Potential of Vermesfluid for Sustainable Cassava Production on a Degraded Ultisol of Southeastern Nigeria

摘要

Field experiments were conducted at the eastern research farm of the National Root Crops Research Institute (NRCRI), Umudike, southeastern Nigeria (SEN), in 2016 and 2017 cropping seasons, to evaluate the effects of inorganic (NPK) fertilizer and vermesfluid on the root yield of cassava (TME 419). The experiment was a single-factorial in a randomized complete block design (RCBD) with three replications. The treatments comprised 16 percentage combinations of the recommended rate of NPK fertilizer (600 kg/ha) and the maximum recommended vermesfluid concentration (4%). The vermesfluid was applied foliarly 4 times at a 4 weekly interval, while the NPK fertilizer was banded in at 6 weeks after planting. The cassava was harvested at 11 months after planting and the yield estimated in tonnes per hectare (t/ha). The results of a 2-year average showed that application of vermesfluid alone between the recommended concentration range of 3 and 4%, induced similar yield responses but resulted in a non-significant and significant reduction in cassava root yield below those of the control (T_(0)) and the application of the full dosage of NPK fertilizer (T_(7)), respectively. However, combined application of 75% of the recommended rate of NPK fertilizer with 100% of vermesfluid concentration (T_(12)), gave exceptionally high cassava yield of 57.8t/ha, which significantly out-yielded every other treatment including T_(7) and T_(0) by 18.6% and 55.2%, respectively. On the basis of this result, T_(12), which not only gave the best yield but also reduced the application rate of the NPK fertilizer with the associated cost and environmental risk components by 25%, is recommended for sustainable cassava production on a degraded Ultisol of SEN.