Resource-poor farmers in developing nations cultivate marginal lands, thereby exacerbating the problem of soil degradation through poor plant growth and ground coverage. An assessment of ground cover under such a practice will provide a guideline for soil conservation. Ground cover by leguminous cover crops (e.g., Mucuna pruriens, Pueraria phaseoloides and Vigna unguiculata), associated with yam, maize and rice was measured in three different experiments in southwestern Nigeria using beaded-string method while leaf area was measured using a flat-bed scanner. The leaf area was used in obtaining equivalent of ground cover fraction from the leaf area index. Ground cover by yam was < 15% at 10 wap (weeks after planting) in the second year of cropping and was < 25% at 25 wap in the fourth year of cropping. Maize+legume ground cover was < 40% at harvest (14 wap) in the third year of cropping. At 10 wap, rice 'WAB 189' had significantly higher ground coverage (43.8%) than 'ITA 321' (32.5%) and 'WAB 450' (33.2%). Both the beadedstring and scanning methods were close in the values of ground cover fractions for upland rice, but not for maize, indicating that prediction equation cannot be generalized for crops with different morphology. Cover cropping and residue mulching are good practices for low-intensity cultivation of marginal lands to achieve soil conservation effectiveness.Additional key words: cover cropping, crop rotation, Dioscorea spp, Oryza sativa, residue management, soil conservation, Zea mays. ResumenRecubrimiento del suelo con tres cultivos en tierras marginales del sudoeste de Nigeria e implicaciones en la erosión Los agricultores con pobres recursos de las naciones en vías de desarrollo cultivan tierras marginales, aumentando el problema de la degradación del suelo debido a un escaso crecimiento de las plantas y pobre cobertura del suelo. Evaluar la cobertura del suelo bajo estas prácticas aportará información para la conservación del suelo. En tres experimentos diferentes en el sudoeste de Nigeria se ha medido la cobertura del suelo en cultivos asociados de leguminosas (Mucuna pruriens, Pueraria phaseoloides y Vigna unguiculata) con maíz, ñame, y arroz, usando el método de la cuerda marcada y un medidor de área foliar. Se obtuvo la fracción de cubierta del suelo a partir del índice de área foliar. La cobertura del suelo por el ñame fue < 15% 10 sdp (semanas después de la plantación) en el 2º año de cultivo, y < 25% a las 25 sdp en el 4º año del cultivo. La cobertura del suelo con la asociación de maíz y leguminosas fue < 40% en el momento de la cosecha (14 sdp) en el 3 er año del cultivo. El arroz 'WAB 189' cubrió el 43,8% a los 10 sdp, considerablemente más que 'ITA 321' (32,5%) y 'WAB 450' (33,2%). La cuerda marcada dio valores de la cubierta del suelo pró-ximos a los del medidor de área foliar en el caso del arroz de las tierras altas, pero no en el maíz, indicando que la ecuación de predicción no puede generalizarse para diferentes cultivos. La cobertura de cultivos y el acolchado con residuo...

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This study was carried out at Abeokuta, south-western Nigeria, to understand the variation in soil strength, gravel distribution, and bulk density along a toposequence. In 2003, a 120-m transect on a fallowed land was sampled at every 1 m for topsoil bulk density measurement by excavation (3278 cm3 pits), while soil strength was measured at every soil depth increment of 25 mm to 0.50 m depth. Total dry (ρt) and fine earth (<2 mm) (ρf) bulk densities were determined. Soil water content was also determined. Gravel was divided into classes of 2–4, 4–8, 8–16, and >16 mm. In 2006, four 100-m transects were considered; two each on adjacent fallowed and cultivated lands. Soil strength and water content were measured. The fine earth fraction of topsoil ranged from 62 to 90.6%. Gravel in the 2–4 mm class was dominant with a range of 0.8–35.7%. Thus, cores ≥50 mm could be used in the topsoil to obtain reliable estimates of bulk density. Total bulk density (ρt) was reduced by 4–19% when corrected for gravel to obtain ρf. Soil strength of the lower slope was highest in 2003 (1981–4482 kPa) and lowest in 2006 (1546 kPa). In spite of the apparent significant influence of water content on soil strength, the relationship was weakly expressed by regression analysis, as only 35% of variation in soil strength was explained by water content at 0.10–0.15 m soil depth in 2003. No relationship was found in 2006; the cultivated segment had higher soil strength (2045 kPa) than the fallowed segment (1970 kPa) even though the water contents were similar. Also, only the 2–4 mm gravel significantly influenced ρt. Land use, soil depth, and slope position significantly affected soil strength. Root-limiting soil strength (>2000 kPa) would certainly be encountered below 0.20 m soil depth in the wet season irrespective of land use. Management of this gravelly landscape must be based on the heterogeneous nature of soil physical properties along the toposequence, and this could be made effective by grouping the soils according to slope position and taking interest in the few portions of the landscape with extreme values of gravel distribution and high soil strength.

Soil physical properties play significant function in the yield of crop produce. Sustaining food supply of the teeming population depends on the degree of preserving soil physicalproperties, therefore enhancing soil productivity. Experiments were conducted to establish the influence of poultry and cow dung from different housing and stacking types on physical properties of soil following Telfairia occidentalis production in 2017 and 2018. Amendments were applied in both years after which data were analyzed using Analysis of Variance. The experiment reveals that amendments statistically increased soil porosity, moisture content, hydraulic conductivity and therefore reduced bulk density above control in both years. It is concluded that for improved soil physical properties in the study area, bagged poultry manure in palm fronds house (PPB) at 5.4 tha-1 is recommended to farmers.