Assessment of Soil Fertility and groundnut ( Arachis hypogeae ) Yield Performance under different Weeding Regimes

A two–year field experiment was conducted at the Teaching and Research Farm of the Ekiti State University, Ado – Ekiti, Nigeria, during 2008 and 2009 cropping seasons to determine the effects of different weeding regimes on soil chemical properties and yield of groundnut ( Arachis hypogeae ). The experiment was laid out in a randomized complete block design (RCBD) with three replications. The different weeding regimes included: weeding once (W 1 ) at three weeks after planting (WAP); weeding twice (W 2 ) at 6 and 9 WAP; weeding thrice (W 3 ) at 3, 6 and 9 WAP and no weeding (W 0 ), which served as the control. The results indicated that there were significant (P = 0.05) differences among the different weeding regimes with respect to their effects on yield of groundnut. Relative to the initial nutrient status of the soil before 2008 cropping season, the percentage decreases in soil organic carbon (SOC) after cropping, adduced to weeding regimes were 58, 39, 49 and 28 % for W 0 , W 1 , W 2 and W 3 , respectively. W 1 and W 3 resulted in 7 and 14 % increases in total N, respectively, contrasting decreases of 48 and 40 % for the respective W 0 and W 2 . The percentage decreases in available P after cropping were 37, 20, 27 and 8 % for the respective W 0 ,W 1 ,W 2 and W 3 . Across the two years of experimentation, weeding significantly increased groundnut seed yield from 0.43 t ha -1 for W 0 to 1.23, 0.96, 1.51 t ha -1 for W 1 , W 2 and W 3 , respectively. KEY WORDS: Soil Fertility, Groundnut, Yield, Weeding.