Volume 45 (2012): Issue 4 (December 2012)

In the present study, the putative allelopathic potential of aqueous extracts (10 % w/v) of three legumes, i.e. alfalfa, berseem and brassica spp., including distilled water treatments as check were evaluated on germination and early seedling growth indicators of rice, sorghum and millet under laboratory conditions. The treatments were compared in completely randomized design with factorial arrangements in four replications. The recorded observations clearly indicated that the germination process and seedling growth of receptor plants were negatively affected in the presence of legume extracts. The extract of Brassica had the strongtest inhibitory effect on germination process in form of increased mean germination time (MGT) and lowered the coefficient of velocity of germination (CVG), germination % age and germination index (GI) as compared to other extracts. Likewise, the lowest root and shoot length, their fresh and dry weight was also noted in petri dishes with Brassica extracts. Among the receptor crops, rice was the most susceptible in term of both seedling growth and germination attributes. The interaction between test crops and legume extracts was found to be significant for most of studied parameters except germination % age, fresh and dry weight of root and shoot. The presence of allelochemicals in the studied legumes entitled them to be used in weed management programme and is also signal for designing specific production technologies able to reduce their effects on succeeding crops.

The authors investigated the impact of government agricultural policies on exports of cocoa and rubber in Nigeria using cointegration and Error Correction Model approach. The analysis was carried out on time series data collected from 1970 to 2008. The result shows that Policies like Agricultural Credit Guarantee Scheme Fund (ACGSF), Structural Adjustment Programme (SAP) and Post-Structural Adjustment Programme (PSAP) have a significant positive impact on exports of cocoa and rubber. A possible reason been that the export promotion incentives provided in the SAP and PSAP periods probably encouraged the production of these crops. Among these incentives are liberalization of agricultural exports, liberalization and devaluation of the Naira exchange rate. Similarly, the ACGSF provided incentives in the form of credit which probably encouraged the production of these crops.

This study investigates the influence of vetiver grass strips (VGS), vetiver mulch (VGM) and composted vetiver prunes (veticompost) on soil quality of an eroded land in the Institute of Agricultural Research and Training, Ibadan (70 22’ N; 30 50’E), Nigeria. The treatments were 3-m wide VGS established at 10-m inter-row spacing, VGM imposed at 5 Mg ha-1, veticompost applied at 5 Mg ha-1 and a control (no-vetiver grass). All quality indicators including physical, chemical and biological indices and soil erodibility (K) factors were determined between 2008 and 2011. Results show that soil organic matter (SOM) and associated nutrients play a major role in soil quality variation. VGM had the highest impact on soil quality (76.5%) but not significantly different (P<0.05) from veticompost (72.5%). Soil quality ratings were in the order of VGM > veticompost > VGS > control. Significant and positive relationship (r = 0.92*) exist between soil quality ratings and maize yield, with 70% of grain yield variability accounted to the soil quality. K factor ranged from 0.013 to 0.030 Mg h MJ-1 mm-1 with the VGM and control plots having the least and highest K factors, respectively. Although the soil quality under veticompost is lower than vetiver mulch but the SOM and associated nutrients under veticompost enhanced better soil productivity, and thus accounted for higher crop yields than other treatments.