Date of Award
Doctor of Philosophy
Agricultural and Biosystems Engineering
Stephen J. Marley
Seed furrow sidewall smearing by planter double disk openers in clay loam and loam soils was investigated in field and growth chamber experiments. Treatment variables were row preparation, soil moisture, and planting period. Evaluation parameters were soil bulk density, air permeability, cone index, emergence rate index and total emergence, and plant dry matter weight. The experiments were conducted in somewhat poorly drained soils near Ames, Iowa. The fields were not cultivated before planting and the residue from the previous year's corn was removed. Experiments were conducted in two cropping seasons. Each experiment consisted of a factorial design of three coulter treatments, three moisture ranges and three planting periods. Crop growing seasons were divided into three planting periods. Treatments were replicated three times using a split-split design. After planting in the field, undisturbed soil blocks were removed and transferred to growth chambers. Soil blocks were not watered and left for 28 days at 21° to see the plant shoot and root responses. Triple coulter produced lowest bulk density, lowest penetration resistance, and highest permeability in both the field and growth chamber experiments. In clay loam soil field experiments, the triple coulter seed placement was deeper and this treatment resulted in slower emergence and lower plant dry weight 42 days after planting than the other two row preparation treatments. In the growth chamber experiment, triple coulter had lower dry shoot weight and lower dry weight of roots in the furrow than the other two row treatments. In loam soil, triple coulter generally had faster emergence in cold and wet soil conditions and produced the highest plant dry matter weights 28 and 42 days after planting in the field experiment. In the growth chamber experiment, no significant differences among plant shoot and in-furrow root dry weights were observed for the three row treatments in loam soil. More roots were observed growing in no-coulter and single coulter seed furrows than in the triple coulter row treatment. Seed furrow sidewall smearing was greater, especially at higher soil moisture, in the no-coulter and single coulter treatment. This did not significantly affect the dry weights of plant components as long as plant moisture and nutrient needs were fulfilled.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Iqbal, Muhammad, "Seed furrow sidewall smearing by double disk openers " (1995). Retrospective Theses and Dissertations. 11060.