Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Kristofor R. Brye

Committee Member

Lisa S. Wood

Second Committee Member

Mike Richardson

Third Committee Member

David M. Miller

Keywords

Aggregate Stability, Agroecosystem, Double-ring Infiltrometer, groundwater depletion, Infiltration rate, Landuse effects, Soil

Abstract

Following European settlement of the Lower Mississippi River Valley (LMRV), agricultural expansion and unsustainable, agriculturally related practices have caused groundwater depletion, soil erosion, and surface water contamination by eroded sediments and sediment-bound nutrients to become major environmental threats to the region. The objective of this study was to evaluate the effects of common landuses [i.e., native prairie, deciduous forest, coniferous forest, Conservation Reserve Program (CRP) grassland, and conventional-tillage (CT) and no-tillage (NT) agriculture] on surface water infiltration and aggregate-stability-related properties [i.e., water-stable macroaggregate (WSA) size distribution, total water-stable macroaggregate (TWSA) concentration, and mean weight diameter (MWD)]. The overall infiltration rate for the deciduous forest (1.17 mm min-1) was 9.25 times greater than the overall infiltration rate for the other five landuses, which did not differ and averaged 0.13 mm min-1. The y-intercept characterizing the linear relationship between the natural logarithm of the infiltration rate and mid-point of time for the deciduous forest was more than 75% greater than the landuse with the next largest y-intercept, while the coniferous forest, native prairie, and CRP grassland had similar (P > 0.05) y-intercepts to each other. Total WSA concentrations in the top 10 cm in the native prairie, CRP, and coniferous forest were similar (P > 0.05) to each other, averaging 806 g kg-1, and were 35% greater than that of the NT and CT agroecosystems, which did not differ and averaged 605 g kg-1. Similarly, the MWD in the top 10 cm in the native prairie, CRP, and coniferous forest were similar (P > 0.05) to each other, averaging 2.15 mm, and were 70% greater (P < 0.05) than that of the NT and CT agroecosystems, which did not differ and averaged 1.27 mm. In the top 5 cm, the MWD and TWSA concentration were 17 and 8% greater, respectively, than that in the 5- to 10-cm depth interval. Results of this study demonstrated that landuse affects surface infiltration, water-stable aggregation, and select near-surface soil physical and chemical properties in fine-textured, loessial and alluvial soils in the LMRV Delta region of eastern Arkansas.

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