WEED DYNAMICS, GROWTH AND YIELD OF CASSAVA (Manihot esculenta Crantz) AS INFLUENCED BY ORGANIC FERTILIZER SOURCES AND RATES INAN ULTISOL

This study was conducted at the National Cereals Research Institute Owot Uta, lbesikpo Asutan, Nigeria between 2012 and 2013 cropping seasons to evaluate the effects of organic fertilizer sources and rates on the growth and yield of cassava varieties A randomized complete block design with a split-plot arrangement and replicated three times was used. The main treatments were two cassava varieties (improved variety “TMS 30572” and local variety Obubit Okpo”, sub treatments were organic fertilizer sources (poultry manure and oil palm empty fruit bunch ash) while sub-sub treatments were rates of the two organic manure rates at 0, 5, 10 and 15 t/ha. Results indicated that leaf area was only significantly (P<0.05) influenced by the fertilizer rates. There was no significant in stem girth and number of stems per stand between the cassava varieties and among the fertilizer sources and rates. Local cassava variety had significantly taller plants than the TMS 30572 variety in all the months sampled in both cropping years. Organic manure rates showed significant difference in cassava height with application of 15 t/ha producing the tallest plant irrespective of fertilizer source. No significant difference was recorded in foliar yield in both cassava varieties and fertilizer sources. The TMS 30572 produced significantly higher tuber yield (21.03 and 22.13 t/ha in 2012 and 2013, respectively) compared to the local variety (15.88 and 15.94 t/ha) while 15 t/ha rate superseded other rates. Generally, improved cassava variety (TMS 30572) and application of PM in particular at 10 t/ha would be more economical compared to 15t/ha and as such is recommended for farmers in the study area.