Effects of burning intensity on soil water storage and transmission characteristics in an Ultisol under cropping in Southern Cameroon
AbstractTo assess changes of some physical properties of an Ultisol under slash-and-burn practice, an experiment was conducted after clearing and burning a secondary forest in Mbalmayo (3°51’N and 11°27’E), Cameroon. Four levels of biomass burn were considered: (i) slight burn (SB), (ii) moderate burn (MB) and (iii) heavy burn (HB) versus (iv) control or noburn (NB), corresponding to 30, 55 and 100 kg/m2 dry biomass; the control consisting of 30 kg/m2 dry biomass without burn. The biomass of the rest of treatments was burned once before the beginning of the cropping season. The experiment was set up in a randomised complete block design (RCBD) with eight replications. At the conclusion of this study, it was
found that at 0 – 10 cm soil depth, moisture content on the heavy burn was significantly the highest (P less than 0.05) during the first cropping period, but decreased to be the least compared to the no-burn during the second cropping period. Moreover, the saturated hydraulic conductivity (6.6 – 3.2 cm / sec) between 5 and 25 cm depths and infiltration rates at 0.5 minute during the first year were significantly the highest on heavy burn compared to other treatments. However, during the second year, steady state infiltration was the highest on no burn. Significantly higher yields were found on burned plots, with 9, 15 and 27% increases for cassava and 41, 116 and 223 % for groundnut, respectively in the moderate burn, slight burn and heavy burn over no burn. Burning appeared beneficial to both soil water movement and crop yield although with temporary effects. To maintain soil productivity, leguminous species were suggested to protect the soil from leaching and erosion and to improve both soil physical and chemical conditions.