Characterization of Soil Available Nitrogen in the Major Vegetable Production Areas of Pearl River Delta,China

A macro scale survey was performed to investigate the content of soil available nitrogen （N） and its spatial distribution in the main vegetable production areas of the Pearl River Delta.Preliminary enrichment-deficient index of available N was then developed,which was a base for increasing fertilizer application efficiency and vegetable yield as well as for constructing soil testing and fertilizing formula.In general,most of the vegetable growth areas in Pearl River Delta were N-deficient or medium-N-deficient.There was 30%-62% increase in yield of Chinese cabbage on the N-deficient soil after application of N; when soil available N content was less than 145 mg/kg,the yield increased with application of N fertilizer at a rate of 60-70 kg/hm^2.     

吉林西部土壤微量营养元素有效量及其影响因素

通过对吉林西部3个工作区土样的微量营养元素全量、有效量以及土壤pH值和有机质含量的测定,分析了土壤微量营养元素有效量特征及其影响因素结果表明,吉林西部有效B基本不缺乏;有效Mn含量极丰富;有效Cu含量农安极丰富,明显高于其它2区,大安有效Cu含量样点间差异较大;土壤有效Zn基本不缺乏;有效Mo严重缺乏,且地区差异性较大;吉林西部有效Fe含量极丰富.土壤有效Mn、Cu和Fe含量受全量控制;B、Zn 元素有效量受土壤pH值的制约;土壤有机质则与有效Mn和Fe呈极显著正相关. Abstract： Based on the assay of the total content and available content of the trace nutrient elements and the soil pH and organic matter of the soil samples,the characteristic of the available content of the trace nutrient elements and their affecting factors are studied.The results show that the available B in western Jilin is in a middle level,the content in Nong'an is higher than that in the others;the available Mn is extremely abundant;the available Cu in Nong'an is obviously higher than other areas,and the content in Da'an differs greatly;the available Zn is in a middle level;the severe shortage of available Mo differs between different areas;and the available Fe is extremely abundant.The available Mn,Cu and Fe have significantly positive correlation with their total content;the available B has significantly positive correlation with pH,and Zn has obviously negative correlation with pH;the available Mn and Fe had significantly positive correlation with soil organic matter.     

高氯酸盐与铬复合污染对水稻幼苗生长的影响

通过营养液沙培盆栽试验,研究了水稻幼苗的根长、株高和鲜重对高氯酸盐(ClO4-)、六价铬(Cr6+)及其复合污染(ClO4-+Cr6+)胁迫的响应。结果表明,随着污染物处理浓度的提高,ClO4-、Cr6+和ClO4-+Cr6+对水稻幼苗主要生长指标根长、株高和鲜重的抑制作用越明显,呈现出明显的浓度-效应关系;在同一浓度下,ClO4-、Cr6+和ClO4-+Cr6+对水稻幼苗根长、株高和鲜重的抑制率呈明显的时间-效应关系,处理时间越长,抑制率越高;复合污染对水稻生长的抑制效应大于其中任一污染物在同浓度条件下的单一污染的影响,且随着浓度和时间的增加,抑制作用也越明显;复合污染对水稻幼苗生长的交互作用类型因处理时间和浓度组合的不同而更趋复杂。     

氧化铁试纸法测定暗棕壤中有效磷

[目的]研究用氧化铁试纸法测定暗棕壤中有效磷的可行性。[方法]利用氧化铁试纸对4种暗棕壤中的有效磷进行测定,同时研究氧化铁试纸的载荷量和最佳吸附时间,并通过氧化铁试纸2种测定方法（直接浸提法和直接插入法）与传统双酸法的测定结果进行相关分析。[结果]该研究所制氧化铁试纸的最大吸磷容量可达每条520μg左右,最佳吸附时间为24h;氧化铁试纸法仅能吸附土壤溶液中很少一部分磷,但能很好地反映植物真实的吸磷情况。不同测定方法的相关性分析表明,氧化铁试纸直接浸提法和直接插入法所测定结果均与双酸法的高度正相关,相关系数分别为0.9795和0.8824,说明氧化铁试纸能够正确评价土壤有效磷状况。[结论]氧化铁试纸可以用于暗棕壤有效磷的测定。     

不同产田土壤速效磷钾供应能力研究

采用田间试验法,探讨了容城县冬小麦高、中、低产田土壤速效磷钾的供肥能力。结果表明:高、中、低产田土壤磷素贡献率分别为82.37%、90.36%和84.82%,土壤钾素贡献率分别为88.68%、85.89%和87.05%;土壤的供磷能力分别为67.64 kg/hm2、63.75 kg/hm2和57.11 kg/hm2,土壤的供钾能力分别为145.64 kg/hm2、121.19 kg/hm2和117.22 kg/hm2。表明该区土壤中的磷钾不是限制冬小麦产量的主要因素。     

一种复方聚维酮碘凝胶有效碘稳定性研究

制备复方聚维酮碘凝胶,研究一种对复方聚维酮碘凝胶中有效碘含量影响相对较小的配方。采用正交试验法筛选复方聚维酮碘凝胶的最佳配方;以各温度项下有效碘质量浓度的自然对数（lgC）对时间（t）做线性回归分析,得到直线方程,推算出贮存期。结果表明,制备的凝胶剂均匀细腻,筛选出复方聚维酮碘凝胶最佳配方为：100 g复方聚维酮碘凝胶中氢氧化钠0.075g,4%聚维酮碘3.75 g,碘酸钾0.50 g,丙二醇10 g。各温度条件下加热时间与有效碘质量浓度对数变化线性关系良好,25℃时贮存期为799 d。     

贺兰山西坡不同海拔梯度上土壤-植物系统磷相关性的研究

以阿拉善左旗境内贺兰山中段(西坡)及其山前地带主要草地类型为研究对象,于2004年7～8月沿贺兰山中段西坡以海拔高度、草地类型、土壤类型和草地利用方式等因素为指标分别在亚高山草甸、荒漠化草原和草原化荒漠上设置了5个调查样地,在各样地上对土壤全磷、速效磷、植被空间变异特征、植物含磷量以及土壤的理化性质等进行了系统的野外植物营养学试验和室内分析研究。结果得出:在海拔1 370～2 940 m,土壤全鳞、速效磷含量随海拔高度的降低而降低。回归分析显示,土壤速效磷与土壤含水量、全磷、全氮、有机质、群落中植物密度、地上生物量、盖度之间呈极显著正相关,与土壤容重、pH值呈极显著负相关。研究区植物群落的组成具有明显地带性垂直分布的规律,随着海拔的降低,各样地植被的物种组成和优势种均有较大的差异,其中,Ⅰ样地优势种为矮生嵩草和珠芽蓼;Ⅱ样地为沙生针茅和冷蒿;Ⅲ样地为沙生针茅、糙隐子草和珍珠柴;Ⅳ样地为小画眉草、狗尾草和霸王;Ⅴ样地为黄蒿和小叶锦鸡儿。     

Comparison of soil depths between evergreen and deciduous forests as a determinant of their distribution, Northeast Thailand

In several areas in Northeast Thailand, evergreen and deciduous forests coexist under uniform terrain and climatic conditions. We compared depth and physical properties of soils between evergreen and deciduous forests in the Sakaerat Environmental Research Station to clarify what factor determines their distribution. The averaged soil depths were 79 ± 27 cm and 135 ± 58 cm in the deciduous and evergreen forests, respectively. The soils in the deciduous forests were relatively coarser in soil texture than those in the evergreen forests, particularly in the surface layers. The average available water capacity of the solum was lower in the deciduous forest soils (78 mm) than in the evergreen forest soils (123 mm). Compared with the evapotranspiration from the evergreen forest in the study area, the available water capacity of the evergreen forest soil was almost the same as the water deficit during the dry season (November–February), while that of the deciduous forest soil was lower and insufficient to maintain the evapotranspiration. These results suggest that the distribution of deciduous and evergreen forests in the study area was associated with soil water availability, which mainly depends on soil depth.     

鸡粪和化学肥料配施对砂质梨园土壤有效养分的影响

在条山农场进行了追施不同肥料对砂质梨园土壤有效养分影响的研究,结果表明:梨园单一追施鸡粪和化学肥料或是鸡粪和化学肥料配施,土壤有效氮磷钾含量均显著高于不施肥料土壤,其中以每棵梨树追施25 kg鸡粪+0.435 kg尿素+0.272 kg磷酸二铵+0.47 kg硫酸钾[m(氮)∶m(磷)∶m(钾)=2∶1∶2]后土壤中的氮磷钾含量最高.当单一追施鸡粪和化学肥料或当鸡粪与化肥配施时化学肥料中氮磷钾的配比为1∶1∶1和2∶1∶1时,土壤有效养分增长的顺序为有效氮＞有效钾＞有效磷,当鸡粪和化肥配施时化学肥料中氮磷钾的配比为2∶1∶2时,土壤中有效养分的增幅为有效氮＞有效磷＞有效钾.     

吡啶甲酸铬对新生仔猪原代肝细胞氧化作用的影响

 【目的】研究不同剂量吡啶甲酸铬（CrPic）对新生仔猪原代肝细胞氧化作用的影响。【方法】选用3日龄新生仔猪作为细胞供体,用剪切消化法分离肝细胞,分别用0、8、200、400 μmol?L-1的吡啶甲酸铬处理细胞48 h,研究吡啶甲酸铬对细胞内活性氧（ROS）水平、丙二醛（MDA）的含量、培养上清液中乳酸脱氢酶（LDH）活性以及对细胞DNA单链断裂(彗星试验)的影响。【结果】与对照组相比,各处理组ROS水平、LDH活力和彗星试验指标无显著差异（P＞0.05）,8 μmol?L-1组MDA含量显著降低（P＜0.05）;与8 μmol?L-1组相比,400 μmol?L-1处理组ROS、MDA、LDH和DNA损伤程度均显著升高(P＜0.05),随着吡啶甲酸铬添加水平的升高,ROS、LDH分别呈先下降后上升的二次曲线型变化趋势（P＜0.05）。【结论】体外条件下适量的吡啶甲酸铬能抑制肝细胞内脂质过氧化物的生成,增强猪肝细胞的抗氧化能力;400 μmol?L-1吡啶甲酸铬对猪肝细胞无抗氧化作用,也不会引起肝细胞的氧化损伤。