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1.
黄土丘陵沟壑区退耕地植物群落土壤抗蚀性能研究 总被引：3，自引：0，他引：3
以黄土丘陵沟壑区安塞县的纸坊沟小流域为例,对小流域内退耕地植被恢复后各群落土壤抗蚀性进行了研究,研究结果表明：（1）从土壤有机质含量指标讲,老荒坡和狼牙刺群落抗侵蚀能力最强,其次是刺槐、沙棘等人工林地,以猪毛蒿为优势种的群落和农耕玉米地抗侵蚀能力最弱;（2）从土壤团聚度、分散率和分散系数指标看,刺槐和黄刺梅群落抗侵蚀性能最强,农耕地和以猪毛蒿为优势种的群落抗侵蚀性能最差,人工林地和其它退耕还草地抗蚀性能居中;（3）从土壤生物结皮盖度讲,抗蚀性能为以茭蒿为优势种的群落〉以铁杆蒿为优势种的群落〉以猪毛蒿为优势种的群落;（4）从土壤侵蚀量来看,刺槐和沙棘群落抗侵蚀性能最强,以猪毛蒿为优势种的群落抗侵蚀性能最弱。综合分析得出抗蚀性能为：老荒坡,狼牙刺〉刺槐,黄刺玫,沙棘〉柠条〉白羊草,茭蒿〉铁杆蒿〉猪毛蒿,农耕地。随着退耕时间的延伸,退耕还林还草地的抗蚀性较农耕地不断提高,而与当地老荒坡群落的抗蚀性越来越接近。狼牙刺群落、刺槐和沙棘群落抗侵蚀性能最好,猪毛蒿群落群落抗侵蚀性能最弱,老荒坡各群落抗蚀性能较强,农耕地抗蚀能力有待提高。 相似文献
2.
安塞黄土丘陵沟壑区退耕地植物群落土壤抗蚀性分析 总被引：4，自引：1，他引：4
以黄土丘陵沟壑区安塞县的纸坊沟小流域为例,对小流域内退耕地植被恢复后不同植物群落土壤抗蚀性进行了研究,研究结果表明:(1)从土壤有机质含量指标讲,老荒坡和狼牙刺群落抗侵蚀能力最强,其次是刺槐、沙棘等人工林地,以猪毛蒿为优势种的群落和农耕玉米地抗侵蚀能力最弱;(2)从土壤团聚度、分散率和分散系数指标看,刺槐和黄刺梅群落抗侵蚀性能最强,农耕地和以猪毛蒿为优势种的群落抗侵蚀性能最差,人工林地和其它退耕还草地抗蚀性能居中;(3)从土壤生物结皮盖度讲,抗蚀性能为以茭蒿为优势种的群落＞以铁杆蒿为优势种的群落＞以猪毛蒿为优势种的群落;(4)从土壤侵蚀量来看,刺槐和沙棘群落抗侵蚀性能最强,以猪毛蒿为优势种的群落抗侵蚀性能最弱.综合分析得出抗蚀性能为:老荒坡,狼牙刺＞刺槐,黄刺玫,沙棘＞柠条＞白羊草,茭蒿＞铁杆蒿＞猪毛蒿,农耕地.随着退耕时间的延伸,退耕还林还草地的抗蚀性较农耕地不断提高,而与当地老荒坡群落的抗蚀性越来越接近.狼牙刺群落、刺槐和沙棘群落抗侵蚀性能最好,猪毛蒿群落抗侵蚀性能最弱,老荒坡各群落抗蚀性能较强,农耕地抗蚀能力有待提高. 相似文献
3.
晋西黄土丘陵沟壑区土壤抗侵蚀能力的试验研究 总被引：1，自引：0，他引：1
通过大量的野外试验及调查,探讨了晋西黄土丘陵沟壑区土壤抗蚀性的时空变化规律、天然撂荒地的抗冲刷性能以及表土生物结皮、农耕地的犁底层等对土壤抗侵蚀能力的影响。结果表明:(1)晋西黄土丘陵沟壑区小流域的坡地土壤抗剪力及抗蚀性存在明显的时空变化规律。总体上,旱季的土壤抗蚀性高于雨季;峁顶缓坡地的土壤抗蚀性高于梁坡下部陡坡地。(2)只要土壤的整体结构不被破坏,即便水流冲刷力很大,黄土易蚀的特点也不易表现。尽量避免人为破坏黄土的整体结构,也是减少黄土侵蚀的重要手段。(3)黄土生物结皮,可大大增强土壤的抗侵蚀能力,减沙效应同结皮覆盖率成正比;犁底层在黄土地区的农耕地普遍存在,且会加剧耕作层的侵蚀作用。 相似文献
4.
黄土丘陵沟壑区人工林地的土壤抗蚀性评价 总被引：2，自引：0，他引：2
以延安、安塞、吴旗的人工刺槐林、柠条林为研究对象,选取同一地区的自然恢复草地和坡耕地为对照,通过对5个表征土壤抗蚀性的指标即>0.25 mm水稳性团粒含量、>0.5 mm水稳性团粒含量、平均重量直径、团聚状况和团聚度的比较分析,对人工刺槐林、人工柠条林相对于自然恢复草地和坡耕地改善土壤抗蚀性的效果进行了评价,同时分析了不同林龄人工林土壤抗蚀性的变化.研究表明,人工林地相对于坡耕地,显著提高了土壤抗蚀性,但不及自然恢复草地,尤其在安塞和吴旗表现更明显;随着林龄的增长,人工林地土壤抗蚀性能增强,并趋于稳定.并通过对样地的聚类分析,也得出与上述相似的结果.综合分析表明,封禁条件下的植被自然恢复是黄土丘陵沟壑区比较适宜的植被恢复方式和控制土壤侵蚀的有效措施. 相似文献
5.
桂西北喀斯特地区不同土地利用类型土壤抗蚀性研究 总被引：7，自引：0，他引：7
土壤抗蚀性是反映土壤抵抗侵蚀能力的重要参数之一,是土壤侵蚀研究的重要内容。本文选取土壤有机质、水稳性团聚体、团聚体结构破坏率、团聚状况、团聚度、分散率和<0.05 mm粉黏粒含量等7个指标,通过单因素方差分析及主成分分析,探讨了桂西北喀斯特地区5种不同土地利用类型土壤抗蚀性的差异。结果表明:原生林和次生林土壤有机质含量显著(P<0.05)高于撂荒地、坡耕地和人工林,撂荒地土壤有机质含量较坡耕地和人工林高,但差异不显著。原生林、次生林及撂荒地土壤>0.25 mm水稳性团聚体总量及团聚状况显著高于坡耕地及人工林,但其土壤团聚体结构破坏率及分散率显著低于坡耕地;人工林土壤团聚体结构破坏率显著高于次生林,但与原生林、撂荒地和坡耕地差异不显著;人工林土壤分散率则与坡耕地类似,显著低于原生林、次生林及撂荒地;原生林、次生林土壤团聚度与撂荒地、坡耕地差异不显著,但显著高于人工林;次生林、撂荒地及人工林<0.05 mm粉黏粒含量与原生林、坡耕地差异不显著,但坡耕地土壤<0.05 mm粉黏粒含量显著高于原生林。由主成分分析综合评分得到土壤抗蚀性强弱顺序为:原生林>次生林>撂荒地>坡耕地>人工林。因此,喀斯特地区人为干扰严重降低了土壤的抗蚀性,耕地通过撂荒方式能够提高土壤抗蚀性。 相似文献
6.
关于土壤可蚀性指标的讨论 总被引：20，自引：6，他引：20
该对主要土壤可蚀性指标进行了评述，指出土壤的可蚀性是一个相对概念，同一土壤在不同侵蚀动力条件下，其抗侵蚀能力是不同的。每一土壤均具有抗蚀性的抗冲性，在土壤侵蚀过程中，何居主导地位，主要取决于侵蚀动力的方式和强度。 相似文献
7.
北川河流域退耕地植物群落土壤抗蚀性研究 总被引：23，自引：0，他引：23
土壤抗蚀性指土壤抵抗水的分散和悬浮的能力。国家退耕还林还草科技试验县———青海省大通县北川河流域的抗蚀性试验研究结果表明 ,用于衡量土壤抗蚀性的 12项指标 ,经过主成分变换后 ,能够反映特征根大部分信息 (85 .6 % )的主成分包括无机黏粒类、团聚类、无机胶粒类和水稳性团粒类 4大类。通过对 4个主成分进行聚类 ,北川河流域植物群落分为 3大类 ,其中抗蚀性最好的一类以天然林为主 ;抗蚀性居中的一类以退耕时间较长的人工林地为主 ;抗蚀性较差的一类以新退耕还林地为主。随着退耕时间的延伸 ,退耕地人工林的抗蚀性较耕地不断提高 ,而与当地天然次生林的抗蚀性愈来愈接近。以仿自然林为手段的退耕地人工林的营造是成功的 ,以土壤抗蚀性为基础 ,结合其他多方面的生态功能 ,退耕地人工林可以起到很好的水土保持作用 相似文献
8.
黄土丘陵沟壑区欧李人工林对坡面土壤分形特征及可蚀性的影响 总被引：1，自引：1，他引：0
[目的]研究中国特有经济作物欧李对坡面土壤性质的影响,为其在黄土丘陵沟壑区推广种植提供参考依据。[方法]布设5块立地条件不同的试验样地,在汛期前后,分别对各样地土壤相关指标进行测定,利用PSD分形模型及EPIC土壤抗侵蚀模型,定量分析欧李对坡面土壤颗粒分形维数及抗侵蚀能力的影响。[结果](1)在汛期,欧李人工林对坡面土壤黏粒具有显著的拦截作用,鱼鳞坑式欧李林可有效保护坡顶处土壤,水平阶式欧李林在坡中、坡底位置可有效拦截径流中的土壤细颗粒并富集黏粒;(2)坡面土壤分形维数与土壤砂粒含量呈显著负相关,相关系数为-0.611;与土壤黏粒含量呈显著正相关,相关关系为0.770;(3)欧李林的种植可降低研究区土壤可蚀性因子K值,提高土壤抗侵蚀能力,不同整地方式下欧李林对土壤可蚀性因子K值的影响效果总体表现为:水平阶鱼鳞坑自然坡;(4)土壤可蚀性因子K值与土壤的有机质和黏粒含量呈极显著负相关,相关系数分别为-0.957,-0.928;与土壤容重、砂粒含量和粉粒含量呈显著正相关,相关系数分别为0.704,0.667,0.512。[结论]种植欧李对黄土丘陵沟壑区控制坡耕地黏粒流失,提高土壤有机质含量,优化土壤结构,增强土壤抗蚀能力具有积极的意义。 相似文献
9.
关帝山不同植被恢复类型土壤抗蚀性研究 总被引：1，自引：1，他引：0
《水土保持学报》2014,(2)
对关帝山4种植被恢复类型(包括云杉-落叶松-杨桦针阔混交林(简称针阔混交林)、杨桦阔叶林、沙棘灌木林和华北落叶松林)和撂荒地(对照)0-20cm土层土壤抗蚀性进行研究。结果表明,与撂荒地相比,不同植被恢复类型土壤抗蚀性均明显增强(P0.05),各种恢复林地土壤有机碳含量、0.25mm风干及水稳性团聚体含量均明显增加,水稳性团聚体平均重量直径(MWD湿)和水稳性指数均显著增大,团聚体结构破坏率和土壤容重显著减小;同时,植被恢复也改善土壤微团聚状况,使分散率降低,团聚度增加。采用主成分分析法,确定土壤抗蚀性评价指标的3个主成分,并确定土壤抗蚀性的综合评价模型,即Y=0.718Y1+0.167Y2+0.115Y3,依据土壤抗蚀性综合主成分值,得出土壤抗蚀性强弱顺序为:针阔混交林(2.621)杨桦阔叶林(1.204)沙棘灌木林(-0.159)华北落叶松林(-1.056)撂荒地(-2.609)。建议在该区进行生态修复的营林过程中,加强对人工林的抚育管理,以增强其水源涵养和水土保持功能。 相似文献
10.
长江上游人工林与天然林土壤结构质量及保水抗蚀性研究 总被引：10，自引：0，他引：10
对长江上游人工林与天然林下代表性剖面的土壤结构分析看出,人工林较天然林土壤的结构状况要差。选择12项指标对不同林地土壤结构质量进行评价,结果表明人工林土壤结构质量远不如天然林土壤。测定和计算人工林、天然林土壤的持水量和侵蚀率,也看出前者比后者的保水抗蚀性差。其原因主要与林下土壤结构质量有关。长江上游地区人工林分布面积大,现暴露出的很多问题,与其土壤结构质量低下有紧密的关系。建议加强林下土壤结构质量的保护和培育研究。 相似文献
11.
【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
12.
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
13.
《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
14.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
15.
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
16.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献
17.
《中国生态农业学报》2014,(7)
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
18.
《中国生态农业学报》2014,(6)
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
19.
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
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