To guide soil fertility investment programmes in sub-Saharan Africa, better understanding is needed of the relative importance of soil and crop management factors in determining smallholder crop yields and yield variability. Spatial variability in crop yields within farms is strongly influenced by variation in both current crop management (e.g. planting dates, fertilizer rates) and soil fertili...

soil samples from the jakara irrigation project site were evaluated with respect to possible degradation caused by irrigation. most of the soils were neutral to alkaline with ph values ranging between 6.58 + 0.04 and 10.45 + 0.03. the electrical conductivity ranged from 0.3 + 0.01 to 75.2 + 0.06 dsm-1 which implies low to very high salinity. the concentrations of the exchangeable cations in the...

A method is proposed to transform the red and near infrared data into a soil index in order to map soil features. The index maximises soil variation and helps improve soil feature mapping while it suppresses spectral response from vegetation cover. Geo-statistical analysis of fi eld data, on the other hand, helps understand spatial dependency pattern and map it, which may not be directly visibl...

Objective: To highlight the need and the potential for an integrated understanding of three key soil-based drivers of plant community structure and dynamics – soil fertility, soil heterogeneity, and microbes. Location: European and North American grasslands. Methods: Review and discussion of conceptual models and empirical literature, including examples of observational and manipulative studies...

Multistrata agroforestry systems with tree crops comprise a variety of land use systems ranging from plantations of coffee, cacao or tea with shade trees to highly diversified homegardens and multi-storey tree gardens. Research on plant-soil interactions has concentrated on the former. Tree crop-based land use systems are more efficient in maintaining soil fertility than annual cropping systems...

Nitrogen (N)-fixing species have a function to enrich N in soil. Mixing N-fixing shrub species into poplar stands can be assumed as a measure to increase productivity while improving soil fertility. To verify this assumption and to understand the temporal influences of N-fixing shrub species mixed into poplar plantations on soil fertility, we investigated selected soil chemical and microbial pr...

This study was carried out to evaluate the capability of a combined fuzzy-analytic hierarchy process (AHP) method for soil fertility evaluation of common bean in Shiraz, Iran. A set of membership functions was constructed to represent the soil fertility classes, which were derived from 50 field samples collected through a purposive sampling approach. Seven soil parameters including phosphorus (...

Plantation agriculture is more than 400 years old and contributes to the regional and national economies in many tropical countries. This paper reviews some of the main environmental issues related to plantation agriculture with perennial crops, including soil erosion, soil fertility decline, pollution, carbon sequestration and biodiversity. Soil erosion and soil fertility decline are of concer...

A project of the CGIAR systemwide program on Soil, Water and Nutrient Management (SWNM), concerned with improving integrated nutrient management practices on small-scale farms in Africa, has been carried out in Kenya, Tanzania and Uganda for last two years (September 1999 to September 2001). The project aims to enable small-scale farmers to profitably reverse nutrient depletion of their soils b...