Soils interact with the biological environment in a number of ways. Our understanding of these interactions can often be enhanced by computer modelling. The primary function of this book is to introduce basic modelling skills and to show how even complex problems in the relationship between soil and the biosphere can be solved using modelling packages. The author presents numerous examples using ModelMaker, an easily learnt software package. Only basic mathematical skills are expected of the reader. A demo of ModelMaker is available on CD from Cherwell Scientific.