土壤和植物中元素含量的Zipf法则描述

土壤中含有人类已经发现的大多数化学元素,构成了植物矿质营养的主要来源.植物体内元素的种类也高达70余种,其含量从10-16到10-1,差异巨大.如果把土壤的化学组成和植物体内必须营养元素组成加以比较,可以看出两者之间存在相当大的差别.其中一些元素在土壤中的含量很高,但植物的需求量很低,如Si、Al、Fe等;而另一些元素在土壤中含量很低,但却是植物需求量较多的元素,如N、P、S;正是这些差异构成了土壤化学组成和植物营养之间关系的基础[1].元素的原子序数即核电荷数决定了元素的内在性质,一般的土壤和植物分析结果也表现出原子序数越大的重金属元素,其在土壤和植物中的含量也越低.Zipf法则由于具有普适性的特点,已被广泛地应用于离散型分布的研究[2],为了解土壤与植物中元素含量与元素原子序数之间存在的关系,利用Zipf法则对土壤与植物体内元素含量与原子序数之间的关系进行了研究.     

水稻与小麦吸硅规律与硅肥应用

In the paper, experiments with the graminaceous crop-rice and wheat were carried out by using water culture and sand culture to study the relationship between the uptake of silicon by graminaceous crop and silicon supply of the different growth period. The preliminery experiment results showed that the most efficient time for applying silicon fertilizers was at tillering and jointing stage. According to the uptake characteristic of silicon by rice and wheat, we have suggested that apply silicon fertilizer at proper growth stage of the graminaceous crop.     

防止植物样品中无机砷形态转化的样品保存方法

随着砷污染问题越来越受到人们的关注,有关砷污染区土壤、植物和水体的研究也日益得到重视[1-3].砷污染区粮食作物、蔬菜和饲料作物等砷含量过高,通过食物链会直接或间接地影响到人类的身体健康[4].不同形态的砷对人体健康的影响不同,一般无机砷的毒性大于有机砷,无机砷中As(Ⅲ)的毒性大于As(Ⅴ)[5].准确测定植物样品中砷的形态,不仅可了解其生理毒性,而且还有利于评价其环境风险.     

华北太行山前平原农田氨挥发损失

我国氮肥用量约占全世界氮肥总用量的三分之一[1],但当季利用率仅为30%～35%左右[2].据报道,石灰性土壤中氨挥发是氮素损失的主要途径之一[3-4],其损失量相当于氮素总损失量的20%～71%[2,5-7 ].进入大气中的氨引起自然土壤和水体的氮素含量升高,产生富营养化[8],导致植物种类更替和部分物种灭绝[9].     

不同氮、硅用量对水稻产量和品质的影响

硅素和氮素是水稻正常生长必需的两大营养元素.水稻氮肥的施用技术及氮肥对水稻产量和品质的影响已有大量的研究[1-5].结果表明,适宜的氮素施用量和施肥时期,可以提高抽穗期群体源库质量和群体成穗率,形成高势粒比群体而高产;氮肥施用量对水稻的品质也会产生一定的影响,但不同品种对氮素施用量的反应不同.     

确定春蚕饲养量的方法

本文根据试验和调查资料,建立了春桑叶生产与时间、温、光累积值的函数关系式,在此基础上,设计了确定春蚕饲养量的动态变化方程,反映了春蚕饲养量与桑叶鲜重的供求关系,为充分利用桑叶资源,提高春蚕产量和质量提供了决策依据。     

人工降雨对减轻中稻旱灾损失效益初探

本文运用随州市历年中稻产量资料和气象资料,对人工降雨在减轻中稻旱灾损失的经济效益评估进行探讨     

利用植物 监测大气污染

<正> 环境保护是我国的一项基本国策,利用植物的伤害症状来监测、推断大气中污染的成份,危害程度和范围,是一种行之有效的方法。我们试图根据国内公队的植物遭受各类污染气体危害的典型症状,从1981年至1986年对上海市普陀区少年宫宫内的植物进行常年定点、定株的观测,并结合对附近工厂、街道树木的初步调查,了解这地区大气污染状况,为制订防治措施、进行大气质量评价,以及植树造林种类的选择与配置,提供一些     

A simplified method for determining acetic acid soluble phosphorus in plant tissue

Abstract

The proposed procedure greatly simplifies the determination of 2% HOAc soluble P in plant tissue. Extraction with Darco G 60 eliminates the need for the H₂O₂ oxidation of the extract. The use of vanadomolybdic acid as the chromogen results in a high degree of color stability eliminating the need for careful timing of the period between color development and transmission readings.     

土壤中有效结合态氨的一种测定方法

Dynamics of fixed NH₄⁺ in NH₄⁺-treated soils incubated with glucose at 37±2 ℃ during the course of incubation and factors affecting it were studied. Results showed that content of fixed NH₄⁺ in soil reached a minimum on day 7 after incubation and then increased gradually regardless of the amount of glucose added and the kind of soil tested. However, the amount of fixed NH₄⁺ released from the soil at the given time varied with both the amount of glucose added and the kind of soil examined. In cases glucose was added at a rate of 10.0g C/kg soil, the amount of fixed NH₄⁺ retained in soil after 7 days of incubation was almost identical to that found by Neubauer test. Addition of K⁺ depressed the release of fixed NH₄⁺ significantly. Based on the results obtained a method for determining the content of available fixed NH₄⁺ in soils was proposed and the amount of N as available fixed NH₄⁺ in two soils measured by this method on an area profile-depth basis was presented.     

A new method for determining free iron in paddy soils

For pedological or edaphological study, it is very important to find a suitable method for determining free iron in soils. The removal of free iron also facilitates the identification and determination of minerals present in soils and clays by X-ray and thermal analysis and microscopic observation. Up to the presnt time many methods have been proposed for the removal or the determination of free iron in soils and clays. With some exceptions these methods are all based on the principle that the free iron compounds existing mainly as ferric iron in soils are reduced to ferrous iron and extracted with suitable reagents. A short historical review is as follows.     

A new method for determining ferrous iron in paddy soils

Introduction

To make clear the chemical behavior of free iron compounds in paddy soils, it is necessary to find an accurate and rapid method for determining ferrous iron in waterlogged paddy soils. Several methods^1,2,3) have been proposed for this purpose, most of which use dilute acids, such as sulfuric and hydrochloric acid, as extracting reagents. According to the writers' experience, however, these methods seem to be inadequate. The reason is that the acid solutions extract not only ferrous iron, but also ferric iron and reducing substances from soils, and the latter two react immediately in the extract to produce ferrous iron, thus we obtain larger value for ferrous iron than the one actually existing in soils. The writers have found that acetate buffer of pH 2.8 is a very suitable extractant for ferrous iron, and they have been able to establish a new method for the determination of ferrous iron in soils using this buffer. The experimental details will be given in this paper.     

A new method for determining mineral weathering rates in soils

Abstract

A new procedure based on measuring the amounts of H⁺ consumed when a pulse of acidic artificial soil solution is passed through a soil column was used to determine mineral weathering rates of a soil (Humo‐Ferric Podzol) from Roundtop Mountain near Sutton, Quebec. The method allows for quantification of H⁺ consumption due to weathering and H⁺ consumption due to cation exchange. Initial experiments yield a soil mineral weathering rate of 0.263 kmol ha^‐1 yr^‐1. This value is well within the range of results obtained by other workers in similar ecosystems. Multiple soil samples can be analysed in a relatively short time, allowing for better quantification of vertical and horizontal variation of H⁺ consumption within a site.     

Video image method compared to a hand method for determining root lengths

Root lengths are much more sensitive to treatment effects than root weights. Therefore, root length measurements are essential to research concerning rhizosphere effects on plant roots. A video image analyzer method was compared to a hand method for determining the root length of sorghum [Sorghum bicolor (L.) Moench] seedlings resulting from nutrient solution experiments. Initial root lengths were not significantly different, thus only final lengths were recorded. T‐tests for differences between hand and instrument values showed that although absolute values were often significantly different, there were much fewer significant differences in normalized data. Normalized instrumental root length data were well correlated with hand data (r > 0.96) and slopes of the regressions were equal to 1.00. Intercepts were higher than zero. Thus, although the normalized instrumental values for root length were somewhat higher than for hand root lengths, the instrument lengths were very precise in indicating relative differences among treatments.     

Comparison of a tissue solubilization and a wet combustion method for determining14C in plant tissue

Abstract

Nine different types of plant material labeled with¹⁴CO₂were used to compare two methods for analyzing¹⁴C in biological material. The methods were total carbon by wet oxidation (TC) and tissue solubilization using hyamine hydroxide (HH). In addition 3 sizes of material were used and 3 variations of the HH method were evaluated. Overall there were no significant differences between the HH and TC methods for¹⁴C activity, provided the samples are finely ground. Significant differences occurred in total counts and counting efficiency when the plant particle size decreased from .84 mm to .25 ram. Differences also were found between quench reducing treatments in the HH method. Differences between methods in terms of total counts, may be plant material specific     

土壤全硫测定方法的改进及其在燃煤电厂周边土壤分析中的应用

为了提高硫酸钡比浊法测定土壤中全硫含量方法的准确性,对其进行改进,考察了乙酸和硝酸镁添加量对比浊液吸光度的影响,并对某燃煤电厂周边土壤样品进行测定。结果表明:乙酸溶液(1∶1)和硝酸镁溶液(308 g/L)的最佳添加量分别为 15、5 mL。改进后的方法具有较高的准确度和精确度。某燃煤电厂周边土壤全硫的含量范围为 95.71～ 1 102.03mg/kg,平均值为 412.48mg/kg,总体平均含量未超过全国一般水平,但有 32%的样品高于全国一般水平,说明该燃煤电厂周边土壤的硫发生了一定程度的蓄积,需引起重视。