Experiment was conducted to obtain information on seperate and interaction effects of tillage passes and 15-15-15 NPK fertilizer application rates on some growth parameters, N, P and K uptake by Amaranthus viridis, hence the use of a tractor implement with specified specification on sandy clay soil planted with Amaranthus viridis. The research was conducted at vegetable research plot, Department of Agricultural Technology, The Oke-Ogun Polytechnic, Saki, between 2 nd July and 30 th September, 2015. Soil treatments consisting of three levels of tillage passes (0, 3 and 6) equivalent to 1.7, 1.3 and 1.5 g/cm 3 soil bulk density respectively, four levels of 15-15-15 NPK fertilizer rates (0, 100, 150 and 200 kg/ha) and replicated three times in a completely randomized design. The results showed that no-tillage pass had significant effect on bulk density, zero tillage reduced the percent uptake of N (0.58-0.46), P (0.002-0.0005) and K (0.13-0.04), however, statistically, the reduced effects were more pronounced on Nitrogen and Potassium. Fertilizer rates significantly improved percent uptake of N (0.11-0.58), P (0.0004-0.005) and K (0.04-0.07). Interactions (tillage passes × fertilizer rates) effects were observed on plant height, stem girth, fresh weight, root length and percent N, P and K uptake, but T2F2 (6 passes × 150 kg/ha) significantly increased plant height and improved uptake of Phosphorous, therefore, 6 passes and 150 kg/ha 15-15-15 could be more suitable for optimum production for Amaranthus viridis on a sandy clay soil.

Research was conducted to determine the effects of different tillage methods on the soil bulk density and growth parameters of Watermelon (Citrullus lanatus). The study was carried out at the Vegetable Research Farm, The Oke -Ogun Polytechnic, Saki; with treatments at three levels of tillage (T0-zero tillage, T1-one pass of moldboard plow and T2-two passes of moldboard plow); all treatments replicated three times and arranged in three blocks in a Completely Randomized Block Design (CRBD). Each plot was (1.2 m x 1.2 m) with 1 m and 1.5 m gap between the plots and blocks. Tillage methods affected the soil bulk density and watermelon growth parameters as shown that one pass of moldboard plow (1.3 gm/cm3) had the greatest mean vine length, stem girth and number of leaves (5.3 cm, 3.1 cm and 13) respectively. Paired t-minitab 17.0 showed that the zero tillage (1.6gm/cm3) and one pass of moldboard plow (1.3 gm/cm3) bulk densities are significantly (p ≤ 0.05) different, while two passes of moldboard plow (1.5 gm/cm3) and one pass of moldboard plow (1.3 gm/cm3) are statistically (p ≤ 0.05) the same. The summary of analysis of variance of effects of tillage methods on the watermelon growth parameters, revealed that blocks had no significant (p ≤ 0.05) effects on all the growth parameters, while tillage had significant (p ≤ 0.05) effects on the mean vine length, stem girth and leaf area. Least significant (p ≤ 0.05) different therefore, revealed that one pass of moldboard plow (1.3 gm/cm3) significantly (p ≤ 0.05) increased the vine length and stem girth than other tillage methods. The study concluded that for a one pass of moldboard plow (1.3 gm/ cm3) at 11.5 % moisture content; the growth of watermelon could be enhanced on sandy clay soil, in the derived savannah of Southwest zone of Nigeria.