2019 ASHS Annual Conference

The low activity clay content results in low soil exchangeable cations and crop productivity in the Southwest Nigeria. Most fertilizers applied to the soil for vegetable production are lost through leaching or runoff. The study examined the effects of fertilizer rate and time of application on yield, soil exchangeable cations and cation contents of Telfairia occidentalis, Solanum macrocapon and Amaranthus viridis. This was with a view to establishing the appropriate fertilizer application methods for vegetable production in Southwest Nigeria. The experiment was located at the rainforest (Ilesha) in southwest Nigeria. The experiment was a Randomized Complete Block Design laid out in a split plot arrangement with four replicates. The main plot was time of application of urea N: at planting and at two weeks after planting, sub plot was five levels of urea at 0, 20, 40, 60 and 80 kg N ha^-1. Basal application of organic fertilizer (3.5% N) at 5 tons ha^-1 was made a week before planting except for 80 kg N ha^-1 plot (which is the farmers practice). Soil physical and chemical properties were examined prior experiment. Soil exchangeable bases were determined after harvesting of the vegetables. Telfairia occidentalis shoot was harvested at five weeks after planting (WAP), Solanum macrocarpon shoot was harvested at seven WAP and Amaranthus viridis shoot was harvested at four WAP. Shoot above ground biomass per plot was determined and dry matter estimated. Calcium, Mg, K and Na contents of the vegetables were evaluated. The data generated were subjected to statistic analysis. The data generated were subjected to analysis of variance and the means separated using Duncan’s New Multiple Range Test at 5% level of probability.

The results showed that fertilizer rate had significant effect on the yield of the three vegetables. On the other hand, time of fertilizer application had no significant relationship on the yield and the nutrient contents of the three vegetables. Application of 20 kg N ha^-1 along with 5 tons OF ha^-1 were optimal for S. macrocarpon and A. viridis while 40 kg N ha^-1 along with 5 tons OF ha^-1 were optimal for T. occidentalis.

It was concluded the fertilizer rates sustained the soil fertility and also gave balanced Ca, Mg, K and Na compositions in the vegetables.