African Journal of Soil Science

African Journal of Soil Science ISSN 2375-088X Vol. 8 (2), pp. 001-008, February, 2020. © International Scholars Journals

Full Length Research Paper

Degradation of the soil physicochemical properties resulting from continuous logging of Gmelina arborea and Tectona grandis plantations

O. O Awotoye¹*, O. Ekanade² and O. O. Airouhudion¹

¹Institute of Ecology and Environmental Studies, Obafemi Awolowo University, Ile-Ife, Nigeria.

²Department of Geography, Obafemi Awolowo University, Ile-Ife, Nigeria.

Accepted 13 August, 2019

Abstract

This study assessed the changes in soil properties in sites subjected to continuous logging in exotics plantation sites of Gmelina arborea and Tectona grandis with the aim to evaluate the deterioration level of the soil productivity in respect to human disturbance. Thirty five sampling plots, each measuring 40 m x 25 m were used for soil sampling. Standard field and laboratory methods were employed in the collection of data for 18 soil characteristics (sand, silt, clay, water holding capacity, electrical conductivity, bulk density, total porosity, pH, organic matter , total nitrogen, available phosphorus, exchangeable calcium, magnesium, potassium, sodium, exchangeable acidity, cation exchange capacity and base saturation) at depths of 0 - 15 cm and 15 - 30 cm. The results indicated that values of soil and plant parameters decreased with length of continuous logging (1, 5 and 10 years respectively). The soil deterioration indices of the logged plots showed high deterioration of all the soil properties except electrical conductivity, bulk density exchangeable acidity and in exchangeable sodium, percent silt and sand at both levels of soil depths. The two exotic species were impacted differently on the soil properties on the study area as a result of adverse logging. If these plots area are left to fallow for a considerable period of time, the lost soil nutrients may be replaced.

Key words: Deterioration level, soil productivity, textural properties, electrical conductivity, Gmelina species, Tectona species, continuous logging and sustainable productivity.

African Journal of Soil Science ISSN 2375-088X Vol. 8 (1), pp. 001-008, January, 2020. © International Scholars Journals

Full Length Research Paper

Soil mapping approach in GIS using Landsat satellite imagery and DEM data

Ertugrul Aksoy, Gökhan Özsoy* and M. Sabri Dirim

Uludag University, Faculty of Agriculture, Department of Soil Science, 16059 Görükle-Bursa, Turkey.

Accepted 12 October, 2019

Abstract

The objective of this study was to create base soil survey maps of the studied lands using Landsat satellite imagery and Digital Elevation Model (DEM) data in a GIS framework. Specific goals were to generate soil maps and to test the usage probability of slope class map overlies colour composite images as a preliminary map for soil survey in a hilly terrain. Surrogate soil-landscape data layers were derived from Landsat satellite imagery and a 10 m DEM. The data were also used to produce 3D-view with slope class boundaries superimposed Landsat image and relief shaded map as a colour map in order to select possible site of soil profile pits and to define physiographic units. Six soil series formed on two different physiographic units were determined, described and sampled. Soil profiles have been classified according to Soil Taxonomy and FAO-Unesco soil map of the World legend classification systems. The methodology was adequate for soil survey and mapping of some types of soils.

Key words: Soil survey, soil mapping, soil classification, GIS, DEM, satellite data.

African Journal of Soil Science ISSN 2375-088X Vol. 7 (11), pp. 001-008, November, 2019. © International Scholars Journals

Full Length Research Paper

Comparative productivity of nitrogen-use efficient and nitrogen-inefficient maize cultivars and traditional grain sorghum in the moist Savanna of West Africa

S.O. Oikeh^*, V.O. Chude¹, G. J. Kling² and W. J. Horst³

¹National Special Program on Food Security, Abuja, Nigeria.

²107 Crop Science Building, Oregon State University, Corvallis, OR 97331-3002, U.S.A.

³Institut für Pflanzenernährung, Universität Hannover, Herrenhäuser Str. 2, D 30419 Hannover, Germany. Africa Rice Center, (WARDA), 01 BP 2031, Cotonou, Benin Republic.

Accepted 18 July, 2019

Abstract

Strategies to cope with low fertilizer use in West Africa include choice of crop (that is., sorghum vs. maize) and the development of nitrogen-use efficient maize (Zea mays L.) varieties. A two-year field study was undertaken to compare the N response of an N- use efficient maize (hybrid, cv. 8644-27) and a nitrogen-inefficient maize (cv. TZB- SR), and to compare the productivity of the two cultivars with a traditional grain- sorghum (Sorghum bicolor [L.] Moench) in the moist savanna agroecosystem in Zaria, Nigeria. The two maize cultivars were evaluated under three N levels (0, 60, and 120 kg ha^-1). Sorghum (cv. ‘mori’) was evaluated under 0 and 120 kg N ha^-1. Mean grain yield was 0.5 Mg ha^-1 greater for N-use efficient than for N-inefficient maize, mostly because of its larger harvest indices for dry biomass and for N, and a greater N-utilization efficiency. In both years, with 120 kg N ha^-1 applied, grain yield and grain-N were 54 to 275% higher in maize than in grain sorghum. Under nitrogen stress (zero-N), grain yield of the N-efficient maize was similar to that of grain sorghum. But sorghum had 2 to 3 times greater total aboveground dry-matter yield and 165 to 230% higher total N-uptake than the maize cultivars, suggesting that sorghum was exhausting the soil of a greater amount of mineral-N than maize. Results showed that even under limiting nitrogen supply, a maize-based system with N-efficient maize was potentially more ecologically sustainable than a sorghum-based system involving traditional grain sorghum.

Key words: Cereal-based systems, grain sorghum, moist savanna, N-efficient maize, N-inefficient maize, N-utilization efficiency, West Africa.