氮肥分配对冬小麦-夏玉米轮作产量和氮肥效率的影响

通过田间小区试验研究了控制氮肥总量(N 420 kg/hm2)条件下氮肥分配对冬小麦/夏玉米轮作体系内的作物生物量、产量、纯收益、农学效率及肥料利用率的影响,结果表明,氮肥在冬小麦/夏玉米轮作体系的分配量及比例显著影响冬小麦/夏玉米轮作的产量、纯收益和氮肥的效率,冬小麦季施总氮55％ (N 231 kg/hm2)、夏玉米季施总氮45％ (N 189 kg/hm2)时,获得最高的轮作总产量(13 026 kg/hm2)和最大的净收益(22 146元/hm2),氮肥的农学效率和利用率较其它分配方式均有所提高,是晋南地区冬小麦/夏玉米轮作氮肥分配的适宜比例.就单季小麦而言,施N 189 kg/hm2可以获得较高的产量和较高的氮肥效率.值得指出的是,由于作物生长期间受春寒和夏旱的影响,冬小麦/夏玉米轮作体系内的氮农学效率和氮肥利用率均表现较低,仅分别为4.6 kg/kg和20.8％.     

华北平原冬小麦/夏玉米轮作体系对氮素环境承受力分析

通过田间试验研究了华北地区冬小麦/夏玉米轮作体系对氮素的环境承受力。结果表明,冬小麦和夏玉米达到最高产量时的施氮量分别是112和180.kg/hm2。氮肥利用率和农学利用率随施氮量的增加而降低,生理利用率表现出抛物线的趋势。在农户习惯施氮条件下,冬小麦和夏玉米的氮肥利用率分别是10%和6%,每千克氮肥分别增产2和3千克。灌水和集中降雨是引起土壤硝态氮明显下移的主要因素。氮素平衡计算的结果表明,低施氮量时,氮素盈余以残留Nmin为主,高量施氮则以表观损失为主。将收获后090.cm土壤中的硝态氮的量控制到150kg/hm2,可以在兼顾环境的前提下获得较高的产量;此时冬小麦季的施氮量是122.kg/hm2,产量(干物重)达到最高产量4331.kg/hm2;夏玉米季的施氮量是145.kg/hm2,产量(干物重)是7965.kg/hm2,达到最高产量的97%。     

好氧发酵猪粪部分替代化肥提高夏玉米氮素利用率和土壤肥力

  【目的】  化肥及畜禽粪便的不合理施用不仅影响作物增产,还严重威胁土壤健康和环境安全。探究不同发酵方式猪粪有机肥及有机肥替代化肥的比例对夏玉米氮素吸收及土壤碳、氮含量的影响,为规模化养猪场粪便快速处理,及制定其与化肥的适宜配比提供理论依据。  【方法】  以‘先玉335’为供试材料,在中国农业大学丰宁动物试验基地进行田间试验。设置5个处理:不施肥 (CK),100%化肥氮 (CF),100%自然堆肥猪粪氮 (PM),100%好氧发酵猪粪氮 (PC),50%好氧发酵猪粪氮 + 50%化肥氮 (FM)。分析猪粪不同发酵方式及有机氮替代比例对夏玉米氮素吸收及土壤碳氮的影响。  【结果】  在等氮条件下,与CF处理相比,FM处理产量、穗粒数、千粒重均以FM处理最高,其中FM处理显著增产13.2%,PC、PM处理与CF处理差异均不显著。FM处理玉米氮素积累量最高,两年平均为304.6 kg/hm2,较CF处理氮素累积量显著提高15.5%;PC、PM处理与CF处理氮素积累量差异不显著。与CF 处理相比,FM处理的氮素当季回收率、氮素农学利用率和偏生产力两年平均分别显著提高85.9%、59.5%和13.2% (P < 0.05),PC、PM处理与CF 处理之间无显著差异。在玉米拔节期和抽穗期,FM处理0—40 cm土壤无机氮含量均最高,与 CF 无显著差异;在成熟期,FM处理土壤无机氮含量较CF处理显著增加41.8%,而PC和PM处理与CF处理无显著差异。此外,施用有机肥可不同程度地增加土壤有机碳和全氮含量,与CF处理相比,PC和FM处理使有机碳含量分别显著提高13.3%和9.8%;FM处理土壤全氮含量显著提高33.4%。  【结论】  在等氮条件下与单施化肥相比,50%好氧发酵猪粪氮 + 50%化肥氮配施不仅显著提高了夏玉米产量和氮素累积吸收量,还提升了土壤全氮和有机碳含量以及0—40 cm土层土壤无机氮含量。单独施用自然堆肥、好氧发酵猪粪及化肥在产量和氮素积累方面没有显著差异,但可增加土壤全氮和有机碳含量,有利于土壤培肥,而施用好氧发酵猪粪的效果又优于施用自然堆肥。     

冬小麦-夏玉米轮作体系中不同施氮水平对玉米生长及其根际土壤氮的影响

在河北衡水潮土上进行田间试验,以当地习惯高氮用量(小麦季施N 300 kg/hm2,玉米季施N 240 kg/hm2)为对照,研究冬小麦-夏玉米轮作体系中减少氮肥用量对玉米季植株生长、氮素吸收及根际土壤中无机氮与微生物量氮的影响。结果表明,两季作物氮肥施用量减少25%和40%,对玉米产量、生物量及植株体内氮累积量未产生明显影响,氮肥利用率提高。不同氮肥施用量对根际和非根际土壤铵态氮含量的影响不显著;减少氮肥施用量,对玉米根际土壤硝态氮含量也没有明显影响。在玉米苗期、抽雄期和成熟期,习惯高施氮量处理的非根际土壤硝态氮含量较高,其中抽雄期,非根际土壤硝态氮含量较氮肥减施40%用量处理高出近一倍,但非根际土壤微生物量氮水平含量明显降低。氮肥减施未影响根际土壤微生物量碳、氮含量,反而增加了非根际土壤微生物量碳、氮水平。在高肥力的潮土上,冬小麦/夏玉米轮作体系中适当减施氮肥并未影响玉米根际土壤氮素水平,可保证玉米稳产,实现减氮增效。     

不同氮肥管理对吉林春玉米生长发育和养分吸收的影响

针对吉林春玉米氮肥施用中存在氮肥用量偏大,且具盲目性的现状,采用田间试验研究农民习惯施氮量和推荐施氮量下氮肥不同施用方式对春玉米干物质积累、子粒产量、氮素吸收和利用效率的影响。结果表明,推荐施氮量下,苗期和灌浆期春玉米干物质积累量显著高于习惯施肥,有机无机配合提高了春玉米干物质积累速率。施氮处理与不施氮相比均显著增加玉米子粒产量,增产11.2%～16.8%; 推荐施氮量下玉米子粒产量与习惯施氮量相当,但显著提高氮素的偏因子生产力和农学效率。在氮磷钾用量一致的基础上,用30%有机肥氮替代化肥氮与100%化肥氮处理的产量相当,对氮素利用效率也没有影响,并降低收获期土壤无机氮含量。说明合理施用氮肥不但能够维持玉米产量,还可减少氮肥投入,提高氮肥利用效率;有机肥部分替代化肥氮是吉林春玉米氮素管理的有效途径之一。     

Root growth and nitrogen uptake of carrot, early cabbage, onion and lettuce following a range of green manures

An experiment was performed to study the significance of rooting depth of four vegetable crops on their utilization of green manure nitrogen (N). Rates of rooting depth development were estimated as approximately 0.2, 0.7, 1.2 and 1.2 mm day °C^?1 for onion, carrot, lettuce and cabbage, respectively. At harvest, onion and lettuce were found to be shallow‐rooted with final rooting depths of only 0.3 and 0.6 m, respectively, whereas carrot and cabbage reached rooting depths of at least 1.1 m. The two deep‐rooted vegetables increased their N uptake by 46, 24 and 7 kg N ha^?1 when following winter‐hardy legumes, non‐hardy legumes and rye, respectively; the equivalent responses by the two shallow‐rooted crops were 23, 9 and 15 kg N ha^?1, respectively. Thus the deep‐rooted crops used the legume N more efficiently but the shallow‐rooted crops made better use of N left by the non‐legume rye crop. These interactions between green manure type and vegetable crop N response are the result of the dual effects of the green manures: biological N fixation by the legumes, and the variable ability of the green manure crops to concentrate available N in the topsoil. Before shallow‐rooted crops, the ability of rye to concentrate N in the topsoil may be as important as the N fixing ability of legumes.     

Nitrous oxide emissions in a winter wheat – summer maize double cropping system under different tillage and fertilizer management

An accurate estimation of nitrous oxide (N₂O) emission from 110 million ha of upland in China is essential for the adoption of effective mitigation strategies. In this study, the effects of different tillage practices combined with nitrogen (N) fertilizer applications on N₂O emission in soils were considered for a winter wheat (Triticum aestivum L.) – summer maize (Zea mays L.) double cropping system. Treatments included conventional tillage plus urea in split application (CTF1), conventional tillage with urea in a single application (CTF2), no‐tillage with straw retained plus reduced urea in a split application (NTSF1) and no‐tillage with manure plus reduced urea in a split application (NTMF1). The amounts of N input in each treatment were 285 and 225 kg N/ha for wheat and maize, respectively. Both NTSF1 and NTMF1 were found to reduce chemical N fertilizer rates by 33.3% (wheat) and 20% (maize), respectively, compared to CTF1 and CTF2. N₂O emissions varied between 3.2 (NTSF1) and 9.9 (CTF2) kg N₂O‐N/ha during the wheat season and between 7.6 (NTFS1) and 14.0 (NTMF1) kg N₂O‐N/ha during the maize season. The yield‐based emission factors ranged from 21.9 (NTSF1) to 60.9 (CTF2) g N₂O‐N/kg N for wheat and 92.5 (NTSF1) to 157.4 (NTMF1) g N₂O‐N/kg N for maize. No significant effect of the treatments on crop yield was found. In addition to reducing production costs involved in land preparation, NTSF1 was shown to decrease chemical fertilizer input and mitigate N₂O emissions while sustaining crop yield.     

Strategies to encourage better use of nitrogen in animal manures

Abstract. Research conducted in the MAFF Nitrate Programme has been used to formulate new and improved guidelines on the efficient use of manure nitrogen (N). In order to reduce nitrate leaching losses, manures containing large amounts of available N (i.e. slurries and poultry manures) should not be applied to free-draining soils in the period from autumn to early winter. Also, for efficient nutrient utilization manure application rates should be consistent with agronomic requirements (up to 250 kg total N ha⁻¹ yr⁻¹). Existing farm machinery was shown to be capable of applying manures evenly to grassland and arable stubbles, but required an accurate estimate of application rate and the careful matching of spreading widths. To provide growers with detailed guidance on the fertilizer N replacement value of manures the computer-based decision support system MANNER (MANure Nitrogen Evaluation Routine) has been developed. The much improved understanding of manure N losses and availability has been summarized in a series of 'Managing Livestock Manures' booklets, the MAFF Fertilizer Recommendation booklet and the Codes of Good Agricultural Practice.     

Nitrate leaching in field lysimeters at an agricultural site in Zimbabwe

Abstract. Nitrate leaching in lysimeters containing a tropical sandy agricultural soil was studied over two summers with maize ( Zea mays L.) and one winter season with wheat ( Triticum aestivum L.). The treatments included two moisture regimes and two nitrogen sources, cattle manure and inorganic fertilizer-N (either ammonium nitrate or ammonium sulphate) applied at 100 kg N/ha in the summers. Neither manure nor fertilizer-N was applied in the intervening winter. Leachate volume from the manured lysimeters was mostly larger than from fertilized ones because of poor growth and less evapotranspiration. The largest seasonal nitrate loads (17–39 kg N/ha) were obtained in the wet summer immediately after installation of the lysimeters. Nitrate loads in winter (3.7–18.6 kg N/ha) were larger than those obtained in fertilized (0.6 and 9.3 kg N/ha) and manured (0.3 and 3.0 kg N/ha) lysimeters for the two moisture regimes in the second summer. The drier conditions in the second summer decreased N-mineralization and leaching of manure.     

施氮量对滴灌冬小麦–夏玉米周年产量及氮素利用效率的影响

  【目的】  当前华北平原冬小麦–夏玉米生产中,存在氮肥投入量大、氮肥利用效率低等问题,在滴灌水肥一体化条件下研究施氮量对冬小麦–夏玉米周年产量、氮素利用效率和土壤全氮含量、硝态氮残留的影响,以期为该地区小麦–玉米节肥、高产高效的栽培模式提供理论依据。  【方法】  于2018—2020年在青岛农业大学胶州现代农业示范园开展小麦、玉米滴灌施肥田间试验。设冬小麦/夏玉米生长季不施氮(N0)和施氮 150/150 kg/hm2 (N1)、210/225 kg/hm2 (N2) 和270/300 kg/hm2 (N3) 4个水平,以传统施肥方式和常规施氮量240/240 kg/hm2为对照(CK)。分析冬小麦和夏玉米产量、氮素吸收量和土壤氮素残留量。  【结果】  N2处理冬小麦、夏玉米产量最高,与N3处理无显著差异,但显著高于N0、N1和CK处理;N3处理冬小麦、夏玉米的干物质积累量、氮素吸收量最高,与N2处理差异较小,而显著高于N0、N1和CK处理。冬小麦、夏玉米氮肥偏生产力随着施氮量的提高而降低;冬小麦季氮素利用效率随着施氮量的提高而降低;夏玉米季,N2、N1和N0处理的氮素利用效率显著高于N3和CK处理,且N0、N1和N2处理间无显著差异;冬小麦、夏玉米氮肥农学利用率均随着施氮量的提高而降低,N2施氮水平下,氮素利用效率和氮肥农学利用率均表现较优。随着施氮量的增加,0—100 cm土层土壤全氮含量和硝态氮含量呈增加的趋势,全氮积累主要集中在0—40 cm土层,N3、N2和CK处理0—100 cm土层土壤全氮含量与N0和N1处理之间的差异随着轮作年数的增加而逐渐增大,N2处理较N3和CK处理有效抑制了硝态氮在表层土壤的积累和向深层土壤的迁移,降低了硝态氮淋失风险。  【结论】  冬小麦季施氮210 kg/hm2和夏玉米季施氮225 kg/hm2 (N2)可实现周年作物增产高效,提高氮素利用效率,显著降低硝态氮向深层土壤迁移,降低硝态氮淋失风险,是滴灌水肥一体化下华北平原麦玉周年轮作适宜的施氮量。     

Nitrogen Mineralization as Influenced by Different Organic Manures in an Inceptisol in the Foothill Himalayas

Nitrogen-use efficiency can be enhanced through an understanding of the nitrogen (N) mineralization behavior of organic sources. An incubation study was conducted to assess the impact of organic manures on N mineralization. The manures, farmyard manure (FYM), Leucaena leucocephala, and poultry manure, were applied to the soil alone or along with urea. There was a rapid increase in the amount of mineral N released with a peak appearing either at 14 days (+urea treatments) or 21 days (manure only) of aerobic incubation. Thereafter the net N mineralized decreased gradually and levelled off beyond day 56. Overall the cumulative net N mineralized after 98 days of incubation was in the order urea > Leucaena + urea > poultry manure + urea _> FYM + urea > Leucaena > poultry manure > FYM > zero N. The potentially mineralizable N (N₀) was lower in treatments where urea was not applied.     

玉米对尿素减量与复合氮肥增效剂配施的响应

用15N-尿素进行盆栽和田间试验(盆栽试验尿素标准用量为120mg/盆,田间试验尿素标准用量为157.5kg/hm2),研究了复合氮肥增效剂用量、尿素减量与复合氮肥增效剂配施对玉米生长、籽粒产量和氮素吸收利用的影响。结果表明,适量(施氮量的20%~60%)的复合氮肥增效剂能显著促进玉米幼苗生长发育。氮素减量5%~15%时配施复合氮肥增效剂对玉米生长和含氮量影响不显著,15N和吸氮总量与不施增效剂的处理相当或有所提高。除尿素减量30%处理外,其余各尿素减量配施复合氮肥增效剂的处理,玉米氮素利用率比不施增效剂的处理提高5.6%~7.3%,尿素减量5%~50%配施复合氮肥增效剂,玉米氮素表观利用率提高7.7%~17.0%。在大田条件下,尿素氮减少5%~15%(即减少施氮7.8~23.7kg/hm2)配施复合氮肥增效剂不影响玉米的单季产量,玉米植株吸氮总量、氮素净吸收量、氮肥生理效率和农学效率与不施增效剂的处理相当或增加,氮素表观利用率提高14.8%~15.2%。尿素减量达30%时,配施复合氮肥增效剂对玉米植株生长和氮素吸收利用明显不利。尿素与20%施氮量的复合氮肥增效剂配施,不影响玉米植株生长和单季产量,能提高玉米氮素利用率,节省氮肥投入达15%。     

肥料配施枯草芽孢杆菌对夏玉米产量及养分利用的影响

目的枯草芽孢杆菌能增加土壤养分、改善土壤结构、提高化肥利用率,并能促使土壤中的有机质分解,促进作物生长,提高产量。研究枯草芽孢杆菌与肥料配施对夏玉米产量、肥料吸收利用的影响,为提高肥料的增产效果、降低农业面源污染提供理论指导。方法2016和2017年以登海605(DH605) 为试验材料,设置不施氮肥 (CK)、单施化肥 (N)、单施牛粪 (M)、牛粪 + 枯草芽孢杆菌 (MB)、化肥 + 枯草芽孢杆菌 (NB) 5个处理,分析了夏玉米产量和肥料吸收利用状况。结果牛粪配施枯草芽孢杆菌处理的籽粒产量及肥料利用效率最高,显著高于单施牛粪处理。与单施牛粪相比,牛粪配施枯草芽孢杆菌两年产量平均增幅为20.2%,植株氮、磷、钾积累量平均增幅分别为30.8%、63.5%、30.8%,肥料偏生产力平均提高20.7%;化肥配施枯草芽孢杆菌两年产量平均值比单施化肥提高2.55%,植株氮、磷、钾积累量平均增幅分别为12.5%、10.6%、3.84%,肥料偏生产力平均提高3.18%。牛粪配施枯草芽孢杆菌的经济效益比单施牛粪提高16.9%,化肥配施枯草芽孢杆菌的经济效益与单施化肥基本相同。分析表明,植株干物质积累量和氮素积累量,尤其是花后干物质和氮素积累的增加是增产增效的主要原因。其中牛粪配施枯草芽孢杆菌的效果要优于化肥配施枯草芽孢杆菌。结论肥料配施枯草芽孢杆菌能显著增加夏玉米的干物质积累量及产量,促进肥料的吸收利用。在施用氮肥的基础上,配施适量的枯草芽孢杆菌不仅能实现增产增效的目的,还能提高玉米的经济效益。有机肥配施枯草芽孢杆菌是实现夏玉米节肥增效的有效措施之一。     

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。     

Substituting urea by organic wastes for improving maize yield in alkaline soil

Abstract

Nitrogen (N) deficiency is a very common problem of alkaline soils. Incorporation of organic residues with urea could be promising practice for improving soil properties and crop yield. This study was aimed, to evaluate the responses of two maize cultivar (Azam and Jalal) to organic wastes and Urea (sole organic residues i.e. seed cake (SC), poultry manure (PM), press mud (PrM) and mineral nitrogen (urea) and their combinations with urea (25%, 50% or 75%) applied at 150?kg N ha^?1 under field conditions. Significant differences were recorded for leaf area index, plant height, number of grains ear^?1, 1000 grain weight, biological and grain yield to N sources. Maize cultivar Jalal performed significantly better than Azam for all tested traits. The performance of both cultivars was significantly better when N was applied as either SC/PM with urea at 25:75, SC and PM with urea at 25:25:50, 100% sole urea, SC/PrM with urea at 50:50, or all organic N sources (25%) with urea (75%). Integration of organic wastes with urea gave the higher maize yield however, it was similar to the yield obtained from sole urea but due to allied environmental and health hazards, the sole use of urea could not be encouraged.     

长期施肥对土壤微生物生物量碳、氮及矿质态氮含量动态变化的影响

利用位于陕西杨凌的17年长期定位试验研究了长期不施肥(CK)、单施化肥(F)、化肥配施有机肥(F+M)和化肥加秸秆还田(F+S)处理对小麦-玉米轮作体系中作物不同生长时期土壤微生物生物量碳、氮(SMBC、SMBN)和矿质态氮含量的影响。结果表明,0—10 cm土层土壤SMBC、SMBN和矿质态氮含量的变化范围分别为264.8~752.2、37.51~14.8和3.83~8.5 mg/kg。不同处理相比,F+M处理中各采样时期(小麦苗期、拔节期、灌浆期及玉米播种期、大喇叭口期、灌浆期和收获后)土壤SMBC和SMBN含量均为最高,分别为不施肥对照的1.382~.65和1.892~.50倍;F+S处理矿质态氮含量最高,SMBC和SMBN也高于F和CK处理,大部分采样时期的差异达显著水平(P0.05);与CK相比,长期单施化肥也使各时期SMBC和SMBN含量提高。在小麦拔节期到灌浆期的旺盛生长阶段各施肥处理土壤SMBN含量均下降,而矿质态氮含量变化不大,处于较低水平;在玉米大喇叭口期到灌浆期的旺盛生长阶段,F+M、F+S和F处理土壤矿质态氮含量显著下降,而SMBN含量均有所升高。表明在土壤矿质态氮含量较高时,作物首先利用矿质态氮,而在土壤矿质态氮含量处于较低水平时,微生物固持的氮素可能会释放出来供作物吸收利用。     

川中丘陵区紫色土冬小麦/夏玉米轮作氨挥发研究

大气中过量的氨会造成诸多环境问题并危害人类健康。我国农田氮肥施用后的氨挥发是一个重要的氨排放源。紫色土的土壤性质以及该区的气候条件导致其氨挥发潜力较大。与其他集约化农作区相比,该区农田氨挥发研究相对较少。本文探讨了川中丘陵区紫色土冬小麦/夏玉米轮作体系氨挥发情况,为开展陆地生态系统大气碳氮气体交换研究提供基础数据,同时也为氨排放清单的编制及农田氨减排措施研究提供依据。选取川中紫色土丘陵区典型的坡耕地作为研究对象,采用风洞法研究了紫色土冬小麦/夏玉米轮作体系的氨挥发动态过程。每次试验设置1个施肥处理,3次重复。风速、风向、大气温湿度、土壤温湿度等气象数据由试验田微型气象站获取。每隔2~3 d采集土壤样品用以测定土壤NH4+-N含量。两年的田间试验结果表明,受氮肥深施及低温的影响,冬小麦季氨挥发损失率明显低于夏玉米季;2013年和2014年冬小麦季氨挥发损失率分别为7.4%和8.8%;2013年夏玉米季三叶期氮肥撒施的氨挥发速率为34.1%;2014年夏玉米季三叶期氮肥条施覆土降低了氨挥发损失,损失率为21.4%;2014年夏玉米季十叶期出现极端干旱的气候条件,撒施氮肥后立即灌水使氨挥发损失率高达46.6%,这是由于干旱条件下施肥灌水提供了利于氨挥发的土壤水分条件。因此在极端干旱的气候条件下,应避免采用此施肥方式。综合分析两年的数据可得:紫色土冬小麦季氨挥发损失占施氮量的(8.1±1.0)%,夏玉米氨挥发损失占施氮量的(32.8±1.8)%。     

控释掺混肥对麦玉轮作体系农田温室气体排放和硝态氮残留的影响

为阐明控释肥对冬小麦-夏玉米轮作体系作物产量、温室气体排放和硝态氮残留的影响,该研究以郑单958（夏玉米）和济麦22（冬小麦）为供试材料,设不施氮对照（CK）、常规施氮（FFP）、优化施氮（OPT）、含30%控释尿素的控释掺混肥（夏玉米）和含50%控释尿素的控释掺混肥（冬小麦）（CRBF1）、含50%控释尿素的控释掺混肥（夏玉米）和含70%控释尿素的控释掺混肥（冬小麦）（CRBF2）共5个处理,对比分析了不同处理的冬小麦、夏玉米及周年产量、温室气体排放和土壤硝态氮残留的差异。结果表明,施氮可显著提高麦玉轮作系统单季和周年作物产量（P<0.05）。与FFP相比,CRBF1和CRBF2处理的夏玉米、冬小麦和周年产量分别提高了1.4%～3.0%、1.9%～3.4%和1.6%～3.1%（P>0.05）。施氮显著增加了麦玉轮作体系的土壤N₂O和CO₂的周年排放（P<0.05）。CRBF1和CRBF2处理的土壤N₂O周年排放总量较FFP处理显著降低了27.7%～34.6%（P <0.05）。施氮显著增加了麦玉轮作体系的周年全球增温潜势（GWP）（P<0.05）。CRBF1和CRBF2处理的周年GWP较FFP处理降低了4.2%和5.7%,其中CRBF2处理差异显著（P<0.05）。施氮降低了麦玉轮作体系的周年温室气体排放强度（GHGI）。CRBF1和CRBF2处理的周年GHGI较FFP处理降低了5.6%～8.6%（P>0.05）。与FFP相比,CRBF1和CRBF2处理的100~200 cm土层硝态氮残留降低30.6%～34.3%（P<0.05）,减少了硝态氮淋失风险。综上所述,控释掺混肥在稳定作物产量、减少温室气体排放和土壤硝态氮残留方面具有积极作用,研究结果可为麦玉轮作体系的轻简高效氮肥管理提供数据支持和理论支撑。     

猪场肥水施用对玉米-小麦农田氨排放、氮素利用与表观平衡的影响

规模化生猪养殖废弃物已成为当前重要污染来源,为有效解决猪场废水所引发面源污染问题,有必要开展将其替代矿物氮肥(作为肥水)施用于农田的探索。以华北平原高度集约化玉米-小麦一年两熟轮作体系为对象,通过田间小区试验,定量研究猪场肥水施用对作物产量、氮素吸收、氮素利用效率、土壤矿质氮累积、氨挥发损失及轮作体系氮素表观平衡的影响。试验包括7个处理:不施肥对照(CK)、尿素表施(CK1)、尿素注射施用(CK2)、猪场肥水替代25%尿素氮表施(25%WB)、猪场肥水替代50%尿素氮表施(50%WB)、猪场肥水替代25%尿素氮注射施用(25%WI)和猪场肥水替代50%尿素氮注射施用(50%WI)。猪场肥水作为基肥施用。结果表明,与CK相比,施用尿素和猪场肥水均可显著提高玉米、小麦产量和籽粒氮吸收量,其中25%WI最高,50%WI次之。与尿素表施相比,尿素注射施用、猪场肥水表施和注射施用均可明显提高氮肥农学效率、偏生产力和表观利用率,且肥水注射施用最高,肥水表施次之,而25%WI和50%WI之间无显著差异。与不施肥处理相比,施用尿素和猪场肥水0～100cm土体矿质氮残留量显著增加50.8%～87.9%,其中50%WB、25%WI和50%WI无显著差异。与尿素表施相比,尿素注射施用、肥水表施和注射施用均可显著降低玉米和小麦基肥期土壤氨损失总量,降幅分别为26.5%～48.6%和11.4%～29.1%;同时,肥水表施和注射施用下轮作体统氮盈余显著降低7.6%～16.0%,其中25%WI降幅最高,但与50%WI无显著差异。综合考虑作物产量、氮素利用和环境效应,猪场肥水替代25%和50%尿素氮注射施用是该区玉米-小麦轮作农田猪场肥水最佳施用方式。     

Integration of rice crop residue into sustainable rice production system

Rice is the staple food for nearly 40% of the world's population. In Malawi, rice is ranked second only to maize as a cereal food crop. In rainfed areas of Malawi, grain yields typically average 1.0–1:5 t ha^‐1 while potential yield is 4–5 t ha¹. To bridge the gap between current and potential yields, several novel nutrient management systems were studied. Many research reports indicate that rice responds to silicon (Si) application as well as to nitrogen (N), phosphorus (P), and potassium (K) which are commonly applied. Rice crop residues (straws and hulls) are rich in Si and K, but are not utilized currently in rice production. The effect of rice‐hull ash, rice straw, and method of N application (prilled or briquetted urea) on a transplanted rice crop was studied through field experiments in Malawi during 1995 and 1996. Application of urea in briquette form increased rice grain yield by 1056 and 122 kg ha^‐1 compared to prilled urea in the 1995 winter and 1996 summer experiments, respectively. However in the 1996 winter experiment, prilled urea was superior to urea briquette and increased the rice grain yield by 307 kg ha¹. Incorporation of rice straw significantly increased rice grain yields over the control in three consecutive experiments. Rice‐hull ash alone increased the rice grain yields in all three experiments up to 12%; however, the increase was not statistically significant. The combination of rice straw and rice‐hull ash along with optimum N rates (60 kg ha^‐1) increased the rice grain yields significantly in 1996 winter season but the increase was not significant in the other two experiments.