Zhuojing Liu

Document Type

Thesis - University Access Only

Award Date

1994

Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

S.A. Clay

Abstract

Ammonia fertilizers applied to soil (anhydrous ammonia, aqua ammonia, and urea) produce conditions that increase soil pH, that in turn solubilize organic carbon and changes atrazine adsorption/desorption characteristics. A batch study was conducted to evaluate atrazine (2-chloro-4- ethylamino-6-isopropylamino-1,3,5-triazine) adsorption and desorption characteristics as influenced by ammonia. Ammonia treatment rates were equivalent to the N concentrations rates of banding o, 100, and 200 kg N/ha to soil. Atrazine treatments were O (0.01 M CaC12), 2.08, 6.57, 50.80 or 224.61 umol L-1 atrazine. Soil pH was raised to 9 and soil DOC increased from approximately 60 ppm where no ammonia was applied to approximately 700 ppm following high rate ammonia application. Atrazine adsorption decreased and desorption increased when atrazine was applied immediately or 8 days after fertilizer application. The greater amount of atrazine in solution due to ammonia application may increase the potential of atrazine to leach through soil. A column study was conducted in the laboratory to further investigate atrazine leaching behavior when ammonia and atrazine applications overlap. Nondisturbed 15-cm diameter by 15-cm depth soil columns were excavated in August from area planted to corn. Ammonia treatments applied to soil surface of a Brandt silty clay loam (fine silt, Pachich Udic Haploborolls} and a Ves clay loam (fine silty, mixed mesic typic Hapludalf) were O or 27 ml of concentrated ammonium hydroxide (equivalent to banding 220 kg N/ha). Each soil surface was treated with 3.3 mg of atrazine (equivalent to 1.7 kg/ha) immediately after ammonia application. One day after chemical application, 3 pore volumes of water were leached through each soil column. The amount of atrazine that leached through ammonia-treated soil columns was approximately 30 - 60% greater than the amount that leached through untreated columns. Less atrazine remained in the ammonia-treated column surface than untreated column surface. Overlapping the atrazine and applications increased the potential ammonia agrichemical for atrazine to be transported through the soil columns. The laboratory study suggests that interactions between the fertilizer solubilized C or reduced Kf values may be responsible for the increased movement. These findings suggest that a best management practice for atrazine would be to physically separate the ammonia fertilizer and atrazine application.

Library of Congress Subject Headings

Soil absorption and adsorption
Soils -- Herbicide movement
Atrazine
Ammonia as fertilizer

Format

application/pdf

Publisher

South Dakota State University

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Rights Statement

In Copyright