灌溉排水耦合调控稻田水分转化关系

该文利用装配有地下水位自动控制系统的蒸渗仪,分析节水灌溉与旱地控制排水技术耦合调控对于稻田水分转化关系的影响。结果表明,灌排耦合调控在小幅减少水稻产量的同时,显著减少了稻田灌溉水量、地下排水量及水稻蒸发蒸腾量,最终显著增加了水稻水分生产效率。与常规灌排稻田相比,灌排耦合调控稻田水稻产量减少1.9%,灌溉水量、地下排水量及水稻蒸发蒸腾量分别显著减少41.7%、49.9%及24.9%,水分生产效率增加30.5%。随着控灌稻田排水控制限的提高,稻田灌溉水量、地下排水量及水稻蒸发蒸腾量减少,水稻产量保持稳定,使得水稻水分生产效率进一步增加。提高控灌稻田的排水控制限,减缓了稻田土壤水分的衰退速度,并增加稻田地下水位低于排水控制限的比例,稻田灌溉次数与发生地下排水的时段均减少,使得控灌稻田灌溉水量与地下排水量下降,两者综合作用下控灌稻田水稻蒸发蒸腾量减少。在采用控制灌溉模式的基础上,适当提高稻田排水控制限,可以较好地实现水稻生产中水分的高效利用,研究结果可为优化稻田水管理模式提供依据。     

Effects of bamboo biochar application on global warming in paddy fields in Ehime prefecture,Southern Japan

Biochar application can reduce global warming via carbon (C) sequestration in soils. However, there are few studies investigating its effects on greenhouse gases in rice (Oryza sativa L.) paddy fields throughout the year. In this study, a year-round field experiment was performed in rice paddy fields to investigate the effects of biochar application on methane (CH₄) and nitrous oxide (N₂O) emissions and C budget. The study was conducted on three rice paddy fields in Ehime prefecture, Japan, for 2 years. Control (Co) and biochar (B) treatments, in which 2-cm size bamboo biochar (2 Mg ha^?1) was applied, were set up in the first year. CH₄ and N₂O emissions and heterotrophic respiration (Rh) were measured using a closed-chamber method. In the fallow season, the mean N₂O emission during the experimental period was significantly lower in B (67 g N ha^?1) than Co (147 g N ha^?1). However, the mean CH₄ emission was slightly higher in B (2.3 kg C ha^?1) than Co (1.2 kg C ha^?1) in fallow season. The water-filled pore space increased more during the fallow season in B than Co. In B, soil was reduced more than in Co due to increasing soil moisture, which decreased N₂O and increased CH₄ emissions in the fallow season. In the rice-growing season, the mean N₂O emission tended to be lower in B (?104 g N ha^?1) than Co (?13 g N ha^?1), while mean CH₄ emission was similar between B (183 kg C ha^?1) and Co (173 kg C ha^?1). Due to the C release from applied biochar and soil organic C in the first year, Rh in B was higher than that in Co. The net greenhouse gas emission for 2 years considering biochar C, plant residue C, CH₄ and N₂O emissions, and Rh was lower in B (5.53 Mg CO₂eq ha^?1) than Co (11.1 Mg CO₂eq ha^?1). Biochar application worked for C accumulation, increasing plant residue C input, and mitigating N₂O emission by improving soil environmental conditions. This suggests that bamboo biochar application in paddy fields could aid in mitigating global warming.     

控制灌溉稻田的甲烷减排效果

为探讨节水灌溉水分调控对稻田甲烷（CH4）排放的影响,寻找节水减排的稻田灌溉模式,依据5a田间原位观测资料,分析控制灌溉稻田CH4排放规律及其减排效果。结果表明,控制灌溉稻田稻季CH4排放量为1.07±0.17 g/m2,较淹水灌溉稻田（6.49±0.17 g/m2）降低83.5%,差别极显著。本研究得到的中国东南部稻田稻季和全年CH4排放量均低于已有报道中的中国稻田CH4排放量,其中控制灌溉稻田全年CH4排放量低于世界大部分地区稻田。根据本研究结果估算中国稻田CH4排放总量为2.06 Tg/a,大面积推广控制灌溉后,中国稻田CH4排放量还将进一步下降。控制灌溉模式显著影响水稻全生育期稻田CH4排放通量的变化,削峰效果显著。控制灌溉稻田CH4排放通量在返青期至分蘖中期（移栽后18 d内）逐渐上升至最大值,然后逐渐减小,从水稻分蘖后期（移栽后21 d）开始至生育期结束均维持在较低水平。控制灌溉稻田CH4排放通量峰值为3.69 mg/m2·h,较淹水灌溉稻田降低69.0%。在持续降雨的作用下,控制灌溉和淹水灌溉模式下稻田CH4排放通量均呈现下降趋势。控制灌溉模式的土壤水分调控,使稻田经历一系列的脱水过程,改变了根层土壤的水气状况,减小了稻田CH4排放。控制灌溉模式在水稻全生育期的应用可显著地减少稻田CH4排放。     

农作措施对中国稻田氧化亚氮排放影响的研究进展

农业是全球最主要的温室气体排放源之一,稻田不仅是全球重要的甲烷(CH4)排放源,亦是氧化亚氮(N2O)的重要排放源。灌溉、施肥、耕作等农作措施能够改变稻田生态系统土壤微环境,影响土壤硝化与反硝化过程,进而影响N2O的排放。目前,关于农作措施对农田生态系统N2O排放特征研究很多,但系统地综述农作措施对稻田N2O排放影响的研究还比较少。该文着眼于中国的农业发展趋势,基于稻田灌溉、施肥及耕作等方面的新技术,综合分析新型农作措施对中国稻田生态系统N2O排放的影响及其机制,为相关研究提供参考。在此基础上,提出了中国稻田生态系统N2O排放深入研究的方向:1)加强研究新型农作措施下稻田N2O产生及排放途径;2)系统研究稻田生态系统直接与间接N2O排放的影响及其机制;3)开展农作措施集成技术对稻田生态系统N2O排放影响的研究;4)加强模型模拟的调参验证并进行相关预测分析。     

节水灌溉对稻田N2O季节排放特征的影响

为了揭示节水灌溉对技术对稻田N2O排放的影响,采用静态暗箱-气相色谱法对稻田N2O排放进行了田间原位观测,分析了节水灌溉对稻田N2O季节排放特征的影响。结果表明,水稻全生育期节水灌溉稻田N2O平均排放通量为41.84 μg/(m2 ?h),较淹水灌溉稻田N2O平均排放通量增加了33.3%;节水灌溉稻田N2O排放总量为119.86 mg/m2,比淹水灌溉稻田显著增加了17.8%;节水灌溉稻田N2O排放通量呈现明显的季节变化规律,有两次较大的排放峰值,峰值主要出现在施肥后1周左右;节水灌溉稻田土壤的每次脱水过程均不同程度地加剧了N2O排放,复水后N2O排放通量有增有减但变幅不大,而淹水灌溉稻田在黄熟期落干阶段N2O排放出现反弹。由此可见,不同灌溉模式下的稻田土壤水分状况决定了N2O季节排放的差异,与淹水灌溉相比,控制灌溉显著增加了稻田N2O季节排放量。     

适宜节水灌溉模式抑制寒地稻田N_2O排放增加水稻产量

2014年在大田试验条件下,设置控制灌溉、间歇灌溉、浅湿灌溉及淹灌4种水分管理模式,采用静态暗箱-气相色谱法田间观测寒地水稻生长季N2O排放特征,研究不同灌溉模式对寒地稻田N2O排放的影响及N2O排放对土壤环境要素的响应,同时测定水稻产量,以期为寒地稻田N2O排放特征研究提供对策。结果表明:不同灌溉模式下N2O排放的高峰均出现在水分交替频繁阶段,水稻生育阶段前期,各处理N2O排放都处于较低水平,泡田期几乎无N2O排放。与淹灌相比,间歇灌溉使N2O排放总量增加47.3%,控制灌溉和浅湿灌溉使N2O排放总量减少40.7%和39.6%。寒地稻田N2O排放通量与土壤硝态氮含量关系密切,与土壤10 cm温度显著相关(P0.05)。水稻生长期间各处理N2O排放顺序间歇灌溉淹灌,二者均显著高于浅湿灌溉和控制灌溉(P0.05)。各处理水稻产量以浅湿灌溉最低、其他方式差异不显著。可见,间歇灌溉有助于提高水稻产量,但会促进稻田N2O的排放。在综合考虑水稻产量及稻田温室效应的需求下,控制灌溉为最佳灌溉方式,应予以高度重视。该研究可为黑龙江寒地稻作区选择节水减排模式提供科学支撑。     

节水灌溉稻田氨挥发损失及影响因素

为了揭示节水灌溉稻田氨挥发特征,开展了不同灌溉模式稻田氨挥发损失的田间试验,分析了节水灌溉稻田氨挥发速率季节变化规律与稻季氨挥发损失量,以及稻田氨挥发速率与影响因素之间的相互关系。结果表明,控制灌溉稻田氨挥发速率与淹水灌溉稻田变化规律基本一致,且在分蘖肥引起氨挥发出现峰值后的大部分时间里都要低于淹水灌溉;控制灌溉与淹水灌溉稻田稻季氨挥发损失总量（以纯氮计）分别为125.27 kg/hm2和145.64 kg/hm2,分别占稻季施氮量的31.06%和36.11%。除了受施肥影响外,稻田氨挥发还与田面水（表层土壤水）铵态氮浓度、空气温度、风速、日照时数及空气湿度等有密切关系。与淹水灌溉相比,控制灌溉减少了稻田氨挥发损失。     

不同有机肥对稻田温室气体排放及产量的影响

为研究有机肥施入稻田对温室气体排放的影响,设置猪粪、鸡粪和稻草分别与化肥混施处理,利用静态箱法-气相色谱仪监测稻田甲烷(CH_4)和氧化亚氮(N_2O)排放通量并进行分析。研究结果表明,化肥处理(CF)CH_4季节排放为202.1、279.9和332.5 kg/hm~2,与猪粪(PM)无显性差异,明显低于鸡粪(CM)和稻草(RS)处理;CF处理N_2O排放总量最高,与有机肥处理无显著性差异;CH_4季节排放通量与土壤Eh值呈极显著负相关关系,与土壤温度呈极显著正相关关系;肥料中不同活性有机碳质量分数为18.4~114.5 g/kg,肥料中被167 mmol/L高锰酸钾氧化的有机碳(ROC167)与稻田CH_4排放总量呈显著正相关关系(相关系数为0.872,P0.05);施有机肥第三年水稻平均产量比CF处理增加14.3%(P0.05);不同有机肥中,以PM处理的增温潜势和温室气体排放强度最小,与不施肥和CF处理无显著性差异,猪粪的ROC167含量低,能较好的协调环境与产量之间关系,是值得推荐的有机肥种类。     

水稻田间育秧水肥药变量喷灌装置设计与试验

为解决南方水稻工厂化田间育秧水肥药人工管理作业中存在的灌溉均匀性差、化肥和农药浪费以及劳动强度大等问题,该研究设计了一种水稻田间育秧水肥药变量喷灌装置,阐述了水肥药变量喷灌装置总体结构和工作原理,进行了关键部件设计与试验;以可编程逻辑控制器（programmable logic controller,PLC）为控制核心,构建了注肥量在线调控及整机变量喷灌控制系统。采用Box-Behnken试验设计方法,对装置喷灌均匀性与主要影响因素进行试验研究,应用单目标优化方法对喷灌关键参数进行优化,并通过验证试验,得到最优参数组合为：干管入口水压0.20 MPa、球阀开度90°、喷头喷角80°,此时装置的喷灌均匀性为92.69%;构建了氯化钾肥液质量浓度与电导率（electrical conductance,EC）值的线性模型,开展了装置变量灌溉施肥性能试验,3种喷灌等级下各作业区的肥液EC值分别为1.65、1.66和1.68 mS/cm,平均喷灌强度分别为900.85、1092.04和1263.67 mm/h,施肥均匀系数分别为85.21%、87.86%和91.62%。采用水肥药变量喷灌装置开展水稻育秧田间管理试验,华航51常规稻和广8优165杂交稻的秧苗长势均匀度均高于95%,成毯性良好,各项素质指标满足机插作业要求。所设计的水肥药变量喷灌装置能够满足水稻田间育秧水肥药变量喷灌作业要求,对提高水稻工厂化田间育秧机械化水平、保证秧苗质量具有实际应用价值。     

Effect of the number of tillages in fallow season and fertilizer type on greenhouse gas emission from a rice (Oryza sativa L.) paddy field in Ehime,southwestern Japan

Agricultural fields, including rice (Oryza sativa L.) paddy fields, constitute one of the major sources of atmospheric methane (CH₄) and nitrous oxide (N₂O). Organic matter application, such as straw and organic fertilizer, enhances CH₄ emission from paddy fields. In addition, rice straw management after harvest regulates CH₄ emissions in the growing season. The interaction of tillage times and organic fertilizer application on CH₄ and N₂O emissions is largely unknown. Therefore, we studied the effects of fallow-season tillage times and fertilizer types on CH₄ and N₂O emissions in paddy fields in Ehime, southwestern Japan. From November 2011 to October 2013, four treatments, two (autumn and spring) or one (spring) in the first year, or two (autumn and spring) or three (autumn, winter, and spring) in the second year times of tillage with chemical or organic fertilizer application, were established. Gas fluxes were measured by the closed-chamber method. Increasing the number of tillage times from one to two decreased succeeding CH₄ emission and the emission factor for CH₄ (EF_CH4) in the rice-growing season, suggesting that the substrate for CH₄ production was reduced by autumn and spring tillage in the fallow season. Higher EF_CH4 [1.8–2.0 kg carbon (C) ha^?1 d^?1] was observed when more straw was applied (6.9–7.2 Mg ha^?1) in the second year. Organic fertilizer application induced higher CH₄ emission just after the application as basal and supplemental fertilizers, especially at a lower straw application rate. This indicated that EF_CH4 in the organically managed fields should be determined individually. Organic fertilizer application with two tillage times induced N₂O efflux during the rice-growing season in the second year, but N₂O emissions were not affected by winter tillage. Although paddy fields can act as an N₂O sink because of reduced soil conditions when straw application was high, application of organic C and nitrogen as fertilizer can enhance N₂O production by the denitrification process during the growing season, especially in the ripening stage when soil anaerobic conditions became moderate. These results suggest that negative emission factors for N₂O (EF_N2O) can be applied, and EF_N2O of organic fertilizer should be considered during the estimation of N₂O emission in the paddy field.     

Effect of the long-term application of anaerobically digested residual slurry on methane emissions in a rice paddy field

ABSTRACT

The anaerobic digestion of livestock manure is an environmentally compatible technology used for the production of renewable energy. Anaerobically digested residual slurry has been used worldwide as a liquid fertilizer in both upland and paddy fields. However, a controversial question remains as to whether the application of slurry to rice paddy fields increases methane emissions; although methane is one of the most prevalent greenhouse gases, little is known about the effects of the long-term application of residual slurry on methane emission. In this study, we repeatedly applied slurry to a paddy field for six years at different application rates (10, 15, and 20 g N m^?2 based on ammonium-nitrogen content). At the fifth and sixth years of application, we evaluated the effect in terms of methane flux and soil total carbon content. The effect of the long-term application of the slurry (10 g N m^?2) on grain yield was equivalent to that of chemical fertilizer (10 g N m^?2). The application of the residual slurry was likely to increase the cumulative methane emissions during rice growing season in both 2006 and 2007. On the other hand, we observed that soil total carbon did not accumulate significantly in the soil. Thus, we cannot rule out the potential risk of additional methane emissions caused by the application of the residuary slurry to paddy fields.     

生物质炭输入减少稻田痕量温室气体排放

为揭示不同水平生物质炭输入对稻田土壤理化性质、水稻产量及温室气体排放的影响,采用自制竹炭在4种不同施用水平下(0、10、20、40 t/hm2)输入稻田土壤,开展了水稻一个生长周期的田间试验。结果表明,生物质炭输入可显著提高土壤p H值和有机碳含量(P0.05),且有机碳含量增幅与生物质炭施用水平呈正比(相关系数为0.78,P0.01)。生物质炭施用可显著降低土壤容重(P0.05),最大降幅为0.25 g/cm3,土壤容重随着生物质炭施用量的增加而降低。不同处理水稻产量无显著性差异(P0.05)。CH4累积排放量与生物质炭施用量呈负相关性(相关系数为-0.24,P0.01),投加生物质炭可显著降低稻田CH4排放通量和累积排放量(P0.05),但过量施用生物质炭(超过20 t/hm2)并不能显著降低CH4累积排放量(P0.05)。相比对照处理(不输入生物质炭),生物质炭输入后一周内可显著性降低N2O排放通量(P0.05),并在排水烤田时升高,最终稳定于9.80 mg/(m2·h)。生物质炭输入可显著性降低N2O累积排放量(P0.05),但不同水平生物质炭输入处理之间差异不显著(P0.05)。该试验条件下,生物质炭施用量为20 t/hm2时可实现稻田稳产和固碳减排目标,该研究可为太湖地区苕溪流域稻田增汇和温室气体减排提供参考。     

灌排调控的稻田排水中氮素浓度变化规律

基于农田排水氮素浓度及湿地进出口断面总氮（TN）、氨态氮（NH4+-N）、硝态氮（NO3--N）浓度的监测,研究了灌溉排水措施以及沟塘湿地对农田排水中氮素浓度变化的影响。结果表明,控制灌溉的水稻全生育期稻田排水中TN、NH4+-N和NO3--N浓度分别较常规灌溉处理低12.08%、20.33%和13.51%;控制排水处理下稻田排水中TN、NH4+-N和NO3--N浓度分别较常规排水处理低2.21%、7.08%和20.92%;湿地出口水体中TN、NH4+-N和NO3--N浓度分别比入口降低了16.8%、14.4%和50.9%,湿地水体中TN、NH4+-N、NO3--N浓度随时间近似服从指数函数衰减趋势。控制灌溉、控制排水及沟渠塘湿地系统的调控措施对农田排水中氮素的净化效果比较显著。     

Effect of the long-term application of organic matter on soil carbon accumulation and GHG emissions from a rice paddy field in a cool-temperate region,Japan-II. Effect of different compost applications-

ABSTRACT

The influence of long-term application of different types of compost on rice grain yield, CH₄ and N₂O emissions, and soil carbon storage (0 ? 30 cm) in rice paddy fields was clarified. Two sets of paddy fields applied with rice straw compost or livestock manure compost mainly derived from cattle were used in this study. Each set comprised long-term application (LT) and corresponding control (CT) plots. The application rates for rice straw compost (42 years) and livestock manure compost (41 years in total with different application rates) were 20 Mg fresh weight ha^–1. Soil carbon storage increased by 33% and 37% with long-term application of rice straw compost and livestock manure compost, respectively. The soil carbon sequestration rate by the organic matter application was 23% higher with the livestock manure compost than with the rice straw compost. The rice grain yield in the LT plot was significantly higher than that in the corresponding CT plot with both types of compost. Although the difference was not significant in the rice straw compost, cumulative CH₄ emissions increased with long-term application of both composts. Increase rate of CH₄ emission with long-term application was higher in the livestock manure compost (99%) than that in the rice straw compost (26%). In both composts, the long-term application did not increase N₂O emission significantly. As with the rice straw compost, the increase in CH₄ emission with the long-term application of livestock manure compost exceeded the soil carbon sequestration rate, and the change in the net greenhouse gas (GHG) balance calculated by the difference between them was positive, indicating a net increase in the GHG emissions. The increase in CH₄ and net GHG emissions owing to the long-term application of the livestock manure compost could be higher than that of the rice straw compost owing to the amount of applied carbon, the quality of compost and the soil carbon accumulation. The possibility that carbon sequestration in the subsoil differs depending on the type of composts suggests the importance of including subsoil in the evaluation of soil carbon sequestration by long-term application of organic matter.     

田块和小区尺度下节水灌溉稻田腾发量差异分析

为了揭示节水灌溉稻田腾发量在不同尺度间的差异,基于田间实测数据,对比分析了节水灌溉田块尺度与小区尺度间稻田腾发量的差异性。结果表明,节水灌溉水稻整个生育期不同尺度腾发量间存在显著差异,田块尺度的总腾发量比小区尺度小18.7%。各生育期稻田腾发量尺度间差异显著(P0.05),不同时段(旬、候)稻田腾发量尺度间差异极显著(P0.01)。节水灌溉条件下稻田下垫面状况、大气湍流状况、灌溉补水过程、土壤水分状况以及气象因子是造成不同尺度稻田腾发量差异的主要原因。气象因子中空气相对湿度和气温造成了尺度间腾发量差异的变化。稻田腾发量尺度差异的揭示可为稻田腾发量在尺度间的转换提供依据。     

排水循环灌溉驱动的稻区水循环模型与评价

排水循环灌溉可补充灌溉和减少涝水排放,具有缓解南方稻区旱涝急转和农业面源污染危害的潜力,但仍无有效的模型来模拟排水循环灌溉驱动下的水文过程。为此采用penman-monteith公式和作物系数法并考虑稻田渗漏与降雨有效性条件下应用水量平衡估算水稻灌溉需水量,改进SCS(soil conservation service)模型估算排水量,再以塘堰为对象建立调蓄排水和灌溉需水的水平衡演算模型。在漳河水库灌区应用该模型发现,水稻种植区存在大量的排水可供灌溉利用,而排水循环灌溉利用量受灌排面积比、塘堰容积率和塘堰初始蓄水率的影响;提高灌排面积比和塘堰容积率能明显提高补充灌溉率和排水再利用率,当两者达到一定值时补充灌溉率和排水再利用率便稳定在最高值,补充灌溉率高达20%;补充灌溉率随塘堰初始蓄水率的增加而缓慢增至20%,排水再利用率先随初始蓄水率的增加而稳定不变,随后逐渐降低。排水循环灌溉驱动的水循环模型为合理匹配排水循环灌溉的塘堰或排灌规模提供有效方法。     

基于排水过程分析的水稻灌区农田面源污染模拟

对前郭灌区主要面源污染物迁移、转化及汇集过程开展了2a的系统试验与监测,模拟了灌区面源污染水质水量过程,分析了灌区农田面源污染形成机制。水均衡测定结果表明,灌区排水主要由灌溉退水、稻田地表弃水和稻田渗流排水3部分组成,采用马斯京根法和连续分段马斯京根法能够有效地模拟各级排水沟道的排水过程。主要面源污染物随水体发生迁移及掺混,采用一级动力学方法描述污染物转化过程,模拟的灌区水质水量过程与实际过程符合较好,稻田地表退水主要影响水稻抽穗前的面源污染入河过程,而渗流排水则在抽穗后灌区排水水质中起主要作用。结果表明水稻灌区中地表排水和稻田渗漏排水对于面源污染过程起主要作用。     

Methane production and its fate in paddy fields

Abstract

Oxidation of methane and total water soluble organic carbon (TOC) in the subsoil, which percolated from the plow layer, was investigated in a column experiment. The amounts of both methane and TOC in the leachate decreased by percolation in the subsoil.

Fe²⁺ percolated from the plow layer was nearly completely retained in the subsoil. The decomposition of methane and TOC in the subsoil was considered to result in the coupling with the formation of Fe²⁺. Methane was estimated to contribute ca. 19–21% to the total amount of Fe²⁺ formed in the subsoil by the organic materials in the leachate.     

中国农业源温室气体排放与减排技术对策

农业是重要的温室气体排放源。该文通过对文献资料和大量研究结果进行分析,得出中国农业活动产生的甲烷和氧化亚氮分别占全国甲烷和氧化亚氮排放量的50.15%和92.47%,农业源占全国温室气体排放总量的17%;通过改善反刍动物营养可降低单个肉牛甲烷排放15%～30%;推广稻田间歇灌溉可减少单位面积稻田甲烷排放30%;一个户用沼气每年最大可减少温室气体2.0～4.1 t二氧化碳当量;推行缓释肥、长效肥料可减少单位面积农田氧化亚氮50%～70%。该文建议尽快开展减排技术示范,对减排技术的适应性和经济性进行评价。     

磁场对稻谷干燥特性的影响

针对稻谷的传统干燥过程存在能量消耗大,发芽率低和爆腰率高等缺点,把磁场引入稻谷干燥过程中,能快速而经济地降低稻谷的水分并保持其良好品质。采用永磁场强化稻谷的干燥过程,比较干燥时间、发芽率和爆腰率的变化。结果表明：在相同功率下稻谷在磁场中干燥时间比无磁场时缩短5％,平均失水速率加大,稻谷的发芽率有所升高、爆腰率下降;随着干燥功率的增加,磁场对稻谷的发芽率和爆腰率的影响加大。在试验基础上探讨了磁场对稻谷干燥过程的影响机理。