含水率差值法初探

概述了国内外确定湿润锋面处的有效基质吸力的方法.根据实验数据得知,饱和含水率和初始含水率的差值与湿润锋面处的有效基质吸力S f为成正比的关系,并在此基础上提出了一种求解S f值的新方法,即含水率差值法,由实验数据拟合得到二者的关系式.列出了3种土质的含水率差值法关系式,相关系数均接近于1.表明含水率差值法是目前求解Green-Ampt模型入渗湿润锋面处的有效基质吸力简单和准确的一种方法.     

苏南经济快速发展区土壤有效态钴含量影响因素及分布特征

以江苏省昆山市为典型区,研究农田土壤有效态Co含量的影响因素及分布特征。结果表明:(1)全Co含量平均值为12.58 mg/kg,高于全国平均值11.2 mg/kg,变异系数为13.59%;土壤有效态Co含量为0.05~0.80 mg/kg,平均值为0.26 mg/kg,变异系数为81.63%;土壤Co活化率平均值为2.17%,变异系数为94.24%。(2)在土壤全Co含量变异较小的情况下,土壤有效态Co和土壤Co的活化率与pH值呈极显著负相关,均以指数模型拟合更优;回归分析表明,pH值是影响土壤有效态Co含量和土壤Co活化率的主要因素,说明研究区内土壤酸化直接导致土壤有效态Co含量增加。(3)全Co含量在不同的经济功能区和不同的地貌区差异均不显著;有效态Co含量和土壤Co的活化率在菜地区极显著地高于化工区和印染造纸区;有效态Co含量和土壤Co的活化率以南部湖荡区较高,南部湖荡区土壤有效态Co极显著地高于中部平原区。(4)土壤有效态Co含量及Co的活化率在土壤剖面上均以表层为高。     

Effect of high rates of zinc on several crops grown on an irrigated plainfield sand

Abstract

A field experiment was conducted to determine whether Zn applied for pathogen control could accumulate to a level which would be toxic to snapbeans, cucumbers, or corn. Zinc sulfate (ZnSO₄) was applied at rates varying from 0 to 363 kg Zn/ha on a Flainfield loamy sand to approximate 3, 9, 27 and 81 years of fungicidal treatment.

Even at the high rate of Zn, yields of snapbeans, cucumbers, or corn generally were not reduced. As rates of applied Zn increased, there was a corresponding increase in the level of Zn in the leaf tissue of all crops grown. At the high Zn rate, snapbean and cucumber leaf tissue accumulated over 350 ppm Zn. Available soil Zn was extracted with 0.1N HCl, EDTA, or DTPA. Highly significant correlations were observed between the Zn removed by each extractant and plant tissue Zn, thus, indicating that the various extractants were equally effective in predicting Zn uptake.

Very little downward movement of Zn was observed. Two and one‐half years after application, the Zn had leached to a depth of only 30 cm in the soil profile at the higher Zn rates.

These data indicate that application of Zn‐containing fungicides and bactericides should not cause a Zn toxicity problem on the Plainfield sand in the foreseeable future.     

覆膜条件下铁改性磷负载生物炭对花生磷素利用及产量的影响

为探究覆膜条件下铁改性磷负载生物炭对花生植株磷素利用及产量的影响，该研究于2021和2022年设置盆栽裂区试验，研究不同覆膜方式(覆膜处理(M1)和无膜处理(M0))下，铁改性磷负载生物炭处理(常规施磷量+无生物炭处理(P1C0)、3/4常规施磷量+7.5 t/hm²铁改性磷负载生物炭处理(P2C1)、3/4常规施磷量+15 t/hm²铁改性磷负载生物炭处理(P2C2)、2/3常规施磷量+7.5 t/hm²铁改性磷负载生物炭(P3C1)、2/3常规施磷量+15 t/hm²铁改性磷负载生物炭(P3C2))对花生植株叶绿素含量、净光合速率、干物质积累量、磷素利用、土壤有效磷含量及花生产量的影响。研究结果表明，与M0处理相比，M1处理下花生苗期、花针期、结荚期和饱果期叶绿素含量与净光合速率分别提高了7.6%和29.1%、12.4%和25.9%、14.9%和16.0%、6.5%和14.8%，饱果期干物质积累量和产量分别提高了17.7%和18.8%(2 a平均)。同一覆膜方式下，从苗期至饱果期，花生净光合速率...     

Ni—Si—B系非晶合金的结晶度与退火时间的关系

对Ｎｉ６４Ｓｉ１５Ｂ２１非晶合金条带在２５０℃不同退火时间下的结晶度进行了测定。得到了结晶与度火保温时间呈抛物线关系的实验规律。     

鲁南砂姜黑土及其有机无机复合体中无机磷的组成和分布

采用石灰性土壤无机磷分级法研究了不同肥力砂姜黑土无机磷的组成与分布。结果表明，砂姜黑土及其有机无机复合体中无机磷以磷酸＝钙盐和闭蓄态磷酸盐为主，分别占无机磷总量的２７％－４８％和２６％－３７％。土壤无机磷中的Ｃ２－Ｐ，Ｃａ８－Ｐ，Ａｌ－Ｐ，Ｆｅ－Ｐ均与速效磷存在着显著的正相关，并且随着土壤肥力水平的提高，其含量亦随之增加。土壤无机磷主要集中分布于〈５μｍ粒级的有机无机复合体中，各种形态无机磷的含量     

重庆市2005年生态足迹与生态承载量研究

以重庆市2005年统计数据为基础，计算生态足迹和生态承载量，计算结果显示该地区人均生态足迹为1．547841hm^2，人均生态承载力为0．368038hm^2，人均生态赤字为1．179803hm^2。与全国平均水平相比，人均生态足迹高0．427841hm^2，人均生态承载力低0．431962hm^2，生态赤字是全国生态赤字的2．95倍。表明重庆市生态经济系统存在严重的生态赤字，必须采取相应措施，才能减少生态系统的压力。     

肉桂人工林土壤速效养分与酶活性的季节变化

研究了广西高峰林场林龄为3年和6年的肉桂人工林土壤速效养分(水解N、速效P、速效K)和土壤酶活性(过氧化氢酶、脲酶、酸性磷酸酶)的季节变化规律及其相互关系。结果表明：两种林地土壤速效养分含量和土壤酶话性均表现出明显的季节动态．：E壤速效N、P、K含量和L壤脲酶活性均以肉桂生长初期(3月中旬)最高．其次是第一个生长高峰期(6月中旬)或第二个生长高峰期(9月中旬)，最低是生长未期(12月中旬)；而土壤过氧化氢酶和酸性磷酸酶活性以第一个生长高峰期或第二个生长高峰期最高．其次是生长初期,最低是生长末期；士壤速效养分与土壤酶活性的季节变化密切相关。因此，生长初期至第一个生长高峰期是肉桂林地施用N、P、K肥的适当时期。     

麦秆表面硅含量分布的研究

利用ESCA研究了麦秆表面在不同温度下和经氩离子刻蚀后Si元素含量的变化。结果表明：在麦秆横切面上，Si元素含量中间层（接近麦秆外表面）含量较高；随着温度的升高，麦秆表面Si元素含量先降低而后增加，在选定的几个温度中，170℃和220℃时Si含量最低；麦秆表面经氩离子刻蚀后，由外及里，随着氩刻的加深，Si含量呈现升高趋势。麦秆中Si元素存在的化学环境与聚甲基硅氧烷中Si的化学环境比较接近。     

Alley cropping of sorghum with Leucaena during the post-rainy season on Vertisols in semi-arid India

A field experiment was conducted for two years (1989– 1991) on a Vertisol in Bijapur, India in a split-plot design, replicated four times, to evaluate the potential of alley cropping post-rainy season sorghum between Leucaena hedgerows. Leucaena produced on average 2.74 t per ha of prunings and 1.57 t per ha of wood annually. Alley cropping decreased sorghum yields by 28 to 45% when all Leucaena prunings were removed from the system and by 21 to 24%, when on average 1.92 t per ha prunings were applied to the soil annually. The reduction of sorghum yield increased as higher rates of N were applied to sorghum. Although alley cropping increased organic carbon by 21% and available N by 19% at the time of crop sowing, it did not result in increased crop yields because of competition for water between hedgerows and crops. Calculation of land equivalent ratios based on total Leucaena biomass indicated that alley cropping was more productive than sole cropping of sorghum only in one year, and that, too, when no N was applied to sorghum. Therefore, alley cropping of Vertisols with post-rainy season sorghum is not likely to have any advantage in the short term. This revised version was published online in June 2006 with corrections to the Cover Date.