Effects of seedbed properties on crop emergence: 3. Effects of firming of seedbeds with various sowing depths and water contents |
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| Authors: | Inge Håkansson Tomas Rydberg Thomas Keller |
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| Institution: | 1. Department of Soil and Environment , Swedish University of Agricultural Sciences (SLU) , P.O. Box 7014, SE-750 07, Uppsala, Sweden;2. Department of Soil and Environment , Swedish University of Agricultural Sciences (SLU) , P.O. Box 7014, SE-750 07, Uppsala, Sweden;3. Agroscope Reckenholz-T?nikon Research Station ART , Reckenholzstrasse 191, CH-8046, Zurich, Switzerland |
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| Abstract: | Abstract Extensive experiments were carried out in shallow plastic boxes placed directly on the ground in the field to study the effects of seedbed properties on the emergence of various crops in a cool temperate climate. In a group of experiments with barley (Hordeum vulgare L.), we studied the effects on crop emergence of firming (slight compaction) of the seedbed, simulating the recompacting effects of rolling after sowing or press wheels on the seed coulters. Most of the experiments were carried out without irrigation after sowing. The firming usually had a slightly positive effect on emergence when the water content in the surface layer at sowing was below the wilting point. When the water content in the surface layer was higher, firming often reduced emergence drastically, particularly with deep sowing and in coarse-textured soils. The main reason for negative effects was harmful hardening of the surface layer when the more firm seedbed gradually dried out. When irrigation kept the seedbed continuously moist, the negative effect of firming was almost eliminated. Very high initial water content in the basal layer tended to delay surface layer drying and hardening, and to reduce the negative effect of firming. Firming only slightly influenced the evaporative water losses from the soil. In contrast to the results presented here, previous field trials with cereals have usually resulted in more positive effects of rolling after sowing. This indicates that other effects than firming, such as modification of sowing depth and reshaping of the soil surface, are other important effects of rolling. |
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| Keywords: | Barley (Hordeum vulgare L ) compaction evaporation rolling after sowing soil texture |
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