水氮耦合对设施农田土壤自养和异养硝化作用的影响

水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80% WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH4+-N、NO^3--N含量以及参与自养硝化的AOA amoA和AOB amoA基因拷贝数均有显著差异。无乙炔培养7 d后,NO^3--N含量显著增加,而NH4+-N含量显著降低,AOA amoA和AOB amoA的基因丰度显著增加。添加乙炔后,NO^3--N、NH4+-N含量基本保持恒定,AOA amoA和AOB amoA基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH4+-N含量、AOB amoA、NO^3--N-C2H2、AOA amoA可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%～80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%～86%;仅40%WHC下,氮纯养分量300和525 kg·hm-2处理以异养硝化为主,占总硝化速率的61%～77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。     

硝化抑制剂对毛竹林土壤N_2O排放和氨氧化微生物的影响

为了探索硝化抑制剂在毛竹生产中的施用技术,通过培养试验研究3,4-二甲基吡唑磷酸盐(DMPP)和双氰胺(DCD)两种硝化抑制剂对毛竹林施用尿素后土壤N2O排放、氮素转化和相关氨氧化细菌(AOB)、氨氧化古菌(AOA)群落结构和丰度的影响。试验设(1)对照(CK)、(2)单施尿素(Urea)、(3)尿素+1%DMPP(DMPP占总N的1%,下同);(4)尿素+1.5%DMPP;(5)尿素+10%DCD;(6)尿素+15%DCD等6个处理,测定N2O的排放动态以及气体排放转折点时的土壤特征指标。结果表明:与单施尿素相比,160 d的时间内两种DMPP用量处理的土壤N2O累积排放减排幅度均为54%,而10%DCD和15%DCD处理的土壤分别减少28%和41%。DMPP和DCD处理50 d和90 d时土壤的NH4+-N含量均显著高于(p0.05)单施尿素处理,而NO3--N含量和表观硝化率则恰好相反,但两种抑制剂间无差异。DMPP处理的AOB群落结构的变化从10 d开始显现,至50 d和90 d时仍保持明显的抑制状态,而DCD处理则至90 d时抑制作用基本消失。单施尿素AOB功能基因(amo A)的丰度均显著高于硝化抑制剂处理(90 d时尿素+10%DCD处理除外);在整个培养期内,尿素和对照土壤的AOA群落结构相似,硝化抑制剂反而增加了AOA功能基因的丰度,表明硝化抑制剂对AOA丰度无明显抑制作用。即两种硝化抑制剂主要通过抑制AOB起作用;调节土壤p H至中性范围,并在1%DMPP施用条件下,硝化抑制剂的抑制效果最显著。     

聚天门冬氨酸尿素对稻田田面水氮素浓度及产量的影响

为揭示聚天门冬氨酸尿素在水稻上的施用效果,特别是降低田面水中氮素浓度、防控水稻氮素面源污染的效果,采用田间小区试验,对聚天门冬氨酸尿素对水稻产量、吸氮量、田面水中氮素形态及浓度的影响进行研究。结果表明:与普通尿素处理相比,聚天门冬氨酸尿素处理的水稻籽粒产量和吸氮量分别增加 2.9%和10.5%,且有一定的增加单穗实粒数和千粒重的作用。聚天门冬氨酸尿素处理施肥后初期(基肥后 1～7 d,分蘖肥后 1～5 d,穗肥后 1～3 d)田面水中 TN、NH 4+-N、NO^3--N的平均浓度分别比普通尿素处理低 10.6%、11.1%、5.4%,但二者田面水中TN、NH 4+-N、NO^3--N浓度的动态变化规律基本一致,且二者田面水中NH 4+-N/TN、NO^3--N/TN没有差异。因此,聚天门冬氨酸尿素对水稻有一定的增产和促进氮素吸收的作用,同时会降低稻田田面水中氮素浓度,是一种可以用于防控稻田氮素流失,并能保障水稻产量的新型肥料。     

脲酶/硝化抑制剂对尿素氮在白浆土中转化的影响

采用室内恒温培养方法,研究了脲酶抑制剂（NBPT）、硝化抑制剂（DMPP）及其协同对尿素氮在三江平原白浆土中转化作用效果。研究表明,在白浆土中NBPT有效作用时间小于13 d,作用时间较在棕壤和黑土中短;对土壤中铵态氮、硝态氮及表观硝化率影响与普通尿素基本一致。NBPT与DMPP组合缓释尿素施入4-7 d,能够有效抑制脲酶活性,减缓尿素水解;只添加DMPP与添加NBPT与DMPP协同作用对抑制铵态氮硝化作用效果相同,二者能保持土壤中NH4+-N高含量时间超过80 d。DMPP作用时间可达80 d以上,能有效抑制NH4+-N向NO3--N的转化;在第80 d,土壤中仍有54.58%～56.85%的氮以铵态氮形式存在,表观硝化率只有50%左右。DMPP抑制硝化作用效果十分显著,因此,在白浆土中施用添加NBPT缓释尿素、DMPP缓释尿素、NBPT与DMPP缓释尿素时,应首选添加1%DMPP的缓释尿素肥料。     

北方土石山区横坡垄作坡面土壤氮的空间分布特征

横坡垄作是坡耕地广泛采用的水土保持措施,垄沟内雨水的汇聚和泥沙沉积,使得土壤氮的空间分布特征明显有别于传统耕作坡面。以北方土石山区横坡垄作坡面为研究对象,样带法采集土壤样品,基于经典统计、地统计学、Kriging插值等方法,分析垄面、垄沟等特征点位全氮(TN)、硝态氮(NO^3--N)、铵态氮(NH4+-N)含量沿坡位变化及其剖面分布,明晰横坡垄作坡面土壤氮的空间分布特征。结果表明:北方土石山区土壤氮含量属于中低水平,变异系数介于17.64%～33.60%,但垄面土壤氮的变异水平高于垄沟。TN含量沿坡位的变异最为显著,表现为坡下>坡脚>坡中>坡上;仅垄沟NO^3--N、NH4+-N含量沿坡位存在显著变化,坡脚NO^3--N、NH4+-N含量较其他坡位显著增加66.30%～83.85%。垄面与垄沟间氮含量的差异在坡上、坡下和坡脚体现的较为明显;与垄沟相比,垄面坡上TN含量减少21.34%,坡脚NO^3--N和NH4+-N含量减少17.42%～37.47%,坡下土壤氮含量增加21.56%～38.16%。TN剖面分布与坡位和特征点位有关,NO^3--N、NH4+-N的剖面分布主要受控于特征点位,但氮含量剖面分布符合指数函数关系。综上,横坡垄作坡面土壤氮空间异质性明显,且主要受控于特征点位和坡位。研究结果可为提高横坡垄作措施下氮肥利用效率、精准农业的顺利推广提供技术支撑。     

脲酶/硝化抑制剂双控下红壤性水稻土氮素变化特征

以红壤性水稻土为对象,设置大田试验处理:不施肥(CK)、单施氮肥(U)、氮肥配施0. 5%脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)与1%硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)(U+N/D)、氮肥配施1%NBPT与2%DMPP [U+2 (N/D)],研究4种施肥组合下双季稻土壤脲酶、土壤NH+4-N、田面水NH+4-N和NO-3-N的变化特征。结果表明,与CK和U处理相比,各施肥处理在施肥后第1～15 d,土壤脲酶活性、土壤NH+4-N、田面水NH+4-N含量增加,田面水NO-3-N含量无显著变化。与U+2 (N/D)处理相比,早稻中U+N/D处理的脲酶活性显著增加了0. 03～0. 70 mg·g-1,土壤NH+4-N含量显著增加了19. 11～61. 44 mg·kg-1,田面水NH+4-N含量显著增加了34. 48～40. 70 mg·L-1。相关分析表明,土壤NH+4-N与土壤脲酶、田面水NH+4-N均呈显著负相关,田面水NH+4-N与土壤脲酶、田面水NO-3-N均呈显著正相关(P 0. 05)。综上,与其他处理相比,U+N/D处理是在短期内有效提高土壤脲酶活性、土壤NH+4-N和田面水NH+4-N含量的最优处理,合理配施尿素及0. 5%脲酶抑制剂NBPT和1%硝化抑制剂DMPP能够显著提高NH+4-N供水稻吸收,减少氮素损失。     

两种硝化抑制剂在不同土壤中的效果比较

采用室内培养试验,比较了两种硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)和双氰胺(DCD)在4种典型农田土壤(水稻土、潮土、黑土、红壤)中的抑制效果。结果表明,在培养期内土壤pH和NH4+-N呈先上升后下降的趋势,NO3--N和表观硝化率呈逐渐上升的趋势。与单施尿素处理(U)相比,添加硝化抑制剂显著增加了土壤NH4+-N含量,降低了NO3--N含量,表观硝化率表现为UU+DMPPU+DCD。在水稻土和潮土中,单施尿素处理的硝化过程到第14天时基本完成,添加硝化抑制剂使硝化过程延长了至少28天。在黑土和红壤中,尤其是在红壤中,硝化过程相对缓慢,施用抑制剂虽然降低了土壤的表观硝化率,但降低的程度低于水稻土和潮土。总之,在推荐用量下10%DCD的硝化抑制效果优于1%DMPP,且这两种抑制剂在不同土壤中的抑制效果不同。     

肥液浓度对单膜孔入渗NO-3-N运移特性影响的室内试验研究

该文通过室内入渗试验，研究了不同浓度的单膜孔肥液入渗NO^-₃-N的分布特性。研究表明：不同浓度的膜孔肥液入渗土壤NO^-₃-N浓度的湿润锋运移距离与土壤水分运动的湿润锋一致；肥液浓度越大，相同入渗时间的NO^-₃-N浓度锋运移距离越大，土壤剖面NO^-₃-N浓度最大值越大，相同深度处土壤NO^-₃-N浓度也越大。肥液入渗土壤NO^-₃-N浓度分布特征与湿润体深度符合分段函数模型。供水入渗过程中，NO^-₃-N浓度锋运移距离和浓度最大值均随时间的延长而增大；再分布过程中，NO^-₃-N浓度锋运移距离继续增大，而NO^-₃-N浓度最大值逐渐减小。     

不同氮肥在石灰性潮土中的转化及ATS对尿素氮转化的调控效应

根据氮肥施入土壤后的转化特性进行氮肥的高效调控和管理是提高氮肥利用效率、缓解氮肥污染的重要措施。为探究不同氮肥在石灰性潮土中的转化特性差异及硫代硫酸铵（ammonium thiosulfate，ATS）作为氮肥调控剂对尿素氮转化的影响，该研究采用室内土壤培养（土壤水分含量为田间持水量的60%，温度25 ℃）试验方法，以尿素、硫酸铵、氯化铵和ATS作为供试肥料，比较4种氮肥施入石灰性潮土后的转化特性差异，并以ATS作为氮素调控剂，以单施尿素作为对照，探究尿素配施不同用量ATS对尿素氮转化的影响。结果表明，4种供试氮肥在石灰性潮土中的转化过程明显不同。尿素在石灰性潮土中的水解速率最快，硝化作用强度也最高，硫酸铵其次；氯化铵由于Cl^-的硝化抑制作用，土壤表观硝化率在7～21 d显著低于尿素和硫酸铵（P＜0.05）；ATS施入土壤后，NH₄⁺-N转化为NO₂^--N的速率最高，而NO₂^--N转化为NO₃^--N的速率最低，NH₄⁺-N在土壤中的存留时间最长，出现峰值之后也一直保持最高的含量，表观硝化率最低。将ATS作为氮素调控剂与尿素配合施用，当其用量在60 mg/kg（含S量）以上时，既表现出了明显的抑制尿素水解的作用效果，也表现出了显著的硝化抑制作用（ P <0.05），且随着ATS用量的增加，抑制效应明显增强。这对于减少氮素损失，提高氮肥利用效率具有积极意义。但供试4种氮肥施入土壤后均出现了亚硝酸盐的累积，其中ATS处理的累积量显著高于尿素、硫酸铵和氯化铵（P＜0.05），累积持续时间也最长。ATS作为氮素调控剂调控氮素转化，也出现了类似的结果，且随着ATS用量增加，亚硝酸盐在土壤中存留时间明显延长，含量和峰值明显提高，出现峰值的时间也明显延后。     

几种硝化抑制剂和包硫尿素(SCU)对土壤N素形态和小麦产量的影响

采用土壤盆栽法,研究了双氰胺(DCD)、硫脲(THU)和硫脲甲醛树脂(TFR)以及包硫尿素(SCU)对土壤氮素形态和小麦产量的影响。试验共设不施氮(CK)、单施尿素、包硫尿素(SCU)、以及尿素分别与DCD、THA、TUF的3个浓度梯度(分别按尿素用量的0.5%、1%、2%)配合施用共12个处理。结果表明:随添加浓度的增加,硝化抑制作用逐渐增强,高剂量硝化抑制剂显著降低土壤NO-3-N含量,在2%添加浓度下,DCD、THU、TFR的土壤NO-3-N浓度分别比单施尿素降低29%、22%和14%,对土壤表观硝化率的抑制强度也是2%DCD2%THU2%TFR;SCU处理与2%DCD作用强度接近,且在施用早期就体现抑制效果,并在追肥后第74 d土壤表观硝化率显著低于使用硝化抑制剂的处理(P0.05);硝化抑制剂和SCU都可以使土壤NH+4-N含量稳定在较高的水平,抑制剂用量越多,土壤NH+4-N含量越高;与单施尿素相比,尿素+DCD模式,均可提高小麦产量,且在0.5%、1%、2%添加浓度,都达到显著水平(P0.05);THU在1.0%和2.0%添加浓度,小麦产量显著高于单施尿素,但增产效果次于DCD。总体上,包硫尿素(SCU)比硝化抑制剂在控释氮素方面效果更持久,而3种硝化抑制剂中,在控制土壤NH+4-N转化、土壤硝化抑制方面,DCD和THU优于TFR;作为外源添加物的抑制剂长期应用可能对土壤环境造成潜在的危害,不同硝化抑制在土壤中的形态归趋和长期作用还有待进一步研究。     

Accumulation of copper in soils and leaves of tomato plants in greenhouses in Turkey

Copper (Cu)‐containing fertilizers, fungicides, and bactericides has been used extensively in the greenhouses in the Antalya province in recent decades with the use of such materials tending to increase year by year. The level of DTPA‐extractable Cu was determined in 210 soils (0–20 and 20–40 cm depth) and 105 leaf samples obtained from 105 tomato greenhouses. The DTPA‐extractable Cu contents of the soils taken from the 0–20 depth ranged between 0.76 and 88.03 mg kg^‐1 (mean 7.79 mg kg^‐1). The percentage of soils containing DTPA‐extractable Cu greater than the critical toxicity level (20 mg kg^‐1) was 8.1. The Cu content of tomato leaf samples ranged between 2.4 and 1,490 mg kg^‐1 (mean 166.5 mg kg^‐1). The Cu concentration in leaf samples was very high due to the intensive use of foliar applied Cu‐containing chemicals. As a consequence, 24.8% of the leaf tomato samples analyzed contained over 200 mg Cu kg^‐1, the maximum accepted tolerance level. Therefore, it may be necessary to reduce the use of Cu‐containing pesticides and fertilizers, or at least reduce the amount of Cu‐containing fertilizers being used in those greenhouses where Cu‐containing pesticides have been or are being used.     

Role of selenium in mitigation of cadmium toxicity in pepper grown in hydroponic condition

Selenium (Se) is an essential element for humans but is not considered as essential for plants. However, its beneficial role in improving plant growth and stress tolerances is well established. In order to study the role of Se in cadmium (Cd) toxicity in pepper (Capsicum frutescens cv. Suryankhi Cluster), this experiment was carried out in greenhouse conditions. Treatments comprised Cd [0, 0.25, and 0.5 mM cadmium chloride (CdCl₂)] and Se [0, 3, and 7 µM sodium selenite (Na₂SeO₃)] with three replications. The result showed that Cd decreased chlorophyll a, chlorophyll b, and carotenoids, whereas Se supplementation diminished Cd toxicity on photosynthetic pigment. Selenium at 7 µM significantly increased the leaf area in the plants grown at 0.25 mM Cd. The application of Se at 3 µM with 0.25 mM Cd and Se at 3 µM and Se at 7 µM with 0.5 mM Cd increased the activity of catalase (CAT). Selenium at 7 µM decreased the proline content of pepper leaves exposed to Cd at 0.5 mM (30%). Selenium significantly enhanced the antioxidant activity of leaves, which was diminished by Cd toxicity. In general, Se has a beneficial effect on plant growth and is an antioxidant enzyme of pepper cv. Suryankhi Cluster under Cd stress and non-stress conditions.     

红壤区不同肥力水稻土根际硝化作用特征

通过根际培养箱(三室)——速冻切片技术研究了红壤地区高、低两种肥力下水稻苗期根表、根际和土体土壤矿质态氮含量和硝化强度,以及水稻生长、氮素积累的差异。结果表明,肥力水平对水稻根表和根际土壤铵态氮(NH4+-N)含量无显著影响,但高肥力显著提高土体土壤NH4+-N含量,以及根表、根际和土体土壤硝态氮(NO3--N)含量及硝化强度。两种肥力水稻土硝化强度最大值均出现在距根表2 mm处,分别为0.20和0.31μmol kg-1 h-1。土体土壤硝化强度随距根表距离增加而降低,低肥力土壤在距根表10～40mm处时硝化强度接近本底值,而高肥力土壤在距根表20～40 mm处时接近本底值。与不种水稻的CK相比,种植水稻显著提高根际土壤硝化强度。高肥力能显著改善水稻生长,增加植株氮素积累量,尤其显著促进根系生长及通气组织发育。由于红壤稻田肥力水平的差异造成水稻根际硝化强度以及水稻吸收NO3-的差异,导致高肥条件下水稻显示出更强的生长势和氮素吸收利用能力。因此,合理提高红壤稻田肥力水平对改善红壤区水稻根际土壤硝化作用及水稻氮素营养具有重要意义。     

自由基在鸡肾病发生中的作用研究

肾病即急性肾小管坏死.鸡肾病在养鸡生产中极为常见,尤其近年来,鸡肾病的发生日益增多,由于其发生机制不清楚,临床治疗鸡肾病的依据不足,致使治疗效果不佳,为此,提出本研究以探讨鸡肾病的发生机制,为本病防治提供理论依据.     

Occurrence of Sexual Hormones in Sediments of Mangrove in Brazil

The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-??-estradiol (E2), and 17-??-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75?±?3.89 ng/g. E2 was also found, with its concentration ranging from 0.90?±?0.03 to 39.77?±?1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO₂ and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic.     

Meta-analysis in the Selection of Groups in Varieties of Citrus

Brazil is the largest producer of oranges (Citrus sinensis) in the world. The nutrient management of tree orchards is designed from experiments with a limited number of varieties. This knowledge is transferred to other varieties by diagnosing tissue nutrient composition and tree demand. Compositional data analysis has been first applied to tissue analysis of agricultural crops using centered log ratios with compositional nutrient diagnosis (CND-clr). The isometric log ratio (ilr) transformation is a new approach based on binary nutrient ratios and the principle of orthogonality (CND-ilr). We analyzed eleven nutrients: nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) in leaf tissue samples across 108 commercial plots (thirty-one grow Valencia, twenty-two Hamlim, twenty Pera, and thirty-five Natal). Nutrients were partitioned between macro- and micronutrients as well as anionic and cationic species. The effect size of varieties over Valencia was quantified by the mean and standard deviation of ilr values across ilr coordinates. Specific varietal nutrient profiles and ilr norms were defined. The nutrient profile of orange varieties could be classified into homogeneous groups to take advantage of fertilizer trials conducted on varieties of the same group. The Aitchison distance and a perturbation vector could be instrumental for diagnostic purposes and nutrient management.     

Effect of iron-quercetin complex on reduction of nitrite in in vitro and in vivo systems

This study investigated whether reducing agents such as quercetin and iron(II) facilitate formation of nitric oxide (NO) gas from orally ingested nitrite in an vivo study. When 3 mg/kg Na (15)NO2 was orally administered to rats with or without iron(II) or quercetin, Hb (15)NO, which is indicative of systemic (15)NO, was detected in the blood, with the maximum blood concentration of Hb (15)NO at 15 min after nitrite or nitrite plus quercetin treatment, whereas after administration of nitrite plus iron(II) or nitrite plus iron(II) and quercetin, the time was shortened to 10 min. Interestingly, iron(II), quercetin, or iron(II) plus quercetin did not affect the total amount of Hb (15)NO generated from orally administered Na (15)NO2. However, the systemic nitrite concentration was significantly decreased in the presence of iron(II) or iron(II) plus quercetin. These results may indicate that iron(II) is critical to the generation of NO gas from nitrite, whereas quercetin contributed little under the in vivo experimental conditions.     

旱地果园水肥管理模式研究进展

分析了旱地果园水肥管理模式的研究进展和存在问题,指出水肥胁迫尤其是水钾已成为旱区果树高产稳产优质化的主要限制因子。在系统探讨旱地果园水分管理、养分管理、综合管理以及果树叶营养综合诊断施肥标准的基础上,提出了旱地果园的高效水肥管理模式。     

Role of aldehyde oxidase in the hepatic in vitro metabolism of 3-methylindole in pigs

The metabolism of 3-hydroxy-3-methylindolenine (HMI), a recently discovered metabolite of 3-methylindole (3MI, skatole) produced by porcine liver microsomes, was investigated in vitro using porcine liver cytosol. HMI was rapidly metabolized to a single product, 3-hydroxy-3-methyloxindole (HMOI), by porcine cytosol. By the use of the selective inhibitors menadione and quinacrine, it was shown that the enzyme responsible for the oxidation of HMI into HMOI was aldehyde oxidase (AO; aldehyde:oxygen oxidoreductase, EC 1.2.3.1). The activity of AO in the conversion of HMI to HMOI was measured in a population of pigs (n = 30) with a wide range of 3MI levels in back fat (0.07-0.30 mg/kg). AO activity was found to be negatively correlated (r = -0.70; P < 0.001) with the level of 3MI in fat. The results of the present study suggest that AO plays an important role in the metabolism of 3MI in the pig and that its catalytic activity is related to an adequate 3MI clearance.     

东北黑土土壤磷的纬向分异

以中国东北的中纬度黑土区为样带,研究了有机磷浓度与有机质、全氮浓度的关系;全磷、有机磷、无机磷及有机磷和无机磷的比率与纬度分布的关系。结果表明,有机磷和有机质、全氮浓度具有良好的相关性,它们之间的相关系数分别为0.90和0.92,呈极显著正相关(P<0.01)。全磷、有机磷、无机磷、P_o/P_i在纬度上都存在不同程度的分异规律,即随着纬度的升高,其浓度或比率均有逐渐升高的趋势;其相关系数分别为0.68、0.77、0.26和0.60,相关分析表明,这些纬向分异规律都达极显著水平(P<0.01)。除了无机磷的纬向分异原因尚不明确之外,其他纬向分异的原因可能是由于黑土南北样带气候热量上的差异和人类活动的影响所致,从而造成南北样带之间有机质的矿化程度和速率产生差异。