EFFECTS OF CORALLINE LIME ON NUTRIENT-UPTAKE AND YIELD OF FIELD-GROWNSWEET CORN AND PEANUTS IN OXIDIC SOILS OF WESTERN-SAMOA

Effects of coralline lime on yield and nutrient uptake by sweet corn ( Zea mays saccharata Sturt.) and peanut (Arachis hypogea) were studied at three locations in Western Samoa. Coarse (0-10 mm) coralline materi al containing 31.1% Ca and 1.67% Mg was used as lime. There were two m odes of application: band and broadcast, and three rates: 6, 12 and 18 ton ha-1. In the highest rainfall location, marketable yields were in creased by 250% for peanut and 160% for sweet corn by liming at 6 ton ha-1, relative to the unamended control. Peanut yield increases were a ssociated with reduced Mn toxicity and/or with Ca and Mg deficiency. S weet corn was less susceptible to Mn toxicity, but more responsive to exchangeable Ca. The critical level of exchangeable Ca was found to be about 2.0 cmol(+)kg Applying lime to a band of 0.25-m wide did not re duce yield relative to broadcast. Soil cultivation caused the lime to spread over a wider band, diluting the applied calcium with a larger s oil volume, suggesting that less than 6 ton ha-1 broadcast coarse cora lline lime could still be adequate for most Samoan soils.