Document Type

Thesis - University Access Only

Award Date

2005

Degree Name

Doctor of Philosophy (PhD)

Department / School

Civil and Environmental Engineering

Abstract

Phosphorus (P) buildup on manured soils has occurred over the past 20 years in South Dakota. The relationship between soil test phosphorus (STP) and P loss in runoff has not been evaluated for soils in South Dakota. The objectives of this research were to:

1) Establish a relationship between Olsen, Bray-1, Mehlich-3, and water extractable P and surface runoff P concentration on in situ rainfall simulations on three Eastern South Dakota manured soils.

2) Correlate TOP concentrations of indoor with outdoor surface runoff using rainfall simulations.

3) Determine the relationship between Olsen, Bray-1 and Mehlich-3 P and water and/or a dilute salt extractable P for three dominant soils in Eastern South Dakota.

4) Establish a relationship between P saturation and Olsen P for three dominant agricultural soils in Eastern South Dakota.

Vienna (fine-loamy, mixed, superactive, frigid, Calcic Hapludoll), Kranzburg (fine-silty, mixed, superactive, frigid Calcic Hapludoll), and Poinsett (fine-silty, mixed, superactive, frigid Calcic Hapludoll) (Malo, 1994) soils were used for this study because they represent major cropped soils in the North Central Big Sioux River Drainage Basin in Eastern South Dakota. Outdoor rainfall simulations in accordance with the National Phosphorus Research Protocol (NPRP) (National Phosphorus Research Protocol, 2001) were conducted on the soils in the spring months of 2002, 2003, and 2004. Soil samples were collected following rainfall simulations using a 2.0 cm diameter soil probe to a depth of 0-15 and 0-5 cm. Chemical analyses, including nitrate, potassium, pH and, Olsen P were performed on the 0-15 cm and 0-5 cm soil samples. A bulk soil sample (0-5 cm) was also collected from each field site immediately following rainfall simulations and used for subsequent indoor evaluations. Organic matter, pH, Olsen P, Bray-1 P, and Mehlich-3 P were conducted on the 0-5 cm bulk samples. A particle size analysis was conducted on the 0-15 cm samples. For the field and indoor study, runoff was collected for three consecutive days, with days two and three representing field capacity. For the indoor study, soils were packed into runoff boxes constructed as per the NPRP (2001 ). Indoor rainfall simulations were conducted on the soils in the following winter and summer months as rainwater was available. For the threshold study, deionized water and 0.01 M CaCl2 P extractions were conducted on the 0-5 cm bulk samples. A soil to solution ratio of 1: 10 with a contact time of one hour was used. Phosphorus saturation was determined on the 0-5 cm bulk samples using the PSI method (Sims, 2000). Samples were incubated with 75 mg P L·1 as KH2PO4 at a soil to solution ratio of 1 :20 for twenty-four hours. Phosphorus was determined in both of the laboratory studies colorimetrically by the Ascorbic Acid Method (Kuo, 1996). As STP increased, total dissolved P (TOP) and total P (TP) concentration in both field and laboratory surface runoff increased. The relationships of TOP loss for Vienna, Kranzburg, and Poinsett soils were not statistically different from each other, therefore one relationship can be derived for TOP loss using the 0-5 cm probe soil sampling depth (r2 0.77***). One relationship was derived predicting outdoor TOP loss using indoor rainfall simulations for all three soils (r2 0.83***). Although no thresholds were observed using water or 0.01 M CaCl2 extractable P, one equation was derived to predict TOP loss using water extractable P for all three soils (r2 0.89***). As STP increased, the P saturation percentage of the Vienna, Kranzburg, and Poinsett soils increased (r2 0.98***, 0.85**, 0.97***, respectively). The three soils exhibited different abilities to hold P, which may have been due to influences of organic matter. Manure disposal guidelines have been developed using the P saturation data derived in this study. Using the established critical limit of 25 percent P saturation, a threshold of 100 mg kg·1 P was designated and above this value, no manure may be used on confined animal feeding operations (CAFOs) to supplement crop nutrient requirements according to the South Dakota Department of Environment and Natural Resources (SD DENR).

Library of Congress Subject Headings

Soils -- Phosphorus content -- South Dakota
Runoff

Format

application/pdf

Number of Pages

225

Publisher

South Dakota State University

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