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One of the options for achieving an adequate food supply in tropical Africa is by bringing more land into production. This often requires clearing and developing new vegetation areas for agricultural production. In subSaharan Africa, large areas of forest are being cleared for cultivation without adequate knowledge as to the consequences of the clearing method employed. This study was therefore initiated to, among other objectives, assess the effects of some forest clearing methods on soil compaction, texture, and micronutrients. Treatments were the following five clearing methods: (1) mechanical (MC), (2) semimechanical (SMC), (3) slash and burn (manual) (SB), (4) mechanical -no planting (MCNP), and (5) slash and burnno planting (SBNP). After clearing, we planted maize and cowpea in every other row during the first year, and planted maize and cassava during the second year in the plots of treatments 1-3. Changes in soil texture, bulk density, and exchangeable Fe, Zn, Mn, and Cu were determined. Soil bulk density increased (with depth) in all treatments from the intitial (0-15 cm) level of 1.1 g cm Ϫ3 to between 1.27 and 1.39 g cm Ϫ3 2 years after clearing, with the highest levels occurring in the MC plots. This indicated that clearing was accompanied by soil compaction. Some changes were noted in soil textural composition, but these were not of practical significance. Exchangeable Mn, Fe, and Cu (0-15 cm) decreased markedly after clearing, especially under MC in the first year. Zinc levels changed little during the study period. The decline in micronutrient levels was paralleled by a decline in soil organic carbon.

Assessing soil compaction using soil bulk density as an index for measurement could provide background information on the critical range of soil compaction for groundnut production in Nigeria. Therefore, field experiments were conducted in 2012 (year 1) and 2014 (year 2) to assess the effects of five levels of soil compaction (1.1 Mg m−3 [control], 1.2, 1.3, 1.4, and 1.5 Mg m−3) on groundnut yield. The experiment was laid in completely randomized design with four replicates. Number of Pods (NP) and Fresh Pod Mass (FPM) of groundnut were estimated using standard procedures and subjected to ANOVA at α 0.05. The NP of groundnut differed significantly among the treatments and was reduced by 70.1 and 76.0% in 1.4 and 1.5 Mg m−3 relative to 1.1 Mg m−3 in year 1, while corresponding low values were 40.4% (1.4 Mg m−3) and 48.4% (1.5 Mg m−3) in year 2. It was noteworthy that the NP in 1.2 and 1.3 Mg m−3 were statistically similar. Consequently, FPM of groundnut was in the order of 1.1 > 1.3 > 1.2 > 1.4 > 1.5 Mg m−3 in years 1 and 2, respectively. Hence, soil compaction at 1.1–1.3 Mg m−3 could be critical for groundnut cultivation.

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