Sole and Integrated Application of Cocoa Pod Ash and Urea Fertilizer on Soil Chemical Properties and Performance of Kale (Brassica oleracea) in Derived Savanna Zone of Nigeria

Pot experiments were carried out at the Teaching and Research Farm of Landmark University, Omu-Aran, kwara State Nigeria between January and March (first crop) and April and June (second crop) 2015. The aim was to investigate the sole and integrated application of cocoa pod ash (CP) and urea fertilizer (UF) on soil chemical composition and performance of kale (Brassica oleracea). The treatments were 3 levels of UF (0, 100, 200 kg/ha) and 4 levels of CP (0, 5, 10 and 15 t/ha). These were combined to have 12 treatments. The 12 treatments were arranged in a Completely Randomised Design, replicated three times. For crops of kale (first and second crops), CP alone and integration with UF increased soil chemical properties compared with no application of either CP or UF. Treatments 5 t/ha cocoa pod ash + 100 kg/ha urea fertilizer (CP5U100) and 5 t/ha cocoa pod ash + 200 kg/ha urea fertilizer (CP5U200) consistently have the higher values of N, K, Ca and Mg in both times of cropping kale and the mean values of both crops. Treatments CP5U100 and CP5U200 have significantly higher and similar values of plant height, number of leaves and other yield parameters (root weight, stem weight, leaf weight, stem girth and stem length) of kale compared with other treatments. Compared with no application of CP or UF (CP0U0), CP5U100 and CP5 U200 increased the leaf weight of kale by 84 and 85%, respectively. Therefore due to the rising cost of fertilizer, integration of cocoa pod ash at 5 t/ha with 100 kg/ha urea fertilizer is recommended for cropping of kale in derived savanna zone of Nigeria