长期不同养分投入对土壤养分和水稻生产持续性的影响

以中国科学院桃源农业生态试验站15a长期田间定位试验为研究对象,分析了不同养分投入对稻田土壤养分和水稻产量可持续性的影响.结果表明,化肥与系统内循环的有机物料循环的肥力效力和产量效应基本一致,有机物料循环更有利于土壤有机质和氮素的积累;在不同养分投入下,土壤耕层有机质和全氮均呈上升趋势,年均增长率分别为1.5%～5.8%和2.5%～9.4%;与试验前相比,不同养分投入耕层磷素变动幅度在-18.3%到30%之间,钾素养分有所亏缺,下降幅度在8.1%～22.6%之间;通过可持续性指数的分析得出,土壤N素养分的可持续性对化肥的依赖性较大,而P、K养分的可持续性则对有机肥的依赖性更高.稻田生态系统具有良好的自维持能力,系统内有机物循环有利于提高稻谷产量的稳定性和可持续性.     

中国小麦季氮素养分循环与平衡特征

通过汇总2000—2011年文献数据以及国际植物营养研究所实测试验数据,研究了华北、长江中下游和西北地区小麦季经过土壤界面的氮素输入和输出各项养分循环参数,分析并评估了3大区域的氮素养分平衡状况.结果表明:华北、长江中下游和西北地区小麦季氮肥平均施入量分别为170、183和150 kg N·hm-2,上季作物秸秆氮素还田量分别为74.6、15.2和8.1 kg N·hm-2,种子带入量分别为4.9、4.2和3.5 kg N·hm-2.华北地区来自非共生固氮、大气沉降和灌溉水氮素养分输入量分别为15、12.9和9.9 kg N·hm-2,长江中下游地区分别为15、14.5和5.8 kg N·hm-2,西北地区分别为15、9.4和7.7 kg N·hm-2.小麦收获时华北、长江中下游和西北地区地上部作物吸收的氮分别为174.3、144.4和122.3 kg N·hm-2,华北地区通过氨挥发、N2O排放和淋溶损失的氮素分别为19.9、2.6和11.8 kg N·hm-2,长江中下游地区分别为9.4、2.4和15.5 kg N·hm-2,西北地区小麦季氨挥发和N2O排放量分别为3.4和0.7 kg N·hm-2,不计淋溶损失的氮素.由此计算的小麦季氮素养分平衡结果显示,华北、长江中下游和西北地区的氮素养分均表现为盈余,盈余量分别为78.7、66.0和67.3 kg N·hm-2,超出了养分允许平衡盈亏率,应适当调整氮肥投入,避免氮肥的不科学施用带来的负面环境影响.     

有机肥对陇东黄土旱塬冬小麦产量和土壤养分的调控效应

以冬小麦'陇鉴301'为材料,在大田条件下于2005～2008年在甘肃陇东旱塬研究了不同有机肥料对旱塬冬小麦产量、水分利用效率及土壤肥力的影响.结果表明:不同化肥有机肥料配施处理对旱塬冬小麦产量、水分利用效率和土壤养分含量有明显的调控效应,并以氮磷化肥与生物有机肥配施处理表现最佳,其籽粒产量、水分利用效率和土壤养分含量最高.与单施化肥对照相比,氮磷化肥配施生物有机肥处理3年平均籽粒产量和水分利用效率分别显著增加17.53%和16.42%,3年平均土壤有机质、全氮、碱解氮、速效磷含量分别提高11.4%、8.9%、0.2%、19.7%.因此,氮磷化肥与生物有机肥配施可以有效改善陇东黄土旱塬区农田土壤肥力,提高冬小麦水分利用效率,显著增加冬小麦产量,可能是该区农田目前最佳的施肥方式.     

华北平原种养一体规模化农场氮素流动特征及利用效率——以河北津龙循环农业园区为例

种养一体规模化、集约化是华北平原农业发展的必然趋势,而氮素是连接种植养殖的主要养分资源,以河北津龙循环农业园区为例,采用文献资料、实地调查方法分析农场水平氮素流动特征及利用率,并通过情景分析方法提出农场氮素管理措施,为实现农场水平氮养分资源高效利用、提高农场生产系统生产力和改善华北平原循环农业模式提供技术支撑和科学依据.结果表明: 在农场水平下,化肥和有机肥输入氮量674.6 kg·hm^-2·a^-1,占总输入氮量的88.3%,氮利用率为41.5%,种植系统氮盈余量190.7 kg·hm^-2·a^-1,施氮量过多是造成种植系统氮利用率低和氮素盈余量高的主要原因.养殖系统中外购饲料提供氮量占饲料总输入氮量的83.2%,粪尿排氮量为776.6 t·a^-1,而还田比例仅为36.3%,氮利用率19.7%.农场水平氮总利用率为40.7%.情景分析表明,农田减少化肥施氮量50%(情景1)、增加来自农场内部玉米籽粒产量(情景2)措施,可分别使种植系统氮利用率提高34.6%和15.6%,同时农场水平氮总利用率分别提高18.7%和9.8%;另外,优化养殖系统饲料结构(情景3),可使氮总利用率提高19.1%.因此,减少化肥氮施用量、调整作物种植结构、优化饲料结构等,是提高农场氮生产力和实现环境友好双赢效果的措施和途径.     

京郊典型集约化"农田-畜牧"生产系统氮素流动特征

城郊畜牧业的集约化发展在满足人们日益增长的肉蛋奶等动物性产品需求的同时,也带来了巨大的环境压力。本文利用养分流动和模型分析的方法,分析北京市郊区某村三种不同类型"农田-畜牧"生产系统(大型集约化种猪场、种养结合小规模生态养殖园和集约化单一种植区)的氮素流动特征。结果表明:饲料是集约化种猪场和生态养殖园氮素输入的主要来源,饲料投入氮量分别为12469.0和9268.5 kg.hm-.2a-1);集约化种猪场农牧体系间生产脱节,致使农田氮素输入主要依赖于化肥投入,化肥氮输入量(435.0 kg.hm-.2a-1)占农田氮素输入量的82.7%。相反,生态养殖园农牧体系结合紧密,猪粪尿氮还田比例达28.6%,这使得园区化肥氮输入量仅为135.0 kg.hm-.2a-1,因此畜禽粪尿的合理循环利用可作为减少化肥投入的有效途径;集约化种猪场、生态养殖园和单一种植区农牧生产系统氮素利用效率分别为18.8%、20.6%和17.3%,均处于较低水平;集约化种猪场猪粪尿在猪舍和储藏处理过程的氮素损失率为15.8%和25.4%,分别低于小规模生态养殖园相应损失率约8.7和4.8个百分点;生态养殖园粪肥氮还田量高,导致农田氮素盈余量高达1962.8 kg.hm-.2a-1,未能实现生态型养殖的理想效果,优化氮素管理、确定合理的消纳畜禽粪尿的农田面积和调整畜禽养殖密度是解决该问题的关键。     

城镇化对我国食物消费系统氮素流动及循环利用的影响

城镇化的快速发展,在改变养分氮素流动模式的同时带来了巨大的生态环境压力和严重的污染问题.以1982年、1992年和2002年我国城镇与农村居民食物消费系统氮素流动为对象,采用物质流分析方法,探讨了城镇化对氮素流动特征及循环利用率的影响.结果表明:2002年我国城镇居民人均消费氮量为4.770kg,高于农村居民(4.314kg)10%.1982年到2002年,随着城镇化率的提高,城镇居民消费的食物氮提高了145.3%,农村减少了8.1%;城镇排入水体环境的氮增加了18.4倍,而氮素循环利用率只有13.0%,降低了40个百分点.情景分析结果表明,如果在人口增加的同时,食物结构达到国家营养纲要的标准,到2010年我国植物性氮消费量比2002年将增多142.3万t,增加了37.6%,动物性氮消费量将增多53.8万t,增加了 27.1%,城镇产生的粪尿和垃圾中氮将增加126万t.因此,伴随城镇化快速发展,在带来食物氮素需求和环境排放氮素大幅度增加的同时,也会对动植物生产带来巨大压力.     

不同有机肥对砂田西瓜产量、品质和养分吸收的影响

探讨不同有机肥对西北砂田西瓜生长、产量、品质和养分吸收利用的影响,为砂田西瓜合理施肥、优质高效生产提供理论依据.本试验以单施化肥为对照,在氮、磷、钾等养分条件下,设置了牛粪、鸡粪、羊粪、猪粪4个处理,测定了西瓜不同生育时期生长指标、产量、品质及养分吸收积累量.结果表明: 施用牛粪、鸡粪和猪粪有机肥较单施化肥可促进西瓜营养生长和氮、钾养分的运转,显著提高西瓜产量和养分的吸收积累量,其中西瓜产量较化肥处理分别显著提高了27.4%、31.6%和30.2%,氮素积累量分别提高了26.3%、39.8%和47.4%,磷素积累量分别提高了49.3%、48.3%和55.9%,钾素积累量分别提高了35.8%、41.6%和51.9%.猪粪处理的西瓜品质最优,中心、边缘可溶性固形物含量较化肥处理分别显著提高了5.5%和11.6%,Vc含量提高了19.9%.羊粪处理各指标与化肥处理间差异不显著,甚至略低于化肥处理.综上,砂田西瓜种植应优先选用猪粪和鸡粪有机肥,避免或减少施用羊粪有机肥.     

城市居民食物氮消费变化及其环境负荷——以厦门市为例

食物消费是城市养分流动的重要环节,以厦门市为例,分析了1988—2009年居民食物氮素消费的变化特点,分析与其变化相关的经济、社会因素,并探讨了居民食物氮素消费变化所带来的环境负荷。研究结果表明,厦门市人均食物氮消费量变化与食物消费量变化并不完全一致,人均氮消费量2000年以前维持在3.29 kg N.人-1.a-1,2000年以后呈现波动性的增长,2004年达到最高值4.00 kg N.人-1.a-1。厦门市食物氮素消费总量增长幅度较大,由1988年的0.54万t增至2009年的1.50万t。同时,粮食在食物氮消费量中所占比例由45.5%下降到15.9%。畜禽肉、奶制品所占比例分别由25.0%和0.4%上升至29.8%和8.8%。通过将相关经济、社会因素与居民食物氮消费量进行相关性分析表明,人均可支配收入、食物价格指数、具有大学学历以上人口比重均与其联系较为密切,呈正相关;恩格尔系数、平均家庭人口数与居民食物氮消费量呈负相关。通过选取1988、1994、2001、2008年分析居民食物氮素消费造成的环境氮负荷发现,由其带来的环境氮负荷量由3509.12t增加至7629.36t,约90%的氮素进入了土壤和水体。其中,进入土壤的氮素占进入环境氮总量的比例由37%增长到60%,进入水体的氮素比例由57%降至35%。     

紫云英配施化肥对水稻氮素吸收利用和紫云英氮在水稻-土壤体系分配、残留的影响

明确紫云英配施化肥条件下水稻对氮素吸收利用和紫云英氮在水稻-土壤体系的吸收利用、分配及残留规律,能够为豫南稻区合理施肥提供依据。本研究利用原状土柱模拟和¹⁵N示踪技术,研究等氮条件下不施肥(CK)、化肥+22500 kg·hm^-2紫云英(FM1)、化肥+30000 kg·hm^-2紫云英(FM2)、化肥+37500 kg·hm^-2紫云英(FM3)、化肥+22500 kg·hm^-2紫云英+石灰(FM1+CaO)、化肥+30000 kg·hm^-2紫云英+石灰(FM2+CaO)、化肥+37500 kg·hm^-2紫云英+石灰(FM3+CaO)对水稻氮素吸收利用、水稻-土壤体系氮素养分平衡和紫云英矿化分解的氮在水稻各部位吸收利用、分配及残留的影响。结果表明: 与CK相比,施肥显著提高了稻谷氮吸收量、稻秆氮吸收量和氮素表观损失量、氮素盈余量。稻谷氮吸收量、稻秆氮吸收量和水稻氮利用率随紫云英翻压量增加呈先升高后降低趋势,氮素表观损失量和氮素盈余量随紫云英翻压量增加呈先降低后上升趋势,均以翻压30000 kg·hm^-2紫云英配施化肥处理效果较好。增施石灰可提高水稻稻谷氮吸收量、稻秆氮吸收量和水稻氮利用率,降低氮素表观损失量和氮素盈余量,以FM2+CaO处理效果最好。各施肥处理水稻吸收的氮来源于紫云英的比例为6.3%～13.2%,来源于土壤和肥料的比例为86.8%～93.7%;水稻对紫云英氮的当季利用率为23.8%～33.6%,水稻各部位对紫云英氮的利用率表现为籽粒>茎叶>根;紫云英氮在土壤中的残留率为37.6%～62.4%,损失率为7.8%～38.6%。综合考虑水稻氮素吸收利用、水稻-土壤体系氮素养分平衡和紫云英氮在水稻中的分配状况,该研究区以FM2+CaO处理为最优。     

市域尺度农村系统氮素流动及污染氮足迹核算——以沈阳市为例

理解农村系统的氮素流动、排放和利用过程对减少农业活动引起的潜在环境污染和促进养分资源的可持续利用具有重要意义。本研究基于集成食物链养分流动模型和氮足迹模型,提出市域尺度农村系统氮核算框架,并从种植、动物养殖和农村人居3个子系统对1998—2018年沈阳市的氮素流、循环利用和污染氮足迹开展量化比较研究。结果表明: 2018年沈阳市种植子系统、动物养殖子系统和农村人居子系统的氮素利用率分别为36.1%、59.7%和70.1%,分别比1998年增长了15.9%、9.1%和0.7%;2018年沈阳市农村系统污染氮足迹总量为123.5 Gg,比1998年增长了21.6%;1998—2014年沈阳市农村系统污染氮足迹增长较快,随后有所下降;2018年种植子系统、动物养殖子系统和人居子系统中未利用氮素分别为129.5、62.2和8.7 Gg,相当于420.4、202.1和8.7 Gg氮肥的养分资源量。总体上,农村系统氮素利用率从生产端到消费端逐渐递增,但对农村系统氮素的时空分异情况还有待进一步的研究。     

Spatial and seasonal variation in nutrient excretion by benthic invertebrates in a eutrophic reservoir

1. Nitrogen (N) and phosphorus (P) fluxes via excretion by benthic invertebrates were quantified in a eutrophic reservoir (Acton Lake, Ohio, U.S.A.). We quantified variation in nutrient fluxes seasonally (June until November 1997), spatially (three sites) and among taxa (chironomids, tubificid oligochaetes and Chaoborus). 2. The three taxa differed in spatial distribution and contribution to nutrient fluxes. Tubificids were the most abundant taxon at two oxic sites (1.5 and 4 m depth), and were exceedingly rare at an anoxic, hypolimnetic site (8 m). Chironomids were abundant only at the shallowest oxic site. Chaoborus was the only abundant taxon at the anoxic site. Total benthic invertebrate biomass was greatest at the shallowest site and lowest at the anoxic, hypolimnetic site. 3. Mass‐specific excretion rate [μmol NH₄–N or soluble reactive P (SRP) excreted mg dry mass^–1 h^–1] varied among experiments and was influenced by temperature. Differences among taxa were not significant. Thus, nutrient flux through benthic invertebrates was affected more by total invertebrate biomass and temperature than by species composition. 4. Fluxes of N and P via benthic invertebrate excretion (μmol NH₄–N or SRP m^–2 day^–1) were greatest at the oxic sites, where fluxes were dominated by the excretion of tubificids and chironomids. The N and P fluxes at the anoxic site were much lower, and were dominated by excretion by Chaoborus. The ratio of N and P excreted by the benthic invertebrate assemblage varied seasonally and was lowest at the anoxic site. 5. Comparison with other measured inputs shows that excretion by benthic invertebrates could be an important source of nutrients, especially of P. However, the relative importance of nutrient excretion by the benthos varies greatly spatially and temporally.     

在杉木林和马尾松林中雨水的养分淋溶作用

本试验地是在杉木林和马尾松林中,主要对降雨和径流水中所含各种养分物质进行测定。结果表明:降雨的养分含量与降雨量存在着半对数函数关系。降雨输入林地的养分量显著地大于径流输出的养分量。林内雨和树干茎流淋溶的养分量占养分还原总量的48—53％。林内雨和树干淋溶的K、Mg、N养分物质量超过凋落物归还养分量。     

Nutrient transport in mycorrhizas: structure,physiology and consequences for efficiency of the symbiosis

Nutrient transport in mycorrhizas occurs across specialized interfaces which are the result of corrdinated development of the organisms. The structural modifications give rise to large areas of either inter- or intra-cellular interface in which wall synthesis is frequently modified and in which altered distribution of membrane bound ATPases is important, particularly with respect to mechanisms that may be involved in bidirectional transfer of nutrients. Except in orchid mycorrhizas, net movement of organic carbon from plant to fungus occurs, complemented by mineral nutrient movement in the opposite direction. The general consensus is that sustained transfer at rates that will maintain the growth and development of the organisms requires increases in the rates at which nutrients are lost from the organisms; possible mechanisms for this are discussed. The transfer processes are essential in determining both plant and fungal productivity and an approach to calculating the efficiency of the symbiosis in terms of the expenditure of carbon (or of phosphorus) is discussed.     

Sources of nutrients to rooted submerged macrophytes growing in a nutrient-rich stream

1. The relative contribution of roots and leaves to nutrient uptake by submerged stream macrophytes was tested in experiments where plants were grown in an outdoor flow-channel system. Water was supplied from a nutrient-rich stream with inorganic nitrogen and phosphorus concentrations typical of Danish streams.
2. Four submerged macrophyte species were tested, Elodea canadensis , Callitriche cophocarpa , Ranunculus aquatilis and Potamogeton crispus, and all species were able to satisfy their demand for mineral nutrients by leaf nutrient uptake alone. This was evident from manipulative experiments showing that removal of the roots had no negative impact on the relative growth rate of the plants. Further, the organic N and P concentrations of the plant tissue was constant with time for the de-rooted plants.
3. Enrichment of water and/or sediment had no effect on the relative growth rate of two species, E. canadensis and C. cophocarpa , indicating that in situ nutrient availability was sufficient to cover the needs for growth. Despite the lack of a response in growth rate, a reduced root/shoot biomass ratio was observed with nutrient enrichment of water and/or sediment, and an increased tissue-P concentration in response to open-water enrichment.
4. The open-water nutrient concentrations of the stream in which the experiments were performed are in the upper part of the range found for Danish farmland streams (the majority of Danish streams). Still, however, the negligible effect of nutrient enrichment on the growth of submerged macrophytes observed suggests that mineral nutrient availability might play a minor role in controlling macrophyte growth in most Danish streams.     

Optimizing nutrient management for farm systems

Increasing the inputs of nutrients has played a major role in increasing the supply of food to a continually growing world population. However, focusing attention on the most important nutrients, such as nitrogen (N), has in some cases led to nutrient imbalances, some excess applications especially of N, inefficient use and large losses to the environment with impacts on air and water quality, biodiversity and human health. In contrast, food exports from the developing to the developed world are depleting soils of nutrients in some countries. Better management of all essential nutrients is required that delivers sustainable agriculture and maintains the necessary increases in food production while minimizing waste, economic loss and environmental impacts. More extensive production systems typified by 'organic farming' may prove to be sustainable. However, for most of the developed world, and in the developing world where an ever-growing population demands more food, it will be essential to increase the efficiency of nutrient use in conventional systems. Nutrient management on farms is under the control of the land manger, the most effective of whom will already use various decision supports for calculating rates of application to achieve various production targets. Increasingly, land managers will need to conform to good practice to achieve production targets and to conform to environmental targets as well.     

缺苞箭竹密度对养分元素贮量、积累与分配动态的影响

研究了缺苞箭竹(Fargesiadenudate)-紫果云杉(Piceapurpurea)原始林下不同密度缺苞箭竹群落的养分元素贮量与分配动态以及养分元素在一个生长季节内的积累量。结果表明:地上、地下部分的N、P、K、Ca、Mg贮量均随着箭竹密度的增加而增大,养分元素贮量排序为:K>N>Ca>P>Mg。密度较大的箭竹群落(D1和D2)中,地上部分的N、P和K贮量大于地下部分,而密度较小的箭竹群落(D3)中P和K贮存于地下部分的比例较大,3个群落中的地下部分Ca和Mg贮量均大于地上部分,且地下部分的养分元素贮量的比例随着箭竹密度的增加而减少。养分元素的总积累量排序为:K>N>Ca>P>Mg,且地上部分和群落的总积累量随着箭竹密度的增加而增加,总积累率以D1群落最大,3个群落的养分元素积累率大小顺序为:Mg>Ca>P>N>K。地下部分(根系和鞭)养分元素贮量比例随着箭竹密度的增加而下降,而地上部分(叶、枝和竹杆)养分元素贮量比例随着箭竹密度增加而上升。密度对缺苞箭竹养分贮量、积累和分配动态有深刻影响。     

Constructing nutrient budgets

We present a formalised, yet flexible, scheme for classifying and symbolising the components of nutrient budgets. The scheme distinguishes hierarchically both among components of the ingesta and among the various sinks to which they are allocated. The primary terms in the budget are distinguished according to either methodological criteria (whether in a given time period they are retained by the animal or dissociated from the body) or functional criteria (whether they contribute to fitness). In both methodological and functional classifications, the primary terms of the budget may be progressively expanded to represent with increasing resolution nutrient allocation. The interplay between the various components of the ingesta and their subsequent allocation may be considered simultaneously using a two-dimensional nutritional matrix.     

不同施肥模式下潮棕壤稻田的速效养分状况和水稻的养分分配

研究了不同施肥模式下下辽河平原潮棕壤稻田土壤速效养分的供应能力及水稻的养分分配.结果表明:各处理0～20 cm速效养分供应能力均高于20～40 cm,其变异也大于20～40 cm(速效氮除外);有机、无机肥相结合有利于提高土壤速效养分的供应能力;水稻氮和磷的分配主要集中在籽实中,钾的分配则主要集中在秸秆中.采用秸秆还田措施有利于缓解钾肥资源的不足,保持钾素的循环再利用,维持土壤钾库,减少钾肥投入,降低农业生产成本,减轻环境污染.