The impacts of drainage water management on water table depth, drain flow and yield

Roxanne Kameka Adeuya, Purdue University

Abstract

Drainage water management is one conservation practice that is used for reducing drainage outflow and nitrate loss from agricultural fields, maintaining water table depth and improving crop yields. Although drainage water management has been adopted in a number of Midwest locations, the consequences of this practice have not been fully evaluated for Indiana soils and weather conditions. The overall goals of the research presented were to determine the impact of drainage water management on field hydrology on four farms in Indiana, and develop a tool based on the DRAINMOD capable of predicting yield spatially across a field. Paired field studies were conducted on four farms following the paired watershed approach. Drainage water management resulted in significant (p ≤ 0.1) reductions in total drain flow with an average reduction for all sites of 29%, although results varied widely ranging from 9% to 43%. The water table was significantly higher during both the dormant and growing season period at three of the four sites with an average increase in the mean water table depths across all fields of 6 cm for the growing season; and 24 cm for the dormant season. The drainage simulation model DRAINMOD was used to simulate the water table depth, drain flow, and crop yield for 92 years of climate data. Model efficiency values between 0.54 to 0.76 for water table depth and between 0.20 and 0.59 for drain flow were achieved. Predicted relative yields were within 1.7% to 8.0% of observed. The results of these simulations showed drainage water management reduced annual drain flow and nitrate loss by an average of 16%. A new tool based on DRAINMOD was developed to predict the spatially-varying yield potential. Results of this study support the use of drainage water management as a conservation practice and provide information for decision-makers about the level of benefits that can be anticipated.

Degree

Ph.D.

Advisors

Frankenberger, Purdue University.

Subject Area

Natural Resource Management|Agricultural engineering|Water Resource Management

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