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Understanding the Relationships between plants and soil is important in the development of methods of crop production. Although physical properties of soil conducive to plant growth can be recognized by experienced observers, many of these properties have not been defined satisfactorily in mathematical or physical terms. A method of measuring penetration resistance and energy exerted by a mechanical seedling (a steel probe simulating a seedling) as it moved upward through the soil surface under different levels of surface compaction and soil moisture was examined. Mechanical seedlings with 2.06, 3.19 and 4.65 mm tip diameters were tested at soil moisture levels of 13, 17, and 20%. The penetration rate of the mechanical seedling while moving through the soil was held constant at 10 mm/min. Results showed that the emergence energy increased directly with soil surface compaction pressure, initial soil moisture content, and mechanical seedling diameters.

Tillage is an importantcomponent of crop production system and may be defined as any mechanical manipulation of soil to improve its appearance and physical condition for crop production. The factors affecting the energy requirement by a tillage tools include initial soil conditions, tool shape, and manner of tool movement in the soil and the desired final soil conditions. Soil bin facilities have generally been used to evaluate soil forces and compare energy required by tillage tools. Commonly used cultivator sweeps in the Canadian Prairies were tested in the soil bin to evaluate their suitability on energy demand. The draft of the sweeps was found to be a function of the depth and speed of operation. Tool shape plays an important role in the energy demand. The smooth sweep with low soil lifting characteristics was found to be the most suitable under these test conditions.