Long term field research for developing nitrogen bmp s
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Long-Term Field Research for Developing Nitrogen BMP’s. Gyles Randall Univ. of Minnesota Southern Research and Outreach Center [email protected] http://sroc.coafes.umn.edu/. Factors relating to BMP’s for N. Cropping systems N rate applied Time of application Nitrification inhibitors

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Long-Term Field Research for Developing Nitrogen BMP’s

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Long-Term Field Research for Developing Nitrogen BMP’s

Gyles Randall

Univ. of Minnesota

Southern Research and Outreach Center

[email protected]

http://sroc.coafes.umn.edu/


Factors relating to BMP’s for N

  • Cropping systems

  • N rate applied

  • Time of application

  • Nitrification inhibitors

  • N source

  • Tillage

  • Cover crops


CROPPING SYSTEMS


Effect of CROPPING SYSTEM on drainage volume, NO3-N concentration, and N loss in subsurface tile drainage during a 4-yr period (1990-93) in MN.


Nitrate losses in tile drainage water from soil mineralization.

Established grass

Dry years


CONCLUSION

  • Cropping system has greater effect on hydrology and nitrate losses than any other management factor!

    “Preventive Management”


RATE OF APPLICATION


Continuous Corn, 2001–03 Olmsted Co.


Effect of N rate for corn after soybean on NO3-N concentrations in tile drainage water in 2001.


Effect of N rate on yield of corn after soybean, net return to fertilizer N, and nitrate-N concentration in tile drainage at Waseca (2000–2003).


Effect of N rate applied for corn in 2003 on nitrate-N concentration and loss in tile drainage during May–September 2004 from soybeans at Waseca.


Conclusion

  • Corn yields were increased 5% and nitrate losses in drainage were reduced by 27% when reducing the N application rate from 160 lb/A applied in the fall to the recommended 120-lb rate applied in the spring.

  • Reducing the N rate from 120 lb/A to 80 lb/A reduced yield by 17% and nitrate loss by 13%.

  • Forty-six percent of the nitrate lost in tile drainage from a corn-soybean rotation was lost in the year soybeans were grown.


TIME OF N APPLICATION


Effect of time of N application and N-Serve on corn yields after soybean from 1987–2001 at Waseca.


Nitrate-N concentration in tile drainage from a corn-soybean rotation as influenced by time of N application and N-Serve at Waseca.


1999 tile water NO3-N loading at Waseca vs. NO3-N concentrations in the Le Sueur River 2.3 miles from Mankato.


Conclusion

  • Compared to late fall N application without N-Serve over the 15-year period:

    • Corn yields were increased 9 and 12 bu/A/yr (6 and 8%) by either fall N+N-Serve or spring preplant N, respectively.

    • Nitrate losses were decreased 14 and 15% by either fall N+N-Serve or spring preplant N, respectively.


Region Specific BMPs for N


Proposed BMP’s for South-Central MN

  • Recommended

    • Spring preplant or split applications of ammonia, urea, or UAN are highly recommended.

    • Incorporate broadcast urea or preplant UAN within three days.

    • Apply sidedress application before corn is 12” high.

    • Inject or incorporate sidedress applications of urea or UAN to a minimum depth of 4 inches.


Proposed BMP’s for South-Central MN cont.

  • Recommended, but with greater risk

    • Fall application of AA + N-Serve after soil temperature at 6-inch depth is below 50° F.

    • Side dressing all N before corn is 12 inches high.

  • Not recommended

    • Fall application of urea, UAN, or anhydrous ammonia without N-Serve


THANKS

Gyles Randall

[email protected]

Southern Research and Outreach Center

[email protected]

http://sroc.coafes.umn.edu/


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