SOIL 204: Chemical and Biochemical Properties of Soils

Theory: Chemical Properties (6 weeks): Soil colloids and ion exchange phenomenon; adsorbed cations- basic and acidic cations, cation exchange capacity (CEC); effective cation exchange capacity (ECEC) of soils; cation exchange and availability of nutrients; anion exchange (AEC). Buffering of soils, buffer capacity of soils.  Soil reaction.  Biochemical/ Microbiological Properties (7 weeks): The soil as a habitat for organisms.  The study of some microorganisms in soil (i.e. bacteria, fungi and actinomycetes and composition of their cell walls).  Factors influencing microbial growth, microbial nutrition i.e. autotrophy and heterotrophy.  Introduction to microbial genetics (study of DNA structure and replication, transformation, transduction, conjugation and transposon).  Methods of studying the soil microbial population.  Inter-relationships between soil organisms i.e. symbiosis, protocooperation, commensalism, ammensalism, predation, parasitism and competition.  Carbohydrates, organic nitrogen and organic acids in soil, soil enzymes.  Organic matter composition and functions in soil.

Practicals: (13 weeks): Soil pH, soil organic carbon/organic matter, total soil nitrogen, total soil phosphorus, available soil phosphorus, cation exchange capacity, exchangeable bases. Safety instructions in the laboratory, aseptic transfer techniques, growth requirements of microorganisms (ascertaining the effect of different growth conditions such as temperature, pH, salt and sugar concentrations on different organisms).  Inducing bacterial mutations, Gram staining procedure for typing microbes, plate method for estimating microbial numbers, streaking to obtain pure isolates, microbial determination by the static incubation method.