Restoring Depleted Soils & Improving Soil Health With Cover Crops Bob Kremer University of Missouri [email protected] Integration  of  cover  crops  in  diverse  management  systems  is  a  primary  means   for  protecting  our  soil  resource,  maintaining  soil  function,  improving  soil  health.     R.J. Kremer Cover crop screening trials - MU Bradford Farm - 1997 2 Covers  crops  can  aid  in  reducing  soil  degrada1on  on  fragile  landscapes  converted  to   large-­‐scale  commodity  crop  produc1on   Responsible  integra1on  of  conserva1on  prac1ces  remains  a  cri1cal  issue.   Need  to  limit  off-­‐site  movement  of  inputs,  soil.   Photo: R.J. Kremer Example:  soybean  on  highly  erodible  loess  soils  of  Missouri  River  uplands   (Howard  County,  MO  -­‐  2010) Covers  crops  can  be  included  in  riparian  buffer  strips  to  reduce  soil  loss  on  alluvial   landscapes  under  intensive  crop  produc1on   Photo: R.J. Kremer Photo: D. Hemmelgarn Example:  corn  on  alluvial  soil  resul1ng  in  soil  loss  due  to  sloughing  into  river   (Gasconade  River,  MO  -­‐  2013) Cover Crops X Soil Health Spring oats + berseem clover mixture Biodiversity in a hypothetical block of field soil -- Source: Reganold et al. 1990. Important biological attributes of ‘healthy soils’ are influenced by vigorously growing plants •S  oil Microbial Diversity (Biodiversity) • Soil Carbon Content & Quality -- Plant root contributions •  (SOM ≈ 58% C) Rhizobacteria on plant root surface metabolize Crimson clover provides Carbon and plant-derived C and interact with plant. Nitrogen to soils 5000X magnification Soil Microbial Diversity (Soil Biodiversity) [biodiversity = most valuable property of any ecosystem; E.O Wilson, 1999] Accommodates diverse soil processes (i.e., nutrient cycling) •   Diverse  microbial  communi0es  (“Consor0a”)   carry  out  soil  processes  completely   Earthworms •  Ecosystem stability and resistance to stress Nematode Example of Structural Diversity: Bacteria Algae Fungi Opera1onal  food  webs  are   essen1al  for  op1mum   environmental  func1oning   and  “ecosystem  services” Mi#er,  B.  et  al.  2013.  Advances  in  elucida8ng  beneficial  interac8ons  between  plants,  soil,  and  bacteria.   Advances  in  Agronomy  121:381-­‐445. Crop residue SOM Components Bacteria Actinobacteria Fungi SOM CO 2