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Effects of Cover Crop Management on Corn Production

Effects of Cover Crop Management on Corn Production. Brian Jones Agronomy Extension Agent 245-5750 brjones8@vt.edu http://www.valleycrops.cses.vt.edu. Benefits of Cover Crops - Review. Cut fertilizer costs “Fix” atmospheric N (legumes)

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Effects of Cover Crop Management on Corn Production

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  1. Effects of Cover Crop Management on Corn Production Brian JonesAgronomy Extension Agent 245-5750 brjones8@vt.edu http://www.valleycrops.cses.vt.edu

  2. Benefits of Cover Crops - Review • Cut fertilizer costs • “Fix” atmospheric N (legumes) • Scavenge / redistribute nutrients (grasses, some legumes) • How much?? • Big question • Depends on: time of killing, season, etc. • More later…

  3. Benefits of Cover Crops - Review • Suppress weeds / other pests • Smother early emerging annuals • Competition for water, light and nutrients • Root exudates or compounds provide natural chemical and nematode control (sometimes) • Encourage beneficial insects

  4. Benefits of Cover Crops - Review • Improve yields • Increased infiltration (less runoff) • Decrease compaction • Improve soil structure • Increase organic matter • Improve nutrient cycling

  5. Benefits of Cover Crops - Review • Prevent erosion • Dense roots hold soil in place • Prevents the “splash” effect • Cover over the winter months

  6. Benefits of Cover Crops - Review • Conserve soil moisture • Residue increases infiltration • Surface and root zone • Reduce evaporation from bare soil • Must avoid killing too late • Problem with mechanical control systems

  7. Challenges of Cover Crops • Main Challenge: • Fitting them into your system • Have to have the feed… • Nutrient cycling • How much N? May be variable and will need to test (PSNT) • N tie up with high C:N cover crops • Rye killed late • May not see N until following year

  8. Challenges of Cover Crops • Cropping challenges • Allelopathy may affect cash crop • Stand / emergence issues • Planting equipment adjustments • Mechanically killing for some • Good environment for harmful insects • Cost of production

  9. Challenges of Cover Crops • Need to understand these questions with our systems and conditions • No perfect cover • Depends on rotation, needs, etc. • Need local research…

  10. Objectives • Quantify the effects of cover crop species on soil fertility and nutrient cycling • Determine how cover crop kill date affects cover crop biomass, corn yield and nutrient cycling • Part of a larger study looking at low-input cover crop management • Funded by the Shenandoah RC&D Council

  11. Methods • Project established in 2006 in Rockingham County • Planted seven different cover crop treatments in fall of 2006 • Three replications of each • Each treatment was killed at three different timings • Residue rolled flat • Cover crop biomass, soil samples, and cover samples were taken prior to each rolling • Corn was planted no-till after each rolling • 0 lbs N applied to corn • Whole plot was harvested with chopper and yield determined

  12. Methods 10’ 40’

  13. Methods • Timing of killing was based on small grain development: • May 10 (boot stage) • June 1 (soft dough) • June 11 (hard dough) • Only talk about data from May 10 and June 1 treatment today • Latest that most of us will be planting corn

  14. Results: Cover Crop DM and Yield

  15. Results: Cover Crop DM and Yield a a

  16. Not a traditional radish Being marketed as biological compaction relief Some evidence of increased microbiological activity as a cover crop Daicon Radish

  17. QUESTIONS?

  18. Total N from Cover Crop a a a a a a

  19. Available N From Cover • Total N is not all available for mineralization and crop uptake • Loss factors include: • Volatilization (loss to atmosphere) • Immobilization (tied up by bacteria) • Leaching (loss to groundwater)

  20. Available N From Cover • Volatilization losses • Depend largely on whether or not cover was incorporated • Without incorporating cover crop in our climate figure approximately 50% loss due to volatilization

  21. Available N From Cover • Immobilization losses • Depend largely on the carbon to nitrogen ratio (C:N) of the cover crop species • Low C:N (<25) bacteria quickly break down vegetation making N available immediately • High C:N (>25) N will become available, but may not be until the following growing season • Also, bacteria will tie up soil N in order to digest high carbon residue • Often see this with the yellowing of corn in early spring with high residue

  22. Net Loss of PANfrom immobilization Net gain of PANfrom mineralization Available N From Cover

  23. Available N From Cover

  24. Available Soil N • Sampled the NO3-N and NH3-N fraction at the time of kill and corn planting to see how much was potentially available • These are highly mobile • Most of crop uptake

  25. Available Soil N

  26. Available Soil N

  27. QUESTIONS?

  28. Crop Response • So how much N was actually available to the corn crop from our cover crop treatments? • Best observed by looking at the plant itself • Ear leaf samples show the % N in the plant at silking and provide a good “in-season” analysis of N uptake

  29. Crop Response – Ear Leaf N a a a

  30. Crop Response – Silage Yield a a a a

  31. QUESTIONS?

  32. Economics • Bottom line • Seed and establishment not cheap

  33. Economics – Yield Advantage

  34. Economics – N Advantage

  35. Economics – $ Advantage

  36. THANK YOU! QUESTIONS?

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