Effect of Different Application Rates of Organic Fertilizer on Growth, Development and Yield of Rape (Brassica napus L.)
A field experiment was carried out at Botswana College of Agriculture content farm, Sebele about 10 km from the center of Gaborone city to evaluate the effect of different application rates of organic fertilizer on growth, development and yield of rape from November 2014 to March 2015. The experiment was laid out in a complete randomized block design (RCBD) with four different application rates of organic fertilizer being 0, 5, 7.5 and 10 kg m-2 each replicated three times. Plant parameters measured were; plant height, leaf number, leaf area and leaf fresh weight. For plant height and number of leaves a non-significant treatment effect was observed for the first 7 weeks and 8 weeks respectively whereas, plants provided with 10 kg m-2 of organic fertilizer significantly (p<0.05) increased plant height and number of leaves in the last 4 weeks and 3 weeks respectively. Similarly, the highest application rate of 10 kg m- 2significantly (p<0.05) increased the leaf area and fresh weight for the entire period of study as compared to the rest. In general, soil amended with the highest application rate of organic fertilizer outperformed other treatments and produced a relatively higher market yield of rape. Therefore, the use of organic fertilizer is recommended to farmers because its constituents are readily available locally.