The two aspects of soil conditions and root growth in reduced cultivation systems are reviewed. Generally, an uncultivated soil is characterized by increased mechanical strength, reduced porosity greater moisture, more organic matter and structural stability at the surface, more earthworms and the development of nutrient gradients. Effects on root growth are much more variable and reflect the indirect relationship that exists between bulk soil properties and root growth.

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The results of a field experiment on winter wheat are presented in which the effects of the soil physical properties produced by different cultivation systems were studied in relation to root development.The extension rate of the seminal root axes was slower in undisturbed or shallow (5 cm) cultivated soil than in ploughed or deep (20 cm) cultivated soil leading to earlier lateral branching and the production of an effectively shallower seminal root system which persisted throughout the season. During the first four weeks after drilling the soil in the ploughed and the deeper cultivated plots was of lower bulk density and there were more pores of a diameter suitable for unimpeded root extension. It is suggested that seminal root development in uncultivated soils, which are less readily deformed than cultivated ones, is related to the probability of the extending seminal axes contacting pores of suitable dimensions.The implications of shallower rooting are discussed and related to field experience with cereal crops drilled directly into uncultivated soils where success has consistently been achieved on free-draining, open-textured soils.

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SUMMARY The results of a field experiment with winter barley in which severe mildew occurred early in the autumn are described. Where the disease was controlled with ethirimol (‘Milstem’)* seed dressing, the production of adventitious roots and tillers in the autumn was significantly increased and more of the tillers developed to maturity leading to higher grain yields.