南亚热带森林演替过程土壤水分、有机质和交换性阳离子的变化格局

Information on the distribution patterns of soil water content （SWC）, soil organic matter （SOM）, and soil exchangeable cations （SEC） is important for managing forest ecosystems in a sustainable manner. This study investigated how SWC, SOM, and SEC were influenced in forests along a successional gradient, including a regional climax （monsoon evergreen broad-leaved forest, or MEBF）, a transitional forest （coniferous and broad-leaved mixed forest, or MF）, and a pioneer forest （coniferous Masson pine （Pinus rnassoniana） forest, or MPF） of the Dinghushan Biosphere Reserve in the subtropical region of southern China. SWC, SOM, and SEC excluding Ca^2＋ were found to increase in the soil during forest succession, being highest in the top soil layer （0 to 15 cm depth） except for Na^＋. The differences between soil layers were largest in MF. This finding also suggested that the nutrients were enriched in the topsoil when they became increasingly scarce in the soil. There were no significant differences （P = 0.05） among SWC, SOM, and SEC. A linear, positive correlation was found between SWC and SOM. The correlation between SOM and cation exchange capacity （CEC） was statistically significant, which agreed with the theory that the most important factor determining SEC is SOM. The ratio of K^＋ to Na^＋ in the topsoil was about a half of that in the plants of each forest. MF had the lowest exchangeable Ca^2＋ concentration among the three forests and Ca^2＋：K^＋ in MPF was two times higher than that in MF. Understanding the changes of SWC, SOM, and CEC during forest succession would be of great help in protecting all three forests in southern China.     

Changes in potassium availability and other soil properties due to soil ingestion by earthworms

An incubation experiment was conducted to study the changes that occur in potassium availability and other soil properties with ingestion of soil by earthworms. Two soils were used. Raumai soil with high non-exchangeable K and Milson soil with low non-exchangeable K were incubated with two species of earthworm, Aporrectodea caliginosa and Lumbricus rubellus, for 8 weeks. The casts and soil samples were analysed for exchangeable K, Ca, Mg, Na, and H, pH, organic C, and texture. The results indicated that in Raumai soil, the exchangeable K levels of the casts of both earthworm species were significantly higher than for the control soil, the effect being more marked for L. rubellus than for A. caliginosa. In Milson soil, the exchangeable K levels were significantly lower in the casts of both types of earthworm than in the control soil. The nitric acid-extractable K of the soil and casts was not markedly different for either soil type, but available non-exchangeable K values were significantly higher for the casts of L. rubellus from Milson soil than for the noningested Milson soil. In Raumai soil, the exchangeable Ca was higher in the casts of L. rubellus, exchangeable Mg and H were reduced, and exchangeable Na did not change markedly in the cast compared to the control soil. For Milson soil, the casts contained lower exchangeable Ca and H but higher Na and Mg than the control. The casts of both species of earthworm had significantly higher pH values for both soil types. There was no marked difference in the organic C content of the control soil and cast samples for Milson but a reduction in the casts of A. caliginosa for the Raumai soil. Finer fractions increased in the casts of both earthworm species in both soil types.     

长期施用牛粪对松嫩平原盐渍化土壤脱盐碱化效果的影响

为了探究施用有机肥对盐碱土壤脱盐效果的长期效应,以腐熟牛粪为改良材料,根据牛粪施用年限共设置4个处理,分别为：施用牛粪8,12,18 a,以未施用牛粪的作为对照。通过对土壤可溶性盐分组成、交换性盐基、有机质、容重、EC和pH值等指标的测定,定量化探讨牛粪对各个指标影响及其关系,阐明长期施用牛粪对盐碱土脱盐效果的影响。结果表明,长期施用牛粪显著降低了土壤HCO₃^-的含量,消除了CO₃^2-;降低了土壤容重,增加了土壤孔隙度和土壤有机质;降低了Na⁺含量,增加了土壤交换性Ca²⁺、可溶性K⁺和Mg²⁺含量。相关性分析表明：土壤ESP和pH值与交换性Na⁺、HCO₃^-和CO₃^2-含量呈显著正相关,土壤pH值与土壤有机质呈显著负相关关系。回归分析表明：影响钠吸附比的主要因素是可溶性Mg²⁺,其...     

模拟酸雨下生物炭添加对土壤盐基离子淋失的影响

通过室内土柱试验,研究模拟酸雨淋洗下添加生物炭对土壤交换性盐基离子(Ca^2+、Mg^2+、K^+、Na^+)的影响。采用双因素全面试验法,在pH值3.5、5.6和7.0的3种模拟酸雨条件下,设置0、0.5%、1%和2%的4个生物炭添加量,测定淋出液及淋洗后土壤中4种盐基离子含量。结果表明:酸雨淋洗条件下,与无生物炭处理相比,较高生物炭添加量(2%和1%)会增加盐基离子的淋失总量。同一处理淋出液中,Ca^2+的淋失总量最大,Mg2+最易淋失。相同生物炭添加量下,4种盐基离子淋出总量均随淋洗液pH值升高而降低,淋洗液pH值为3.5时各盐基离子的淋出总量均最高;相同pH值淋洗液下,Ca^2+、Mg^2+、K^+的淋出总量为2%生物炭>1%生物炭>无生物炭处理>0.5%生物炭,而Na^+的淋出总量为2%生物炭>无生物炭处理>1%生物炭>0.5%生物炭。在酸雨淋洗条件下,与无生物炭处理相比,添加生物炭的处理可提高土壤pH值及交换性盐基离子的含量,生物炭添加量为2%时对土壤交换性盐基离子的提升效果最佳。淋洗后各处理土壤中4种盐基离子含量表现为Ca^2+>K^+>Mg^2+>Na^+。研究表明,在生物炭添加下,酸沉降同样会加剧土壤盐基离子的淋洗损失。与无生物炭处理相比,模拟酸雨条件下,生物炭添加量增加提高了pH值及盐基离子含量,其中以添加2%生物炭的处理效果最佳。     

茶树根际土壤性质及氮肥的影响

本文报导了对盆栽茶树根际土壤性质的研究结果。经外力抖落后仍粘在根系上的土壤作为根际土壤,其余土壤为非根际土壤。施氮显著降低土壤pH、交换性K、Ca、Mg含量和盐基饱和度,增加水溶性铝、有机交换态铝和吸附羟基态铝的含量。与非根际土壤相比,根际土壤pH、交换性Ca、Mg和盐基饱和度明显降低,而交换性K高于非根际土壤。根际土壤的水溶性铝、交换性铝、交换性铝饱和度和吸附羟基态铝的含量显著高于非根际土。上述结果说明茶树根际土壤明显酸化,增强了土壤铝有效度。铝在茶树根际微域环境中的这种变化,可能在茶树吸收铝的过程中起着重要作用。     

Calcium accumulation alleviates soil acidification in Japanese cedar (Cryptomeria japonica) stands

Based on chemical and mechanical compositions and quartz content of red and/or yellow colored soil materials in the southwestern part of Japan, lithology index (LI) and weathering index (WI) were derived using a multivariate statistical method (factor analysis). The variables used for factor analysis are Fe₂O₃/Al₂O₃, TiO₂/Al₂O₃, Fe₂O₃+Al₂O₃+Quartz, Si(non-quartz)/(Fe₂O₃ + Al₂O₃), CaO + MgO + K₂O₃, MgO/K₂O₃ and Quartz/Sand, all of which represent certain different aspects of weathering and/or Iithological characteristics. Since LI and WI are mutually independent, it is possible to evaluate the effect of the degree of weathering on the characteristics of red and/or yellow colored soil materials independently from that of lithology.     

Reappraisal of methods of application of nitrogen and phosphorus at sowing on the yield,grain protein content and nitrogen economy of malting barley in Sweden

Abstract

To compare the relative efficiency of different fertilisation strategies, malting barley was fertilised with calcium ammonium nitrate (CAN) or compound ammonium nitrate with phosphorus (NP) applied in two ways: broadcast and harrowed into the seedbed before seeding or banded using the Scandinavian combi-drill design, with the fertiliser between every second seed row, and 40 mm below. A fixed nitrogen level (120 kg N ha^?1) was used, giving four fertiliser treatments. Eleven experiments were carried out the years 1992–1994, with latitudes 55° 55′ N as southern and 59° 36′ N as northern limit. Fertiliser-use efficiency, defined as grain yield, or grain nitrogen yield, per unit of applied N, was strongly affected by the treatments: values for combi-drilled were higher than for broadcast fertiliser and higher for NP than for CAN, with the effects being additive. The best treatment, using both banding and NP, resulted, as a mean of all trials, in a grain yield increase of 939 kg ha^?1 at 15% moisture content, or a nitrogen yield increase of 18 kg nitrogen ha^?1 compared with the poorest, using broadcast CAN. The N combi-drill effect was expected to be dependent on water availability, but this could not be confirmed when accumulated rainfall during crop establishment was used as test variable. The combi-drill effect was strongest in places where major extractable cations were abundant, possible explanations for this are discussed. Application of P to the crop and the use of combi-drill are recommended for malting barley fertilisation in Sweden.     

典型喀斯特林地土壤养分空间变异的影响因素

为了探明喀斯特森林生态系统土壤养分空间异质性的成因及其对养分生物地球化学过程的指示意义,该研究以广西木论国家级自然保护区典型喀斯特峰丛洼地为研究对象,利用地统计学和经典统计方法分析了土壤养分的空间变异特征,并探讨了其主要影响因子。结果表明,研究区土壤有机碳(SOC)和全氮(TN)的块金值/基台值较大,分别为49.9%和28.6%,表现为中等程度的空间自相关,全磷(TP)和全钾(TK)的块金值/基台值较小,分别为10.4%和2.9%,表现为强烈的空间自相关,说明随机因素对TP和TK的影响相对较小;逐步回归分析表明,各环境因子对TK的方差解释最大,对SOC的方差解释最小。其中,土壤交换性Ca2+离子和凋落物中N含量是SOC和TN的主要控制因素,随着交换性Ca2+和凋落物中N含量升高,土壤SOC和TN积累增加;TP的控制因素比较单一,仅受凋落物中P含量影响。TK的影响因素比较复杂,除主要受交换性Ca2+控制外,凋落物N:P比、海拔高度和黏粒含量也有显著影响。     

氮肥施用对砖红壤硝态氮和盐基离子淋失特征的影响

氮肥品种的合理选用对作物增产增收、 土壤酸化改良有重要的影响。本文以海南省海口市观澜湖采集的砖红壤为研究对象,采用室内土柱模拟试验,对尿素、 硝酸铵和硫酸铵3种氮肥处理下砖红壤硝态氮及盐基离子（Ca2+、 Mg2+、 K+、 Na+）淋失特征进行了研究。结果表明, 1）硝态氮累积淋溶量表现为硫酸铵硝酸铵尿素N0,且硝态氮的淋溶量与施肥量呈正相关关系,整个淋溶过程中硝态氮累积淋溶量（y kg/hm2）与施肥量（x kg/hm2）之间满足线性方程 y=3.3064x+315.74（R2=0.8848）; 2）尿素、 硝酸铵、 硫酸铵处理整个淋溶过程的盐基离子淋溶量均表现为 Ca2+Mg2+K+Na+,且盐基离子淋溶总量（kg/hm2）表现为硫酸铵（1821.12）硝酸铵（1080.27）尿素（872.24）N0（417.23）; 3）砖红壤盐基离子迁移速率表现为硫酸铵（26.28%）硝酸铵（13.37%）尿素（11.78%）,尿素、 硝酸铵和硫酸铵处理分别以线性方程 y=0.1178x+123.18（R2=0.9121）、 乘幂方程 y=15.634x0.4423（R2=0.9259）和对数方程 y=128.38e0.0007x（R2= 0.9244）的拟合度最高。     

碱金属离子在汞金属界面吸附作用的量子化学研究

应用量子化学方法对碱金属离子在汞金属界面的吸附作用进行了研究.选取汞金属界面的3个典型的位置（空穴、桥位和顶点）,采用MP2方法计算得到Li＋、Na＋、K＋3种离子在汞表面不同位置的吸附能.结果表明：3种金属离子都是在空穴位置有较大的吸附能,然后是桥位和顶点位置;对于平衡结构,从Li＋到Na＋和K＋,随着离子半径的增大,离子与汞金属界面的平衡距离在逐渐增大,吸附作用逐渐减弱,而且离子与汞之间的电荷转移在逐渐减小.