ARSENIC SUPPLY CHARACTERISTICS OF 4 COTTON-PRODUCING SOILS

Citation
Ms. Cox et al., ARSENIC SUPPLY CHARACTERISTICS OF 4 COTTON-PRODUCING SOILS, Plant and soil, 180(1), 1996, pp. 11-17
Citations number
27
Categorie Soggetti
Agriculture Soil Science","Plant Sciences",Agriculture
Journal title
ISSN journal
0032079X
Volume
180
Issue
1
Year of publication
1996
Pages
11 - 17
Database
ISI
SICI code
0032-079X(1996)180:1<11:ASCO4C>2.0.ZU;2-R
Abstract
Cotton-producing soils in Louisiana average 23 mg kg(-1) arsenic (As) due mainly to use of As-containing agrichemicals. Bioavailability of s oil As could become an important management factor if As-tolerant cott on is rotated with other more sensitive crops. The first step in model ling As bioavailability and its uptake by plants is to characterize so il supply of As. We sought to: i) determine the relationships among so lution As, resin-exchangeable solid-phase As, and As addition, and ii) examine soil properties that affect these relations. Four diverse sur face soils were collected from the cotton-producing areas of the state . Five rates of As from 0 to 200 mg kg(-1) were applied and the soils allowed to equilibrate at 80% of ''field capacity'' water content for 30 days. Total initial As, As in displaced soil solution, and resin-ex changeable solid-phase As were determined for each treatment. For all soils, the concentration of solution As increased curvilinearly with A s addition, conforming to the equation As-sol = ax(c)+d. Values of ''c '' describing the curvilinearity ranged from 1.09 to 3.19. Curvilinear ity was negatively related to both initial solution As and diethylenet riaminepentaacetic acid (DTPA)-extractable manganese (Mn) (r(2) = 0.99 ). DTPA-extractable Mn complexed As from the solution phase. The conce ntration of resin-exchangeable solid-phase As increased at a decreasin g rate with As addition. The relation was described by the equation As -resp = mx(l)+n, where values for the curvilinearity, l, ranged from 0 .048 to 0.986. Concentrations approached a point where the adsorption sites for this phase became saturated and any additional As remained i n solution. These relationships provide valuable information for model ling As uptake by plant roots.