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1.
麦秸覆盖条件下土壤蒸发阻力及蒸发模拟 总被引：8，自引：4，他引：8
模拟覆盖条件下的土壤蒸发对于农田水管理具有重要的作用。该文分析了留茬和秸秆覆盖模式下影响土面蒸发的因素,提出了留茬覆盖模式下蒸发阻力和土面蒸发模型,基于试验数据确定了公式中的参数。主要结果和结论:当表层2 cm土壤含水率高于0.23 cm3/cm3(约60%田持)时,土面相对蒸发量(土面蒸发量与20 cm蒸发皿蒸发量比值)基本保持稳定;当表层2 cm土壤含水率在0.05~0.23 cm3/cm3之间时,土面相对蒸发量随土壤含水率的降低而线性减小。覆盖会明显降低土壤蒸发,覆盖阻力随秸秆覆盖量增加呈指数增长。当表层2 cm土壤含水率在0.05~0.23 cm3/cm3之间时,土壤表面阻力随土壤体积含水率降低而线性增加。验证结果显示建立的土面蒸发模型及相应阻力参数能较好的模拟覆盖条件下的土面蒸发量。 相似文献
2.
沟灌夏玉米棵间土壤蒸发规律的试验研究 总被引：28，自引：11，他引：17
棵间土壤蒸发是农田土壤耗水的重要组成部分。该文采用两种规格的微型棵间蒸发皿(Micro-Lysimeter)分别测定沟灌夏玉米田沟、垄土面蒸发量,并对沟灌条件下夏玉米棵间土壤蒸发与作物蒸腾变化规律进行了试验研究,分析了相对棵间土壤蒸发强度与土壤含水率的关系以及棵间土壤蒸发强度与作物叶面积指数的关系。结果表明,沟灌条件下夏玉米棵间土壤蒸发量占全生育总耗水量的33.06%～34.35%,棵间土壤相对蒸发强度与表层土壤含水率和作物叶面积指数之间均呈现良好的指数函数关系,灌溉或降雨后2～3 d内土壤蒸发强度较大,受大气蒸发力影响明显。因此,在不影响作物蒸腾的条件下减少表层土壤的湿润面积和湿润次数是减少棵间土壤蒸发、提高作物水分利用效率的主要技术途径与措施。 相似文献
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对新疆库尔勒灌溉实验站香梨地不同灌水技术处理的土面蒸发进行了试验研究,并分析了土面蒸发强度与土壤含水量和土面蒸发强度与土壤耗水强度间的关系。结果表明,各处理在整个生育期的平均土面蒸发强度由大到小依次为微喷、小管和环管,其累积土面蒸发值分别为116.05,104.53和89.60mm。各处理棵间相对土面蒸发强度与0-20cm土层深度的土壤含水量相关关系显著,呈二次递增规律。土壤耗水强度在生育期内整体上呈现从大到小的变化规律,大小顺序依次为微喷、环管和小管,且土面蒸发强度均随着土壤耗水强度的增大而增大,二者之间呈幂函数关系。 相似文献
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基于Hydrus-1D模型的玉米根系吸水影响因素分析 总被引：2，自引：1，他引：1
为探索土壤质地、植物生长状况和气象条件对不同土壤水分条件下根系吸水速率的影响机理,该文以相对根吸水速率与土壤含水率的关系衡量土壤水分有效性,利用Hydrus-1D模型模拟了3种土壤（壤黏土、黏壤土和砂壤土）中不同玉米生长状况（包括叶面积指数、根系深度和根系剖面分布）或蒸发力条件下根系吸水速率随含水率的动态变化,确定了不同条件下根系吸水速率开始降低的临界含水率。结果表明：土壤质地、植物的叶面积指数和根系分布及大气蒸发力都对根系吸水动态曲线的临界含水率有一定影响,其中根系深度和根系分布形状还影响根系吸水速率与含水率关系曲线的形状,但在3种土壤中,根系吸水速率的动态变化对植物生长和大气蒸发力的响应不同。总体而言,3种土壤临界含水率的大小是壤黏土＞黏壤土＞砂壤土;临界含水率随大气蒸发力的升高而升高,随根系深度和深层根系分布的增加而降低;各因子对玉米根系吸水影响程度的大小是土壤质地＞根系分布形状＞根系深度＞大气蒸发力＞叶面积指数。 相似文献
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间作模式下作物根系与坡耕地红壤抗蚀性的关系 总被引：5，自引：2，他引：3
通过径流小区试验,结合土壤理化性质分析和根系指标测定,研究了玉米单作、大豆单作以及玉米/大豆间作模式下,不同作物根系特性与坡耕地红壤抗蚀性的关系。结果表明,玉米/大豆间作模式在改善土壤理化性质、提高红壤质地和结构方面优于玉米或大豆单作,玉米/大豆间作模式在0—10,10—20,20—30cm土层的含根量、根系表面积、根系体积、根尖数和根长较玉米单作或大豆单作均有提高,其中0—10cm土层范围内差异显著;玉米/大豆间作模式较玉米单作模式在根量、根系表面积、根系体积和根长分别提高了80.95%,50.93%,90.30%和77.99%,较大豆单作模式分别提高了58.70%,73.36%,123.05%和149.27%;在20—30cm土层范围内,间作模式根长较玉米单作模式提高了150.48%,较大豆单作模式提高了206.94%;不同种植模式下,土壤抗蚀性指数在10—20cm土层差异不显著,在0—10cm和20—30cm土层之间差异显著;不同深度土层范围内,间作模式土粒抵抗分散能力均最强;在间作模式下,同期土壤流失量较单作减少,土壤流失量与作物根系量、根系表面积、总根长、根系体积和根尖数呈显著负相关。玉米大豆间作可以通过改善根系特征,提高土壤有机质含量,进而提高土抗蚀性。 相似文献
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表层有效土壤水分参数化及冠层下土面蒸发模拟 总被引：1，自引：7，他引：1
通过观测田间微气象数据、土壤表层水分变化状况及荞麦作物冠层下土面蒸发等资料,引进一个表面体积含水率的函数,构建了基于表层有效土壤水分的土壤蒸发模型。该模型包含了土面蒸发的2个过程:水蒸气从土壤孔隙中扩散到地表面及水蒸气由地表面传输到大气中。模型中表层有效土壤水分参数不仅取决于表层土壤含水状况,而且受风速影响。采用波文比能量平衡法及微型蒸发器观测荞麦地实际蒸腾蒸发量及冠层下土面蒸发的变化规律,并验证模型精度。结果表明,所构建模型可以成功预测冠层下土面蒸发,其平均相对误差为13.5%。该研究对于实现土壤蒸发及作物蒸腾的分离估算,减少无效水分消耗具有重要意义。 相似文献
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单作与间作的棵间蒸发量差异及其主要影响因子 总被引：5，自引：0，他引：5
在甘肃河西走廊区, 通过大田试验, 研究了不同供水水平下小麦间作玉米与单作小麦、单作玉米的耗水量和棵间蒸发量差异, 探讨了影响作物棵间蒸发量的关键因子。结果表明, 小麦间作玉米的耗水量较单作小麦、单作玉米耗水量的平均值增加了41.44%~47.15%; 间作全生育期的总棵间蒸发量显著大于单作, 但间作的日均棵间蒸发量显著低于单作玉米、高于单作小麦; 间作的棵间蒸发量占总耗水量的比重显著低于单作玉米, 说明间作可提高农田水分利用的有效性。随灌水水平的提高,间作总耗水量显著增加,单作相邻灌水处理间的差异不显著;灌水水平对单作玉米、间作棵间蒸发量的影响不显著,说明间作耗水量增加主要是由蒸腾作用造成的。作物的日均棵间蒸发量与0~30 cm的土壤含水量、0~25 cm的土壤温度、全生育期的平均叶面积指数均呈显著正相关关系。单作玉米日均棵间蒸发量较大的主要原因是0~30 cm的土壤含水量、0~25 cm的土壤温度均相对较高。小麦间作玉米可提高作物的土地利用率, 其水分利用效率较单作平均提高25%以上。 相似文献
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夏玉米冠气温差及其影响因素关系探析 总被引：4，自引：0，他引：4
测定了夏玉米主要生育期四个不同水分处理的冠层温度、气温、土壤含水率、叶面积指数和株高,分析了冠气温差与土壤含水率、叶面积指数及株高间的关系。结果表明:不同的灌溉水质和灌溉量措施对夏玉米冠气温差有显著的影响;中午12~14时左右H1高度(2/3株高)处的冠气温差较H2高度(H1+50 cm)更能反映作物和土壤的水分特征,可以用此时刻的卫星遥感冠层温度结合地面气象站数据监测作物和土壤的旱情;80~100 cm土层的土壤体积含水率与节水灌溉处理的冠气温差之间存在良好关系(α=0.05),0~80 cm四个土层中以中午20 cm和40 cm处的土壤体积含水率与冠气温差相关关系最好且稳定,可以利用此关系评价作物的缺水状况;充足灌溉下的夏玉米主要生育期的叶面积指数与冠气温差也有显著的相关关系,节水灌溉下二者关系不显著,说明水分充足条件下叶面积指数对冠气温差的影响更大;株高与不同水分处理的冠气温差也有一定的相关关系,冠层2/3高度处二者的相关系数分别为:0.7027(淡水节水处理)、0.4150(淡水充足处理)、0.3683(咸水节水处理)、0.3062(咸水充足处理)。这为区域上遥感反演夏玉米冠气温差进而监测农田蒸散和土壤含水率提供了试验依据。 相似文献
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黄土高原不同玉米-大豆间作模式对玉米生长发育的影响 总被引：2，自引：0，他引：2
以玉米品种(郑单958,豫玉22)和大豆品种(中黄24,中黄13)为材料进行田间试验,在单作和间作两种模式(间作比例分别为2:2,2:4)下研究了黄土塬区不同玉米-大豆间作模式对玉米生长发育的影响。研究结果表明,郑单958分别与大豆两个品种间作,玉米叶片叶绿素相对含量、单株叶面积、茎粗和干物质积累量从大喇叭口期开始均高于单作,株高在生育后期表现为间作高于单作。豫玉22分别与大豆两个品种间作,玉米叶片叶绿素相对含量和茎粗从大喇叭口期开始高于单作,干物质积累量从吐丝期开始高于单作,单株叶面积在吐丝期显著高于单作,株高在生育后期表现为间作低于单作。间作下的郑单958干物质积累量在生育后期高于豫玉22,更有利于增产。在所选的玉米和大豆间作模式中,郑单958和中黄24以2:4间作是黄土塬区对玉米增产更为有利的间作模式。 相似文献
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低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响 总被引：2，自引：2，他引：0
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
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Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
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I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options. 相似文献
14.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate. 相似文献
15.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
16.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献
17.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
Abstract A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species. 相似文献
18.
Yoav Bashan Bernardo Salazar Ma. Esther Puente Macario Bacilio Robert Linderman 《Biology and Fertility of Soils》2009,45(6):585-594
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse
trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus
were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB;
the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons
reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened
later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons
growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants,
no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi,
enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant.
In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after
30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination
only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity
to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as
compost or PGPB can either amplify the effect or else attenuate it. 相似文献
19.
Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. 相似文献