Determination of N, P and K fertilizer rates for katuk (Sauropus androgynus (L.) Merr.) production

Abstract

The objective of the research was to determine optimum rate of N, P, and K fertilizer for katuk (Sauropus androgynus (L.) Merr.) production. Experiments were conducted at vegetables garden Darmaga Field Unit University Farm, Bogor Agricultural University from May to December 2010. Treatments were N, P and K fertilizer at rate of 0%, 50%, 100%, 150% and 200% of fertilizer recommendation (100% N = 100 kg N.ha-1, 100% P = 135 kg P2O5.ha-1, 100% K = 135 kg K2O.ha-1). One hundred percent P, 50 % N, and 50 % K were applied before planting, while 25% N and 25% K were applied at 3rd and 6th week after planting. This experiment used randomized completely block design with four replications. Plot size was 5 m x 1.5 m. Katuk cuttings were planted in double rows per plot, with plant spacing of 50 cm x 25 cm. Results showed that N application had no effect on vegetative growth but increased on yield with a linear response pattern. P fertilizer application increased on plant height but had no effect on yields. K fertilizer treatment effected on yield with quadratic respon pattern. Multi-nutrient response approach was not applicable to this experiment, but the results of K fertilization treatment could be used to determine the maximum dose of fertilizer. Based on these formulated, equation was y=-0.0012x2+0.2529x+68.059 for K2O. The optimum rate for K was 105 kg K2O.ha-1.