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035			_a.b10187492
099		9	_aAIT Thesis no. 842
100	1		_aGarcia, Felipe V.
245	1	0	_aDepth of liming of very acid soils
260			_aBangkok : _bAsian Institute of Technology, _c1975
300			_a62 p.
490	1		_aThesis ; _vno. 842
500			_aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at the Asian Institute of Technology, Bangkok, Thailand .
502			_aThesis (M.Sc.) - Asian Institute of Technology, 1975
520			_aThis research was conducted to investigate the effect of depth of liming on pH of the underlying not limed soil layers of a very acid soil classified as acid sulphate soil. The experiment was carried out by means of 50-cm. tall soil columns, limed at varying depths namely; (i) 0-cm. (ii) upper 15-cm. and (iii) upper 30-cm. layer and followed by leaching with distilled water at a 4-day interval for a period of four months. Calcium carbonate chemical powder was used at the amounts of 13 grams and 26 grams per soil column of known weight of 2885 grams. Leachate was collected during the entire leaching period. The effect of liming on some chemical properties of the leachate was studied. __it was find that narrow and straight line relationships exist between EC, S04 and Ca++ in all treatments. The most narrow relationship occurs between Ca++ and EC. Thus, the EC of the leachate can be used to predict the approximate amounts of ca++ and to some extent so4- that would be leached out from an acid sulphate soil only if CaC03 is mixed with the soil. The effect of depth of liming on soil pH varies a good deal. Statistical analyses had revealed that CaC03 application had not influenced an appreciable pH increase in all layers of soil columns that received surface liming. A highly significant pH increase had been restricted mainly to the limed layers as well as to the 5-cm. layer underlying the limed layer of soil columns that were limed at the upper 15-cm. and upper 30-cm. layers. However, higher pH increase at the 5-cm. unlimed layer had been observed in soil columns that were limed at the upper 15-cm. layer than those that received lime at the upper 30-cm. layer. The influence of amount of liming on pH was also compared. The existence of a positive effect was observed mainly at the limed layers with the exception of the 5-cm. unlimed layer adjacent to the limed layer of soil columns receiving lime at the upper 30-cm., where the higher amount of liming gave significantly higher pH than the lower amount of liming. Tests were also carried out on the amount of adsorbed calcium from various treatments. As revealed by statistical analyses, there appears to be a significant increase in adsorbed Ca at the same layers where there was a significant increase in pH including the whole soil column that received 13 grams of Caco3 on the surface. The results obtained do not seem to reflect the actual value of Ca that is truly in exchangeable form because of the presence of undissolved CaC03 in the lime-treated columns.
650		0	_aSoil acidity
650		0	_aLiming of soils
700	1		_aBalasubramaniam, A.S., _eChairperson
700	1		_aPaiboon Prabuddham, _eExamination Committee
700	1		_aPetersen, J. L., _eExamination Committee
700	1		_aMoh, Za-Chieh, _eExamination Committee
710	2		_aBrand, E.W., _eExamination Committee
710	2		_aCanadian Government, _eScholarship Donor
810	2		_aAsian Institute of Technology. _tThesis ; _vno. 842
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B24092
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