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: xӵı    rg: 2012-5-31 09:09
}: Bֳ|W_ʼmУ
      ǰһփԡWWOIˮa“ϲBֳ|   PעҲ^ӳһ}@փԾȻӢİֻܶsM_һ¿Ӣİľ
      x齭ˮaооTҪˮaIоˮW|߀ԭλȣgˊWWBoydڵijBֳˮ|Bֳ|ɱҪBˮW͵|ă@Bֳ|ɊWWBoydڵ˾xgġBֳˮ|Bֳ|@ɱϡȱܶ˶]Ҋ^Wϸo@ɱӰˆǷ@ɱȻ]ϾWBoydڵĴBֳˮ|Bֳ|@ɱӢӰУҵˡBֳ|@Сփcҷϧ@փӢİģӢˮƽԼgҪrgʲܷgoʽ뵽һkҰփϵăһһNρһgһW
       ȫWӢZӾʽ_ʼAre you ready?
һ퓣
                                                                                   INTRODUCTION

                 Water quality management has been considered one of themost important aspects of pond aquaculture for many years,but less attention has been given to the management of pondbottom soil quality. There is increasing evidence that thecondition of pond bottoms and the exchange of substances between soil and water strongly influence water quality(Boyd, 1995). More attention is being devoted to the study of pond soils, and practical aquaculturists are beginning to seek information on pond bottom management.
               The purpose of this small manual is to provide a practicalguide to the management of aquaculture pond soils.

                                                   POND SOILS
Development
              During pond construction, surface soil in the area to become the pond bottom usually is scraped off and used as earth fill for embankments. The newly finished pond bottom normally is subsoil low in concentrations of organic matter and nutrients. In tropical and subtropical areas with highly leached soils, pond bottoms often are high in clay content and of low pH.After filling with water, various processes begin to transform the bottom of a new pond into a pond soil. Erosion of the watershed results in suspended particles of mineral soil and organic matter entering a pond in runoff. Wave action, rainfall, and water currents from mechanical aeration erode embankments and shallow edges to suspend soil particles. In addition,nutrients added to ponds in fertilizers, manures, and feeds cause phytoplankton blooms that increase the concentration of suspended organic particles. Suspended particles settle in ponds with large sand particles settling first, followed by

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: xӵı    rg: 2012-5-31 09:10
xӵı 2012-5-31 13:29 ݋

        @ôҲ]ˁ텢ӷg{:soso_e150:}
       Ҿ́gһ°֪ʲʴ_X﷭geM

                                                                                        ǰ
       ˮ|һֱJdzBֳ ҪĭhȻ|톖}PעԽԽC@ʾײrԼcˮw֮g|QBֳˮwܴӰ푣Boyd,1995.˂ԽԽPעBֳ҂Ҳ_ʼij|ЌҸϢ
       @СփԿɞṩBֳ|ČHָ
                                                                                       
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       ڽrرȥ½ijײͨȱЙC͠IBɷڟᎧᎧֲ؅^ײSճҵײPHҲ^
       ˮNʹײγࡣˮgʹV|еđҸwЙC|ˮwáԼCеؚaˮg̺͜\ˮ߅ʹ΢ҸˮwSͨ^ʩʡͶˮwIBɷʹֲ_ʼLˮwЙCҸwu_ʼrЙCҸwSɳMS󣬳ɞɰw׃ճwMȫСЙCw

: fishfirst    rg: 2012-5-31 09:31
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һҪ֧

ֵ֧ͯЬ20Ŷ
: xӵı    rg: 2012-5-31 13:43
ڶ퓣
ˮaǰؾW
silt-sized particles, and finally clay particles and fine-divided organic matter. The names and sizes of soil particle classes are provided in Table 1. Water currents and activity of fish and other organisms continually resuspend particles from the bottom, and these particles settle again. Boyd (1976, 1977) reported that continuous input, deposition, resuspension, and redeposition of particles in a pond result in a sorting of particles with the fine clay and organic matter particles settling in the deeper water and the coarser particles settling in shallower water (Figure 1). Deeper areas gradually fill in, and ponds may decrease in volume. Sediment thickness in deep areas of aquaculture ponds usually increases at 0.5 to 1 cm yr-1(Munsiri et al., 1995; Tepe and Boyd, unpublished data).
         Organic matter settles to the bottom and is decomposed by microorganisms. Easily decomposable organic matter, such as simple carbohydrates, protein, and other cellular constituents, is quickly degraded. More resistant material, such as complex
carbohydrates and other cell wall components, accumulates because it is degraded slowly. There is a continuous input of organic matter to the bottom, so microorganisms are continuallydecomposing both fresh, easily degradable (labile)
: ˮO    rg: 2012-5-31 13:48
xӵı l 2012-5-31 09:10
@ôҲ]ˁ텢ӷg
       Ҿ́gһ°֪ʲʴ_X ...

еgôǺͦe܉߅о߅W@׌ǰһ݅ˮaڛ]НhZr£ԼһӢhֵǻ谵ğ·gӛ䛣
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: {嶾    rg: 2012-5-31 14:19
֧ ֧   ٝPľ҂@Щäо
: xӵı    rg: 2012-5-31 15:22
xӵı 2012-5-31 16:04 ݋

ڶ퓷g
ɳСɰɳ֞鲻ͬNԔҊ1.
ˮaǰؾW
ˮ\Լ~\ӲʹصճٴΑҸȻгBoyd (1976, 1977)оˮwБҸwBmݔ롢eّҸٳeʹճЙCwĵײ^ɳ\ˮ^ҊD1ˮ^صuาwݷesСгeÿ0.5~1cmĺӣMunsiri 1995; TepeBoyd, δl픵
ˮaǰؾW
  ЙCصױ΢ֽ׷ֽЙC纆ε̼ˮ|ɷֺܿ챻ֽ⡣Щ͸gԵ|s̼ˮڳɷڷֽ⾏eڲµЙCMײ΢ﲻHҪͣطֽµ׷ֽЙC߀ҪֽǰfͽЙC
: xӵı    rg: 2012-5-31 16:03
퓣@퓴ҁg
          Because there is a more or less continuous resuspension and redeposition of particles and stirring of the surface sediment by fish and other organisms, the organic matter becomes rather uniformly mixed in the upper layer of sediment. Nevertheless,there usually is a layer of fresh organic matter at the sediment surface that has not been completely mixed into the sediment. Organic matter concentration usually is greatest near the sediment surface (Munsiri et al., 1995). The ratio of labile organic matter to refractory organic matter also is greatest near the sediment surface (Sonnenholzner and Boyd, 2000).Organic matter concentrations in pond soils do not continue to increase indefinitely. If aquaculture practicese.g., species; stocking, fertilization, and feeding rates; water exchange;amount of mechanical aeration; and treatment of fallowbottom between cropsremain about the same, the annual input of organic matter and rate of organic matter decomposition also will remain about the same (Avnimelech et al., 1984;Boyd, 1995).

ʲôsog


: xӵı    rg: 2012-6-3 15:23
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: xibeiyd    rg: 2012-6-6 09:20
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: xibeiyd    rg: 2012-6-6 10:11
xӵı l 2012-5-31 16:03
퓣@퓴ҁg
          Because there is a more or less continuous resuspension and re ...

һЩҸͳewԼ~ӳeĔόӳeЙC|׃ஔϡȻ,ͨһrЙC|ڳe,δȫϳɳeЙC|ͨije渽(Munsiri et al., 1995)ЙC|cyЙCıҲڳe渽(Sonnenholzner and Boyd, 2000)еЙC|ܟo޵ȥBֳӷԒBֳƷN;ʩʣͶ;Qˮ;;͵ײֲִͬÿͶЙCЙCķֽҲִͬ(Avnimelech et al., 1984;Boyd, 1995).

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: xӵı    rg: 2012-6-6 17:37
xӵı 2012-6-6 17:39 ݋

퓣æԇҎæg£
       New ponds usually have little organic matter in bottom soil, and the labile organic matter added each year will largely decompose, while a considerable proportion of refractory organic matter will accumulate (Boyd, 1995). Over a fairly short period, often only four or five crops, organic matter in the soil will reach a high enough concentration that the annualrate of decomposition of organic matter will equal the an nual input of organic matter. At this time, equilibrium will occur and soil organic matter concentrations will remain about the same from year to year.
        Dissolved oxygen cannot enter rapidly in bottom soil because it must diffuse through the tiny, water-filled pore spacesamong soil particles. At a depth of only a few millimeters below the soil surface, the demand for dissolved oxygen by microorganisms will exceed the rate that dissolved oxygen can move to that particular depth, and anaerobic conditions will develop. The oxidized (aerobic) layer of surface sediment will have a lighter color than the deeper, reduced (anaerobic) sediment. The anaerobic sediment usually will be gray or black, and this color results from the presence of ferrous iron.

: lijiepascal    rg: 2012-6-6 17:41
炃ҷ
ķgһǿ뷭g{:soso_e179:}

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: lijiepascal    rg: 2012-6-6 23:09
lijiepascal l 2012-6-6 17:41
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: r~    rg: 2012-6-11 17:19
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: xӵı    rg: 2012-6-11 18:10
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: 糿ĺ    rg: 2012-6-22 10:27
New ponds usually have little organic matter in bottom soil, and the labile organic matter added each year will largely decompose, while a considerable proportion of refractory organic matter will accumulate (Boyd, 1995). Over a fairly short period,

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: 糿ĺ    rg: 2012-6-22 10:34
often only four or five crops, organic matter in the soil will reach a high enough concentration that the annualrate of decomposition of organic matter will equal the an nual input of organic matter. At this time, equilibrium will occur and soil organic matter. At this time, equilibrium will occur and soil organic matter concentrations will remain about the same from year to year.



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: xӵı    rg: 2012-6-22 10:35
糿ĺ l 2012-6-22 10:27
New ponds usually have little organic matter in bottom soil, and the labile organic matter added eac ...

@λlxѽ
: 糿ĺ    rg: 2012-6-22 10:51
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: xӵı    rg: 2012-6-22 11:26
xӵı l 2012-6-6 17:37
퓣æԇҎæg£
       New ponds usually have little organic matter in ...

      һֻЙCÿӵ׽ЙC̶ܴϱ⣬󲿷yЙCu۷e̕rgͨ45ЙC_һߵĝֱЙCオЙCݔ@rЙCc_ƽЙCһ걣@ˮƽ
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: xӵı    rg: 2012-6-22 11:34
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       Processes described above result in sediment forming distinct layers with respect to bulk density (weight of soil per unit
volume, usually given in grams dry soil per cubic centimeter)(Figure 2), organic matter concentration (Figure 3), and color.

ˮaǰؾW
ˮaǰؾW

     A core taken through the sediment and extending into the original bottom soil is called a profile. Layers in the profile are
known as horizons. Munsiri et al. (1995) described these horizons and assigned letters to them to facilitate discussion
(Figure 4). For practical purposes, the F and S horizons are most important in aquaculture because they exchange substances
with overlaying water to influence water quality (Munsiri et al., 1995; Boyd, 1995). Research conducted in ponds at PD/A CRSP sites and vicinity has demonstrated that aquaculture ponds typically develop profiles shown in Figure 4 and attain equilibrium concentrations of soil organic matter within a few years. A procedure for classifying pond soil based on the characteristics of horizons has been formulated (Boyd et al., 2002), but pond soil classification is beyond the scope of this report.

The word soil is used for the weathered surface layer of the earths crust in which plants grow, various animals burrow,
and humans have frequent contact. Sediment is used to refer to geological material that has been suspended and transported by water to another place where it settles from the water and forms a deposit. In many places, the soil was formed by sedimentation. All aquaculture pond bottoms become covered with sediment, and this sediment can be considered an aquaculture pond soil. In describing various physical, chemical, and biological processes occurring in the pond bottom, it is convenient to refer to bottom deposits as sediment. However, in the discussion of management of pond bottoms, we usually will refer to the sediment layers in the bottom of an aquaculture pond as pond soil.


: wdy    rg: 2012-7-9 16:44
ܰѕһ†᣿xx41536080@QQ.com
: ɽ    rg: 2012-7-9 20:30
齭СُI@
: 仨ˮ25    rg: 2012-7-13 14:29
픣
: j379220283    rg: 2012-7-16 20:10
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: Can    rg: 2012-9-14 17:10
ѽ Ќһ^gÆ҂@NäúŸo
: xӵı    rg: 2012-9-14 18:07
Can l 2012-9-14 17:10
ѽ Ќһ^gÆ҂@NäúడŸo

Bֳ| Bֳˮ| ɱİѷՓ炃Լȥd
: lemon    rg: 2012-9-15 17:11
xӵı l 2012-9-14 18:07
Bֳ| Bֳˮ| ɱİѷՓ炃Լȥd

@˅~^mlP~
: Can    rg: 2012-9-15 17:31
xӵı l 2012-9-14 18:07
Bֳ| Bֳˮ| ɱİѷՓ炃Լȥd

朽ӆxx
: xӵı    rg: 2012-9-15 20:35
Can l 2012-9-15 17:31
朽ӆxx

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: OV    rg: 2012-9-17 09:08
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̼ˮıڲYeǾ˻һBmЙC|Ͷĵײ΢continuallydecomposingrオģģ
: OV    rg: 2012-9-17 09:10
лٵBmّҸٳew͔~ıeЙC׃ஔػόеije^ҲͨrЙC|ڳe棬]бȫeЙCͨĸije棨Munsiri1995ЙCyЙCıҲ󸽽eı棨SonnenholznerBoyd2000ڳЙC|^mȥˮaBֳƷNBʩʣͶ;ˮwQęCеͨLίfallowbottom֮gִͬÿͶЙC|ЙC|ķֽٶҲִsͬģAvnimelech1984;1995޸
: OV    rg: 2012-9-17 09:11
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: chenyaxiong168    rg: 2012-9-28 18:14
齭ˮaоѽ@gĵˣǃ̫ܶ]лA˲׿ֻдһŬһо@{:soso_e100:}
: jianjia    rg: 2012-9-29 17:54
@ԓBoydڵѪɣ
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ӢȫĆܷlһݽo375912375@qq.com
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xӵı l 2012-9-15 20:35
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ˆҵզþÛ]Єooݵ|Æxˡqq1176271941@qq.com
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{:soso_e118:}~~~ү
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Õ֧һ
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ˮaǰ݅ãˮaИIҹ˾ˮ|AϵġFҪBֳ|͡Bֳˮ|@ɱİęnϣܽoæٸмҵ]ǣpenghuiyu1986@163.com
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