Rock phosphate amendment effects on Kenaf (Hibiscus cannabinus L.) growth and yield

ogun rock phosphate (orp) amended with an organic waste and urea on growth and seed yield of two varieties of kenaf (cuba 108 and tainung 1) was evaluated. use of orp as a phosphorus source was compared with npk 20-10-10. performance on the effects of treatments: orp + cowdung; orp + compost; orp + poultry manure and orp + urea on kenaf growth and seed yields were assessed and compared with a no fertilizer control treatment. results showed that p application significantly increased kenaf plant height and seed yield. npk -treated plants were significantly taller than the unfertilized plants. however, plants treated with amended orp had comparable heights among the three organic sources and with npk fertilization. npk fertilization gave the highest seed yields with the two varieties. the highest relative agronomic efficiency (rae) value of 87 and 48 % relative to mineral fertilizer (100 %) were obtained from plants treated with orp + compost for cuba 108 and tainung 1 respectively, in 2006. in 2007, the highest rae value of 89% was obtained from plants treated with orp + pm for cuba 108 and 95% with orp + urea for tainung 1. npk - treated soil had the highest soil available p. orp application is comparably effective with npk 20-10-10 when applied with organic manures and urea for kenaf production.