LEAF NUTRIENT STATUS OF RUBBER TREE IN DIFFERRENT ECOLOGY ZONE OF NORTH SUMATRA

Abstrak

A study of nutrient status of rubber leaf in five years after planting in terms of the difference of growth location was conducted in three rubber ecology zones of North Sumatra i.e. AL, LI and TE. During the immature period, all zones were applied 500 g of N, 200 g P₂O_5, 350 g K₂O and 50 g MgO. The result showed that general recommendation of fertilizer was just able to make sufficient of nitrogen in AL and TE zones (0.6% and 0.46% respectively); available phosphorus in AL zone (23.57 ppm); exchangeable potassium in Al zone (0.49 me 100g^-1); exchangeable magnesium in AL and TE consecutive 1.76 and 2.08 me 100 g^-1. Nitrogen, phosphorus, potassium and magnesium in the soil of AL, LI and TE zones relatively had a positive correlation with leaf nutrient status. N and Mg showed stronger positive correlation than P and K with coefficient of correlation 0.55 and 0.64 respectively. An indepth comprehensive study in relation to fertilizer dosage of immature rubber period (TBM) regarding soil and leaf analysis is important to be conducted.      

Keywords: Hevea brasiliensis, nutrient, leaf, soil