4, 2, 31, and 13%, whereas for fall potato the tuber yield increases were 13, 27, 20, and 35% for N fertilizer rates of 70, 140, 210, and 280 kg N/ha, respectively. Shoot dry matter and tuber yields at the bulking stage were not good parameters to estimate marketable tuber yield. The effect of N treatments on potato yield with furrow irrigation and fertigation was limited and not significant. Drip fertigation improved tuber yield of fall potato relative to national average yield. Nitrogen uptake increased with increasing N input under both irrigation methods. Reducing N input under both irrigation methods improved N recoveries. Increasing N input significantly increased total N content in plant tissues at the bulking stage. Spring potato yields were almost double those of fall potato under both irrigation methods and all N treatments.

Nitrate (NO₃) movement in the soil solution for fall potato was monitored using soil solution extractors. Furrow irrigation resulted in greater movements of NO₃‐N below the rooting zone than drip fertigation.

Harvest index did not follow a clear trend but tended to decrease upon increasing N fertilization rates beyond 140 kg N/ha under both irrigation methods. Drip fertigation improved field water‐use efficiencies at the bulking and harvest stages. Fertigation increased specific gravity of potato tubers relative to furrow irrigation. Higher N input decreased specific gravity of potato tubers under both irrigation methods.     

水肥一体化配合硝化/脲酶抑制剂实现油菜减氮增效研究

【目的】研究水肥一体化方式下减氮施肥并添加硝化和脲酶抑制剂对油菜生长及土壤硝态氮和铵态氮含量的影响,旨在筛选出配合硝化/脲酶抑制剂施用的最适减氮量,为减少氮素损失、提高蔬菜生产中氮素利用率和降低蔬菜硝酸盐含量提供理论依据。 【方法】采用盆栽试验,利用负压灌溉水肥一体化系统 [(–5 ± 1) kPa],设不施氮肥 (T1)、尿素 150 kg/hm2 (T2)、尿素 150 kg/hm2 + 10%DCD (双氰胺) + 1%HQ (氢醌)(T3)、尿素 127.5 kg/hm2 + 10%DCD + 1%HQ (T4)、尿素 105 kg/hm2 + 10%DCD + 1%HQ (T5) 共 5 个处理。监测了油菜生长期间供水量、土壤含水量、油菜生长指标及土壤硝态氮与铵态氮含量的变化,分析调查了收获后油菜的产量、品质指标和养分含量。 【结果】在油菜生长期间,负压灌溉各处理的总出水量非常接近 (12174～13869 mL)。当施肥量相同时,与不添加抑制剂处理 (T2) 相比,施用硝化和脲酶抑制剂 (T3) 能够有效抑制土壤中铵态氮向硝态氮的转化,提高叶长、叶宽和叶绿素含量,显著提高油菜产量 25.2%,提高氮肥利用率 85.2%,硝酸盐含量显著降低 51.9%。与不添加抑制剂处理 (T2) 相比,减氮 15%～30% 同时添加硝化和脲酶抑制剂对油菜产量、品质、养分吸收也均有不同程度的促进效果,并能够抑制硝化作用,减少土壤中硝态氮累积,减氮 30% 并添加硝化和脲酶抑制剂的处理 (T5) 能将油菜产量提高 15.9%,氮、磷、钾含量分别提高 8.4%、21.5% 和 27.8%,氮肥利用率提高 1.26 倍,油菜体内硝酸盐含量降低 66.6%。 【结论】适当减氮并添加硝化和脲酶抑制剂对油菜产量和养分吸收均有明显的促进效果,而且能减少油菜硝酸盐含量和土壤中硝态氮累积。在本试验负压水肥一体化条件下,减氮 30% 并添加硝化和脲酶抑制剂,即尿素 105 kg/hm2 + 10%DCD + 1%HQ 不仅效果最佳,还降低了因氮肥投入高而造成硝酸盐累积的风险。     

灌溉施用氮肥后氮素在土壤中的转化及淋失状况: 土柱模拟研究

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH₄⁺-N + NO₃^--N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH₄⁺-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH₄⁺-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH₄⁺-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH₄⁺-N fixation or volatilization in the soil during the fertigation process.     

Effect of dicyandiamide and hydroquinone on the transformation of urea-nitrogen-15 in soil cropped to wheat

A pot experiment with a loam soil and spring wheat as test crop showed that an application of dicyandiamide (DCD), and especially its combination with hydroquinone (HQ), gave a much larger recovery of soil urea-¹⁵N than treatments based on the application of urea alone or urea plus HQ. Most of the urea-¹⁵N applied to soil was present as organic plus chemically fixed ¹⁵N in the DCD and DCD plus HQ treatments. These two treatments showed the smallest accumulation of urea-derived (NO₃^-+NO₂^-)-¹⁵N. Under well-drained conditions, there was a synergistic effect of the nitrification inhibitor DCD and the urease inhibitor HQ on urea-¹⁵N transformations and the recovery of fertilizer ¹⁵N in soil after the application of urea.     

Studies on method and rate of fertilizer application in apple under mulch in north-western Himalayas

Different methods of fertilizer application-drip fertigation and conventional fertilizer application under drip, surface irrigation, and rainfed conditions were evaluated during 2009–2012 at Krishi Vigyan Kendra, Shimla, India. The experiment was arranged in randomized block design (RBD), replicated thrice. Results suggest that fertigation significantly increased growth parameters over conventional methods. Fruit yield was significantly higher under fertigation (13.7 t ha^?1) over conventional fertilizer application with drip (11.6 t ha^?1), surface irrigation (10.6 t ha^?1), and under rainfed (8.6 t ha^?1). Fruit quality parameters were also superior under fertigation. Fertigation maintained higher available nitrogen (N) and potassium (K) content in 0-30 cm soil layers. Available phosphorus (P) was higher in 0-20 cm soil depths in all the treatments. Fertigation with 80 and 100 percent recommended NPK dose registered statistically comparable results. In addition to higher productivity, fertigation resulted in 20 percent fertilizer savings over drip irrigation and 20 percent fertilizer besides 40 percent water savings over surface irrigation.