Each issue of the SoilCare newsletter focuses on soil threat-specific SICS. In this newsletter the focus is on organic matter decline-specific SICS.

Decline of soil organic matter (SOM) refers to a loss of organic matter mass (and quality) in soils over time, which may lead to a deterioration of soil structure, a loss of water and nutrient retention and biological activity, and in the end to a reduction in crop productivity and water and nutrient use efficiency. Land use change (from forest and pastures to arable land) and intensive soil cultivation are major causes of a loss of soil organic matter. There is some evidence that climate change also contributes to a decline in SOM.

The SoilCare review of SICS (see Newsletter 2) has identified SICS that prevent organic matter decline. These SICS relate to measures that decrease mineralization of soil organic matter and/or increase inputs of organic matter. Organic matter-specific SICS may involve 3 mechanisms: (i) changes in inputs, (ii) substitution, and (iii) redesign. 

 The first mechanism relates to (increased) inputs of compost, crop residues, and animal manures. The second mechanism involves PerennialWheatreduced soil tillage, direct seeding in untilled soil instead of intensive soil cultivation, and controlled drainage. The third mechanism involves the growth of crops with large biomass production and a relatively low harvest index, straw and crop residues return to soil, and the growth of perennial crops, cover crops, leys and green manures.

The most promising organic matter-specific SICS have been identified as:

- reducing net soil organic matter mineralization (minimal tillage, drainage)

- enhancing the organic matter input into the soil (through crop residues, manures, composts) (see the Table).



  Components of cropping system  Components of organic matter decline-specific SICS  Change in profitability
 Crop rotation

 Deep-rooting crops and/or

+ large % cereals in rotation

+ cover crops, green manures

 Nutrient management  Application of manure and compost +/-
C  Irrigation management  optimal  
 Drainage management  Reduced drainage of organic-rich soils and peat soils -
E  Tillage management  Reduced tillage +/-
F  Pest management  optimal  
G  Weed management  optimal  
H Residue management Residue return -/+
J Mechanization management optimal  


For more information about these different SICS, please visit the SoilCare page on SICS