The important position and role of mixed farming systems in land use intensification in subSaharan Africa is reviewed. This is done by examining the current situation that is followed with a justification for mixed farming. Further sections follow on changing patterns of land use, including the effects of tsetse flies and trypanosomiasis, and on constraints to further crop-livestock integration.

Se presenta un manual detallado que describe los metodos estandarizados de procedimiento para el analisis de suelo y tejidos vegetales con el objeto de 1) proveer a los investigadores de America tropical informacion sobre metodologia existente para los analisis de suelos acidos y plantas del tropico, 2) incrementar entre las instituciones nacionales e internacionales un intercambio de informacion sobre las metodologias empleadas en America tropical para definir y aplicar las mejores y 3) hacer que los analisis de suelos y de plantas constituyan una parte dinamica de la investigacion y permi

In the Brazilian savannas, or Cerrados the rapid advance in agriculture and cattle ranching is affecting soils through, for example, accelerated erosion and depletion of soil organic matter (SOM). Changes in soil microbial biomass are good indicators of changes in SOM. We therefore assessed the effects of agricultural and pastoral use of a clayey Oxisol in the Cerrados on soil microbial biomass, and evaluated the usefulness of this parameter in studying SOM dynamics in savanna ecosystems.

Long-term ecological effects of transgenic Bacillus thuringiensis (Bt) crops on nontarget pests have received limited attention, more so in diverse small holder based cropping systems of the developing world. Field trials conducted over 10 years in northern China show that mirid bugs (Heteroptera: Miridae) have progressively increased population sizes and acquired pest status in cotton and multiple other crops, in association with a regional increase in Bt cotton adoption.