Item Code: #9781138583269
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This second edition retains all of the topics covered in the first edition. Each chapter has been revised, to take account of new developments. The two separate contributions relating to penetrometer measurements have been combined into one chapter, and others have been somewhat shortened, in order to include new material on the measurement of infiltration, the measurement of soil strength and friability, and field methods of assessment of soil physical conditions. The chapter on gas movement and air-filled porosity now covers soil- atmoshphere exchange of environmentally important gases, including radon and greenhouse gases.
While some topics have undergone relatively little change in terms of available methods or instrumentation in the period since the first edition appeared, some have changed considerably. The measurement of soil water, which has such an important role in soil physics and which underwent such a change when the neutron probe was developed, can now be undertaken with other sophisticated instruments. For example, time domain reflectrometry (TDR) and frequency domain systems, which share with the neutron methods the desirable feature of allowing nondestructive measurements at the same site to study temporal variations, now provide a reliable alternative to the neutron probe, while avoiding the problems of radiation protection. The widespread availability and use of data loggers has also tranformed our approach to many measurements, particularyly water content, matirc potential, penetrometry, and soil thermal properties, and placed a greater emphasis on those instruments that can be logged.
Like the previous edition, this boook is aimed at the researcher or agricultural or environmental adviser working in environmental science, soil science, or a related field. It should also be useful to teachers and students in postgraduate cources in soil science, soil analysis, and environmental science. One of the significant trends of the past few years has been the development of interdisciplinary activities, in the attempt to improve understanding of complex phenomena in the life and environmental sciences. This places new emphasis on the concurrent measurement of physical, chemical and biological parameters. One typical example of this is the study of losses of nitrogen from soils into waters and the atmosphere, where information may be needed on soil water in infiltration, saturated and unsaturated flow, and water-filled pore space- all of which require physical measurements- as well as on soil mineral nitrogen analysis and plant growth. Researchers who may have trained in chemistry or biological sciences now need to become informed about physical techniques as well. In this book we attempt to provide an introduction to each type of measurement, with enough theory to teach the principles behind the mehtods, and to help in the selection of methods appropriate to the task at hand.