ABSTRACT

The study was conducted at the experimental site of the Department of Soil Science and Land Resources Management, Michael Okpara University of Agriculture Umudike to Evaluate Cow Dung Compost and Cow Dung Biochar on soil properties and okra production under slash and burn agriculture in Umudike, south east Nigeria. The treatments comprised of Composted Cow Dung (CCD), Cow Dung Biochar (CDB), Fresh Cow Dung, NPK fertilizer (15:15:15), and a Control (slash and burn land). The treatments were applied at 5t/ha, equivalent to 24g/pot, 10t/ha, equivalent to 48g/pot and 15t/ha, equivalent to 72g/pot. The effect of the treatments were tested at the first planting and the residual effect on soil properties and okra yield. Composite soil samples were collected from a plot of land after it was slashed and burned. The treatments were arranged in Completely Randomized Design (CRD) with means separated using Fisher’s Least Significant Difference at probability level of 5%. The test crop was okra (Abelmoschus esculentus). Soil from slash and burn land had a significantly higher (p<0.05) soil pH (6.9) than the soil from unburnt land (4.8). Slash and burn land had a significantly higher (p<0.05) value of exchangeable calcium (5.6cmol kg^-1) over the unburnt land with value of 3.60cmol kg^-1.  Also, soil from a slash and burn land had a significantly higher (p<0.05) magnesium value of (3.20cmol kg^-1) over the unburnt land soil with value of 2.00cmol kg^-1. Soil from unburnt land had a significantly higher (p<0.05) value of organic matter (3.36%) over the slash and burnt land having a value of 1.56%, also soil collected from slash and burn land had a significantly higher (p<0.05) value of organic carbon with values of (1.95%), than the unburnt land (0.91%). The application of biochar at 15t/ha gave the highest plant height at 8weeks (45cm). This value was significantly higher (p<0.05) than the control (30.40cm). The results of the proximate analysis on okra fruit showed that biochar at 15t/ha had 29.05% moisture content and was significantly higher (p<0.05) than the rest of the amendments. Fresh cow dung showed a greater increase in fruit protein (3.33%), and was significantly higher (p<0.05) than the rest of the amendments; the control was significantly higher (p<0.05) in ash content (0.78%) over the other treatments. Composted cow dung was significantly higher (p<0.05) in fibre content (4.53%) over the other treatments. The residual effect revealed that biochar at 15t/ha had the highest CEC value (7.96 cmol kg^-1) which was significantly higher (p<0.05) than the control (4.92 cmol kg^-1). Application of CCD 5t/ha gave 0.19cmol kg^-1 K and was significantly higher (p< 0.05) than the CTRL (0.17cmol kg^-1). It can therefore be concluded that the use of composted manure, biochar as organic amendment will play a vital role in replenishing plant nutrients in a slash and burn practice, to increase okra growth and yield and to improve the soil physical and chemical properties.