Abstract

Cultivanon is me man widely practised agricultural art; but its effect on crop yields is not yet fully understood. In a series of articles appear- ing in the Journal of Agricultural Science, B.A. Keen, E. W. Russell and others have discussed the effect of cultivation on increasing crop yields. They have drawn the important conclusion, in this series of papers, that "the yield of field crops is, in general, either unaffected or actually reduced by extra cultivation operations". They draw a distinction between cultiva- tion operations which are absolutely necessary, such as preparing a seed bed and those that are considered desirable but are not absolutely essen. tial. The latter are spare time operations carried on by the cultivator.

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