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Bottom soil quality in Tilapia ponds of different age in Thailand Taworn Thunja i 1 . Cl aude E Boyd 2 & Mali Boonyar atpali n 3 LTha il and De pa rt ment of Fi sher ies, Kasetsar t Universit y Camp us. Bangkok. Thai la nd 2 De pa rt ment of Fl sh er ie s an d Al li ed Aquac ul tu re s. Au bu rn Un iv er si ty. Au bu rn . AL USA 3 Thai la nd De pa rtment of Fi sher ies. Ka setsa rt Univer si ty Campus.. Bangkok.. Tha il and Corres pondence : Dr C E Boyd. Dep ar tment of Fi sher ie s an d Al li ed Aq ua cult ures. Au burn Un iver si ty. Au burn . AL 36849. USA. E. ma il : [email protected] Abstrac t Bottom soil samples were collec ted from 35 ponds in the vicin ity of Samutpr aka rn. Tha ila nd. Pond s ran. ged in age f rom 3 to 39 yea rs and had bee n use d con- tinuousl y for product ion of tilapi a. Liming material s had been appli ed in la rge amounts. and bottom soil s of all pond s had pH a bove 7. low exc hang e aci dit y. and free car bon at e. Pond soils orten contained be- twe en 1% and 2% tot al sul phur . sugg est ing tha t the y wer e potent ial aci d-s ulph ate soil s. However. acidi ty fro m sulph ide oxid ati on was not ex pre ssed becaus e car bona te in the soil ne utr ali zed it. Concentrati ons of t ota l car bon sel dom excee ded 4% and the ave rag e for organic car bon was 1.90%. The correlati ons be- twee n pon d age a nd both total ca rbon and or ganic car bon con cen tra tio n wer e weak (r = 034 an d 036 res pec tive ly) . Conc ent rat ions of nitr oge n in botto m soils did not dif fer with pon d age and ra nge d fr om 0.1% to 0.3% wi th an avera ge of 0.19%. The average rat io of conc entr ati ons of car bon and nitro gen was 11. Acid-ext ractable pho sph or us concentr ations averaged 217 mg kg -1 . but t he phosph orus adso rp- tion capac ity averag ed 768 mg kg -1 sugg est ing that soil s still have cons ide rable res erv e cap aci ty to ad- sorb phos pho rus. Ponds can be used ann uall y for semi- intensive product ion of tilapia . and presumably other specie s. for many years witl10ut seriou s deteri - orati on of bottom soil quality . Keywor ds: Ti la pi a. bottom soil s. so il ca rb on. liming Introduction Wat er qual ity in aqua cul rure pond s is inf lue nce d by the excha nge of subs tan ces betw een soil and water. but only a few studies have clearly demons trated re- lations hips betwee n bottom'soil qualit y and fish pro- duct ion in ponds (Bo yd 1995), Nev ert hele ss. man y aqua cult uri sts beli eve th at soi l quali ty det eri ora tes rapidl y in se mi-int ensive and intensive aquacul ture ponds and that older ponds tend to have low pH and hi gh conce ntr at ion s of or ganic ma tt er in bott om soi ls. Th ere have bee n a few studi es of the rel ati on- ship bet ween pond age a nd bottom soil quality (Tuck- er 1985: Munsir i. Boyd & Hajek 1995: Munsir i. Boyd. Tei che rt- Codd ing ton & Haj ek 1996: Rit vo. Dixon. Lawre nce. Samoch a. NeilL & Speed 1998:Tepe & Boyd 2002). and the results of these studies do not support the opinio n tha t pH dec lin es mar kedl y and organi c mat ter acc umul ate s to hig h conce ntr ati ons in o lde r ponds. The most common pr ac ti ces use d in pond soil manageme nt ar e li mi ng. dr yi ng of pond bot toms betw een cro ps, and sed ime nt remova l (Wur tz 1960: Chie n 1989 : Boyd 199 5). Liming cau ses bott om soi l pH and conc ent rat ions of t ota l alka lini ty and total har dne ss in pon d wat er to incr eas e. Howeve r. the necessit y for an nua l or more fr equent li mi ng. as oft en done . is not suppor ted by re sea rch fin ding s. Dry ing pond bott oms betw een cro ps can accelerate the decomposi ti on of o rganic matter and oxi di ze re duc ed sub stances in soil (Wu rtz 196 0: Boyd & Pipo ppin yo 1994 ). The bene fit of sedi men t removal on sediment qualit y is not well establi shed and likely is unnec essary unle ss se di me nt is so de ep that it ca use s a loss of p ond volu me or inte rfe res wit h pon d management (steeby, Ki ngs bur y. Tuc ker & Hargr eaves 2001: Tepe &Boyd 20(2).. Concentr ations of nit roge n and phosp horus inc rease in p ond soi ls over time (Masuda & Boyd 1994: Munsiri et al. 1995: Ritvo et al. 199 8) . It is not kno wn if the ra ti o of
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Bottom soil quality in Tilapia ponds of different
age in Thailand
Taworn Thunjai1
. Claude E Boyd2 & Mali Boonyaratpalin3
LThailand Department of Fisheries, Kasetsart University Campus. Bangkok. Thailand
2Department of Flsheries and Allied Aquacultures. Auburn University. Auburn. AL USA
3Thailand Department of Fisheries. Kasetsart University Campus.. Bangkok.. Thailand
Correspondence: Dr C E Boyd. Department of Fisheries and Allied Aquacultures. Auburn University. Auburn. AL 36849. USA. E.mail:
Abstract
Bottom soil samples were collected from 35 ponds in
the vicinity of Samutprakarn. Thailand. Ponds ran.
ged in age from 3 to 39 years and had been used con-
tinuously for production of tilapia. Liming materials
had been applied in large amounts. and bottom soils
of all ponds had pH above 7. low exchange acidity.
and free carbonate. Pond soils orten contained be-
tween 1% and 2% total sulphur. suggesting that they
were potential acid-sulphate soils. However. acidity
from sulphide oxidation was not expressed because
carbonate in the soil neutralized it. Concentrations
of total carbon seldom exceeded 4% and the averagefor organic carbon was 1.90%. The correlations be-
tween pond age and both total carbon and organic
carbon concentration were weak (r = 034 and 036respectively). Concentrations of nitrogen in bottom
soils did not differ with pond age and ranged from
0.1% to 0.3% with an average of 0.19%. The average
ratio of concentrations of carbon and nitrogen was
11. Acid-extractable phosphorus concentrations
averaged 217 mg kg -1. but the phosphorus adsorp-
tion capacity averaged 768 mg kg -1 suggesting that
soils still have considerable reserve capacity to ad-
sorb phosphorus. Ponds can be used annually for
semi-intensive production of tilapia. and presumably
other species. for many years witl10ut serious deteri-
oration of bottom soil quality.
Keywords: Tilapia. bottom soils. soil carbon.
liming
Introduction
Water quality in aquaculrure ponds is influenced by
the exchange of substances between soil and water.
but only a few studies have clearly demonstrated re-lationships between bottom'soil quality and fish pro-
duction in ponds (Boyd 1995), Nevertheless. many
aquaculturists believe that soil quality deteriorates
rapidly in semi-intensive and intensive aquaculture
ponds and that older ponds tend to have low pH and
high concentrations of organic matter in bottom
soils. There have been a few studies of the relation-
ship between pond age and bottom soil quality (Tuck-
er 1985: Munsiri. Boyd & Hajek 1995: Munsiri. Boyd.
Teichert-Coddington & Hajek 1996: Ritvo. Dixon.
Lawrence. Samocha. NeilL & Speed 1998:Tepe &Boyd
2002). and the results of these studies do not support
the opinion that pH declines markedly and organicmatter accumulates to high concentrations in older
ponds.
The most common practices used in pond soil
management are liming. drying of pond bottoms
between crops, and sediment removal (Wurtz 1960:
Chien 1989: Boyd 1995). Liming causes bottom soil
pH and concentrations of total alkalinity and total
hardness in pond water to increase. However. the
necessity for annual or more frequent liming. as
often done. is not supported by research findings.
Drying pond bottoms between crops can accelerate
the decomposition of organic matter and oxidizereduced substances in soil (Wurtz 1960: Boyd &
Pipoppinyo 1994). The benefit of sediment removal
on sediment quality is not well established and likely
is unnecessary unless sediment is so deep that
it causes a loss of pond volume or interferes with
pond management (steeby, Kingsbury. Tucker &
Hargreaves 2001:Tepe &Boyd 20(2).. Concentrations
of nitrogen and phosphorus increase in pond soils
over time (Masuda & Boyd 1994: Munsiri et al. 1995:
Ritvo et al. 1998). It is not known if the ratio of
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Materials and methods
Ponds and management
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Samples
Analyses
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Results and discussion
Total alkalinity and total hardness
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Sediment depth
Thickness of S horizon and bulk density
Soil pH and exchange acidity
Total sulphur
Soil carbon
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Nitrogen and phosphorus
Conclusions
Acknowledgments
References
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