Changing the way you learn

Crop Residues Morris et al 2010

Reduced maize emergence
1. Slows soil warming and drying
  1. 2.5C lower
    1. Lengthens emergence due to thermal time
  2. Conserves more soil mc during high water demand
    1. conserves less than ploughing
      1. hence no yield effect
  3. Standing residues retain heat better than flat residues
affects...
1. OM
  1. breaks down to increase OM
  2. binds soil particles
2. soil temp
3. soil moisture
4. soil erodibility
5. seed germination
  1. hence remove residues via ploughing
produces phytotoxins
1. affects seedling establishment
2. reduces tillering
3. yellows leaves
4. reduces yield
5. produces spindly stems
Erosion
1. heavy machinery aids erosion
  1. reduces OM due to frequent operations
2. non-inversion reduces run off
  1. hence reduces...
    1. nitrate leaching
    2. emissions from nutrients and pesticides
    3. sediment losses
3. significantly reduced water run off
4. residues protect soil from wind erosion
5. reduces crust formation
  1. high risk in low OM and high silt soils
Seedbed
1. stable soils are better under non-inversion
  1. for silty soils plough is better
2. smaller aggregate size gives better emergence
  1. Bouaziz and Hicks 1990
3. no plough pan but compaction still occurs
limits soil mineral nitrogen (SMN)
1. straw has high C:N ratio
  1. rapidly immobilises SMN

Crop Residues Morris et al 2010

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