首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Soil quality is one of the most basic and perhaps least understood indicators of land health. Soil supports plant growth and rep
Soil quality is one of the most basic and perhaps least understood indicators of land health. Soil supports plant growth and rep
admin
2010-05-25
53
问题
Soil quality is one of the most basic and perhaps least understood indicators of land health. Soil supports plant growth and represents the living reservoir that buffers the flows of water, nutrients, and energy through an ecosystem. Soil quality refers to the capacity of a soil to perform these beneficial functions and is determined by its texture, structure, water-holding capacity, porosity, organic matter content, and depth, among other properties. Because soils naturally vary in their capacity to perform these functions, we must tie our understanding of soil quality to landscapes and land use. We must understand soil quality for two important reasons: First, we must match our use and management of land to soil capability. Second, we must establish baseline understanding about soil quality so we can recognize ongoing trends. If soil quality is stable or improving, we have a good indicator that the ecosystem is sustainable. If soil quality is deteriorating, the larger ecosystem will almost certainly decline with it.
People describe soil types in all kind of ways such as beavy, light, sandy, clay, loam, poor or good. Soil scientists describe soil types by how much sand, silt and clay is present. This is called texture. It is possible to change the texture by adding different things to the soil. You can roughly estimate the texture of a soil by a simple method called" manual texturing", through determining the feel of a moist sample when robbed between the thumb and forefinger. If the soil sample is predominantly sand, it will feel very gritty, If it is predominantly silt, it will feel smooth or slippery to the touch. And if it’s predominant clay, it will feel sticky.
Particle size has a lot to do with a soil’s drainage and nutrient holding capacity. Sand is the largest particle and doesn’t hold many nutrients. Silt is a soil particle whose size is between sand and clay. When wet, silt feels smooth, but not sticky. Clay is smooth when dry and sticky when wet. Soils high in clay content are called heavy soils. Clay also can hold a lot of nutrients, but doesn’t let air and water throuhgh it well. To better understand how big these three soil particles are, think of them like this. If a particle of sand were the size of a basketball, then silt would be the size of a baseball, and clay would be the size of golf ball.
All of the following words are defined in the passage EXCEPT
选项
A、ecosystem.
B、soil quality.
C、texture.
D、manual texturing.
答案
A
解析
细节题。纵览全文可以看出第一段对soil quality下了定义;第二段对texture和manual texturing分别下了定义,而全文没有对ecosystem下定义,故选A
转载请注明原文地址:https://kaotiyun.com/show/hu2K777K
0
专业英语四级
相关试题推荐
Tourismcancreatejobsandotheropportunitiesforalmostallcommunities.【C1】______,governmentsworldwidehave【C2】______ma
Wereceived______ofhismarriagelastweek.
Sincewearesocialbeings,thequalityofourlivesdependsinlargemeasureonourinterpersonalrelationships.Onestrengtho
WhatdoAmericanparentsusuallydowhentheirchildinjurieshimself?
Accordingtotheprofessor,whatcanaspeakerdotokeepanaudience’sattention?
AreviewofthetreatmentoffemalecharactersinChinesefictionrevealsthatChinesesocialattitudeshaveundergonedramatic
Thereisalwaystheheateddiscussionaboutwhichisbetter,tobemanortobeawomen.What’syouropinion.Writeacomposi
Howcloseparentsaretotheirchildren______astronginfluenceonthecharacterofthechildren.
Wehavebeeneducatedtobehonestsincechildhood.Butsomepeoplealsosaythatweshouldnottellthetruthallthetime.Wha
PerhapsthemostheatedargumentacrosstheUnitedStatestodayisthedeathpenalty.Manyarguethatitisan【C1】______deterr
随机试题
下列各罪是举动犯的有:()
甲公司在面积为10000m2的土地上开发建设一写字楼,建筑覆盖率为45%,总楼层为6层,一层和二层面积相等,三层以上为标准层,总建筑面积为20000m2。建成后,某房地产估价机构接受甲公司委托对该写字楼进行估价,经查验会计凭证以及会计师事务所的审计报告,确
公路工程施工周转材料的摊销方法主要有()。
()是指全部注册资本由等额股份构成并通过发行股票(或股权)筹集资本的企业法人。
注意事项1.申论考试是对应考者阅读理解能力、综合分析能力、贯彻执行能力、提出和解决问题能力、文字表达能力的测试。2.参考时限:建议阅读资料40分钟,作答110分钟。3.仔细阅读“给定资料”,按照后面提出的“作答要求”依次作答。
根据以下资料,回答106-110题。据统计,2009年全年各类自然灾害造成直接经济损失2524亿元,比上年下降78.5%。全年农作物受灾面积4721万公顷,增加18.1%。其中,绝收492万公顷,增加22.0%。全年因洪涝灾害造成直接经济损失655
树木对我来说,一直是言辞最恳切感人的传教士。当它们结成部落和家庭,形成森林和树丛而生活时,我尊敬它们。当它们只身独处时,我更尊敬它们。它们好似孤独者,它们不像由于某种弱点而遁世的隐士,而像伟大而落落寡合的人们,如贝多芬和尼采。世界在它们的树梢上喧嚣,它们的
“干净”的构词方式属于合成词中的()。
设X为随机变量,E(X)=μ,D(X)=σ2,则对任意常数C有().
Thisyear,recordnumbersofhighschoolstudentsobtainedtopgradesintheirfinalexams,yetemployerscomplainthatyoungpe
最新回复
(
0
)