Document Type

Thesis - Open Access

Award Date

1988

Degree Name

Master of Science (MS)

Department

Agricultural Engineering

Abstract

Researchers have expressed the need to relate measurable physical parameters, such as implement draft and the cone index of a soil, to soil chemical parameters (ESP and EC) to assist in the determination of soil reclamation costs. The importance of implement draft in the reclamation of a sodic soil was examined. Field data were collected on a sodium-affected silt loam soil on July 2, 1986 and July 17, 1987. A laboratory study was conducted to investigate the water retention characteristics of the soil at various levels of exchangeable sodium percentage (ESP). The water retention curves verified the theory by Russo and Bresler that for a given soil-water suction head (h), the soil water content increases as the Na+ /Ca++ ratio (R) of the soil solution increases (or h=a*(8/9s )b). Significant linear relationships (P<0.05) were found using the 1986 and 1987 combined sample data that indicated draft (D) decreased as 1) ESP decreased (D=0.20*(ESP)+4.94) (r2 :0.53), as 2) bulk density (BD ) decreased (D= ll. 17*(BD)-5.49) (r2:Q.37), and as 3) cone index (CI) decreased (D=0.0021*(CI)+4.75) (r2 =0.29); CI decreased as 1) ESP decreased (CI=43.22*(ESP)+782) (r2 =0.27), as 2) BD decreased (CI =2,874*(BD) -1,980) (r2 =0.29), and as 3) moisture content (MC ) increased (CI=-52.25*(MC)+2193) (r2 =0.27); and ESP increased as BD increased (ESP=52.06*(BD)-47.59) (r2:0.59). A multiple regression analysis for CI as the dependent variable revealed that 72% of the variability for predicting CI from the sample data could be explained by ESP, MC, and deep plowed (DP). The equation CI=52. 28*(ESP)-56.07*(MC)-193.0*(DP)+1,693 (R2 =0.72) indicated that CI decreased as 1) ESP decreased, as 2) MC increased, and 3) when DP. In September 1984, the plots used in this study were amended with gypsum, fly ash, and sulfur. The applied gypsum resulted in approximately a 40% (1986), 20% (1987), and 30% (1986 and 1987 combined) decrease in the draft requirement for the tillage operation. Also, the linear equation D=f(ESP) for 1986 and 1987 combined indicated a 0.20kN/%ESP reduction in the implement draft for each percent that the ESP was lowered, within an ESP range of 1.87 to 18. 80%. For reclamation to be feasible, the future benefits of 1) reduced water usage and tillage requirements, 2) a longer tillage window, and 3) increased Drop yield need to be greater than the present costs of 1) tillage, 2) water usage, 3) crop yield, and 4) the amendment to be used. Using the results of this experiment, reduced energy per area and drawbar power requirements can be estimated based on either the reduction for a decrease in ESP or the percent draft change due to an effective amendment, such as, gypsum.

Library of Congress Subject Headings

Soil,Salts in

Irrigation water -- Quality

Tillage

Soils, Irrigation

Format

application/pdf

Number of Pages

125

Publisher

South Dakota State University

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