Seedbed quality preparation in Estonia

The field experiments for seedbed quality preparation were performed in five farms and experimenrtal areas. The laboratory tests were carried out with the use of the gutta-diagnostic indication method by E. Reppo, (1979). We have been using the Nordic Countries method for observation of seedbed quality preparation and have been improving this method through measurements of bulk densities and soil aggregate distributions within soil layers of the seed planting zone and immediately below the region of seed placement. We also used Litvinov cylinders (50 cm3), standard compactor (Proctor apparatus - PST) and, for measuring the soil penetration resistance to depths up to 40 cm, the Alexeiev penetrometer. We have found that the optimum range of agronomically valuable aggregates (2-5 mm) at physical maturity of soil for the average soils in Estonia remains within the limits of 40-50%.