Abstract
Press-wheels are wheels designed to compact the soil above seeds in the “seed cover” region. Soil compaction, produced by the press-wheels of seeders, affects seedling emergence and early plant growth. The Discrete Element Method (DEM) was used to model the amount of soil compaction from a press-wheel with varying down forces. The model was used to predict sinkage and rolling resistance of the press-wheel. The model results were validated with data from soil bin tests of the press-wheel in a sandy loam soil under varying soil moisture content levels (low, medium, and high). The sinkage results from the soil bin tests were 27.7, 26.7, and 25.2 mm for the low, medium, and high soil moisture content levels, respectively. The corresponding rolling resistances obtained from the tests were 104.4, 89.9, and 113.6 N. The press-wheel model adequately predicted the sinkage and rolling resistance for each soil moisture content level with overall Relative Mean Errors (RME) ranging from 13 to 23%. Additional simulation results show that average peak soil stresses across the three soil moisture contents at a depth of 0.12 m were 22,466.7, 8700.0, and 6900.0 Pa for vertical, horizontal, and lateral directions, respectively. The results enhance the understanding of the dynamics of the soil–press-wheel interaction and provided useful information for seeder press-wheel design.
Highlights
Soil compaction has an effect on agricultural practices, seedling germination, plant growth, and crop yields
The model results were validated using sinkage data from soil press-wheel experiments performed on sandy loam soil under three soil moisture contents: low, medium, and high
The model results showed that average peak stresses across the three soil moisture contents at a depth of 0.12 m were 22,467, 8700, and 6900 Pa for the vertical, horizontal, and lateral directions, respectively
Summary
Soil compaction has an effect on agricultural practices, seedling germination, plant growth, and crop yields. Existing studies focused on the compaction associated with the wheel traffic of field machines [1,2]. Little research has been done on the compaction associated with the press-wheels of seeding machines. The press-wheels of seeders are wheels that roll on the surface of the soil behind seed openers to apply an amount of compaction to the surface promoting adequate soil–seed contact and seed depth [3]. The required compaction levels from press-wheels are much lower than those from field traffic. Soil compaction levels created by press-wheels affect the seedling depth, seedling emergence, and crop yields [4]
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