Nutrient Management and Edge of Field Monitoring Conference December 1-3, 2015 Memphis, TN

1. Steve Stevens
Fertilizer Efficiency Leads to Both
Profitability and Environmental
Stewardship: Arkansas Discovery
Farms Results

3. • Arkansas Cotton and Corn Discovery Farm
• 4500 acres of cotton, corn, and soybeans
• All fields are furrow irrigated with poly tubing using
computerized hole selection for delivery design
• Conservation Tillage – Stale Seedbed
• Fertilize after stand is obtained
• Liquid Nitrogen injected, P&K broadcast
Stevens Farm

5. Conservation Practice: Cover Crops

6. Return on Investment
PHAUCET (Pipe Hole and Universal Crown Evaluation Tool)

7. Irrigation
• Furrow Irrigation with polypipe
• Phaucet Program used to Determine
hole size to ensure uniform
distribution among
furrows
• Irrigation Flow
Meters

8. Edge‐of‐Field Monitoring of
Runoff
• State‐of‐the‐Art Automated
Samplers
• Trapezoidal Flumes to measure
runoff Volume
• Determine nutrient losses from
fields

11. Runoff after rainfall at the Homeplace Field

12. Runoff after irrigation at the Homeplace Field

13. No-till with cover crop
Stale seedbed with
cover crop
Field Conditions after
3.5 inches of Rain

14. Field Year/Crop N‐Applied N Loss N Loss
lb/A lb/A %
Shopcot 2013 Cotton 108 11.4 10.5
2012 Corn 2014 Cotton 111 4.4 4.0
2015 Cotton 117 3.2 4
Homeplace 2013 Cotton 108 1.8 1.7
2012 Cot 2014 Cotton 111 1.2 1.1
2015 Cotton 117 0.36 0.31
Comparison of N Loss by Year

15. Field Year/Crop N‐Applied N Loss N Loss
lb/A lb/A %
Weaver 2013 Cot 108 11.4 10.5
2012 Cot 2014 Corn 260 4.41 4.0
2015 Cot 117 3.0 2.6
Wellcot 2013 Corn 275 ‐‐ ‐‐
2012 Cot 2014 Cot 111 6.57 5.9
2015 Corn 256 0.39 0.15
Comparison of N Loss by Year

16. Field Year P‐Applied P Loss P Loss
lb/A lb/A %
Shopcot 2013 Cot 27 2.2 8.1
2012 Corn 2014 Cot 30 0.7 2.3
2015 Cot 30 0.3 0.1
Homeplace 2013 Cot 27 0.8 3.0
2012 Cot 2014 Cot 30 0.7 2.4
2015 Cot 30 0.05 0.02
Comparison of P Loss by Year

17. Field Year P‐Applied P Loss P Loss
lb/A lb/A %
Weaver 2013 Cot 27 0.5 1.9
2012 Cot 2014 Corn 48 0.9 1.8
2015 Cot 30
Wellcot 2013 Corn 34 ‐‐ ‐‐
2012 Cot 2014 Cot 30 0.66 2.2
2015 Corn 48 0.02 0.04
Comparison of P Loss by Year

18. Irrigation Efficiency
Field
Crop/
Year
# of
Events
Irrigation
Volume Runoff
Effective
Irrigation
Irrigation
Efficiency
inches inches Inches %
WellCot
Corn
2015 6
Mean 2.23 0.31 1.92 85
Std. Dev 0.72 0.11 0.67 4
Shopcot
Cotton
2015 4
Mean 2.44 0.22 2.22 91
Std. Dev 0.39 0.10 0.31 3
East Weaver
Corn
2013 8
Mean 1.69 0.41 1.29 75
Std. Dev 0.37 0.14 0.38 11
Homeplace
Cotton
2015 5
Mean 1.70 0.31 1.39 81
Std. Dev 0.24 0.10 0.27 6

19. Total Nutrient Losses Per Acre in
Irrigation Runoff
Field
Crop /
Year
Total
Nitrate Soluble P
Total
Nitrogen
Total
Phosphorus
Lbs/A Lbs/A Lbs/A Lbs/A
Wellcot
Corn
2015 0.09 0.0050 0.39 0.03
Shopcot
Cotton
2015 0.03 0.0023 0.16 0.02
East
Weaver
Corn
2013 0.09 0.0226 0.34 0.11
Homeplac
e
Cotton
2015 0.10 0.0164 0.28 0.05

20. Conclusions
• Data indicated very small N & P
losses relative to amount applied
• Crop removal rates plus nutrients
lost often balanced with application
rates
• Data indicates high efficiency and
good environmental stewardship