有机无机肥配施和根瘤菌接种对拉巴豆生长、品质及养分吸收的影响

选取优良高产豆科牧草拉巴豆为供试材料,研究了接种根瘤菌和有机无机肥配施对拉巴豆结瘤、 生长、 饲料品质、 养分吸收及土壤酶活性的影响。结果表明,F0.5M0.5（50%有机肥+50%无机肥）和F0.75M0.25（25%有机肥+75%无机肥）处理的拉巴豆生长最好,F（纯施化肥）和F0.25M0.75（75%有机肥+25%无机肥）处理次之,M（纯施有机肥）处理较差,CK（不施肥）最差,F0.5M0.5和F0.75M0.25处理比F分别增产19.46%和16.49%。F和CK结瘤数最少,瘤重也最低,但根瘤数量和重量随有机肥施用的比例增加而提高。在施用有机肥的4个处理中,拉巴豆净光合速率相似,介于14.39~15.32 CO2 mol/(m2s)之间,显著高于F和CK处理。此外,施用有机肥显著改善拉巴豆饲用品质,尤以F0.5M0.5和F0.75M0.25处理最显著,并提高过氧化氢酶、 蔗糖酶、 脲酶活性。相关分析表明,拉巴豆根瘤重与地上部生物量、 氮、 磷、 钾吸收量呈显著正相关,相关系数依次为0.6758、 0.7269、 0.9759、 0.9488（n=36）,说明根瘤形成改善了拉巴豆的氮、 磷、 钾营养,促进了生长,提高了品质。在重庆市的拉巴豆栽培实践中,提倡接种根瘤菌和有机无机肥适量配施很有必要。     

四川盆地主要紫色土硒的状况及其有效性研究

红紫泥、灰棕紫泥、红棕紫泥依次是四川盆地典型具有代表性的酸性、中性和石灰性紫色土。它们的全硒含量为７９．５７－２９８．４５μｇ／ｋｇ，平均２１２．３２μｇ／ｋｇ。其中，红棕紫泥〉灰棕紫泥〉红紫泥；并且，红棕紫泥全硒量的变幅较小，后两者的变幅较大。在土壤剖面中，全硒含量存在着明显的分布规律，即母质〉耕作层〉心土层〉底土层。石灰性紫色土含有较多的Ｃａ－Ｓｅ；酸性紫色土含有较多的Ｆｅ－Ｓｅ。土壤水溶性硒     

主要紫色土电导率特征及其影响因素研究

本研究初步探讨了四川丘陵区暗紫泥、灰棕紫泥、棕紫泥和红棕紫泥4种主要紫色土电导率的特性。研究结果表明,这四种主要紫色土的平均电导率为185.62±44.33μScm-1,土壤阳离子交换量、有机质、pH和容重与土壤电导率有着不同程度的相关性,其中土壤阳离子交换量和土壤容重与土壤电导率呈极显著相关,土壤有机质和pH与土壤电导率呈显著相关。     

水稻配方施肥产量与效益初探

重庆市铜梁县境内灰棕紫泥水稻土占全县稻田面积的60％,为弄清该类土壤理化性状、养分含量状况、化肥利用率、施肥种类、数量和搭配比例与水稻产量之间的关系,进行了“3417”田间试验研究,结果表明：（1）灰棕紫泥水稻土中等肥力水平大眼泥田,在稿秆还田基础上,以每667m。施N9．2kg、P2054．8kg、K204．8kg为最佳产量和最佳经济效益配肥方案;（2）合理施用氮肥是提高水稻产量的主导因素,在施氮基础上,磷、钾肥的合理搭配对提高水稻产量具有明显效果;（3）在灰棕紫泥水稻土上施用撒可富复合肥比施用等量常规肥增产效果明显;（4）在灰棕紫泥水稻土上施用硼肥对水稻增产效果不明显：（5）在灰棕紫泥水稻土上加锌处理增产效果较明显。     

根瘤菌和AM真菌对紫花苜蓿结瘤和产质量的影响

了解酸性土壤条件下紫花苜蓿(Medicago sativa)接种中华根瘤菌(Sinorhizobium medicae,SM)和丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)的作用,有益于扩大西南地区牧草种植,促进牧业发展。选择当地典型、有代表性的酸性黄壤,设置不接种(CK)、接种SM(SM)、接种AMF(AMF)、混合接种(SM+AMF)四个处理,通过微区试验研究SM与AMF对紫花苜蓿生长、品质、根系结瘤和植株养分吸收等的影响。结果表明:在SM+AMF处理中,菌根真菌感染率和结瘤数分别较单接种提高,但根瘤单重显著减少,固氮效率和吸磷能力增加,其牧草产量、粗蛋白、粗脂肪、灰分、氮、磷、钾、钙、镁积累量均显著高于其他处理,表现出SM与AMF的协同效应。与CK相比,SM或AMF处理均促进苜蓿生长,提高牧草产量,改善品质,但SM和AMF处理之间无显著差异。在SM处理中,地上部氮含量和氮、磷、钾积累量高于CK,植株氮积累量高于AMF。在AMF处理中,其根系活力显著高于SM处理,有益于养分吸收,可解释植株磷、钾、钙、镁含量和积累量高于SM的原因。因此,SM和AMF均能不同程度地促进氮、磷、钾吸收,提高牧草产量品质。在西南酸性土壤上种植紫花苜蓿时,接种根瘤菌和菌根真菌尤其进行混合接种有益于提高牧草的产量和品质。     

丛枝菌根真菌与根瘤菌接种对大豆根瘤分布及磷素吸收的影响

在温室条件下,采用石英砂盆栽试验研究了大豆(冀豆6号)接种丛枝菌根真菌（Glomous mosseae）与根瘤菌 （Bradyrhizobium japonicum）对根瘤的形成、分布以及磷素吸收效率的影响。结果表明,大豆生长至开花期（接种后56 d）,与单接种根瘤菌处理相比,双接种AM真菌和根瘤菌显著增加大豆生物量、氮、磷含量、根系上的总根瘤数。单接种根瘤菌条件下,总根瘤数的48.4%分布在主根上,51.6%分布在侧根上;根瘤菌与AM真菌双接种时,总根瘤数的32.5%分布在主根上,67.5%分布在侧根上。双接种处理的侧根根瘤的固氮酶活性显著高于单接种处理的。双接种条件下大豆侧根中AMF侵染增强,尤其是结根瘤侧根上的AM真菌的侵染率高于未结瘤的侧根的菌根侵染率。接种后28 d单接种菌根真菌处理显著高于双接种处理的植株磷的吸收效率;而56 d 时趋势相反。以上结果表明,AM真菌侵染改变根瘤在大豆根系上的分布,根瘤数量、分布与结根瘤侧根上AM真菌的侵染强度存在正相关关系。     

酸性紫色土上紫花苜蓿的结瘤性能与养分吸收

盆栽试验表明,在pH.5.45的酸性紫色土接种苜蓿根瘤菌,可显著提高紫花苜蓿地上部和地下部生物量。根瘤菌不同株系的结瘤性能和对宿主生长的影响存在显著差异,且不同紫花苜蓿品种的结瘤性能也存在显著差异。结瘤性能良好的菌株显著提高地上部氮、磷和钙的含量,而降低地上部钾含量和铝含量。紫花苜蓿地上部的氮、磷、钾和钙含量高于地下部,镁含量差异不大,而铝含量在接种后地下部含量高于地上部。相关分析表明,紫花苜蓿根瘤重和根瘤数与地上部生物量和地上部氮含量之间存在显著正相关关系;而地下部铝含量与地上部生物量、结瘤性能和植株氮含量呈显著负相关关系。说明酸性土壤良好的结瘤性能可提高生物固氮效率、促进紫花苜蓿生长,但根系铝的过量吸收影响紫花苜蓿的生长、结瘤与氮素吸收。     

低分子量有机酸对三峡库区消落带典型土壤磷素淋溶迁移的影响

以三峡库区分布最广的紫色潮土、灰棕紫泥为对象,通过室内间歇式土柱淋洗试验,探讨了淋溶液酸度及低分子量有机酸对土壤磷迁移淋失的影响。结果表明,淋溶液酸度对磷的溶出具有一定影响,溶液偏酸或偏碱均促进了磷的淋出。2种土壤磷的淋出能力差异较大,灰棕紫泥中的磷更易淋出,草酸和柠檬酸可显著促进灰棕紫泥土壤磷的淋失,而对紫色潮土磷淋出的促进作用不明显。随有机酸浓度的增加,促进作用增强,100mmo/L草酸和柠檬酸的处理使灰棕紫泥可溶性总磷累计淋出量分别较对照(0.344mg)增加了4.40,15.32倍。柠檬酸的促进作用高于草酸,两者对磷淋出的影响是其酸解和螯合作用的综合结果。     

重庆市几种主要土壤有机质化学稳定性研究

采用高锰酸钾和双氧水氧化法,研究比较重庆市6种不同类型土壤有机质的抗氧化稳定性。结果表明:(1)采用KMnO4氧化法评价土壤有机质化学稳定性应控制适宜的氧化剂浓度,KMnO4浓度<0.1mol/L时,主要氧化土壤中的易氧化有机组分,浓度为0.3mol/L的KMnO4可较好地反映土壤有机质的抗氧化能力差异,6种土壤有机质抗氧化能力高低顺序为缙云山黄壤腐殖层>紫色潮土>嘉陵江沿岸冲积土>灰棕潮土>矿质黄泥>灰棕紫泥紫色土。(2)土壤有机质的化学稳定性与pH、有机质含量、<0.001mm粘粒含量以及全氮、速效氮、速效磷含量均存在明显的相关性,其相关特性在KMnO4高、低浓度时表现不同。(3)双氧水氧化法可较好地反映不同土壤密度分级土壤有机质的抗氧化稳定性,灰棕潮土、紫色潮土和矿质黄泥均随酸度增大而提高;灰棕潮土和紫色潮土轻组有机质(LFOM)抗氧化能力明显高于重组有机质(HFOM);矿质黄泥和缙云山黄壤腐殖层LFOM和HFOM抗氧化能力无明显差异;研究发现农地土壤其有机质氧化率随酸度增加而连续提高,但林地土壤有机质氧化率变化幅度较小,均小于50%。     

淋溶条件下低分子量有机酸对淋出液及三峡库区典型土壤性质的影响

[目的]研究低分子量有机酸(草酸、柠檬酸、酒石酸)作用下淋出液及土壤(紫色潮土和灰棕紫泥)性质的变化,以期为三峡库区的环境管理提供参考和科学依据。[方法]采用间歇式土柱模拟试验进行研究。[结果]高浓度低分子量有机酸(≥50mmol/L)能够破坏灰棕紫泥的酸碱缓冲体系,当草酸、柠檬酸和酒石酸浓度≥50mmol/L时,灰棕紫泥土壤pH值均从8左右降到了4.11以下;而紫色潮土的缓冲性能较强,经淋溶后土壤pH值变化不大,仍然维持在6.84~8.71左右,与空白处理差异性不显著。另外,灰棕紫泥淋出液电导率变化较紫色潮土明显,高浓度低分子量有机酸处理下,灰棕紫泥淋出液电导率最高值达到了34.400mS;灰棕紫泥在3种低分子量有机酸淋洗下淋溶出离子量的大小顺序为:柠檬酸酒石酸草酸。[结论]低分子量有机酸的酸解作用和络合作用是影响淋出液pH值、淋出液电导率和土壤pH值变化的主要原因,并能够参与紫色潮土和灰棕紫泥的化学和生物化学过程。低分子量有机酸的存在对三峡库区水环境恶化存在一定的风险。     

我国典型农田长期施肥小麦氮肥回收率的变化特征

为阐明长期不同施肥下小麦氮肥回收率的时间演变特征及空间差异,为农田氮肥合理施用及提高氮肥回收率提供科学依据,对我国典型农田土壤—塿土、潮土、褐土、灰漠土、黄棕壤、黑土、中性紫色土、石灰性紫色土和红壤上设置的15-24年的长期试验的氮肥回收率及相关数据进行统计分析。结果表明,长期单施氮肥（N）、氮钾配施（NK）下,小麦氮肥回收率随时间延长而显著降低,降低速率为红壤（7.24）＞黄棕壤（4.16）＞塿土（1.48）、中性紫色土（1.44）、潮土（1.06）＞石灰性紫色土（0.60）;化肥配合及与有机肥配施（NP、NPK、NPKM）的氮肥回收率在潮土、灰漠土、黄棕壤、黑土、中性紫色土上随时间变化不大。化肥配合施用（NPK）下,塿土、潮土、褐土、灰漠土、黄棕壤、黑土、中性紫色土、红壤和石灰性紫色土上的小麦氮肥回收率平均值分别为76.8%、73.4%、56.4%、44.9%、44.4%、33.8%、41.7%、33.6%、26.2%。小麦氮肥回收率以北方暖温带的塿土、潮土、褐土大于南方中亚热带紫色土和北方中温带的黑土。     

生物炭对我国南方红壤和黄棕壤理化性质的影响

为了探讨生物炭对不同土壤的改良效果,采用盆栽试验,研究了施用生物炭对我国南方两种代表性土壤(红壤和黄棕壤)理化性质的影响及其动态变化差异。结果表明:强酸性红壤施用生物炭能明显提高pH而降低其酸度,同时增加土壤的有机质、速效磷、速效钾和碱解氮含量,且随着生物炭施用量(生物炭量/土壤量:0、0.5%、1.0%、2.0%)的增加,改良效果不断加强;弱酸性黄棕壤施用生物炭也提高了土壤pH、有机质、速效磷、速效钾含量,但对该土壤中的碱解氮含量无明显影响。不同生物炭用量的效应存在较大差异,在2.0%时对两种土壤各理化性质影响均表现为最明显,红壤pH平均增加0.61,有机质、速效磷、速效钾、碱解氮分别平均提高203.4%、369.3%、368.0%、30.4%,而黄棕壤pH、有机质、速效磷、速效钾分别平均增加0.55、124.2%、57.5%、50.3%。因而,相同用量的生物炭对红壤的改良效应好于黄棕壤,且施用生物炭对两种土壤速效钾含量影响最大,其次是有机质、pH、速效磷、碱解氮。     

Competitive ability of selected Cyclopia Vent. rhizobia under glasshouse and field conditions

This study tested the competitive ability of three locally isolated Cyclopia rhizobia and strain PPRICI3, the strain currently recommended for the cultivation of Cyclopia, a tea-producing legume. Under sterile glasshouse conditions, the three locally isolated strains were equally competitive with strain PPRICI3. In field soils, the inoculant strains were largely outcompeted by native rhizobia present in the soil, although nodule occupancy was higher in nodules growing close to the root crown (the original inoculation area). In glasshouse experiments using field soil, the test strains again performed poorly, gaining less than 6% nodule occupancy in the one soil type. The presence of Cyclopia-compatible rhizobia in field soils, together with the poor competitive ability of inoculant strains, resulted in inoculation having no effect on Cyclopia yield, nodule number or nodule mass. The native rhizobial population did not only effectively nodulate uninoculated control plants, they also out-competed introduced strains for nodule occupancy in inoculated plants. Nonetheless, the Cyclopia produced high crop yields, possibly due to an adequate supply of soil N.     

不同土壤抗蚀性能研究

该对四川省农业科学院资阳水土保持试验所布设的７种土壤试验小区，用模拟降雨装置进行了土壤抗蚀性能的初步试验研究，结果表明：（１）７种土壤的抗蚀能力大小依次为：冷沙黄泥＞棕紫泥＞红棕紫泥＞灰色潮土＞红紫泥＞黄红紫泥＞暗棕紫泥；（２）７种土壤的么径流过程累积量与降雨历时、产沙过程累积量与降雨历时，径流过程累积量与产沙过程累积量之间均有显的线性相关关系，以及６种土壤的土壤含水量与开始产流时间之间有非常     

喀斯特山区不同母质(岩)发育的土壤主要理化性质差异性分析

在贵阳市乌当区采集了白云岩、石灰岩、钙质紫色砂页岩等9种母质(岩)上发育的土壤样品763个,分别进行了土壤主要理化性质的测定和差异性分析。结果表明不同母质(岩)发育的土壤理化性质具有很大的差异:红色粘土、老风化壳和页岩上发育的土壤pH值均为酸性至强酸性,有机质和CEC含量中等,土壤质地较粘重;石灰岩、白云岩和钙质紫色砂页岩上发育的土壤pH值为中性至微碱性,有机质和CEC含量较高,质地较为适中;砂页岩和河流冲积物上发育的土壤pH值为酸性至中性,其余理化性质为中等水平;砂岩发育的土壤pH值为强酸性,其余理化性质均较差。     

Population densities of clover rhizobia in Texas pastures and response to liming

Summary Clovers are widely used forage legumes on acidic soils in Texas and need inoculation with appropriate rhizobia when first introduced. Acidic soils are not conducive to survival of clover rhizobia. A survey of pastures was undertaken to determine the number of rhizobia present. The effect of liming acidic soils on the survival of clover rhizobia was also evaluated in the laboratory. The number of clover rhizobia was more than 100 cells g^-1 soil in 70% of the pastures surveyed but populations within pastures varied by more than two orders of magnitude. The number of years of clover production beyond 1 year did not affect the rhizobial population density. The soil pH of twelve samples was below 5.0 and six samples had populations of rhizobial lower than 100 g^-1 soil. Eleven out of sixteen samples from fields that had grown clover and had pH values above 6.0 had populations exceeding 1000 g^-1 soil and only three samples had populations lower than 100 g^-1 soil. Incubating indigenous or inoculated rhizobia in well-mixed soils having pH values of 5.1 or below resulted in populations declining to below 10 g^-1 soil in 6 weeks. Mixing of soils with pH values of up to 5.4 induced reduction of rhizobial numbers, possibly by destroying microsites. Liming of soils to increase pH values above 5.5 improved survival of native or inoculated rhizobia in most cases.     

Symbiotic effectiveness of Bradyrhizobium japonicum in acid soils can be predicted from their sensitivity to acid soil stress factors in acidic agar media

In acid soil, low pH, reduced availability of nutrients, and toxicity of Al and Mn limit plant growth and the survival and effectiveness of rhizobia. The symbiosis between legumes and rhizobia is particularly sensitive to acid soil stress. A pot experiment evaluated whether Bradyrhizobium japonicum strain growth on acidic agar media would predict ability to colonize the rhizosphere and form effective nodules in acidic soils. Three Indonesian strains of B. japonicum with similar effectiveness at neutral pH in sand culture but with different tolerance of acid soil stress factors in agar media, and an acid-tolerant commercial strain (CB1809) of comparable effectiveness, were tested in three acid soils using the Al tolerant soybean (Glycine max cv PI 416937). At 7 days after inoculation all strains had achieved large rhizosphere populations, but by day 14 the rhizosphere population of the acid-sensitive strain had decreased, while the more acid-tolerant strains increased. The acid-tolerant strains had significantly greater nodulation and symbiotic effectiveness than plants inoculated with the acid-sensitive strain. Laboratory prescreening of B. japonicum for acid, Al and Mn tolerance in acid media successfully identified strains which were symbiotically competent in low pH soils.     

Antibiotic-resistant mutants identified from nodules of uninoculated soybeans grown in a strongly acidic soil

Two hypotheses that antibiotic-resistant nodule isolates from uninoculated soybeans grown in a strongly acidic soil were naturally occurring rhizobia which had acquired resistance to spectinomycin and streptomycin or were contaminants from adjacent, inoculated treatments, were tested in laboratory experiments. Soybean nodule isolates (166) as well as 48 cowpea and 89 Rhizobium japonicum strains were used in tests of resistance to six concentrations (0–500 μg ml^?1) of kanamycin, spectinomycin and streptomycin, tolerance of stresses of pH 4.6, with or without 50 μm Al, and serological cross-reactivity.More strains from the strongly acidic soil were resistant to the antibiotics than from slightly acidic soils, but resistance to antibiotics did not necessarily entail resistance to pH 4.6 or to 50 μm Al. Twenty-three nodule isolates which were resistant to spectinomycin or streptomycin cross-reacted with antisera of the inoculum strains, indicating that they were contaminants. None of 59 antibiotic-sensitive nodule isolates from uninoculated plants and none of 31 from inoculated plants cross-reacted with the antisera. All 53 antibiotic-resistant isolates from nodules of plants in inoculated plots cross-reacted with test antisera, indicating stability of the antibiotic markers.Cowpea rhizobia were generally more resistant to the antibiotics and more tolerant of pH 4.6 and 50 μm Al than were R. japonicum. Among strains of R. japonicum, slow growers were more resistant to antibiotics than moderately fast growers.     

三峡库区消落带土壤对磷的吸附和淹水下磷的形态变化

三峡水库建成后在库区周边形成落差30m的消落带,消落带土壤对磷的吸附固定和磷的去向直接影响到周围的水环境。通过批处理和模拟培养法研究了三峡库区小江流域沿岸消落带的黄壤、紫色土在淹水期间铁的形态变化,磷的吸附及形态转变,结果表明：（1）供试黄壤和紫色土在淹水后,晶形铁氧化物含量明显下降,非晶形铁含量有增加趋势,土壤对磷的吸附量增加;(2)淹水期间土壤Olsen-P含量呈下降趋势,而Fe-P和Al-P含量增加,模拟显示黄壤和紫色土在淹水15d后的磷吸附容量增加70.8%和9.5%;（3）用pH 5和pH 9的0.1mol L-1CaCl2、KCl、NH4Cl溶液培养的黄壤,其Olsen-P、Fe-P、Al-P含量均明显增加,意味着消落带土壤中若施加K、Ca或尿素时,土壤有效磷可能增加,这可导致CaCl2提取磷的增多并影响库区水的含磷量,从而影响库区水质。