2015
Reducing Nutrient Loss from Tile Drained Cropland and using Drainage Water Management
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Contributor/Checkoff:
Indiana Soybean Alliance
Category:
Sustainable Production
Keywords:
Abiotic stressField management SustainabilityWater supply
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Jane Frankenberger, Purdue University
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Indiana Soybean Alliance
(n/a)
Institution Funded:
Purdue University
(n/a)
Brief Project Summary:

Subsurface tile drainage is critical to productive agriculture, allowing earlier field work and aeration of the root zone. However, subsurface drains have been shown to be the major pathway for nitrate and phosphorus loads in the Mississippi Basin. Drainage water management shows promise for reducing nitrate losses from tile drained land, while maintaining drainage intensity during critical periods of crop growth cycle. Project objectives include determining the impacts of drainage water management during the spring by extending current drain flow, water table, soil moisture, and crop management monitoring; and assessing the impact of drainage water management on phosphorus, by adding phosphorus analysis for selected drain flow samples.

Key Benefactors:
farmers, agronomists, environmental professionals, Extension specialists

Information And Results
Final Project Results

Update:
Refer to document

View uploaded report PDF file

In this report, we have combined all the nitrate and phosphorus samples taken from January
2012 to February 2016 (funded by a previous project) with those funded by this project (spring
2016). However the annual load results are only through 2015, because that is the last year for
which a full year was available. Figure 5 shows the concentrations of nitrate-N, soluble reactive
phosphorus, and total phosphorus. The average of the 4-year concentrations, calculated for
each nutrient for both free and managed quadrants, indicated that concentration was slightly
higher under drainage water management for all 3 nutrients, but ANCOVA test results showed
that the effect of management on concentration was not statistically significant.
Of more interest than nutrient concentrations, however, is the load or total pounds of nitrate-N
and phosphorus lost through the system per acre. Load was calculated by multiplying our
continuous (6-minute) flow data by the concentrations, and dividing by the drained area of
each quadrant. Figure 6 shows loads in the free and managed quadrants for these three
nutrients. Annual nitrate-N loads ranged from approximately 10 lbs/acre in 2012 (a dry year) to
nearly 40 lbs/acre in one quadrant in 2014. Phosphorus loads were generally low (0.02 to 0.28
lb/acre of soluble reactive phosphorus, and 0.05 to 1.2 lb/acre of total phosphorus) with most
loads less than a target of about 1 lb/acre often recommended to prevent eutrophication in
lakes and streams. Statistical analysis showed that drainage water management decreased nitrate-N by 2.3 and 4.0 lbs/acre (13% and 23%) in the two pairs of quadrants. This is significant and emphasizes the potential of drainage water management. However it is less than has been found in other locations. The reason may be the restrictions in flow at this site due to inadequate downstream drainage. Phosphorus loads increased very slightly under drainage water management (0.06 to 0.09 lbs/acre) and this is not a significant concern. However it does indicate that drainage water management is not an effective practice for reducing phosphorus loads.

Refer to attached documents for images*

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.