1. Managing Cover Crops for More Profitable Corn Production Brian Jones Agronomy Extension Agent (540)245-5750 brjones8@vt.edu http://www.valleycrops.cses.vt.edu

2. Are we facing uncertainty? “There are two kinds of economists making forecasts these days, those who don’t know and those who don’t know they don’t know” Fertilizer prices: 1995 - 2008

3. Efficient Nutrient Use is Essential for Profitability and Sustainability

4. Efficiency…Through cover crops?  Name of the game now more than ever  How can cover crops help our growers be more efficient? By closing the holes in the system  Especially important for our no-till systems Facilitate the “rehab from our tillage addictions”

5. Many Benefits of Cover Crops ENHANCE NUTRIENT CYCLING INCREASE INFILTRATION REDUCE COMPACTION IMPROVE SOIL STRUCTURE INCREASE ORGANIC MATTER REDUCE SOIL EROSION WEED SUPPRESSION

6. Nutrient Cycling “The movement of nutrients through an ecosystem” Holes: Leaching Immobilization Volatilization De-nitrification Plugs: Scavenging N Fixation OM creation Increase crop yield

7. Challenges of Cover Crops  Fitting them into your system Livestock producers:  Have to have the feed… Cash grain producers:  Getting cover crops in the ground  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 local systems and conditions  No perfect cover Depends on rotation, needs, etc.  Need local research… Two ongoing cover-crop projects  Rockingham County (Brian Jones)  New Kent County (Paul Davis)

10. Objectives Rockingham: – Quantify the effects of cover crop species and timing of termination on nutrient cycling and yield New Kent: – Determine the effects of cover crop species, starter fertilizer and side-dress N rates on nutrient cycling and yield

11. Methods - Rockingham  Planted in fall of 2006 in Rockingham County  Planted six different cover crop treatments: Rye (120 lb) Crimson clover (20 lb) Hairy vetch (25 lb) Rye (90 lb) + hairy vetch (25 lb) Rye (60 lb) + crimson clover (10 lb) + hairy vetch (10 lb) Rye (90 lb) + daicon radish (15 lb)  Three replications of each  Two cover crop termination dates: May 10 (boot stage rye) and June 1 (soft dough)  0 lbs N applied to corn

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

13. Methods – New Kent  Planted on Nov 1, 2007 in New Kent  Planted three different cover crop treatments: Rye (90 lb) Rye (56 lb) + hairy vetch (10 lb) Hairy vetch (25 lb)  Starter (40 lb) or no starter  Five injected side-dress rates (0, 40, 80, 120, 160 lb N)  Four replications of each  Cover killed on May 1

14. Methods  At both sites: Cover crop biomass, plant tissue samples and soil samples taken Corn planted no-till following termination  Rockingham: corn silage harvested with forage chopper and weighed  New Kent: corn grain hand harvested and weighed

15. Cover Crop Biomass - RH

16. Cover Crop Biomass – NK 2007 LSD = 2.1 0 1 2 3 4 5 6 7 8 Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late BarleyCrimson Clover OatsRyeRye + Vetch Triticale Biomass Yield, tons/ac

17. Total N from Cover Crop - RH a a a a a a

18. Total N from Cover Crop – NK 07 LSD = 22 0 50 100 150 200 250 300 350 Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late Early Mid Late N uptake, lbs/ac BarleyCrimson Clover OatsRyeRye + Vetch Triticale

19. Available N From Cover - RH  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 - RH  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 - RH  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. Available N From Cover - RH Net Loss of PAN from immobilization Net gain of PAN from mineralization

23. Available N From Cover - RH

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

25. Available Soil N - RH

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 @ RH a a a

30. Crop Response – Ear Leaf N @ NK

31. Crop Response – Silage Yield a a a a

32. Crop Response – Grain Yield

33. Summary - Rockingham  Cover crops provided from 32 to 152 lb of PAN to the corn  Delaying cover crop termination increased PAN by as much as 80 lbs for legume covers, but reduced PAN for small grains (greater C:N) Adversely affected corn yield in 2007 (drought)  Radish+rye increased both rye biomass and corn yield above rye alone Greater water use efficiency? Microbiological effect?

34. Summary – New Kent  No response observed in grain yield following vetch from 0 to 160 lbs side- dress N  Corn following rye and rye+vetch responded to side-dress N Higher C:N ratios Tied up available N

35. QUESTIONS?

36. Economics  Bottom line: Seed and establishment not cheap  Hard sell looking at just seed costs

37. Economics – Yield Advantage @ RH

38. Economics – N Advantage @ RH

39. Economics – $ Advantage @ RH

40. Plant Growth and Plant Nutrition are Complex! “Providing adequate plant nutrients to growing crops is not rocket science, it is a lot more complex!” – Dr. Jerry Hatfield, National Soil Tilth Lab, USDA- Ames Iowa.

41. The Virginia No-Till Alliance  We (advisors) must have answers to grower’s questions as they face these challenges  Formation of the Virginia No-Tillage Alliance organization

42. THANK YOU THOUGHTS OR QUESTIONS?