长期不同施氮量下冬小麦-夏玉米复种系统土壤硝态氮累积和淋洗特征

冬小麦夏玉米是华北平原主要的粮食作物,其集约化的农业种植体系虽然普遍实现了粮食的高产,但氮肥常年大量施用会造成土壤深层硝态氮累积、淋洗等问题.本文以河北清苑冬小麦-夏玉米复种体系为研究对象,设置不同施氮量(N₀、N₁₀₀、N₁₈₀、N₂₅₅、N₃₃₀,分别表示施氮0、100、180、255、330 kg·hm^-2),于2010-2016年开展6个周期定位试验,研究不同施氮量对土壤硝态氮累积和淋洗的影响.结果表明: 在12季冬小麦和夏玉米收获期各处理产量存在显著差异,土壤硝态氮含量表现为冬小麦季累积、夏玉米季淋洗的特点,且90和180 cm土层硝态氮累积量均表现为 N₃₃₀>N₂₅₅>N₁₈₀>N₁₀₀>N₀.从土壤剖面分布看,硝态氮可淋洗至990 cm的深层土壤中,且出现6个累积峰,同时土壤硝态氮累积峰随施氮量增加而下移,N₃₃₀处理累积峰最深在840 cm处.从各土层累积量的分配看,5个处理0～90 cm硝态氮累积量占比在10%左右,大部分都在90 cm以下,不能被植物利用.可见,夏玉米季硝态氮淋洗严重,施氮量越高,土壤硝态氮残留量越大,向土壤深层淋洗量也越多,由此带来的对地下水的污染风险应该引起重视.从产量与硝态氮累积情况来看,N₁₈₀为最优处理.     

土壤硝态氮时空变异与土壤氮素表观盈亏研究Ⅰ.冬小麦

不同氮肥用量下对冬小麦生育期间土壤硝态氮时空变化特征及土壤氮素表观盈亏量的研究结果表明,氮肥用量不同,硝态氮分布特征有差异,并且随着冬小麦的生长,其变化也不同。在冬小麦快速生长阶段,作物吸收可在一定深度的土层出现硝态氮亏缺区。由于灌溉的影响,土壤表层硝态氮向深层淋洗严重,即使在低氮肥水平,土壤深层仍可观察到硝态氮含量升高现象,存在淋出2m土体的可能性。并且氮肥用量越高,土壤硝态氮含量越高,硝酸盐向深层淋洗也越严重,淋出2m土体的可能性和也相应增大;在冬小麦生长前期（播种－拔节）,即使在不施氮肥处理也有土壤氮素的表观盈余,随着施肥量的增加,在拔节－扬花也出现了土壤氮素表观盈余,而扬花后各个氮肥处理均出现土壤氮素的表观亏缺,氮肥用量越高,小麦一生中土壤表观氮盈余量越大,1m土体内平均最大盈余量达199.8kgN/hm^2。研究表明,土壤氮损失是盈余氮素的一个主要去向,而硝态氮淋洗是冬小麦生育期间土壤氮素损失的一个重要的途径。     

青藏高原东缘窄叶鲜卑花灌丛生长季土壤无机氮对增温和植物去除的响应

为了揭示气候变暖背景下高寒灌丛土壤氮转化过程, 该文研究了青藏高原东缘窄叶鲜卑花(Sibiraea angustata)灌丛生长季节土壤硝态氮和铵态氮含量对增温和去除植物的响应。结果表明: 窄叶鲜卑花灌丛土壤硝态氮和铵态氮含量具有明显的季节动态。整个生长季节, 土壤硝态氮含量呈先增加后降低的趋势, 而铵态氮含量均表现为一直增加的趋势。在生长季初期和中期, 各处理土壤硝态氮含量均显著高于铵态氮含量, 而在生长季末期土壤硝态氮含量均显著低于铵态氮含量, 说明该区域土壤氮转化过程在生长季初期和中期以硝化作用为主, 而在生长季末期以氨化作用为主。不同时期土壤硝态氮和铵态氮含量对增温和去除植物的响应不同: 增温对硝态氮的影响主要发生在生长季中期和末期, 且因植物处理的不同而有显著差异, 增温仅在生长季中期使不去除植物样方铵态氮含量显著升高。去除植物对土壤硝态氮的影响仅表现在对照样方(不增温), 去除植物显著提高了生长季初期和中期土壤硝态氮含量, 显著降低了生长季末期土壤硝态氮含量; 同时去除植物显著降低了增温样方生长季中期土壤铵态氮含量。灌丛植被在生长季初期和中期可能主要吸收土壤硝态氮, 其吸收过程不受土壤增温的影响。     

Responses of soil inorganic nitrogen to increased temperature and plant removal during the growing season in a Sibiraea angustata scrub ecosystem of eastern Qinghai-Xizang Plateau

为了揭示气候变暖背景下高寒灌丛土壤氮转化过程, 该文研究了青藏高原东缘窄叶鲜卑花(Sibiraea angustata)灌丛生长季节土壤硝态氮和铵态氮含量对增温和去除植物的响应。结果表明: 窄叶鲜卑花灌丛土壤硝态氮和铵态氮含量具有明显的季节动态。整个生长季节, 土壤硝态氮含量呈先增加后降低的趋势, 而铵态氮含量均表现为一直增加的趋势。在生长季初期和中期, 各处理土壤硝态氮含量均显著高于铵态氮含量, 而在生长季末期土壤硝态氮含量均显著低于铵态氮含量, 说明该区域土壤氮转化过程在生长季初期和中期以硝化作用为主, 而在生长季末期以氨化作用为主。不同时期土壤硝态氮和铵态氮含量对增温和去除植物的响应不同: 增温对硝态氮的影响主要发生在生长季中期和末期, 且因植物处理的不同而有显著差异, 增温仅在生长季中期使不去除植物样方铵态氮含量显著升高。去除植物对土壤硝态氮的影响仅表现在对照样方(不增温), 去除植物显著提高了生长季初期和中期土壤硝态氮含量, 显著降低了生长季末期土壤硝态氮含量; 同时去除植物显著降低了增温样方生长季中期土壤铵态氮含量。灌丛植被在生长季初期和中期可能主要吸收土壤硝态氮, 其吸收过程不受土壤增温的影响。     

土壤硝态氮时空变异与土壤氮素表观盈亏Ⅱ.夏玉米

在不同氮肥用量下研究了夏玉米生育期间土壤硝态氮的时空变化特征 ,同时对不同生育阶段土壤氮素的盈余与亏缺进行了表观估算 ,结果表明 :0～ 1 0 0 cm土体内 ,夏玉米一生中土壤硝态氮均表现为在中间土层含量低 ,上层和下层含量高 ,一般以表层最高 ,但受降雨的影响在高氮肥处理会出现下层高于表层的现象。施氮肥提高了土壤硝态氮含量 ,而且提高程度与用量成正相关。降雨时土壤硝态氮可随水下移 ,在干旱条件下也可随水上移。土壤硝态氮的运移不仅受土壤水分状况的影响 ,还取决于硝态氮含量 ,含量越高 ,向下移动的越深 ,淋失的可能性越大 ;在本试验条件下 ,土壤氮素盈余主要出现在夏玉米播种～ 9叶展和 9叶展～吐丝两个生育阶段 ,吐丝～收获则出现土壤氮素的亏缺。随着氮肥用量的增加 ,玉米一生中土壤氮素的表观盈余量明显增大 ,最高平均可达 2 74 .1 kg N/hm2。研究结果表明 ,土壤氮损失是盈余氮素的一个主要去向 ,而硝态氮淋洗是夏玉米生育期间土壤氮素损失的一个重要途径。     

盐渍区农田氮肥施用量对土壤硝态氮动态变化的影响

土壤硝态氮动态变化和残留与农田硝态氮淋溶以及地下水硝态氮污染密切相关。为了促进海河低平原盐渍区农田氮肥合理利用以及农业可持续发展,试验在盐化潮土条件下,通过设计不同施氮量（0,70,140,210kg N hm^-2）处理,重点研究了该区农田氮肥施用量对土壤硝态氮动态、残留以及土壤氮损失的影响。结果表明：（1）0～100cm土壤剖面硝态氮总量随施氮量显著增加,施用氮肥没有改变剖面硝态氮总量随玉米生育进程波状变化趋势,但明显增强了其变化幅度;（2）施氮改变了硝态氮土壤剖面空间分布状态,表现出施氮后上部土层（0～40cm）硝态氮比例显著增加而后迅速降低的趋势;（3）硝态氮残留与氮素损失随施氮量增加而增加,且N210和N140处理下氮素损失量显著高于N70和N0。     

土壤硝态氮时空变异与土教育界氮素表观盈亏Ⅱ.夏玉米

在不同氮肥用量下研究了夏玉米生育期间土壤硝态氮的时空变化特征,同时对不同生育阶段土壤氮素的盈余与亏缺进行了表观估算,结果表明：0-100cm土体内,夏玉米生中土壤硝态氮均表现为在中国土层含量低,上层和下层含量高,一般以表层最高,但受降雨的影响在高氮肥处理会出现下层高于表层的现象,施氮肥提高了土壤硝态氮含量,而且提高程度与用量成正相关,降雨时土壤硝态氮可随水下移,在干旱条件下也可随水上移,土壤硝态氮的运移不仅受土壤水分状况的影响,还取决于硝态氮含量,含量越高,向下移动的越深,淋失的可能性越大;在本试验条件下,土壤氮素盈余主要出现在夏玉米播种9叶展和9叶展-吐丝两个生育阶段,吐丝-收获则出现土壤氮素的亏缺,随着氮肥用量的增加,玉米一生中土壤氮素的表观盈余量明显增大,最高平均可达274.12kgN/hm^2。研究结果表明,土壤氮损失是盈余氮素的一个主要去向,而硝态氮淋洗是夏玉米生育期间土壤氮素损失的一个重要途径。     

施氮量和底施追施比例对土壤硝态氮和铵态氮含量时空变化的影响

研究了高产栽培条件下,不同施氮量和底施追施比例对土壤硝态氮和铵态氮含量时空变化的影响,同时计算了不同生育阶段土壤氮素的表观盈亏量.结果表明,与氮肥分期施用处理比较,氮肥全部用于拔节期追施处理降低了拔节期之前的土壤硝态氮含量,减少了拔节期之前土壤氮素的表观盈余量,降低了氮素向深层的淋洗;而挑旗期土壤硝态氮含量与氮肥分期施用处理无显著差异,但提高了土壤铵态氮含量;增加了成熟期0～60 cm土壤各土层土壤硝态氮含量和0～20 cm土壤铵态氮含量.氮肥全部用于拔节期追施的两处理间比较,在240 kg·hm^-2的基础上降低施氮量至168 kg·hm^-2,降低了挑旗期土壤硝态氮和铵态氮的含量,减少了挑旗期到成熟期土壤氮素的亏缺量,也使成熟期土壤硝态氮的含量降低.不同处理间籽粒产量和蛋白质产量无显著差异,施氮量为168 kg·hm^-2且全部用于拔节期追施的处理籽粒蛋白质含量最高.     

田间非饱和流条件下土壤硝态氮运移的模拟

运用马尔可夫过程的理论 ,建立了土壤非饱和流条件下 ,模拟硝态氮通过土层运移的随机模型 .模型把时间可变系统假设为由紧密相连的时间均质情况相接而成 ,使得运用马尔可夫过程成为可能 ,在给定土壤水流量及汇源项转移强度的土壤层次中 ,给出了硝态氮溶质的统计分布 .模型将随机过程与确定性过程相结合 ,在计算各土层间的转移概率时考虑了硝态氮的作物吸收、淋洗、硝化和反硝化等主要过程 ,并用相关函数修正 N素转化关系 .在褐土农田土壤非饱和流条件下 ,用微区试验对该模型运行效果进行了验证 ,结果显示模拟计算值与实测值之间吻合性较好 ,说明模型可以用于相似类型区 ,预测和评价土壤 -作物系统中硝态氮溶质的运移行为 .     

三种集约化种植体系氮素平衡及其对地下水硝酸盐含量的影响

选取中国北方3种重要的集约化种植体系小麦玉米轮作、大棚蔬菜和果园,研究了3种体系年度氮素输入输出关系、土壤硝酸盐的累积、不同体系地下水硝态氮含量的动态变化.结果表明,大棚蔬菜年度化肥氮、有机肥氮、灌水带入的氮和总氮输入量分别为135.8、1881、402和36.56kg·hm^-2,分别为小麦玉米田的25、37.5、83.8和5.8倍,为果园的2.1、10.4、6.82和4.2倍.不同系统降水输入的氮在142～189kg·hm^-2之间.3个体系氮输出量分别为280、329和121kg·hm^-2.氮素年度盈余分别为349、332.7和74.6kg·hm^-2.0～90cm土层硝态氮累积量分别为22.1～2.75、1173和613kg·hm^-2,90～180cm土层硝态氮累积量分别为2.13～2.42、10.32和976kg·hm^-2.在0～180cm剖面中,小麦玉米田各层土壤硝态氮处于相对均一分布,大棚蔬菜以表层最高,30cm以下各层也远高于大田,果园土壤硝态氮累积随土壤深度而增加.3种体系均表现出硝酸盐的明显淋洗.大棚蔬菜区浅井地下水硝态氮含量99%超过了10mg·L^-1.而大棚深井和果园浅井超标率均为5%,小麦玉米深井为1%.大棚蔬菜区地下水硝态氮含量与井深呈指数函数降低关系.     

不同施肥条件下玉米田土壤养分淋溶规律的原位研究

利用排水采集器法结合田间原位试验,研究了夏玉米不同施肥处理对棕壤土养分淋失的影响.结果表明:在夏玉米生长期内,影响玉米田土壤水分淋溶的主要因素是大量降雨和灌溉,夏玉米生长前期的土壤淋溶水量较大,但随夏玉米生育进程的推进而递减,各处理差异也逐渐减小;与施氮肥处理相比,秸秆还田配施氮肥处理可加剧土壤水淋溶.在夏玉米生长期内,施肥处理的土壤淋溶水硝态氮浓度均呈"双峰"曲线变化趋势,而铵态氮浓度则呈先升后降的变化趋势.玉米田土壤氮素淋失以硝态氮形式为主,其累计淋失量为12.90～46.53 kg·hm-2,铵态氮的累计淋仅为1.66～5.11 kg·hm-2,两种形态氮的淋失量都随施氮量的增加而升高.秸秆还田配施氮肥处理的氮素淋失率比单施氮肥处理高6.53%～13.07%,低氮处理的氮素淋失率比高氮处理高3.66%～10.10%;玉米田土壤速效磷的累计淋失量较小,仅为0.148～0.235 kg·hm-2,而速效钾的累计淋失量较大,为7.08～13.00 kg·hm-2.在夏玉米生长后期,秸秆还田配施氮肥处理使土壤速效磷淋失量升高,并可加剧土壤速效钾的淋失,而单施氮肥处理作用不明显.     

DNDC模型在农田氮素渗漏淋失估算中的应用

采用田间原装渗漏计测定了山东省济南市典型种植模式下,2008年冬小麦整个生长季水分和 氮素淋失量,并利用该数据对DNDC（DeNitrification-DeComposion）模型进行检验和敏感性分析.结果表明：模型对该地区农田土壤水分运动的模拟效果较好,模拟结果的精度总体上可以接受,但对氮素淋失量的模拟结果存在一定偏差,冬小麦整个生长季的氮素淋失量模拟值（18.35 kg N·hm^-2）比实测值（14.89 kg N·hm^-2）高3.46 kg N·hm^-2,相对偏差在20%左右,模型参数尚需作进一步调整.模型敏感性分析显示,农田氮素淋失更易受到灌水量和施肥量的影响.DNDC模型在该地区有一定的适用性.     

Effects of enhanced nitrogen deposition and phosphorus limitation on nitrogen budgets of semi-natural grasslands

Increased reactive atmospheric N deposition has been implicated in floristic changes in species‐rich acidic and calcareous grasslands, but the fate of this pollutant N in these ecosystems is unknown. This paper reports the first analysis of N budgets and N fluxes for two grasslands in the White Peak area of Derbyshire, one of the most heavily N‐polluted locations in the UK. N fluxes were monitored in lysimeter cores (retaining the original turfs) taken from field plots of unimproved acidic and calcareous grasslands that had received (in addition to ambient N deposition) simulated enhanced N deposition treatments of 3.5 and 14 g N m^?2 yr^?1 for 6 years. The influence of reducing phosphorus limitation was assessed by factorial additions of P. Seasonal leached losses of nitrate, ammonia and organic N were monitored in detail along with estimates of N removal through simulated grazing and gaseous losses through denitrification and volatilization. The rates of N fluxes by these pathways were used to create N budgets for the grasslands. Both grasslands were found to be accumulating much of the simulated additional N deposition: up to 89% accumulated in the calcareous grassland and up to 38% accumulated in the acidic grassland. The major fluxes of N loss from these grasslands were by simulated grazing and leaching of soluble organic N (constituting 90% of leached N under ambient conditions). Leached inorganic N (mainly nitrate) contributed significantly to the output flux of N under the highest N treatment only. Loss of N through ammonia volatilization accounted for less than 6% of the N added as simulated deposition, while denitrification contributed significantly to output fluxes only in the acidic grassland during winter. The implications of the results for ecosystem N balances and the likely consequences of N accumulation on these grasslands are discussed.     

In-Situ Remediation of Lead–Zinc Polymetallic Mine Contaminated Soils by MnFe2O4 Microparticles

In-situ remediation is a practical approach to remediate soils contaminated with heavy metals. The MnFe₂O₄ microparticles (MM) were prepared for the in-situ remediation of contaminated soils from a lead–zinc polymetallic mine in Inner Mongolia province, China. The effects of MM dosage, pH on remediation efficiency, were determined with static vibration leaching experiment, and the release risk of heavy metals of treated soil was studied by column leaching experiment. The results showed that the leached Cu, Pb, Zn, and As concentration decreased drastically with increasing MM dosage, when the dosage was lower than 10 g/kg. Moreover, the decrease of pH caused increase of leached concentration of Cu, Pb, Zn, but slight decrease of leached As concentration. For the amended soil, concentrations of leached heavy metals were lower than Grade III limit of Chinese Environmental Quality Standards for Ground and Surface water (GB3838-2002) under simulated acid rain leaching condition. In comparison with non-amended soils, the total amount of Cu, Pb, Zn, and As release from amended soils was reduced by 93.6%, 69.2%, 57.0%, and 99.7%, respectively. The MM is a kind of promising amendment for heavy metals contaminated soil.     

The use of cover crops in cereal-based cropping systems to control nitrate leaching in SE England

Field experiments were done to evaluate the extent to which cover crops can be used to help farmers comply with current legislation on nitrate leaching from arable land in nitrate vulnerable zones. Nitrate leaching was measured in sandy loam and chalky loam soils under a range of early sown (mid-August) cover crops at two sites in SE England, and in the subsequent winter following their incorporation. Cover crop species tested were forage rape, rye, white mustard, a rye/white mustard mixture, Phacelia and ryegrass. Additional treatments were weeds plus cereal volunteers, a bare fallow and a conventional winter barley crop sown one month later than the cover crops and grown to maturity. Cover crop and bare fallow treatments were followed by spring barley. This was followed by winter barley, as was the conventional winter barley crop. In the winter immediately after establishment, early sown cover crops decreased nitrate leaching by 29–91% compared to bare fallow. They were most effective in a wet winter on the sandy loam where nitrate leaching under bare fallow was greatest. There was little difference between cover crop species with respect to their capacity to decrease nitrate leaching, but losses were consistently smaller under forage rape. The growth of weeds plus cereal volunteers significantly decreased nitrate leaching on the sandy loam compared with a bare fallow, but was less effective on the chalky loam. Nitrate leaching under the later sown winter barley was often greater than under cover crops, but under dry conditions leaching losses were similar. In the longer-term, in most cases, the inclusion of cover crops in predominantly cereal-based cropping systems did not significantly decrease cumulative nitrate leaching compared with two successive winter cereals. In summary, early sown cover crops are most likely to be effective when grown on freely drained sandy soils where the risk of nitrate leaching is greatest. They are less likely to be effective on poorer drained, medium-heavy textured soils in the driest parts of SE England. In these areas the regeneration of weeds and cereal volunteers together with some additional broadcast seed may be sufficient to avoid excessive nitrate losses. In the short-term, mineralization of N derived from the relatively small cover crops grown once every 3–4years in cereal-based cropping systems is unlikely to contribute greatly to nitrate leaching in later years and adjustments to fertilizer N recommendations will not usually be necessary.     

Leaching losses of nitrogen from a clay soil under grass and cereal crops in Finland

Summary A 16-plot experimental field was established in 1975 on a clay soil in Jokioinen, Finland. The water discharge through tile drains was measured and its ammonium and nitrate N contents determined for each plot separately. The surface runoff was also measured and analysed. The annual runoff and the N leached from the surface of moderately fertilized (100 kg/ha/y N) cereal plots varied during 1976–1982 from 21 to 301 mm and from 2 to 7 kg/ha, respectively. The discharge of water and leaching of N through subdrains varied from 65 to 225 mm and from 1 to 38 kg/ha, respectively. The highest leaching was probably caused by a previous fallow. The annual N uptake by the crop varied between 41 and 122 kg/ha.Of the fertilizer-N used for cereals, 20% of that applied in the autumn was lost, but only 1 to 4 per cent was lost when applied in the spring. There was much less N leaching from ley than from barley plots, although the former was given twice as much N. The rate of N fertilization had only a very slight effect on N leaching from both ley and barley plots.The results were compared with those obtained in lysimeters filled with clay, silt, sand and peat soils. No definite conclusions can be drawn because the lysimeter experimental data are only for the first year.     

酸雨对缙云山林地黄壤汞溶出的影响

Forest yellow soil and arable yellow soil in Jinyun Mountain were collected to study the effect of simulated acid rain(adjusted to pH 2.0, 3.0, 4.0 and 5.0) on the Hg leaching from soils by the methods of static extraction and dynamic leaching. The results showed that in forest yellow soils, surface accumulation of Hg occurred, and the accumulated Hg was easier to be leached out than that in arable yellow soil by acid rain. The amount of leached Hg was the largest at pH 4.0. To abate the risk of Hg pollution in water bodies by the Hg leaching from this forest soil, the Mountain should be closed, and timber-felling should be forbidden.     

外加氮源对杉木叶凋落物分解及土壤养分淋失的影响

采用原位（Ｉｎ ｓｉｔｕ）模拟实验方法研究了外加Ｎ源对杉木叶凋落物分解及土壤养分淋失的影响,结果表明,施加ＮＨ＾＋４－Ｎ时,杉木叶凋落物的失重率与对照（未加任何Ｎ的处理）相比,没有差异：而施加ＮＯ＾－１－Ｎ时,使杉木叶凋落物分解速率显著提高（ｐ＝０．０５,达１０％以上,与施加ＮＨ＾＋４－Ｎ相比,施加ＮＯ＾－３－Ｎ明显促进了杉木叶凋落物的分解（ｐ＝０．０５）。施加ＮＨ＾＋４－Ｎ和ＮＯ３＾－－Ｎ会产生     

Assessing nitrate leaching during the three‐first years of Miscanthus × giganteus from on‐farm measurements and modeling

Miscanthus × giganteus is often regarded as one of the most promising crops to produce sustainable bioenergy. This perennial crop, renowned for its high productivity associated with low input requirements, in particular regarding fertilizers, is thought to have low environmental impacts, but few data are available to confirm this. Our study aimed at assessing nitrate leaching from Miscanthus × giganteus crops in farmers' fields, thus including a wide range of soil and cropping system conditions. We focused on the first years of growth after planting as experimental studies have suggested that Miscanthus × giganteus, once established, results in low nitrate leaching. We combined on‐farm measurements and modeling to estimate drainage, leached nitrogen, and nitrate concentration in drainage water in 38 fields located in Center‐East France during two winters (November 2010 to March 2011, November 2011 to March 2012). Nitrate leaching and nitrate concentration in drainage water were on average very low. Nitrate leaching averaged 6 kg N ha^?1 whereas nitrate concentration averaged 12 mg l^?1. These low values are attributable to the low estimates of drainage water (mean = 166 mm) but also to the low soil mineral nitrogen contents measured at the beginning of winter (mean = 37 kg N ha^?1). Our results were, however, very variable, mainly due to the crop age: nitrate leaching and nitrate concentration were critically higher during the winter following the first growth year of Miscanthus × giganteus, reflecting the low development of the crop. This variability was also explained by the range of soil and cropping conditions explored in the on‐farm design: shallow and/or sandy soils as well as fields where establishment failed had a higher risk of nitrate leaching.     

Annual emissions of dissolved CO2, CH4, and N2O in the subsurface drainage from three cropping systems

Indirect emission of nitrous oxide (N₂O), associated with nitrogen (N) leaching and runoff from agricultural lands is a major source of atmospheric N₂O. Recent studies have shown that carbon dioxide (CO₂) and methane (CH₄) are also emitted via these pathways. We measured the concentrations of three dissolved greenhouse gases (GHGs) in the subsurface drainage from field lysimeter that had a shallow groundwater table. Aboveground fluxes of CH₄ and N₂O were monitored using an automated closed‐chamber system. The annual total emissions of dissolved and aboveground GHGs were compared among three cropping systems; paddy rice, soybean and wheat, and upland rice. The annual drainage in the paddy rice, the soybean and wheat, and the upland rice plots was 1435, 782, and 1010 mm yr^?1, respectively. Dissolved CO₂ emissions were highest in the paddy rice plots, and were equivalent to 1.05–1.16% of the carbon storage in the topsoil. Dissolved CH₄ emissions were also higher in the paddy rice plots, but were only 0.03–0.05% of the aboveground emissions. Dissolved N₂O emissions were highest in the upland rice plots, where leached N was greatest due to small crop biomass. In the soybean and wheat plots, large crop biomass, due to double cropping, decreased the drainage volume, and thus decreased dissolved GHG emissions. Dissolved N₂O emissions from both the soybean and wheat plots and the upland rice plots were equivalent to 50.3–67.3% of the aboveground emissions. The results indicate that crop type and rotation are important factors in determining dissolved GHG emissions in the drainage from a crop field.