8342937093

COPPER AND LIMĘ INTERACTION ON THE GROWTH OF CORN ON TROPICAL PEAT

TABLE1

The Chemical conientof peat and limę used in

theexperiment.

+Peat    ♦Limę

%

N	1.40	•
P	0.05	•
K	0.53	-
Ca	0.44	26.35
Mg	0.09	11.60
Cu	5.52	traces
FE	2223.7	1129.2
Mn	42.9	97.8
Zn	22.3	61.3
pH	3.66	-
+- Total analysis was don e usingdryashing technique
(Cottenie<?/«£ 1982).
♦- Total analysis	was done by aquaregia method
(Cottenie etaL	1982).
	TABLE2
Effeets of copper application on dry matter yield of sweet eorn and DTPAextractable copper (values
are meansacross4 levelsoflinie).
Treatment	Dry mater yield	Soil Cu
(kg Cu ha'^1)	(gpof^1)	</Jg Cug-^1)
0	9.77	0.3
5	23.9	8.7
10	24.4	21.3
15	22.6	36.7
20	23.5	41.5
*hsdom	5.6	4.35
* Multiplemeanscomparison was eonducted usingTukeys
Studenti/ed Rangę	Test, highest significant difference
(HSD) wasal P<0.05.
	TABLE 3.
Effeets of limę on	dry matter yield of sweet eorn and
soil pH (values are means across 5 levels of copper).
Treatment	Dry matteryield	Soil pH
(t limę ha^-1)	(gpof')
0	7.82	3.67
2	21.97	4.12
4	27.03	4.44
10	26.48	5.03
^HSD0.05	4.66	0.19

Thesignificantincrease indry matteryield with the application ofcopper toan organiesoil (peat soil) wasdue to the Iow Cucontent in this soil. The in i dal total Cu eon ten t in this peat soil was only 5.52 /ig g“¹ (Table 1). Organiesoils having less than 30jUgg^_l of total Cu are likely to have Cu deficiency (Katyal and Randhawa 1983). The behaviour of soil organie matter in binding Cu ions very strongly would exaeerbate the Iow availabil i ty ofCu in peat soil (McLaren 1972andTisdalee/n/. 1985). This isthe result of a speciflc adsorption ofCu with the numerousfunctional groupsfound in soil organie matter (Stevenson. 1982; Tisdale et ai 1985). Copper is also known to bind the soil organie matter morę strongly compared to other mic-ronutrients,with the relative binding strength being Cu>Zn>Co>Mn (KerndoffandSehnit/er 1980).

The results in Table 3 show that application of limę to a peat soil is of paramount importanee in inereasing the dry matteryield ofsweeteorn. Besides Cu deficiency, limitation of growth is also due to Iow- pH (initial pH, 3.66, Table 1). Therefore, application of limę will overcome this limitation. Liming peat soil in Malaysia has also been shown to inerease the yield of tapioca, groundnut, sweet potato, eorn, chilli and sorghum (Joseph et al. 1974; Kanapathy 1967). The beneficial effect of liming peat soil could also been attributed to pH andcalciumeffects (Chew 1973; Chew etaL 1976). However, no specific study wascarried out tocon-firm these effeets. Liming an organie soil above pH 5.8 was not possible beeause of reduced availa-