Effects of different land management techniques on selected topsoil properties of a forest Ferralsol

Soil erosion is a major threat for Ferralsols in Cameroon. The influence of traditional intercropping (TI), disk-harrow ploughing (DH), no-tillage (NT), and Wischmeier bare fallow (BF) on runoff coefficient, soil loss, organic carbon (OC) content and bulk density was evaluated in topsoils of a forest Ferralsol in Yaounde region, Central Cameroon, using erosion plots. This was to ensure the best conditions for the determination of the soil properties to be assessed. After two years of cropping, the mean runoff coefficient remained very low for TI (<2% of the rain) as compared with NT (14%) and DH (15%). The same held true for soil loss which was in the order of 2, 68 and 109 Mg ha(-1) for TI, NT, and DH respectively, and bulk density which was 1.06, 1.18 and 1.21 Mg m(-3) respectively. Comparing the latter with the measurements obtained from BF (1.23 Mg m(-3)) and the adjacent secondary forest (SF) (1.04 Mg m(-3)) showed that the disk-harrow treatment was the most degraded among the three. The same comparison was made for the OC content. It was found that while in SE OC was as high as 30 g kg(-1), it was only 11, 13, 15 and 18 g kg(-1) in BE DH, TI, and NT respectively. On the average and for the time frame considered, TI adversely affected topsoil properties less than NT, DH and BF in this order. Based on the above, it can be concluded that TI is more conservative than the three other land management techniques investigated. (C) 1999 Elsevier Science B.V. All rights reserved.