Effects of seedbed characteristics and surface layer hardening on crop emergence and early plant growth.

The emergence and early growth of barley were studied in seedbeds of various properties arranged in plastic boxes. The main objective was to check whether results similar to those obtained in Sweden (Hakansson et al., 2001) could be obtained under somewhat different conditions. In an experiment in Tartu, Estonia, the effects of sowing depth in a sandy loam and a silt loam were studied. Under suitable moisture conditions, sowing at 5 or 10 cm led to lower and later emergence than sowing at 2 cm in both soils. In the silt loam, the effects of surface layer hardening caused by irrigation immediately after sowing was also studied. Since the surface layer started hardening before crop emergence, the number of plants that emerged was considerably reduced. Early loosening of the hardening layer eliminated a large part of the detrimental effect. In an experiment in Saku, Estonia, the effects of moderate compaction of the layer under the seed was studied in a clayey silt and a silty sand. Compaction of this layer improved the early growth of the crop.