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 Title: Wheel traffic effects on soil compaction and corn production Author(s): Ngunjiri, Godfrey M.N. Doctoral Committee Chair(s): Siemens, John C. Department / Program: Agricultural and Biological Engineering Discipline: Agricultural Engineering Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Engineering, Agricultural Abstract: A study to investigate the effects of tractor wheel traffic on soil compaction and corn production was conducted at the University of Illinois, Urbana, Illinois. Wheel traffic treatments included; traffic on entire plot, TE; traffic on rows, TO; traffic between rows, TB; and no traffic on the plot, NT. All plots were moldboard-plowed in fall and anhydrous ammonia applied in spring before applying wheel traffic treatments. After the wheel traffic treatments, herbicides were applied and incorporated with a disk harrow and a field cultivator before planting.Soil bulk density, moisture content and cone index were determined before and after wheel traffic treatments. Corn plant populations were determined early in the season and again at harvest. Corn plant height and dry matter weight were measured several times during the growing season. Root density distribution was assessed soon after tasseling and yields were measured at harvest.Tractor wheel traffic was observed to increase soil bulk density and cone index to a depth of 30 cm. In 1992, soil bulk density with the TE treatment increased from 1.24 g/cm$\sp3$ to 1.51 g/cm$\sp3$ in the top 15 cm of the soil and from 1.29 g/cm$\sp3$ to 1.54 g/cm$\sp3$ between depths of 16 and 30 cm. In 1993, with the same TE treatment, bulk density increased by 0.24 g/cm$\sp3$ to 1.55 g/cm$\sp3$ and by 0.12 g/cm$\sp3$ to 1.54 g/cm$\sp3$ at the corresponding soil depths. Soil cone index with the TE treatment in the top 15 cm increased by over 600 kPa to 1090 kPa in 1992 and by nearly 550 kPa to 1100 kPa in 1993.Wheel traffic compaction was observed to inhibit corn growth rate and yield and to increase barren stalk population. Barren stalk population averaged 3710, 2510, 2230 and 2190 plants/ha with the TE, TO, TB and NT treatments, respectively. Corn yields averaged 10 Mg/ha with the TE treatment compared to an average of 12.5 Mg/ha with the other treatments. Wheel traffic did not significantly affect average root density, but it restricted root proliferation. Equations were developed relating corn root density to distance from plant row and to depth. Issue Date: 1994 Type: Text Language: English URI: http://hdl.handle.net/2142/19559 Rights Information: Copyright 1994 Ngunjiri, Godfrey M. N. Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9503287 OCLC Identifier: (UMI)AAI9503287
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