氮素形态在土壤中的转化及对烤烟产量的影响

 试验研究了云南省玉溪地区气候、土壤条件下,铵态氮、尿素施入土壤中的转化,使用硝化抑制剂双氰胺（DCD）研究不同形态氮及其比例对烤烟生长的影响,以及施用秸秆、油饼对烤烟生长的影响。结果表明,施入土壤中的铵态氮、尿素其水解和硝化过程约在施肥后的1个月内完成,土壤中硝态氮含量随时间逐渐下降,1个月后土壤中铵态氮、硝态氨含量都降至痕量水平;硝化抑制剂对铵态氮硝化有显著的抑制效果;铵态氮、硝态氮对烤烟产量没有影响,秸秆、油饼则显著降低烤烟产量。     

退化砂姜黑土的无机磷特性及其活性研究

通过对退化砂姜黑土的无机磷组成和活化方法进行研究，结果表明：砂姜黑土的无机磷以磷灰石（Ca10-P)和闭蓄态磷酸盐（O-P）的含量为高，分别占无机磷总量的27%-48%和26%-37%。砂姜黑土中无机磷的总量以及其中Ca2-P、Al-P、Fe-P的含量均随着土壤肥力的退化而显著降低。在退化砂姜黑土中施用有机肥，能够大幅度提高速效磷的含量，而施用含有一定旦溶磷细菌的肥料则可以在不增加全磷量的情况下，促进土壤中Ca10-P和Ca8-P等向Ca2-P、Al-P等形态无机磷的转化，从而提高土壤中速效磷的含量。     

污泥中几种重金属元素在砂土中的运移

通过土柱实验，研究了污泥中几种重金属元素Ｃｕ，Ｚｎ，Ｎｉ，Ｐｂ的运移特点和形态。实验表明，表层４ｃｍ土壤混入６％的污泥后，显著增加了Ｃｕ，Ｎｉ，Ｚｎ的淋出量，而Ｐｂ没有显著增加。淋出液中Ｃｕ，Ｎｉ几乎都是配位态重金属，Ｚｎ则有较高比例的非配位态离子。土壤对Ｃｕ＾２＋的吸附能力大于Ｚｎ＾２＋，Ｃｕ＾２＋与有机物的配位能力强于Ｚｎ＾２＋。水溶性有机物与重金属的配位反应对Ｃｕ，Ｎｉ运移影响较大。Ｚｎ的运     

土壤腐殖质氮结构的X-光电能谱研究

X－ray photoelectron spectroscopy(XPS) was applied to examine the N structures of soil humic substances and some of their analogues.It was found that for soil humic substances XPS method gave similar results as those obtained by ^15N CPMAS NMR (cross-polarization magic-angle spinning nuclear magnetic resonance) method.70%-86% of total N in soil humic substances was in the form of amide,and 6%-13% was presented as ammes,with the remaining part as heterocyclic N.There was no difference in the distribution of the forms of N between the humic substances from soils formed over hundreds or thousands of years and the newly formed ones.For fulvic acid from weathered coal and benzoquinone-(NH4)2SO4 polymer the XPS results deviated significantly from the ^15N CPMAS NMR data.     

Spatial variability of O layer thickness and humus forms under different pine beech–forest transformation stages in NE Germany

Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest‐transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15–20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) → older mixed stand (3.7 m) → pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest‐transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil‐related investigations at these sites.     

灌溉方法对保护地土壤有机氮组分及剖面分布的影响

用Bremner有机氮分组法测定了连续7年采用不同灌溉方法灌溉的保护地土壤各剖面层次有机氮组分含量。结果表明,土壤全氮及有机氮各组分含量均随土层深度的增加而降低,但有机氮各组分占全氮的比例随土层深度增加的变化却无明显规律。用3种灌溉方法灌溉,不同土层间土壤有机氮各组分含量的差异主要存在于0~50 cm土层,50 cm以下差异很小;相同土层,土壤有机态氮含量均以酸解氮为主,且酸解氮中各组分绝对含量和相对含量的大小排列顺序均为,未知态氮>氨态氮>氨基酸态氮>氨基糖态氮。在0~80 cm土层,土壤酸解氮占全氮的比例大多在58%~60%之间,只有渗灌处理0~10 cm,10~20 cm及沟灌处理0~10 cm土层酸解氮占全氮的比例较低,分别为34.21%,50.75%和48.02%;而非酸解氮占全氮的比例大多在32%~36%之间。3种灌溉方法相比较,除个别层次外,酸解氮中氨基酸态氮、氨基糖态氮及氨态氮占全氮的比例在各土层中滴灌和渗灌处理均高于沟灌处理,而酸解未知态氮和非酸解氮占全氮的比例则为沟灌处理高于滴灌和渗灌处理。     

长期施肥对酸性土壤磷形态及有效性的影响

为明确长期施肥对集约化果园土壤磷形态、分布特征及其有效性的影响，本研究对琯溪蜜柚主产区29个果园的土壤进行调查研究，采用张守敬和Jackson的酸性土壤无机磷分级方法，研究蜜柚果园土壤磷素累积对土壤磷形态及有效性的影响。结果表明：在集约化蜜柚果园中，土壤磷素累积丰富，随树龄增加土壤速效磷含量上升显著，且土壤磷形态在不同土层存在显著性差异；当全磷含量≤0.5 g/kg时，土壤磷形态主要以有机磷、铁磷为主，随着全磷含量的上升，铝磷含量、占比均显著上升；多元线性回归和逐步回归分析结果表明本试验中铝磷与速效磷相关性最好。果园土壤已经形成一个巨大的磷库，且有效性较高，可适当减少磷肥投入，降低土壤磷含量，减少经济成本，提高生态效益。     

不同氮素形态及比例对烤烟长势、产量及部分品质因素的影响

在湖南浏阳,运用田间小区试验研究了硝态氮、铵态氮比例(RN)对烤烟田间长势与产量以及部分品质因素的影响。结果表明:1)RN对烤烟的农艺性状、产量、产值、均价等没有明显影响,而对烤烟的等级结构、内在化学成分含量、氮、钾、氯的吸收量有着显著影响,可以用显著的二次多项式模型或直线相关方程描述产值、均价、上等烟产量、下等烟产量等经济性状以及烟碱、总氮、钾、还原糖、氯、淀粉、挥发碱等内在化学成分的含量与铵态氮份额之间的关系;2)RN为75%∶25%时,中上等烟比例、烟碱、总氮、钾、钾氯比、氮吸收量最高,挥发碱含量最低。RN为25%∶75%时,挥发碱含量最高,总氮、淀粉含量最低。100%铵态氮时,还原糖、氯含量、淀粉的含量最高,碱、钾、钾氯比最低,同时显著地降低烤烟的等级结构。100%硝态氮时,总氮、钾、氯在烟叶中的含量最低,吸收总量也最少,同时产量、产值、均价也处于最低水平;3)本试验的任何RN下,烟碱、总氮、钾、氯、淀粉的含量均符合优质烟叶要求,而还原糖相反。综合考虑经济效益、养分利用率和烟叶内在化学成分的协调性,整体上RN为54%∶46%～50%∶50%较好。     

数字化制图系统(MAPGIS)制作土壤图技巧研究

总结了MAPGIS制图的2个小技巧。一是利用注释赋为属性以及1able合并功能实现对大批量区块进行快速、准确的赋色,从而提高制取土壤图速度;二是介绍了在MAPGIS任何运用简单的报表定义功能快速实现在土壤图或土地开发整理规划图中实现表格的快速生成。     

氮肥形态与大白菜产量及硝酸盐累积的关系

通过田间试验研究了不同形态氮肥对大白菜产量及硝酸盐累积的影响。结果表明 ,大白菜施用尿素比习惯施用碳酸铵更有利于获得高产 ,大颗粒尿素优于普通尿素 ,且净菜产量高。随氮肥追肥量增加 ,大白菜内叶硝酸盐含量增加 ,外叶则维持在一定水平上 ,大白菜外叶硝酸盐含量高于内叶。大量施用氮肥不仅产量低 ,净菜率低 ,而且使大白菜外叶硝酸盐累积水平高 ,并使土体中残留大量硝酸盐。