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1.
Introduction Recent investigations in soil science have shown that physical properties of paddy soils are of great importance to rice-production. There is extensive literature on the chemical property of paddy soils, but little information on the physical property of paddy soils, especially under waterlogged condition. For studying the physical property of flooded paddy soils, it is necessary to collect the soil cores under an undisturbed condition. 相似文献
2.
太湖地区主要水稻土水力特征及其影响因素 总被引：8，自引：6，他引：8
通过田间和室内试验研究了太湖地区3种主要水稻土(白土、黄泥土和乌栅土)的水分特征以及影响因素,得出了各种土壤每一土层的容重、质地、有机质、土壤团聚度、土壤结构系数和土壤水分特征曲线,比较了3种主要水稻土类型的土壤基本物理性质和水分特征状况,并根据水分特征曲线得出了这3种土壤的田间持水量、有效水含量和萎蔫系数。结果表明:土壤田间持水量和有效水含量均与容重呈极显著的线性负相关,有效水与土壤粘粒含量也呈显著的线性负相关;而土壤的田间持水量和有效水含量与土壤有机质、结构系数、团聚度呈极显著的线性正相关,萎蔫系数与质地也呈显著的线性正相关。 相似文献
3.
Degradation of Cry1Ab protein from Bt transgenic rice was examined under both aerobic and flooded conditions in five paddy soils and in aqueous solutions. The hydrolysis rate of Cry1Ab protein in aqueous solutions was correlated inversely with the solution pH in the range of 4.0 to 8.0, and positively with the initial concentration of Cry1Ab protein. Rapid degradation of Cry1Ab protein occurred in paddy soils under aerobic conditions, with half-lives ranging from 19.6 to 41.3 d. The degradation was mostly biotic and not related to any specific soil property. Degradation of the Cry1Ab protein was significantly prolonged under flooded conditions compared with aerobic conditions, with half-lives extended to 45.9 to 141 d. These results suggest that the toxin protein, when introduced into a paddy field upon harvest, will probably undergo rapid removal after the field is drained and exposed to aerobic conditions. 相似文献
4.
为探明稻田厌氧氨氧化菌多样性及其对氮肥用量的响应状况,利用厌氧氨氧化菌16S rRNA基因特异引物对定位试验稻田土壤DNA进行PCR-DGGE(聚合酶链反应变性梯度凝胶电泳)并结合DNA克隆测序,研究了氮肥供应量对厌氧氨氧化菌群落结构的影响。DGGE图谱及依据其条带位置和亮度数值计算的多样性指数均显示:高氮处理[N3:225 kg(N).hm 2]的厌氧氨氧化菌群落结构多样性在表层或根层土壤中均显著(P<0.05)高于中、低氮[N2:150 kg(N).hm 2;N1:75 kg(N).hm 2]处理和不施肥对照(CK);同时,高氮处理下表层土壤厌氧氨氧化菌群落多样性指数显著高于根层土壤(P<0.05)。冗余分析(RDA)结果表明,表层土壤中厌氧氨氧化菌群落结构组成与不同氮肥水平处理存在显著相关性(P=0.006)。此外,本试验获得厌氧氨氧化菌DGGE条带DNA序列18条,登录GenBank并获得登录号。研究表明稻田厌氧氨氧化菌群落结构对高氮水平具有较强的响应,尤其是在表层土壤中。 相似文献
5.
Joo Sung Ahn Jung-Hyun Kim Jae-Gon Kim Yungoo Song Hi-Soo Moon 《Water, air, and soil pollution》2003,150(1-4):23-42
The geochemical behavior of metals, including Fe, Mn, Pb and Zn, in contaminated paddy soils was investigated during the cultivation of rice crops through laboratory microcosm experiments. From the two paddy fields contaminated by mine tailings, Siheung and Deokeum in Korea, paddy soils were collected and analyzed for their geochemical characteristics. The Siheung paddy soil showed higher levels of heavy metals, whereas the higher potential for the release of metals was anticipated due to the extremely acidic conditions at Deokeum. In microcosm experiments of flooded paddy soils over 18 weeks, Fe and Mn were released in subsurface pore waters by reductive dissolution, and Pb and Zn were dissolved in high amounts at the surface by oxidation of sulfides. Although amorphous Fe oxide-rich layers were formed at the surface of both paddy soils, the release of Pb and Zn were controlled at the surface by these layers only under slightly alkaline conditions at Siheung. Lead and Zn were associated with the reducible and carbonate fractions at the surface paddy soil of Siheung from the sequential extraction on core samples collected during the flooded period. In the acidic conditions at Deokeum, Pb and Zn were continuously released until the late stage of flooding. A great increase in the exchangeable fraction of metals was observed after the soils had drained. The bioavailability of metals for rice crops would be high under acidic conditions at Deokeum, despite the lower levels of heavy metal contamination. 相似文献
6.
磷是水体富营养化限制性元素,近年来由于磷肥的过量施用,农田迁移的磷素已成为水体磷素的主要来源。本研究通过野外测坑定位试验,研究有机肥处理(OT)、混施肥处理(MT)和化肥处理(CT)3种施肥处理下,稻田中磷素的迁移流失特征及这3种处理对水稻产量和磷素利用率的影响,以探求稻田系统的最佳施磷方式。结果表明,CT、MT和OT 3种施肥方式的磷径流流失负荷分别为0.56 kg(P)·hm-2、1.13 kg(P)·hm-2和4.20 kg(P)·hm-2,渗漏流失负荷分别为0.42 kg(P)·hm-2、0.44 kg(P)·hm-2和0.45 kg(P)·hm-2;磷的径流流失占流失总量的56.86%~90.38%,是水稻田磷素流失的主要途径。磷的径流流失主要受施肥和降雨的影响,50%左右磷的流失发生在第1次径流过程;磷素渗漏流失特征不受施磷处理的影响,80%以上的流失发生在施肥后的前30 d。在磷素流失形态上,坑面水、渗漏水和径流水中磷素的主要形态均为可溶性磷;在土壤方面,MT处理和OT处理能保证土壤磷营养,CT处理的土壤有效磷和有机质含量则显著下降。3种施肥处理的水稻产量显著高于空白对照,且MT最高,为6 728.84 kg·hm-2;磷肥利用率CT和MT处理显著高于OT,CT和MT间差异不显著。综合比较,混施肥处理在磷素流失、土壤养分利用和水稻产量等方面更符合我国生态农业发展的要求。 相似文献
7.
Restoration of CH4-oxidation activities of desiccated paddy soils and the NH4+ effect after watering were investigated in laboratory incubations. Fresh paddy soil collected from an intermittently flooded rice field in Wuxi, Jiangsu province, showed a parabolic relationship between CH4-oxidation activity and soil moisture with an optimum CH4-oxidation rate at 71% water-holding capacity (WHC), while the paddy soil collected from a permanently flooded rice field in Yingtan, Jiangxi province, showed a much smaller CH4-oxidation ability, which increased exponentially with soil moisture increasing from 28% WHC to 95% WHC at an initial CH4 concentration of ~2,200 µl l-1 and at room temperature (25°C). CH4-oxidation ability was inversely related to N2O emission and related positively with CO2 emission in response to the change in soil moisture. Desiccated paddy soils lost their CH4-oxidation abilities. However, this was recovered after the soils were re-watered. The restoration of CH4-oxidation ability was directly dependent upon soil moisture and the rate of its restoration increased with increasing soil moisture content from 40% to 90% WHC. Addition of NH4Cl at rates of 0-3.57 µmol g-1 soil inhibited the restoration of CH4-oxidation ability significantly (P<0.01), but the inhibitory effect was alleviated by a high soil moisture content. The restoration of CH4-oxidation ability was much slower in the Yingtan soil than in the Wuxi soil. The studies show that the optimum moisture content of paddy soils for CH4 oxidation depends on the methanotrophic bacteria in relation to the prevailing water regime; desiccation damages the CH4-oxidation ability of permanently flooded paddy soil more severely than that of frequently well-drained soils. 相似文献
8.
The conversion factor, kK, for estimation of microbial biomass potassium (K) by the chloroform-fumigation extraction method was determined for some arable soils: upland field soils under different fertilization conditions, an upland field soil under a greenhouse condition, and a paddy field soil under a flooded condition. The kK value varied with land utilization (paddy or upland) or fertilization (chemical or organic fertilizer). Value of kK was different between paddy field soil (0.28–0.38) and upland field soil (0.41–0.73). This study indicates that the value could be useful for the estimation of microbial biomass K in soil by the chloroform-fumigation extraction method and further investigation of the amounts of biomass K in different types of soils under conditions with varied field managements will be necessary. 相似文献
9.
1.设计了一个在田间直接测定水稻土的电导的电导池,用以鉴别水稻土的肥力状况。根据条件试验,在水稻生长期间通常变动的水分含量范围以内,水分含量的差别可以不予考虑。土壤胶体本身的电荷在电导上的贡献也很小,所以一般也不必考虑。土壤含砂粒较多时,应该加以适当的改正值。2.根据大量的田间测定结果,在酸性的水稻土中,电导与肥力水平成明显相关。施肥的数量和种类对土壤电导发生显著的影响。由于水稻对养分的吸收,所以根际土壤的电导较根外为低,并且随着水稻的生长,而使土壤电导降低。3.酸性水稻土的干土渍水后电导的增加数值与土壤的肥力水平成正相关。这种电导的增加,基本上是由于有机质的分解所致。4.根据与化学分析的对照结果,土壤溶液的电导与阳离子的浓度成明显相关。在引起酸性水稻土电导的阳离子中,钙镁占90—95%,钾占2—8%,铁和铵的数量都在1%以下。5.作者根据研究结果,认为电导可以作为鉴别酸性水稻土的肥力水平的一个简便的综合性参考指标。 相似文献
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11.
《Communications in Soil Science and Plant Analysis》2012,43(4):703-715
Abstract Experiments were conducted to seek a better basis for soil testing of rice paddy soils. Soils were incubated under variable conditions of simulated flooding, and then extracted with DTPA5 . The amounts of Cu, Zn, Mn and Fe extracted were sensitive to the imposed soil conditions. Good correlations between Zn extracted from simulated flooded soils and Zn uptakes by rice from flooded soils in pots, suggest that this approach to soil testing may be more useful for paddy soils than existing tests on air dried soils. 相似文献
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13.
Bt-transgenic rice straw affects the culturable microbiota and dehydrogenase and phosphatase activities in a flooded paddy soil 总被引：1，自引：0，他引：1
There have been few investigations of the possible effects of genetically engineered plants on the microbiota and enzyme activities in flooded soil. We studied the influence of the transgenic rice KeMingDao (KMD) straw on the culturable microbiota and enzymatic activities in a flooded paddy soil under laboratory conditions. KMD contained a synthetic cry1Ab gene from Bacillus thuringiensis under the control of a maize ubiquitin promoter and linked in tandem with the gusA and hpt genes. The results showed that there were only some occasional significant differences (P<0.05) in the number of Colony forming units of aerobic bacteria, actinomycetes and fungi and in the number of anaerobic fermentative bacteria, denitrifying bacteria, hydrogen-producing acetogenic bacteria, and methanogenic bacteria between the paddy soil amended with Bt-transgenic rice straw and with the non-Bt parental rice straw during the early stages of incubation. From d14 to d84 there were significant increases (P<0.05) in soil dehydrogenase and soil neutral phosphatase activity in soils amended with rice straw compared to soil without added straw. The dehydrogenase activity was significantly greatly (almost 1.95-fold) in soil amended with Bt-transgenic straw from d7 to d14 but from d21 to d49 there was significantly greater activity (about 1.47-fold) in the soil amended with non-Bt-straw. There were no apparent differences between the activity of soil neutral phosphatase in the soils to which non-Bt-straw and Bt-straw had been added. However, both soils to which rice straws were added demonstrated significant differences in the number of microorganisms except for aerobic bacteria and enzymatic activities with respect to the control soil throughout the incubation. The above results indicated that the Bt-straw from KMD transgenic rice is not toxic to a variety of culturable microorganisms in the studied flooded paddy soil. 相似文献
14.
近30年中国主要农田土壤pH时空演变及其驱动因素 总被引：5，自引：0，他引：5
15.
Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk. 相似文献
16.
水稻土和菜田添加碳氮后的气态产物排放动态 总被引：1，自引：0，他引：1
【目的】动态连续监测添加碳氮底物后各气体产物—O2、 NO、 N2O、 CH4和N2的排放,对土壤碳氮转化过程和气体产生过程做更深入的理解,揭示不同土地利用方式典型红壤的温室气体产生机制。【方法】采集长江中游金井小流域不同土地利用方式稻田和菜地土壤为研究对象,利用全自动连续在线培养检测体系(Robot系统),通过两组试验分别研究土壤碳氮转化过程中各气体产物的动态变化。试验1采用菜地和稻田土壤进行好气培养,设置不施氮对照、 添加40 mg/kg铵态氮、 添加40 mg/kg铵态氮+1%硝化抑制剂、 添加40 mg/kg硝态氮、 添加40 mg/kg硝态氮+1%葡萄糖、 缺氧条件下添加40 mg/kg硝态氮+1%葡萄糖6个处理。试验2采用稻田土壤进行淹水培养,设不施氮对照、 添加40 mg/kg铵态氮、 添加40 mg/kg铵态氮+1%硝化抑制剂、 添加40 mg/kg铵态氮+1%秸秆、 缺氧条件下添加40 mg/kg铵态氮+1%的葡萄糖、 添加40 mg/kg硝态氮、 添加40 mg/kg硝态氮+1%葡萄糖、 缺氧条件下添加40 mg/kg硝态氮+1%葡萄糖8个处理。培养温度均为20℃,土壤水分含量为70% WFPS (土壤孔隙含水量),培养周期为15天。【结果】从菜地和稻田土壤不同碳氮添加处理气态产物及无机氮的动态变化可看出: 1)菜地土壤好气培养初期硝化作用产生了大量N2O; 受低碳和低含水量的限制,反硝化作用较弱。当提供充足碳源和厌氧条件,出现N2O和NO的大量排放。2)在好气稻田和淹水稻田培养过程中,反硝化作用是N2O产生的主要途径。3)稻田土壤中,提供充足碳源和厌氧条件,各气态产物出现的顺序依次是NO、 N2O和N2,与三种气体在反硝化链式反应过程中的生成顺序一致。淹水稻田加铵态氮和碳源处理N2为主要产物,添加硝态氮处理后,N2O成为主要气态产物。当土壤碳源充足时,反硝化过程进行彻底,反硝化产物以终产物(N2)为主。4)在稻田土壤出现厌氧或添加碳源条件下,均检测到大量CH4产生; 且在甲烷产生的同时,NO-3几乎消耗殆尽。【结论】金井小流域典型红壤菜地N2O主要来自于硝化作用,好气和淹水稻田N2O主要来源于反硝化作用; 当碳源充足和厌氧时,菜地及稻田反硝化作用增强; 反硝化产物组成、 产物累积量及出峰顺序与碳源和氧气浓度有关。 相似文献
17.
Methods to aid in the large-scale testing and characterization of Coastal Plain soils based on their susceptibility to root-limiting strength problems were developed and analyzed. They were basically regression equations modeled after a Taylor series expansion. The equations relate changes of soil strength, bulk density and soil water content between field and “critical rooting conditions”. Once equations wered eveloped from a data set of 426 laboratory samples, critical rooting bulk density was predicted for a separate set of laboratory and field samples. All laboratory samples and appropriate field samples were equilibrated at — 100 kPa soil-water potential. Soils used were sandy Ultisols, which may limit the scope of equations.
In many cases, changes in the water contents were not a significant factor in the prediction of soil strength. This may be a reflection of the limited capabilities of the equations, the uniform equilibration of soil-water potential of the soils, or the fact that the slope of the strength vs. bulk density curve is independent of water content over the range of samples considered. Nevertheless, it does simplify the equations and may suggest that a series of several equations for different soil types would be better than a single equation that requires soil-water content. 相似文献
18.
土壤水分状况和质地对稻田N2O 排放的影响 总被引：34，自引：0，他引：34
１９９４年中国科学院封丘生态试验站通过小区试验研究了土壤质地和水分状况对稻田Ｎ２Ｏ排放的影响。结果表明稻田Ｎ２Ｏ排放主要受土壤水分状况的影响,淹水状态下,Ｎ２Ｏ排放很少,水分落于期间Ｎ２Ｏ排放量占水稻生长期Ｎ２Ｏ排放总量的８７．５０％～９８．６５％。土壤质地显影响稻田平均Ｎ２Ｏ排放通量,砂质土壤排放的Ｎ２Ｏ显或极显高于壤质和粘质土壤,水稻生长期砂质、壤质及粘质土壤的平均Ｎ２Ｏ排放通量分别为１３７．６３、８７．５４和６３．６μｇＮ２Ｏ－Ｎ／ｍ＾２．ｈ。 相似文献
19.
Most studies on dissimilatory nitrate reduction to ammonium (DNRA) in paddy soils were conducted in the laboratory and in situ studies are in need for better understanding of the DNRA process.In this study,in situ incubations of soil DNRA using 15 N tracer were carried out in paddy fields under conventional water (CW) and low water (LW) managements to explore the potential of soil DNRA after liquid cattle waste (LCW) application and to investigate the impacts of soil redox potential (Eh) and labile carbon on DNRA.DNRA rates ranged from 3.06 to 10.40 mg N kg 1 dry soil d 1,which accounted for 8.55%-12.36% and 3.88%-25.44% of consumption of added NO 3-15 N when Eh at 5 cm soil depth ranged from 230 to 414 mV and 225 to 65 mV,respectively.DNRA rates showed no significant difference in paddy soils under two water managements although soil Eh and/or dissolved organic carbon (DOC) were more favorable for DNRA in the paddy soil under CW management 1 d before,or 5 and 7 d after LCW application.Soil DNRA rates were negatively correlated with soil Eh (P < 0.05,n=5) but positively correlated with soil DOC (P < 0.05,n=5) in the paddy soil under LW management,while no significant correlations were shown in the paddy soil under CW management.The potential of DNRA measured in situ was consistent with previous laboratory studies;and the controlling factors of DNRA in paddy soils might be different under different water managements,probably due to the presence of different microfloras of DNRA. 相似文献
20.
利用一个长达30年且已进行适当变更的定位肥料试验,采用湿筛法进行土壤团聚体分级,测定并计算土壤容重、孔隙度与平均质量直径(MWD),探讨了长期施用高量有机肥、常量有机肥、化肥及当其施肥措施改变(化改常、常改高、高改化、常改化)3年后红壤性水稻土团聚体组成及结构的变化特征,以期为已培肥红壤性水稻土选择合理的后续施肥策略而促进水稻土可持续发展提供理论依据。结果表明,与施用化肥30年相比,长期施用有机肥(常量、高量)能显著降低土壤容重(10.38%~19.81%),并提高孔隙度(6.77%~13.13%)与MWD(46.84%~61.58%)。有机肥处理(常量、高量、化改常、常改高)下粗大团聚体(2 mm)所占比例最高,而化肥处理(高改化、常改化、化肥)下细大团聚体(2~0.25 mm)所占比例最高。在施肥措施改变3年后,如减少有机肥(高改化、常改化)的施入量将导致土壤容重增加(6.47%~14.34%),土壤孔隙度(3.63%~6.79%)或MWD(21.15%~31.43%)降低;而增加有机肥(化改常、常改高)的施入量将显著降低土壤容重(3.08%~9.02%)并增加土壤孔隙度(1.73%~6.01%)与MWD(5.45%~44.58%)。由此,为进一步维持或改善土壤结构,红壤性水稻土长期培肥后应继续或加大田间外源有机物料的投入量。 相似文献