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Managing Cover Crops as a Nutrient Management Tool


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I shared this presentation at Conservation Cropping System meeting in Jacksonville, IL on January 25th 2017

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Managing Cover Crops as a Nutrient Management Tool

  1. 1. Managing Cover Crops as a Nutrient Management Tool Joel Gruver Western Illinois University School of Agriculture
  2. 2. This is impressive - we are doing more with less!!!
  3. 3. Unfortunately the story isn’t all positive 
  4. 4. Illinois watersheds are delivering 20% of the N and 11% of the P but only 7% of the water
  5. 5. Annual grain production systems are leaky, especially in high precipitation environments. The 4Rs can help but conservation practices (in- field and edge- of-field) are also needed.
  6. 6. Capture Capture = CC uptake + immobilization by microbes eating high C residues C
  7. 7. Click on boxes for related research by Weil et al.
  8. 8. In 2016 the OFN collected 2,172 samples from 272 tile outlets across Iowa. Fields w/ CC had 29% lower nitrate concentrations than fields w/o cover crops and 40% lower total nitrate loss (lbs/ac/yr). In 2015, fields w/ CC had 23% lower nitrate concentrations. field w/cover crops CCs = cleaner water fields w/o cover crops
  9. 9. Nitrate Leaching in Cover Crops and Corn/Soybean Systems in Southern Illinois Rachel Cook, Assistant Professor of Soil Fertility, SIU-Carbondale Jon Schoonover, Professor of Physical Hydrology, SIU-Carbondale Karl Williard, Professor of Watershed Management, SIU-Carbondale Background and Objectives Nitrogen loss to the environment remains one of the biggest issues facing agriculture today. Impacts on water quality can be significant and require immediate attention to develop best management practices to reduce nitrate leaching and run-off from agricultural fields. One suggested means of reducing nitrogen losses is through the use of winter cover crops, but there is very little information on the effect of cover crops on nitrate leaching, particularly in non-tile drained fields. Additionally, there is little information on the interaction of tillage and cover crop type (legume or non-legume) on potential leaching.
  10. 10. - Nitrate-N leaching was reduced by cover crop treatments during the late fall and winter, as the no cover crop plots consistently exhibited the highest nitrate-N levels - The highest DRP levels were observed immediately following DAP application and did not appear to be influenced by cover crop or tillage treatments - Shallow soil water nitrate-N levels were highest in the no cover till treatment in the dormant season, suggesting nitrate-N uptake by cover crops - In the paired watershed study, cover crops reduced soil water nitrate-N levels in all topographic positions following their establishment Summary of key findings
  11. 11. CC and tillage system effects on concentration and depth of nitrate-N
  12. 12. When commodity prices are low,
  13. 13. IA Soybean Association’s On-Farm Network® Replicated Strip Trial Database
  14. 14. The negative CC effects on corn are likely related to nutrient immobilization and/or root pathogens
  15. 15. Soybean health experiment – multiple locations across IL Mustard Rapeseed Canola Cereal rye Cereal rye November 2010 Soybeans no-till drilled into cereal rye were the top yielder in 2011 incorporated pre-plant no-till Publication in press
  16. 16. Abstract: Field trials were conducted from 2010 to 2013 at four locations in Illinois to evaluate the impact of cover crops (cereal rye (Secale cereale), brown mustard (Brassica juncea), winter canola (Brassica napus), and winter rapeseed (B. napus) on soybean (Glycine max) stands and yield, diseases, pathogen populations, and soil microbial communities. Cover crops were established in the fall each year, and terminated the following spring either by using an herbicide (no-till farms), by incorporation (organic farm), or by an herbicide followed by incorporation (research farm). Although shifts in soilborne pathogen populations, microbial community structure were not detected, cover crops were found to induce general soil suppressiveness in some circumstances. Cereal rye and rapeseed improved soybean stands in plots inoculated with Rhizoctonia solani and decreased levels of soybean cyst nematode in the soil. Cereal rye increased soil suppressiveness to R. solani and Fusarium virguliforme, as measured in greenhouse bioassays. Cereal rye significantly improved yield when Rhizoctonia root rot was a problem. Using cover crops repeatedly, in the same field, may achieve more distinct effects on suppressing soybean diseases and build- up beneficial properties in the soil. Healthier roots → > nutrient uptake
  17. 17. Early planting trade-offs – Risk vs. Rooting depth
  18. 18. Plant and Soil August 2001, Volume 235, Issue 2, pp 127-133 Establishment of Bradyrhizobium japonicum for soybean by inoculation of a preceding wheat crop R. J. Goos, B. E. Johnson, P. M. Carr Abstract On fields with no history of soybean (Glycine max (L.) Merr.) production, inoculation alone is often inadequate to provide for adequate nodulation the first time this crop is grown. The objective of this study was to determine if inoculation of spring wheat (Triticum aestivum L.) seed with Bradyrhizobium japonicum would lead to an increase of B. japonicum numbers in the soil, and improve nodulation of a subsequent soybean crop. In the greenhouse, wheat seed inoculation increased B. japonicum numbers from undetectable numbers to greater than 9000/g soil, whereas the numbers of introduced B. japonicum declined in unseeded pots. In the field, inoculation of wheat seed increased B. japonicum numbers in the soil from undetectable levels to greater than 4000/g soil the following year. When soybean seed was inoculated, but grown in soil devoid of B. japonicum, nodules formed only near the point of seed placement. The heaviest nodulation, and widest distribution of nodules in the topsoil were found when B. japonicum was established the year before by wheat seed inoculation, plus soybean seed inoculation. Wheat seed inoculation the year before growing soybean, combined with proper soybean seed inoculation, should provide for abundant nodulation the first time soybean is grown on a field.
  19. 19. +20 lbs N/a A little extra N can make a big difference 2x biomass
  20. 20. Effect of kill date on typical plant available N (PAN) release from cereal, legume, or mixed stands. Based on compilation of field data from Willamette Valley cover crop trials. Source: D. Sullivan
  21. 21. Rape Rye control forage rad oilseed rad Cover crop treatment 0 30 60 90 120 150 SoiltestP,mg/kg a a c b bc Wye, Fall 2003 Means for 0-45 cm Third year of cover crop treatments in a corn- soybean rotation Brassicas appear to be particularly adept at solubilizing P Soil Test P Silt loam at Wye, fall 2003 Means for top 18 inches Biological pumping + organic acid root exudates 50% increase Nutrient cycling: Phosphorus
  22. 22. may be large enough to justify extending your rotation
  23. 23. Frost seeded red clover is a more reliable producer of biomass and fixer of N than legume CCs planted after small grain harvest
  24. 24. Frost seeded red clover is more weather resilient
  25. 25. More than most legumes
  26. 26. Wisconsin data suggest that approximately 70% of whole-plant N will become available in the first year following clover, most released before corn begins its period of rapid uptake. Good timing!!
  27. 27. Wisconsin data suggest that approximately 70% of whole-plant N will become available in the first year following clover, most released before corn begins its period of rapid uptake. Good timing!!
  28. 28. Multispecies CC mixes are much more of an option after small grains
  29. 29. This is a very useful tool for planning CC mixes!
  30. 30. Excellent nutrient scavenger Excellent N fixer Oilseed sunflower Sunn hemp Must be planted by planted by ~8/15 in the central Corn Belt
  31. 31. 11/6/2016 at the WIU Organic Research Farm
  32. 32. Sizing residues, increasing soil contact and planting a very low rate of cereal rye (12 lbs/a)
  33. 33. Additional CC species will be spring planted to provide bee forage and mulch/green manure prior to planting CT and NT pumpkins Likely species include balansa and berseem clover, phacelia, camelina, mustard…
  34. 34. Cereal rye rates ranging from 12 to 120 lbs/a were easily and quickly dialed in
  35. 35. ?