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1.
Jie Song Wei Wei Qin Yao 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(8):730-736
Experiments were conducted to study the inhibitor factors present in suppressive soil that suppressed the soybean cyst nematode (SCN) in the black soil fields with 21 years continuous cropping of soybean (SSSS) and 3 years continuous cropping of soybean followed by 1 year corn (SSSC). Compared with the SSSC field, the densities of SCN significantly (P?0.05) declined in SSSS field. In a soil microcosm with suppressive soil, the population of SCN decreased after the addition of pimaricin (fungal inhibitor) and streptomycin (bacterial inhibitor), but the population of SCN declined more significantly by adding streptomycin to the suppressive soil than adding pimaricin. Fusarium equiseti, Pochonia chlamydosporia and Purpureocillium lilacinum were isolated from cysts, eggs and J2 of SCN and soil in SSSS and SSC field. The population density of these parasitic fungi was significantly (P?0.05) higher in SSSS field than in SSSC field. The density of P. chlamydosporia was higher than other fungi. Real-time PCR was used to test genomic DNA of P. chlamydosporia in SSSS and SSC field soil. The mass of genomic DNA and the population density of P. chlamydosporia were significantly (P?0.05) higher in SSSS field than in SSSC field. This study has revealed that fungi, especially P. chlamydosporia, may play an important role in the suppression of SCN population in the suppressive soil. 相似文献
2.
Wei Wei Lin Zhu Jie Song 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):279-285
Field experiments were set up in 1991 to test if suppressive soil to soybean root diseases could be developed with continuous long-term soybean cropping in black soil of Northeast China. Based on the field observation in 2007, 2009, and 2011, soybean root growth was promoted, and the severities of root disease were reduced in a field with continuous long-term cropping with soybean. Population densities of the pathogens (Fusarium spp. and Heterodera glycines) in the soybean cropping field were significantly (P < 0.05) lower than rotation of soybean with wheat or corn. Higher levels of biological control agents (Trichoderma harzianum, Pochonia chlamydosporia, or Paecilomyces lilacinus) also were found in the long-term soybean cropping field. Therefore, continuous long-term cropping of soybean in black soil of Northeast China could develop suppressive soil to soybean root diseases. 相似文献
3.
Lerat S Gulden RH Hart MM Powell JR England LS Pauls KP Swanton CJ Klironomos JN Trevors JT 《Journal of agricultural and food chemistry》2007,55(25):10226-10231
The presence of the recombinant cp4 epsps gene from Roundup Ready (RR) corn and RR soybean was quantified using real-time PCR in soil samples from a field experiment growing RR and conventional corn and soybean in rotation. RR corn and RR soybean cp4 epsps persisted in soil for up to 1 year after seeding. The concentration of recombinant DNA in soil peaked in July and August in RR corn and RR soybean plots, respectively. A small fraction of soil samples from plots seeded with conventional crops contained recombinant DNA, suggesting transgene dispersal by means of natural process or agricultural practices. This research will aid in the understanding of the persistence of recombinant DNA in agricultural cropping systems. 相似文献
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5.
不同种植模式背景下栽植生姜对紫色土细菌多样性的影响 总被引:1,自引:0,他引:1
为了解栽植生姜对岷江下游紫色丘陵区不同种植模式背景下典型紫色土微生物多样性的影响,采用PCR-DGGE与DNA序列分析方法,研究了紫色丘陵区玉米+红薯间作、大豆单作、生姜连作、水稻-紫云英轮作等4种典型种植模式背景下栽植生姜前后土壤细菌多样性变化特征。PCR-DGGE分子指纹图谱结果表明,同一种植模式下栽种生姜前后DGGE条带数目、位置和亮度差异明显。栽种生姜均降低了各模式下土壤细菌群落丰富度和Shannon-Wiener指数,明显改变了土壤细菌群落结构,其中生姜连作模式背景下土壤细菌丰富度和Shannon-Wiener指数下降幅度最大,玉米+红薯间作模式下降幅度最小,但栽植生姜后4种种植模式之间土壤细菌群落结构相似度明显增加。DGGE特征条带的序列分析表明,栽植生姜后,土壤细菌中的部分绿弯菌门类群消失,部分硝化螺旋菌门类群仅在水稻-紫云英轮作模式中发现、玉米+红薯间作模式中出现了短波单胞菌门的细菌。这些结果为了解栽植生姜对土壤环境的影响以及生姜种植模式的优化提供了一定的科学依据。 相似文献
6.
Xueli Chen Yufeng Wang Weiqun Li Ying Wang Dan Wei Xiaojun Wang 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(5):470-478
Continuous cropping can be a serious problem in Chinese soybean production. This can result in yield reduction, root diseases, and changes in microbial community structure. We studied community structure, clone libraries, and abundance of ammonia oxidizing bacteria (AOB) in soybean fields there were in continuous soybean production for up to 17 years (SC17). Results showed that the potential nitrification rate (PNR) and amoA gene abundance of soybean in continuous cultivation for seven years (SC7) was 0.34 µg NO3? g?1 and 4.71 × 10?5 amoA gene copies/g dry soil, respectively. These values were lower than other treatments. Phylogenetic affiliation analysis based on blast results of amoA gene clone sequencing showed that the sequences belonged to seven clusters: Cluster 1, Cluster 3b, Cluster 3a.1, Cluster 3a.2, Cluster 9, Cluster 10, and Cluster 4. Correlation of AOB community compositions with environmental factors was performed using canonical correspondence analysis (CCA). Results indicated that the composition of AOB communities in maize–soybean (MS) rotation and continuous cropping of soybean for two years (SC2) were positively related to the PNR of soil, soil moisture, and soil total nitrogen content. Soybean fields continuously cropped for 11 years (SC11) and SC7 fields had AOB community compositions that were negatively related to these factors. The AOB community composition of SC17 was positively correlated to the soil total carbon content of soil. The results in this study indicate that the potential activity and abundance of AOB community in soil significantly changed after seven years continuous cropping compared to other continuous cropping intervals. Cropping systems have important effect on the diversity of functional microorganisms and associated nitrogen cycles. 相似文献
7.
新疆棉花长期连作对土壤真菌群落结构组成的影响 总被引:2,自引:0,他引:2
土传性真菌病害给新疆连作棉花造成巨大损失,为了解新疆地区棉花在长期连作过程中土壤真菌群落结构演替与作物产量的增减及病虫害的发作规律。本文利用18S r RNA-PCR-DGGE法对比研究了新疆石河子棉区分别连作0 a(未开垦土壤)、1 a、3 a、5 a、10 a、15 a和20 a棉田0~40 cm范围内4个不同深度土壤中真菌群落组成的变化规律。结果表明,相同深度的土壤样品中真菌群落结构随着连作年限的延长Shannon-Weiner多样性指数、丰富度指数和均匀度指数都表现为不同程度下降后又增加并达到新的稳定状态,其中11~20 cm深度的样品下降最多、最快。聚类分析结果表明,相同深度的土壤样品随连作年限延长也表现出快速变化后并达到新的稳定状态,其中不同深度样品中真菌群落受影响最大的连作年限不同。主成分分析显示,连作年限对真菌群落结构形成直接影响,但随着连作年限延长,样品中真菌群落结构的变化趋缓,甚至有恢复迹象。部分DGGE条带回收、测序并比对后发现,100%的序列信息都属于未培养真菌。整体上连作棉田真菌群落结构变化及演替规律与棉花连作有很强的关联性。 相似文献
8.
玉米秸秆还田对盐碱地土壤真菌多样性的影响 总被引:2,自引:0,他引:2
为揭示盐碱地秸秆还田改良中土壤真菌群落结构及其多样性变化,以未开垦盐碱地(ZH1)、非盐碱连作玉米田(ZH2)和秸秆还田盐碱玉米田(ZH3)为材料,在玉米吐丝期,利用高通量测序技术与相关生物信息学分析结合,研究表层土壤真菌群落丰富度、多样性和群落结构的变化。结果表明,3个处理土壤真菌群落结构和丰度差异大,已知菌属中ZH1的优势属为马拉色菌,ZH2优势属为暗球腔菌属,ZH3优势属为链格孢属。玉米秸秆还田对盐碱地土壤真菌多样性的影响较大,两年玉米秸秆还田盐碱土壤真菌多样性和物种丰度与未开垦盐碱地比较均有所下降。 相似文献
9.
Dirk V. Charlson Theodore B. Bailey Silvia R. Cianzio Randy C. Shoemaker 《Soil Science and Plant Nutrition》2013,59(7):1055-1062
Abstract Iron-deficiency chlorosis (IDC) and soybean cyst nematode (SCN) result in yield and income losses for soybean growers in the U.S. Breeding programs are identifying soybean genotypes with resistance to IDC using calcareous soils infested with SCN, where SCN might interfere with evaluation. Our first objective was to examine whether associations could be established for chlorosis symptoms with SCN infestation of soybean grown on SCN-infested calcareous soils. Two breeding populations, their parents, and five SCN-susceptible, IDC-control genotypes (IDC controls) were evaluated for IDC symptoms on SCN-infested calcareous soils in 2000 and 2001. In general, no significant correlations were detected between chlorosis expression and SCN infestation in either year, although a negative correlation (r = ?0.93, p ≤ 0.05) was observed for the IDC controls in 2001. For our second objective, we examined the relationship between genotype resistance to SCN and IDC. Although IDC controls were all equally susceptible to SCN and chlorosis observed in the field and nutrient solution was similar, SCN-resistant genotypes expressed resistance to IDC in the field, but severe susceptibility to IDC in nutrient solution. Our third objective was to investigate the value of calcareous soil properties to predict IDC in soybean grown on SCN-infested calcareous soils. For one breeding population in 2001, positive correlations (p ≤ 0.05) were detected for chlorosis with calcium carbonate (r = 0.62) and electrical conductivity (r = 0.59), and a negative correlation (r = –0.41) with soil Fe-DTPA-TEA. No significant correlations were observed for the remaining genotypes. Our study indicated that associations between IDC, SCN, and calcareous soil properties are dependent on genotype and environment. In addition, our study demonstrated a potential association between plant health and SCN reproduction in SCN-susceptible genotypes, the possibility that SCNresistant genotypes may be sensitive to iron availability, and the importance of genotype on the detection of associations between IDC expression and SCN infestation. 相似文献
10.
为探讨轮作与连作对烟田根际土壤微生物群落的影响,采用实验室微生物培养联合微生物高通量测序技术,分析了玉米-烤烟轮作和烟叶连作对烟株根际土壤微生物数量、群落结构及其多样性的影响。研究结果表明,轮作烟田根际土壤中可培养细菌和放线菌数量均高于连作烟田根际土壤,但真菌数量低于连作烟田。土壤高通量测序结果表明,轮作烟田根际土壤真菌和细菌群落多样性均高于连作烟田;在烟株的生长过程中,轮作和连作烟田在旺长期和成熟期微生物群落相似度降低。相较于黑胫病/根腐病/根结线虫发病率较高(36. 67%)的连作烟田来说,轮作烟田发病率较低(0%),进一步分析真菌和细菌群落结构发现,轮作烟田根际土壤中拮抗菌如Sphingomonas (鞘脂单胞菌属)、Pseudomonas (假单胞菌属)、Aspergillus (曲霉属)等相对丰度均高于连作烟田,而连作烟田根腐病病菌Pythium (腐霉属)丰度较高。 相似文献
11.
Residual effects of potassium placement for conservation-till corn on subsequent no-till soybean 总被引:2,自引:0,他引:2
Biannual surface application of potassium (K) fertilizer prior to corn (Zea mays L.) in a corn–soybean (Glycine max (L.) Merr.) rotation has been common in conventional-till crop production in North America; however, whether this traditional K management practice is effective for soybean when both corn and soybean are grown with conservation tillage is largely unknown. This study evaluated the residual effects of spring K fertilizer placement in conservation tillage systems applied to previous corn on subsequent no-till soybean. Experiments involving a corn–soybean rotation were conducted from 1997 to 2000 on a silt loam soil (Albic Luvisol) with 12 years of continuous no-till management near Paris, Ontario, Canada. The fields had low initial soil-test K levels (<61 mg l−1) and evident soil K stratification in the top 20 cm. In the “corn” years from 1997 through 1999, spring K fertilizer placement methods of deep band (76 cm centers), surface broadcast, broadcast plus shallow band, and no K were evaluated for no-till, spring zone-till, and spring mulch-till tillage systems (1997 and 1998) but for no-till alone in 1999. From 1998 to 2000, soybean was no-till planted in 19 cm row widths on the respective previous-year corn treatments without further K fertilizer application. Soybean leaf K concentrations responded more frequently and positively to K application in no-till corn than in zone-till and mulch-till corn. Deep band and surface broadcast K placements were similar in their residual effects on soybean leaf K. Positive soybean yield responses to residual K fertilizer were observed in only 1 out of 3 years despite consistent increases in both soil K and soybean leaf K concentrations where K was applied to previous corn. On long-term no-till fields with low soil K levels, interrupting a continuous no-till corn–soybean system with mulch-till corn production provided residual benefits in soil K availability and leaf K nutrition for subsequent no-till soybean. Furthermore, the residual effects of K fertilizer applied to previous corn on subsequent no-till soybean were not affected by K placement method. 相似文献
12.
《Communications in Soil Science and Plant Analysis》2012,43(19-20):1693-1709
Abstract The objective of this study was to provide agronomic, nematode, and economic analysis of alternative production rotation systems for soybeans (Glycine max L. Merr.) on a silt loam soil association in Arkansas. Monocropped soybeans and soybeans double‐cropped with wheat (Triocum aestivam L.) was included as well as grain sorghum (Sorghum bicolor L. Moench) under dryland conditions in order to reduce soybean cyst nematode (SCN, Heteroderaglycine Ichinohe) populations. A total of seven crop rotations and eleven treatments that included alternative tillage conditions and wheat stubble management practices were analyzed using data from 1980–1984 experiments conducted at the Arkansas Cotton Branch Experiment Station on a silt loam Loring‐Calloway‐Henry Association (Alfisols). Although crop rotation was effective for nematode suppression, yields for double‐cropped soybeans were comparable to soybean yields under monocropped’ continuous management practices. Economic results indicated that average net returns of $338.50 per hectare (about $ 137 per acre) were highest for the continuous double‐cropped wheat‐soybean production management systems which combine the conventional tillage method with burning of wheat stubble. For the conditions analyzed and level of SCN present, this research provides evidence that control of the soybean cyst nematode through rotation practices that utilize grain sorghum is not economically efficient where continuous double‐cropped wheat‐soybeans systems can be incorporated. 相似文献
13.
It has been difficult to explain the rotation effect based solely on N availability in maize-soybean cropping systems in
the moist savanna zone of sub-Saharan Africa. Although arbuscular mycorrhizal fungi (AMF) can contribute to plant growth by
reducing stresses resulting from other nutrient deficiencies (mainly P) and drought, their role in the maize/soybean rotation
cropping systems in the Guinea savanna has not yet been determined. Pot and field experiments were conducted for 2 years using
13 farmers' fields with different cropping histories in two agroecological zones (Zaria, northern Guinea savanna and Zonkwa,
southern Guinea savanna) in Nigeria. We quantified the influence of cropping systems and rhizobial inoculation on plant growth,
mycorrhizal colonization and diversity of promiscuous soybean and maize grown in rotation. The relationships between these
variables and selected soil characteristics in farmers' fields were also examined. Percentage mycorrhizal colonization in
promiscuous soybean roots ranged from 7% to 36%, while in maize it varied between 17% and 33%, depending on fields and the
previous cropping history. A large variation was also observed for mycorrhizal spores, but these were not correlated with
mycorrhizal colonization and did not appear to be influenced by rotation systems. Soybean mycorrhizal colonization was higher
(13% increase) in Zonkwa, but not in Zaria, if the preceding crop was maize and not soybean. These differences were related
to the soil P concentration, which was positively related to mycorrhizal colonization in Zonkwa but negatively to this parameter
in Zaria. The previous crop did not affect mycorrhizal colonization of maize in both locations. Soybean cultivars inoculated
with rhizobia had a higher mycorrhizal colonization rate (25%) and more AMF species than maize or uninoculated soybean (19%).
Maize grown in plots previously under inoculated soybean also had higher percentage mycorrhizal colonization than when grown
after uninoculated soybean and maize. Four AMF genera comprising 29 species were observed at Zaria and Zonkwa. Glomus was the dominant genus (56%) followed by Gigaspora (26%) and Acaulospora (14%). The genus Sclerocystis was the least represented (4%).
Received: 28 October 1998 相似文献
14.
抗病性不同大豆品种根面及根际微生物区系的变化 Ⅰ.非连作大豆(正茬)根面及根际微生物区系的变化 总被引:1,自引:3,他引:1
采用平板计数法测定了3个抗病性不同的大豆品种在生育期内根面和根际微生物区系的变化情况,并应用荧光计数法直接测定了根际细菌和真菌的生物量。结果表明,土体的微生物种类最丰富、根际的次之、根面的较单一。播种后从三叶期到鼓粒初期,根面和根际的可培养细菌总数随生育期逐渐增加,鼓粒初期达最大值,而成熟期则有明显的下降;大豆根际细菌生物量也存在相同的变化规律。抗病性不同的大豆品种其根面、根际可培养细菌总数存在差异;抗病品种大豆的根瘤重明显高于感病品种。种植一季后感病品种根际积累的病原生物(镰孢霉Fusarium.sp.和大豆胞囊线虫Heterodera.glycines的胞囊数)明显高于抗病品种。说明大豆根系分泌物对微生物具有选择性的促进或抑制作用,不同大豆品种以及同一大豆品种在不同生育时期根系分泌物的组成和数量不同,从而使大豆根面及根际形成了特定的微生物区系组成。 相似文献
15.
Monsanto’s Bt-cotton NC 33B, planted in northern China for more than one decade, effectively controls cotton bollworms and decreases the use of chemical insecticides. Because of the concern about undesirable ecological side-effects of transgenic Bt-cottons, it is important to assess Bt-cotton NC 33B’s effects on soil microorganisms in this zone. Microbial communities in the rhizosphere soil of Bt and non-Bt cottons were monitored under field conditions by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprints of eubacteria, fungi and actinomycetes at six growth stages after three-year cultivation. Results showed that the population sizes and community structures of eubacteria, fungi and actinomycetes in rhizosphere soil were markedly affected by natural variations in the environment related to cotton growth stages. However, there was no significant difference in eubacterial, fungal and actinomycete population size and community structures in rhizosphere soil between NC 33B and its non-transgenic parent. In general, Bt-cotton NC 33B did not show evident effects on microbial communities in the rhizosphere soil under field conditions after three-year cultivation. This study provides a theoretical basis for environmental impact monitoring of transgenic Bt cottons. 相似文献
16.
Short-term effect of tillage and crop rotation on microbial community structure and enzyme activities of a clay loam soil 总被引:2,自引:0,他引:2
Bin Zhang Yuanjing Li Tusheng Ren Zhengchao Tian Guiman Wang Xingyuan He Chunjie Tian 《Biology and Fertility of Soils》2014,50(7):1077-1085
A field study was carried out to analyze the short-term (2 years) effect of tillage and crop rotation on microbial community structure and enzyme activities of a clay loam soil. The experimental design was a split-plot arrangement of treatments, consisting of two tillage treatments—ridge tillage (RT) and no-tillage (NT)—in combination with two crop rotation treatments—corn (Zea mays L.) monoculture and a 2-year corn-soybean (Glycine max L.) rotation. Phospholipid fatty acid (PLFA) profiles were used to assess soil microbial community structure. No-tillage resulted in significantly higher total PLFAs compared to the RT treatment, which was accompanied by higher activities of protease, β-glucosaminidase, and β-glucosidase. This suggests a close link between soil microbial communities and enzyme activities in response to tillage. The increase of total microbial lipid biomass in the NT soils was due to the increase in both fungal and bacterial PLFAs. Crop rotation had little effect on soil bacterial communities and enzyme activities, but it significantly influenced soil fungal communities, particularly arbuscular mycorrhizal fungi. Soils under monoculture corn had higher fungal biomass than soils under corn-soybean rotation regardless of tillage treatment. 相似文献
17.
Sho Morimoto Tomoko Uchida Hisaya Matsunami Hiroyuki Kobayashi 《Soil Science and Plant Nutrition》2013,59(5):545-553
Winter cover crops increase the amount of indigenous arbuscular mycorrhizal fungi (AMF) in the soil, providing beneficial effects such as enhancement of phosphorus uptake by the subsequent crop. However, its impact on the AMF community structure is not well understood. In the present study, we aimed to reveal the effect of winter wheat cover cropping with no-till cultivation on the AMF community structures in soil and roots of the subsequent soybean. For this purpose, we conducted a field experiment consisting of two treatments, no-till soybean cultivation after winter wheat cover cropping (NTWC) and conventional soybean cultivation after winter fallow management as a control (CONT). At the flowering stage of soybean, higher AMF colonization of soybean roots was observed in the NTWC plots compared with the CONT plots. Additionally, aboveground biomass and phosphorus uptake of soybean in the NTWC plots were significantly higher than those in the CONT plots. Molecular community analyses based on PCR-denaturing gradient gel electrophoresis (DGGE) of AMF 18S rRNA genes indicated that the AMF community structures in the soil and soybean root of the NTWC plots were clearly different from those of the CONT plots. The DGGE profiles showed that the wheat cover cropping preferentially increased some phylotypes belonging to Glomeraceae and Claroideoglomeraceae. In addition, most of the phylotypes were characteristically observed in the subsequent soybean root of the NTWC plots, strongly suggesting that these phylotypes colonizing the cover crop wheat were taken over by the subsequent soybean. Our study revealed the significant effect of winter cover cropping with no-till cultivation on the structure of AMF community colonizing the subsequent soybean. 相似文献
18.
土壤线虫和微生物群落结构与作物健康密切相关。采用田间试验,利用传统分类和高通量测序技术,研究了水稻–番茄轮作(FS)、番茄连作(FF)和休耕(CK)3种种植制度土壤线虫及微生物群落结构差异。结果表明,水旱轮作土壤中线虫种类少,自由生活线虫占比高。土壤中植物寄生线虫属的检出率,轮作最少,仅有5个,连作最多,共13个,且大部分为常见属;水旱轮作同时能降低土壤中植物寄生线虫的种类,包括主要危害番茄的根结线虫属,占比仅2.1%,而连作为29.7%。不同种植制度下真菌和细菌类群OUTs和群落结构差异明显;与连作相比,轮作和休耕真菌、细菌种群丰富度更高,共享占比更多,群落构成更相近;水旱轮作Alpha多样性指数显著高于连作;轮作土壤中植物寄生线虫拮抗微生物类群Chaetomium,Talaromyces,Anaerolineaceae和Acidobacteria相对丰度高于连作。水稻–番茄轮作能大幅减少植物寄生线虫种类,增加微生物群落多样性,改善土壤质量,是番茄生产中防控线虫病害的理想措施。 相似文献
19.
Luke D. Bainard Alexander M. Koch Andrew M. Gordon John N. Klironomos 《Soil biology & biochemistry》2012
Previous research has found that conventional agricultural systems adversely affect arbuscular mycorrhizal (AM) fungi. However, there is little information on how more ecologically sustainable agricultural practices such as tree-based intercropping (TBI) influence AM fungal communities. In this study, we investigated whether TBI promotes a more abundant and diverse AM fungal community compared to conventional monocropping (CM). Abundance was estimated by measuring spore abundance and hyphal length in soil, and AM fungal colonization of corn (Zea mays) roots. Overall, AM fungal abundance was similar in both systems as corn roots from the CM and TBI systems were heavily colonized (>50%) by AM fungi throughout the growing season. Additionally, soil samples from the CM and TBI systems contained similar spore densities and hyphal length. Molecular analysis of the AM fungal community was assessed using terminal restriction fragment length polymorphism (T-RFLP) analysis of large subunit rRNA genes amplified from roots in the two cropping systems. A total of fourteen AM fungal phylotypes that belonged to the Glomeraceae were found in the two cropping systems. The TBI system had a higher AM fungal richness and contained several taxa not found in the CM system. Molecular analysis of AM fungal communities also revealed significant temporal and compositional differences between the TBI and CM systems. Within the TBI system, tree species differentially influenced the AM fungal community composition in the alley cropping regions. Future research should focus on determining whether compositional differences among AM fungal communities in CM and TBI systems have a functional effect on crop growth and productivity. 相似文献
20.
Agriculture intensification has resulted in severe soil nutrient depletion in Africa. Alternative agricultural practices have been promoted to reduce the use of expensive mineral fertilizers and to restore and sustain soil fertility. The use of mineral fertilizer combined with organic inputs (such as crop residues) and different cropping systems (cereal–legume association or rotation) have been particularly promising. Impacts of these agricultural practices on soil communities have been widely studied, yet little is known on the effect on more specific groups such as rhizobia. A field trial was set up in Chuka (Kenya) to assess the impact of different cropping systems (maize and soybean in intercropping, rotation or monocropping) combined with N fertilization and residues application on the genetic diversity of promiscuous soybean rhizobia during two seasons. Soybean yields were severely reduced by moisture stress and the association with maize compared to mono-legume and rotation systems. Nodulation was generally low but was positively affected by residues application. Diversity of native rhizobia was very low (Shannon indices H′ < 0.8) across the experiment and was not affected by the treatments. Only 5 IGS profiles were obtained after RFLP analysis and all isolated rhizobia were identified as Bradyrhizobium elkanii. The distribution of the different IGS groups within the experiment was more affected by season and residues application than by cropping system and nitrogen fertilizer application. These results suggest a limited population and a low diversity of indigenous rhizobia, and emphasize the need of alternative managements to increase and sustain soybean yields in Central Kenya. 相似文献