Book review
Soil Compaction and Agricultural Machinery
Our Farm Land Ð Endangered by Heavy Agricul-tur(es)al Machines? Institut fuÈr den Wissenschaftli-chen Film gem, GmbH, Postfach 2351, D-37013 GoÈttingen, Germany (US$ 75p & p)
This short video ®lm (PAL or NTSC formats) is available in English and German. It describes the processes that are affected by the compaction of agricultural soil, and describes basic principles in soil mechanics. The ®lm starts from the viewpoint that compaction is a major problem in agricultural soil. It provides a reasonable overview of the effects of compaction on soil, including effects on soil fauna. Comparisons between ploughed and no-tilled (direct-drilled) soil form the main body of the ®lm. The quality of the photography and graphics is very good, and shows to advantage the techniques and instru-mentation that can be brought to bear on this topic. Results include data for bulk density, porosity, earth-worm and micro-arthropod numbers, root growth, available water, leaf area development and crop yields. The ®lm was prepared by a consortium of researchers from GoÈttingen, Kiel, Jena and Braunschweig, who are involved in a multidisciplinary project on compac-tion in loess soils. The overall impression is that the ®lm represents a research update on their project rather than an attempt to deal with the issue in its entirety. For example, no attempt has been made to describe possible remedies, either options to reduce traf®cking of agricultural soils, or to repair damaged
soils. The ®lm does mention natural processes of recovery, such as freeze-thaw cycles, and describes on-going work on the activities of the soil fauna, but other than a mention of reducing soil cultivation, maintaining crop cover, and reducing traf®cking of wet soils, teachers will need to supplement the ®lm when discussing how to deal with the use of ®eld machinery.
Regrettably in the English version, titles, close captions and charts were not redrafted from the Ger-man original, so that anglophones cannot always assess the information without help. There are also a number of examples of literal translations of German terms and expressions, which detract from the pre-sentation.
Some sequences, especially those showing the direct damage of compaction on earthworms and the use of electric current to remove them from soil may upset some viewers.
Overall, this ®lm provides an overview of ongoing research in Germany. It may offer useful information that university teachers can use, but the ®lm fails to provide a comprehensive coverage of the subject suf®cient to meet the needs of students, especially with regard to the prevention and remediation of soil compaction.
Ray McBride
Department of Land Resource Science University of Guelph Guelph, Ont., Canada N1G 2W1
Soil & Tillage Research 55 (2000) 219
